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1
Thorpe, Simon J., Rudy Guyonneau, Nicolas Guilbaud, Jong-Mo Allegraud, and Rufin VanRullen. "SpikeNet: real-time visual processing with one spike per neuron." Neurocomputing 58-60 (June 2004): 857–64. http://dx.doi.org/10.1016/j.neucom.2004.01.138.
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Delorme, Arnaud, Jacques Gautrais, Rufin van Rullen, and Simon Thorpe. "SpikeNET: A simulator for modeling large networks of integrate and fire neurons." Neurocomputing 26-27 (June 1999): 989–96. http://dx.doi.org/10.1016/s0925-2312(99)00095-8.
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Delorme, Arnaud, and Simon J. Thorpe. "SpikeNET: an event-driven simulation package for modelling large networks of spiking neurons." Network: Computation in Neural Systems 14, no. 4 (January 2003): 613–27. http://dx.doi.org/10.1088/0954-898x_14_4_301.
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Laudencia-Chingcuanco, Debbie, and Sarah Hake. "The indeterminate floral apex1 gene regulates meristem determinacy and identity in the maize inflorescence." Development 129, no. 11 (June 1, 2002): 2629–38. http://dx.doi.org/10.1242/dev.129.11.2629.
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Meristems may be determinate or indeterminate. In maize, the indeterminate inflorescence meristem produces three types of determinate meristems: spikelet pair, spikelet and floral meristems. These meristems are defined by their position and their products. We have discovered a gene in maize, indeterminate floral apex1 (ifa1) that regulates meristem determinacy. The defect found in ifa1 mutants is specific to meristems and does not affect lateral organs. In ifa1 mutants, the determinate meristems become less determinate. The spikelet pair meristem initiates more than a pair of spikelets and the spikelet meristem initiates more than the normal two flowers. The floral meristem initiates all organs correctly, but the ovule primordium, the terminal product of the floral meristem, enlarges and proliferates, expressing both meristem and ovule marker genes. A role for ifa1 in meristem identity in addition to meristem determinacy was revealed by double mutant analysis. In zea agamous1 (zag1) ifa1 double mutants, the female floral meristem converts to a branch meristem whereas the male floral meristem converts to a spikelet meristem. In indeterminate spikelet1 (ids1) ifa1 double mutants, female spikelet meristems convert to branch meristems and male spikelet meristems convert to spikelet pair meristems. The double mutant phenotypes suggest that the specification of meristems in the maize inflorescence involves distinct steps in an integrated process.
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Zając, Tadeusz, Wiesław Szafrański, and Jacek Strojny. "Kernel mass of winter triticale depending on placing position in a spikelet and a spike, with regard to its productiveness." Acta Agrobotanica 57, no. 1-2 (2013): 175–86. http://dx.doi.org/10.5586/aa.2004.017.
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The investigations were carried outin 1996-1997 on degraded chernozem developed from loess. The winter triticale cv. 'Presto' cultivated after 4 forecrops (spring cereals with red clover undersown and triticale in pure stand). Studied were correlation between the number of spikeIets and kernels and their placing position in a spike and spikelet, and the grain weight from three spike size groups. The number of productive spikelets per spike and fertility of inflorescence per spikelet, measured as a number of kernels, were the biggest in big spikes group. Kernels placed in positions 1 and 2 in a kernel had the biggest mass, whereas the kernels developed from the inflorescence in positions 3 and 4 were conspicuous for their smaller mass, particularly in the small and medium-size spike groups. The analysis of correlation coefficient values revealed that grain weight per spike was strongly correlated with the number of kernels per spike in all determined size classes. Also a significant effect of single kemel weight on yield per spike was noticed, but the coefficient value was lower (r=0.30). Spikelets in positions from 3 to 7 level (on both sides of spike) had the greatest share in grain weight per spike for the smallest spike group, whereas for medium- size and big spikes respectively spikelets in positions 3 through 9 and 2 through 10.
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Li, W., S. Yan, and Z. Wang. "Effect of spikelet position on starch proportion, granule distribution and related enzymes activity in wheat grain ." Plant, Soil and Environment 59, No. 12 (December 1, 2013): 568–74. http://dx.doi.org/10.17221/586/2013-pse.
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The starch proportion, starch granule distribution, and activities of enzymes involved in starch synthesis in different spikelet positions were examined during grain development in two high-yielding winter wheat cultivars. The results showed that grain number and weight per spikelet in different spatial position showed a single-peak curve from the base to the top in a wheat spike. Upper spikelets had the highest starch and amylose proportion followed by basal spikelets, whereas middle spikelets had the lowest. Starch and amylose absolute content was in opposition to their proportion. The volume of B- and A-type granule in grain of middle spikelets was remarkably higher and lower than those of basal and upper spikelets, respectively. However, no significant difference occurred in the number of A- and B-type granule in grains among different spikelet position. Compared with the basal and upper spikelets, the middle spikelets showed higher sucrose and ATP content and activities of starch biosynthetic enzymes, and subsequently higher starch absolute content. The results suggested that superior sucrose providing and degradation capacity and the high activities of enzymes involved in starch synthesis resulted in development of B-type starch granule in grain of middle spikelets.
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Warringa, J. W., P. C. Struik, R. de Visser, and A. D. H. Kreuzer. "The pattern of flowering, seed set, seed growth and ripening along the ear of Lolium perenne." Functional Plant Biology 25, no. 2 (1998): 213. http://dx.doi.org/10.1071/pp96084.
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A greenhouse pot experiment was conducted to elucidate the pattern of decreasing seed set and seed dry weight found from the basal to the upper spikelet in Lolium perenne L. ears and—very markedly—acropetally within a spikelet. The changes in fresh and dry weight of the seed after anthesis were monitored for 12 positions within the ear. To determine the duration of seed growth, the spatial and temporal patterns of flowering and ripening along the ear were assessed. The proximal florets of the central spikelets flowered first, and the upper spikelets in the ear flowered before the basal spikelets, with flowering proceeding acropetally within a spikelet. The upper spikelets ripened earlier than the basal ones, and the seeds within a spikelet ripened simultaneously. These patterns of flowering and ripening along the ear resulted in different durations of seed growth along the ear. Thus from the proximal to the distal seed within a spikelet the duration of growth decreased by 26%, the rate of growth fell by 48% and seed set and seed dry weight also fell sharply. Of the total variation in maximum, final seed dry weight within the ear, 4% could be attributed to the difference in seed dry weight between spikelets and 89% to differences in seed dry weight within spikelets. Differences in duration and rate of seed growth and seed set were also much smaller between spikelets than within spikelets. About 60% of the differences in seed dry weight along the ear were attributable to differences in growth rate and about 30% to differences in the duration of seed growth. The relative growth rate did not differ between seeds in different positions. The main factor determining seed growth rate was the dry weight of the ovule at anthesis, which declined sharply from the proximal to the distal floret within a spikelet. Analysis of the fructose, glucose, sucrose and starch concentrations showed that seed growth was not limited by the availability of sucrose nor by the ability of the seeds to convert sucrose into starch. These conclusions were supported by results from a second greenhouse experiment in which all ovules in 50% of the spikelets were removed at anthesis. Dry weight of the remaining seeds increased by only 15%.
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Panigrahi, Rashmi, Ekamber Kariali, Binay Bhusan Panda, Tanguy Lafarge, and Pravat Kumar Mohapatra. "Controlling the trade-off between spikelet number and grain filling: the hierarchy of starch synthesis in spikelets of rice panicle in relation to hormone dynamics." Functional Plant Biology 46, no. 6 (2019): 507. http://dx.doi.org/10.1071/fp18153.
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The advent of dwarf statured rice varieties enabled a major breakthrough in yield and production, but raising the ceiling of genetically determined yield potential even further has been the breeding priority. Grain filling is asynchronous in the rice panicle; the inferior spikelets particularly on secondary branches of the basal part do not produce grains of a quality suitable for human consumption. Of the various strategies being considered, the control of ethylene production at anthesis has been a valuable route to potentially enhance genetic yield level of rice. The physiology underlying spikelet development has revealed spikelet position-specific ethylene levels determine the extent of grain filling, with higher levels resulting in ill-developed spikelet embodying poor endosperm starch content. To break the yield barrier, breeders have increased spikelet number per panicle in new large-panicle rice plants. However, the advantage of panicles with numerous spikelets has not resulted in enhanced yield because of poor filling of inferior spikelets. High spikelet number stimulates ethylene production and downgrading of starch synthesis, suggesting a trade-off between spikelet number and grain filling. High ethylene production in inferior spikelets suppresses expression of genes encoding endosperm starch synthesising enzymes. Hence, ethylene could be a retrograde signal that dictates the transcriptome dynamics for the cross talk between spikelet number and grain filling in the rice panicle, so attenuation of its activity may provide a solution to the problem of poor grain filling in large-panicle rice. This physiological linkage that reduces starch biosynthesis of inferior kernels is not genetically constitutive and amenable for modification through chemical, biotechnological, surgical and allelic manipulations. Studies on plant genotypes with different panicle architecture have opened up possibilities of selectively improving starch biosynthesis of inferior spikelets and thereby increasing grain yield through a physiological route.
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Panigrahi, Rashmi, Ekamber Kariali, Binay Bhusan Panda, Tanguy Lafarge, and Pravat Kumar Mohapatra. "Corrigendum to: Controlling the trade-off between spikelet number and grain filling: the hierarchy of starch synthesis in spikelets of rice panicle in relation to hormone dynamics." Functional Plant Biology 46, no. 6 (2019): 595. http://dx.doi.org/10.1071/fp18153_co.
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The advent of dwarf statured rice varieties enabled a major breakthrough in yield and production, but raising the ceiling of genetically determined yield potential even further has been the breeding priority. Grain filling is asynchronous in the rice panicle; the inferior spikelets particularly on secondary branches of the basal part do not produce grains of a quality suitable for human consumption. Of the various strategies being considered, the control of ethylene production at anthesis has been a valuable route to potentially enhance genetic yield level of rice. The physiology underlying spikelet development has revealed spikelet position-specific ethylene levels determine the extent of grain filling, with higher levels resulting in ill-developed spikelet embodying poor endosperm starch content. To break the yield barrier, breeders have increased spikelet number per panicle in new large-panicle rice plants. However, the advantage of panicles with numerous spikelets has not resulted in enhanced yield because of poor filling of inferior spikelets. High spikelet number stimulates ethylene production and downgrading of starch synthesis, suggesting a trade-off between spikelet number and grain filling. High ethylene production in inferior spikelets suppresses expression of genes encoding endosperm starch synthesising enzymes. Hence, ethylene could be a retrograde signal that dictates the transcriptome dynamics for the cross talk between spikelet number and grain filling in the rice panicle, so attenuation of its activity may provide a solution to the problem of poor grain filling in large-panicle rice. This physiological linkage that reduces starch biosynthesis of inferior kernels is not genetically constitutive and amenable for modification through chemical, biotechnological, surgical and allelic manipulations. Studies on plant genotypes with different panicle architecture have opened up possibilities of selectively improving starch biosynthesis of inferior spikelets and thereby increasing grain yield through a physiological route.
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Michalikova, Martina, Michiel W. H. Remme, and Richard Kempter. "Extracellular waveforms reveal an axonal origin of spikelets in pyramidal neurons." Journal of Neurophysiology 120, no. 4 (October 1, 2018): 1484–95. http://dx.doi.org/10.1152/jn.00463.2017.
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Spikelets are small spike-like membrane depolarizations measured at the soma whose origin in pyramidal neurons is still unresolved. We investigated the mechanism of spikelet generation using detailed models of pyramidal neurons. We simulated extracellular waveforms associated with action potentials and spikelets and compared these with experimental data obtained by Chorev and Brecht ( J Neurophysiol 108: 1584–1593, 2012) from hippocampal pyramidal neurons in vivo. We considered spikelets originating in the axon of a single cell as well as spikelets generated in two cells coupled with gap junctions. We found that in both cases the experimental data can be explained by an axonal origin of spikelets: in the single-cell case, action potentials are generated in the axon but fail to activate the soma. Such spikelets can be evoked by dendritic input. Alternatively, spikelets resulting from axoaxonal gap junction coupling with a large (greater than several hundred μm) distance between the somata of the coupled cells are also consistent with the data. Our results demonstrate that a cell firing a somatic spikelet generates a detectable extracellular potential that is different from the action potential-correlated extracellular waveform generated by the same cell and recorded at the same location. This, together with the absence of a refractory period between action potentials and spikelets, implies that spikelets and action potentials generated in one cell may easily get misclassified in extracellular recordings as two different cells, albeit they both constitute the output of a single pyramidal neuron. NEW & NOTEWORTHY We addressed the origin of spikelets, using compartmental models of pyramidal neurons. Comparing our simulation results with published extracellular spikelet recordings revealed an axonal origin of spikelets. Our results imply that action potential- and spikelet-associated extracellular waveforms may easily get misclassified as two different cells, albeit they both constitute the output of a single pyramidal cell.
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ANDERSSON, A., E. JOHANSSON, and P. OSCARSON. "Post-anthesis nitrogen accumulation and distribution among grains in spring wheat spikes." Journal of Agricultural Science 142, no. 5 (October 2004): 525–33. http://dx.doi.org/10.1017/s0021859604004563.
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Knowledge of nitrogen accumulation to the grains is of great importance for identifying breeding and growing strategies to improve cereal yield and quality. The aim of this study was to investigate post-anthesis N translocation in the spike and into different spikelets of two cultivars of spring wheat (Triticum aestivum L.) grown to maturity in solution culture. Sport (short grain filling time, low yield and high grain protein concentration) and WL (normal grain filling time, high yield and low protein concentration) were the cultivars used. Plants received stepwise declining rates of N on a daily basis, until 109 days after planting (DAP). Anthesis for cv. Sport was 92 DAP and for cv. WL 78 DAP. On seven occasions (from anthesis in cv. WL until maturity), 15N was given to selected groups of plants for 4 days. Then these plants were sampled and separated into plant parts. Spikelets and grains were separated according to spikelet position. Plant parts were weighed and analysed for N and 15N.The N concentration in the grains was uniform for the spikelets in cv. WL but differed in cv. Sport. Final N concentration in a spikelet position was obtained at 126 DAP in cv. Sport and 112 DAP in cv. WL and was constant to the end of experiment at 154 DAP in cv. Sport and 147 DAP in cv. WL. A positive correlation between % atom excess 15N to spikelet position numbered from the base of the spike was exhibited in the lowermost part of the spike just after anthesis. Later, during grain filling, a negative correlation between % atom excess 15N to spikelet position was exhibited (−0·991 P=0·000). A positive correlation between % atom excess 15N to grain weight in the top of the spike was exhibited. Accumulation of 15N proceeded 14 days longer in the lowermost fertile spikelets than in the uppermost spikelets. It was concluded that the duration of N accumulation in the spikelets was dependent on spikelet position and uppermost spikelets had a shorter N accumulation period and contained lighter grains than lowermost spikelets.
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Zimmer, C. M., I. P. Ubert, M. T. Pacheco, and L. C. Federizzi. "Variable expressivity and heritability of multiflorous spikelets in oat panicles." Experimental Agriculture 55, no. 6 (February 5, 2019): 829–42. http://dx.doi.org/10.1017/s0014479718000418.
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AbstractMultiflorous spikelets are found in oat Avena sativa L. subsp. nudisativa, which is characterised by elongated rachilla and variable number of florets per spikelet. One of the main factors limiting the exploration of multiflorous spikelets in oats, aiming to produce naked grains, is its variable expressivity. This work aimed to detect the environmental influence on the variable expressivity of multiflorous spikelet formation in oats and to estimate the heritability of this trait by analysing its expression in lower, middle and upper third of the panicle in 94 inbred lines of two crosses each. Two populations of recombinant inbred lines were screened for the spikelet formation in 2 years and sowing dates under field experiments. The results demonstrate that the variable expressivity of the multiflorous spikelet formation was highly influenced by the environmental conditions. The variable expressivity varied according to the genetic background, as well as the panicle third where spikelets were produced. The upper third of the panicle showed greater stability for the multiflorous spikelet formation, which is confirmed by the highest heritability coefficients observed in this third, regardless of the assessed population. Our results provide substantial evidences of the contribution exerted by environmental conditions in multiflorous spikelet formation in oats.
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KATO, T. "Effect of spikelet removal on the grain filling of Akenohoshi, a rice cultivar with numerous spikelets in a panicle." Journal of Agricultural Science 142, no. 2 (April 2004): 177–81. http://dx.doi.org/10.1017/s0021859604004265.
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The Japanese rice cultivar, Akenohoshi, has numerous spikelets in a panicle (extra-heavy panicle type) and achieves a large yield sink capacity. However, this cultivar, as well as other extra-heavy panicle types, does not always produce higher yields because of poor grain filling of the spikelets on the secondary branches in a panicle. To determine whether the poor grain filling found in Akenohoshi was due to source-limited or sink-limited conditions, the present study examined the responses of grain-filling characteristics to several spikelet-removal treatments immediately after heading. Only when the spikelets on secondary branches remained was a significant increase in filled grain percentage in this spikelet position observed. This increase seemed to be associated with the increases in rate and duration of the grain-filling process and in single grain weight in this spikelet position. These results clearly indicate that the poor grain filling in the spikelet on secondary branches of Akenohoshi could mainly be attributed not to sink-limited conditions, but to source-limited conditions probably at specific stages of grain filling.
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Chorev, Edith, and Michael Brecht. "In vivo dual intra- and extracellular recordings suggest bidirectional coupling between CA1 pyramidal neurons." Journal of Neurophysiology 108, no. 6 (September 15, 2012): 1584–93. http://dx.doi.org/10.1152/jn.01115.2011.
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Spikelets, small spikelike membrane potential deflections, are prominent in the activity of hippocampal pyramidal neurons in vivo. The origin of spikelets is still a source of much controversy. Somatically recorded spikelets have been postulated to originate from dendritic spikes, ectopic spikes, or spikes in an electrically coupled neuron. To differentiate between the different proposed mechanisms we used a dual recording approach in which we simultaneously recorded the intracellular activity of one CA1 pyramidal neuron and the extracellular activity in its vicinity, thus monitoring extracellularly the activity of both the intracellularly recorded cell as well as other units in its surroundings. Spikelets were observed in a quarter of our recordings ( n = 36). In eight of these nine recordings a second extracellular unit fired in correlation with spikelet occurrences. This observation is consistent with the idea that the spikelets reflect action potentials of electrically coupled nearby neurons. The extracellular spikes of these secondary units preceded the onset of spikelets. While the intracellular spikelet amplitude was voltage dependent, the simultaneously recorded extracellular unit remained unchanged. Spikelets often triggered action potentials in neurons, resulting in a characteristic 1- to 2-ms delay between spikelet onset and firing. Here we show that this relationship is bidirectional, with spikes being triggered by and also triggering spikelets. Secondary units, coupled to pyramidal neurons, showed discharge patterns similar to the recorded pyramidal neuron. These findings suggest that spikelets reflect spikes in an electrically coupled neighboring neuron, most likely of pyramidal cell type. Such coupling might contribute to the synchronization of pyramidal neurons with millisecond precision.
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Patel, R., and PK Mohapatra. "Assimilate Partitioning Within Floret Components of Contrasting Rice Spikelets Producing Qualitatively Different Types of Grains." Functional Plant Biology 23, no. 1 (1996): 85. http://dx.doi.org/10.1071/pp9960085.
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Grain quality, soluble and insoluble carbohydrate contents, and activities of two key enzymes (sucrose synthase and invertase) involved in starch synthesis in the endosperm were measured in the components of the fertile florets of spikelets located at the tip of the uppermost primary branch (top spikelet), and the penultimate position of the lowermost primary branch (basal spikelet) of rice panicles during the period begining some days before anthesis to maturity. The basal spikelet, which reached anthesis a week after the top spikelet, produced a partially filled poor quality grain in contrast to the good quality high density grain produced by the latter. Sucrose was the major translocatable sugar in the organs of the fertile florets of both top and basal spikelets, and poor grain filling of the latter was not caused by deficiency of this material due to any resistance in supply in the external protective organs. The activities of the sucrose synthase and invertase were higher and lower respectively, in the endosperm cells of the top spikelet compared with the basal spikelet. We conclude that poor synthesis of the starch leading to partial grain filling in the basal spikelet is due to a lower activity of sucrose synthase.
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Michalikova, Martina, Michiel W. H. Remme, Dietmar Schmitz, Susanne Schreiber, and Richard Kempter. "Spikelets in pyramidal neurons: generating mechanisms, distinguishing properties, and functional implications." Reviews in the Neurosciences 31, no. 1 (December 18, 2019): 101–19. http://dx.doi.org/10.1515/revneuro-2019-0044.
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Abstract Spikelets are small spike-like depolarizations that are found in somatic recordings of many neuron types. Spikelets have been assigned important functions, ranging from neuronal synchronization to the regulation of synaptic plasticity, which are specific to the particular mechanism of spikelet generation. As spikelets reflect spiking activity in neuronal compartments that are electrotonically distinct from the soma, four modes of spikelet generation can be envisaged: (1) dendritic spikes or (2) axonal action potentials occurring in a single cell as well as action potentials transmitted via (3) gap junctions or (4) ephaptic coupling in pairs of neurons. In one of the best studied neuron type, cortical pyramidal neurons, the origins and functions of spikelets are still unresolved; all four potential mechanisms have been proposed, but the experimental evidence remains ambiguous. Here we attempt to reconcile the scattered experimental findings in a coherent theoretical framework. We review in detail the various mechanisms that can give rise to spikelets. For each mechanism, we present the biophysical underpinnings as well as the resulting properties of spikelets and compare these predictions to experimental data from pyramidal neurons. We also discuss the functional implications of each mechanism. On the example of pyramidal neurons, we illustrate that several independent spikelet-generating mechanisms fulfilling vastly different functions might be operating in a single cell.
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Wolde, Gizaw M., and Thorsten Schnurbusch. "Inferring vascular architecture of the wheat spikelet based on resource allocation in the branched headt (bht-A1) near isogenic lines." Functional Plant Biology 46, no. 11 (2019): 1023. http://dx.doi.org/10.1071/fp19041.
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Substantial genetic and physiological efforts were made to understand the causal factors of floral abortion and grain filling problem in wheat. However, the vascular architecture during wheat spikelet development is surprisingly under-researched. We used the branched headt near-isogenic lines, FL-bht-A1-NILs, to visualise the dynamics of spikelet fertility and dry matter accumulation in spikelets sharing the same rachis node (henceforth Primary Spikelet, PSt, and Secondary Spikelet, SSt). The experiment was conducted after grouping FL-bht-A1-NILs into two groups, where tillers were consistently removed from one group. Our results show differential spikelet fertility and dry matter accumulation between the PSt and SSt, but also showed a concomitant improvement after de-tillering. This suggests a tight regulation of assimilate supply and dry matter accumulation in wheat spikelets. Since PSt and SSt share the same rachis node, the main vascular bundle in the rachis/rachilla is expected to bifurcate to connect each spikelet/floret to the vascular system. We postulate that the vascular structure in the wheat spikelet might even follow Murray’s law, where the wide conduits assigned at the base of the spikelet feed the narrower conduits of the distal florets. We discuss our results based on the two modalities of the vascular network systems in plants.
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Senanayake, N., R. E. L. Naylor, and S. K. De Datta. "Effect of nitrogen fertilization on rice spikelet differentiation and survival." Journal of Agricultural Science 127, no. 3 (November 1996): 303–9. http://dx.doi.org/10.1017/s0021859600078461.
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SUMMARYExperiments were conducted in glasshouses at the Agronomy Department, International Rice Research Institute (IRRI), Philippines, in 1987 and 1988 to test the effects of small amounts of additional N applied at different times during the vegetative and reproductive phases of growth on rice yield components and on spikelet differentiation and survival.The results showed that an additional 10 kg/ha of N fertilizer had the largest effect on maximum spikelet number when applied at growth stage (GS) 1·9 but was too low to sustain the survival of the differentiated spikelets. Applications after panicle initiation did not lead to an increased survival of spikelets. Foliar N application at GS 5·5 did increase spikelet survival.The results confirm the role of limited N supply in restricting yields of rice. Altering the timing of N inputs seems unlikely to improve spikelet survival.
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Sarwar, AKM Golam, Al-Muzahid Mridul, Sontosh Chandra Chanda, and Israt Jahan Shelley. "Effects of potassium on panicle structure and spikelet morphology of a double grained rice cultivar." Bangladesh Journal of Botany 49, no. 3 (September 20, 2020): 663–70. http://dx.doi.org/10.3329/bjb.v49i3.50007.
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Influence of K on panicle structure and spikelet morphology of a double grained rice cultivar was evaluated. Results showed that K enhanced the plant height, leaf number, yield and yield contributing descriptors in double grained rice cultivar. The ratio of single-double grained spikelets on a panicle varied from 70 : 30 to 59 : 41. The position of spikelets on a panicle viz. primary vs. secondary branch, middle vs. upper or lower portion of panicle, had little effect on single-double grain ratio. However, K significantly affected the single-double grained spikelet ratio between primary and secondary branches. Multi-grained spikelets showed the potential to increase grain number per panicle thereby increasing rice yield.
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Zhong, Jinshun, G. Wilma van Esse, Xiaojing Bi, Tianyu Lan, Agatha Walla, Qing Sang, Rainer Franzen, and Maria von Korff. "INTERMEDIUM-M encodes an HvAP2L-H5 ortholog and is required for inflorescence indeterminacy and spikelet determinacy in barley." Proceedings of the National Academy of Sciences 118, no. 8 (February 16, 2021): e2011779118. http://dx.doi.org/10.1073/pnas.2011779118.
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Inflorescence architecture dictates the number of flowers and, ultimately, seeds. The architectural discrepancies between two related cereals, barley and wheat, are controlled by differences in determinacy of inflorescence and spikelet meristems. Here, we characterize two allelic series of mutations named intermedium-m (int-m) and double seed1 (dub1) that convert barley indeterminate inflorescences into wheat-like determinate inflorescences bearing a multifloreted terminal spikelet and spikelets with additional florets. INT-M/DUB1 encodes an APETALA2-like transcription factor (HvAP2L-H5) that suppresses ectopic and precocious spikelet initiation signals and maintains meristem activity. HvAP2L-H5 inhibits the identity shift of an inflorescence meristem (IM) to a terminal spikelet meristem (TSM) in barley. Null mutations in AP2L-5 lead to fewer spikelets per inflorescence but extra florets per spikelet. In wheat, prolonged and elevated AP2L-A5 activity in rAP2L-A5 mutants delays but does not suppress the IM−TSM transition. We hypothesize that the regulation of AP2L-5 orthologs and downstream genes contributes to the different inflorescence determinacy in barley and wheat. We show that AP2L-5 proteins are evolutionarily conserved in grasses, promote IM activity, and restrict floret number per spikelet. This study provides insights into the regulation of spikelet and floret number, and hence grain yield in barley and wheat.
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Fraser, Joanna, and Eric G. Kokko. "Panicle, spikelet, and floret development in orchardgrass (Dactylis glomerata)." Canadian Journal of Botany 71, no. 4 (April 1, 1993): 523–32. http://dx.doi.org/10.1139/b93-058.
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The initial stages of panicle, spikelet, and floret development in field-grown 'Kay' orchardgrass were examined using scanning electron microscopy. Spikelets arose from a complex multilevelled sequence of initiation from branch apices. Spikelets developed indirectly in a two-tiered progression: (i) an acropetal and basipetal sequence of first order, second-order, and third-order inflorescence apices, and (ii) an acropetal development within subclusters of higher-order lateral branch inflorescence apices. The panicle had the unique feature of dorsiventrality as well as bilateral symmetry. The basal apex from first-order, second-order, or third-order apices developed on the same side of the main axis as the first-order apex. The two glumes subtending each spikelet primordium developed alternately and acropetally. Development and initiation of florets within spikelets was basipetal within the panicle, basipetal within clusters and subclusters of spikelets on lateral branches, and acropetal within spikelets. Within florets, paleas developed later than lemmas. Key words: Dactylis glomerata, cocksfoot, scanning electron microscopy, development, panicle.
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Ansari, TH, T. Yoshida, Y. Yamamoto, and A. Miyazaki. "Distribution and Interrelationship of Differentiated, Degenerated and Surviving Spikelets on Panicle Branches in Rice (Oryza sativa)." Bangladesh Rice Journal 17, no. 1-2 (November 18, 2014): 49–63. http://dx.doi.org/10.3329/brj.v17i1-2.20901.
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The present investigation evaluated distribution pattern of differentiated, degenerated and surviving spikelets and interrelationship of spikelets on the basis of their position on rachis branches in a panicle of both japonica and indica cultivars. Distribution of differentiated spikelets on primary brances (PBs) and secondary brances (SBs) followed 1:1 ratio in the japonica cultivars and 1:2 or more than 2 in the indica ones irrespective of plant types revealed the genetic factor had the more influence on the observed distribution pattern in both japonica and indica cultivars. The percentage of degenerated spikelets to the differentiated ones on PBs was slightly higher in the japonica (4.2%?8.3%) than in the indica (0.5%?6.6%) cultivars. The degenerated percentage of differentiated spikelets on SBs varied more widely in the indica (11.9%?56.2%) than in the japonica (26.1%?48.2%) cultivars, although average was almost the same (37.7% in the japonica and 38.9% in the indica cultivars). Correlation coefficients showed that the increase of differentiated spikelets on PBs strongly increase the number of surviving spikelet per panicle or on PBs per panicle in both cultivar groups. But this was not significantly increase the number of degenerated spikelets on PBs but showed possibility of increase the number of degenerated spikelets on SBs per panicle in both cultivar groups. Increased number of differentiated spikelets on SBs substantially increased the numbers of both surviving and degenerated spikelets on SBs per panicle and showed weak negative (in japonica) and positive (in indica) significant correlation with the percentage of degenerated spikelets on SBs. The number of surviving PBs was highly correlated with the surviving spikelets on PBs per panicle. Therefore, above results imply that the increase of differentiated spikelets on PBs of both cultivar groups and on SBs in the japonica group could sustain the survivility of spikelets with higher number of differentiated PBs per panicle.DOI: http://dx.doi.org/10.3329/brj.v17i1-2.20901Bangladesh Rice j. 2013, 17(1&2): 49-63
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Coast, Onoriode, Richard H. Ellis, Alistair J. Murdoch, Cherryl Quiñones, and Krishna S. V. Jagadish. "High night temperature induces contrasting responses for spikelet fertility, spikelet tissue temperature, flowering characteristics and grain quality in rice." Functional Plant Biology 42, no. 2 (2015): 149. http://dx.doi.org/10.1071/fp14104.
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Climate change is increasing night temperature (NT) more than day temperature (DT) in rice-growing areas. Effects of combinations of NT (24−35°C) from microsporogenesis to anthesis at one or more DT (30 or 35°C) at anthesis on rice spikelet fertility, temperature within spikelets, flowering pattern, grain weight per panicle, amylose content and gel consistency were investigated in contrasting rice cultivars under controlled environments. Cultivars differed in spikelet fertility response to high NT, with higher fertility associated with cooler spikelets (P < 0.01). Flowering dynamics were altered by high NT and a novel high temperature tolerance complementary mechanism, shorter flower open duration in cv. N22, was identified. High NT reduced spikelet fertility, grain weight per panicle, amylose content and gel consistency, whereas high DT reduced only gel consistency. Night temperature >27°C was estimated to reduce grain weight. Generally, high NT was more damaging to grain weight and selected grain quality traits than high DT, with little or no interaction between them. The critical tolerance and escape traits identified, i.e. spikelet cooling, relatively high spikelet fertility, earlier start and peak time of anthesis and shorter spikelet anthesis duration can aid plant breeding programs targeting resilience in warmer climates.
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Shang, Yi, Lu Yuan, Zhaocan Di, Yong Jia, Zhenlan Zhang, Sujuan Li, Liping Xing, et al. "A CYC/TB1-type TCP transcription factor controls spikelet meristem identity in barley." Journal of Experimental Botany 71, no. 22 (September 11, 2020): 7118–31. http://dx.doi.org/10.1093/jxb/eraa416.
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Abstract Barley possesses a branchless, spike-shaped inflorescence where determinate spikelets attach directly to the main axis, but the developmental mechanism of spikelet identity remains largely unknown. Here we report the functional analysis of the barley gene BRANCHED AND INDETERMINATE SPIKELET 1 (BDI1), which encodes a TCP transcription factor and plays a crucial role in determining barley inflorescence architecture and spikelet development. The bdi1 mutant exhibited indeterminate spikelet meristems that continued to grow and differentiate after producing a floret meristem; some spikelet meristems at the base of the spike formed two fully developed seeds or converted to branched spikelets, producing a branched inflorescence. Map-based cloning analysis showed that this mutant has a deletion of ~600 kb on chromosome 5H containing three putative genes. Expression analysis and virus-induced gene silencing confirmed that the causative gene, BDI1, encodes a CYC/TB1-type TCP transcription factor and is highly conserved in both wild and cultivated barley. Transcriptome and regulatory network analysis demonstrated that BDI1 may integrate regulation of gene transcription cell wall modification and known trehalose-6-phosphate homeostasis to control spikelet development. Together, our findings reveal that BDI1 represents a key regulator of inflorescence architecture and meristem determinacy in cereal crop plants.
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Chorghe, Alok, K. Prasad, P. V. Prasanna, and Y. V. Rao. "A new species of Themeda (Poaceae: Panicoideae) from the Eastern Ghats, India." Phytotaxa 245, no. 2 (January 25, 2016): 183. http://dx.doi.org/10.11646/phytotaxa.245.2.10.
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Themeda odishae (Poaceae), a new species from the Mahendragiri hill ranges, Odisha (Orissa), India, is described and illustrated. It differs from T. mooneyi in shorter and hairy leaf blades, longer peduncle, length of sessile spikelet callus, number of pedicelled spikelets, and longer anthers. And from T. saxicola by its longer peduncle, number of racemes, number of pedicelled spikelets and hairy involucral spikelets.
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DRAMAS, FLORIAN, SIMON J. THORPE, and CHRISTOPHE JOUFFRAIS. "ARTIFICIAL VISION FOR THE BLIND: A BIO-INSPIRED ALGORITHM FOR OBJECTS AND OBSTACLES DETECTION." International Journal of Image and Graphics 10, no. 04 (October 2010): 531–44. http://dx.doi.org/10.1142/s0219467810003871.
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Although artificial vision systems could potentially provide very useful input to assistive devices for blind people, such devices are rarely used outside of laboratory experiments. Many current systems attempt to reproduce the visual image via an alternative sensory modality (often auditory or somatosensory), but this dominant "scoreboard" approach, is often difficult to interpret for the user. Here, we propose to offload the recognition problem onto a separate image processing system that then provides the user with just the essential information about the location of objects in the surrounding environment. Specifically, we show that a bio-inspired image processing algorithm (SpikeNet) can not only robustly, precisely, and rapidly recognize and locate key objects in the image, but also in space if the objects are in a stereoscopic field of view. In addition, the bio-inspired algorithm allows real-time calculation of optic flow. We hence propose that this system, coupled with a restitution interface allowing localization in space (i.e. three-dimensional virtual sounds synthesis) can be used to restore essential visuomotor behaviors such as grasping desired objects and navigating (finding directions, avoiding obstacles) in unknown environments.
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Doehlert, D. C., M. S. McMullen, J. L. Jannink, S. Panigrahi, H. Gu, and N. R. Riveland. "A bimodal model for oat kernel size distributions." Canadian Journal of Plant Science 85, no. 2 (April 1, 2005): 317–26. http://dx.doi.org/10.4141/p04-054.
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Oat kernel size distributions are important to the oat milling industry because size separation of kernels is routine in oat milling. Dehuller rotor speeds are set in order to deliver the optimal mechanical stress to different kernel size streams for dehulling. In this study, size distributions were evaluated by digital image analysis in 10 cultivars grown in eight environments. Observed distributions were compared with quality characteristics and with panicle characteristics and spikelet type frequencies. Size distributions within samples, as evaluated from individual kernel image areas, tended to depart from normal distributions and graphical depictions of data frequently resembled bimodal populations. A statistical test to compare a bimodal distribution with a normal distribution indicated that a bimodal model was more effective at describing the distributions. Panicle analysis indicated that two-kernel spikelets were the most abundant spikelet type found. Because two-kernel spikelets consist of one larger kernel and one smaller kernel, it is likely that the root of the bimodal distribution can be attributed to these spikelets. Although some departures from the mixture of two normal distributions can be attributed to the occurrence of one- and three-kernel spikelets, many of these departures must be attributed to other sources of variation in oat kernel size. Key words: Oats, panicle, kernel size, spikelets
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TIWARI, ARJUN PRASAD, ALOK R. CHORGHE, SHAHID NAWAZ LANDGE, and SHAIKH MUJAFFAR. "A new species of Parahyparrhenia (Poaceae: Andropogoneae) from India." Phytotaxa 446, no. 1 (May 26, 2020): 55–60. http://dx.doi.org/10.11646/phytotaxa.446.1.7.
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Parahyparrhenia khannae, a new species of Andropogoneae (Poaceae: Andropogoneae) from the grassland of Ratlam and Jhabua districts of Madhya Pradesh, India is described and illustrated. The new species is similar to the Indian endemic species P. bellariensis in having dorsal groove in lower glume of sessile spikelet, but differs in having shorter plant height, lacerate membranous ligule, shorter leaf blade and raceme length, fewer homogamous spikelets, shorter sessile spikelet and anther length.
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SIM, L. C., R. J. FROUD-WILLIAMS, and M. J. GOODING. "The influence of winter oilseed rape (Brassica napus ssp. oleifera var. biennis) cultivar and grass genotype on the competitive balance between crop and grass weeds." Journal of Agricultural Science 145, no. 4 (January 16, 2007): 329–42. http://dx.doi.org/10.1017/s0021859607006764.
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SUMMARYThree experiments conducted over two years (2002–04) at the Crops Research Unit, University of Reading, investigated competition between autumn sown oilseed rape cultivars (Brassica napus L. ssp. oleifera var. biennis (DC.) Metzg.) and Lolium multiflorum Lam., L.×boucheanum Kunth and Alopecurus myosuroides Huds., sown as indicative grass weeds.Rape cultivar (cv.) had a substantial effect on grass weed seed return. Over the six cultivars tested, L. multiflorum spikelet production ranged from just under 400 spikelets/m2 in the presence of cv. Winner to nearly 5800 in competition with cv. Lutin. Cultivar competitiveness was associated with high biomass, large dense floral layers and early stem extension. There was some evidence of differential competitive tolerance between rape cultivars.The results suggested that rape cultivars could be screened for competitiveness by measuring floral layer interception of photosynthetic active radiation.L.×boucheanum cultivars varied in ability to compete with rape. In the absence of inter-specific competition, spikelet density was similar for Aberecho and Polly (circa 31 000 spikelets/m2) but when grown with rape Polly outyielded Aberecho (i.e. 12 090 and 7990 spikelets/m2 respectively).
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Ahmad, Nabil M., Peter M. Martin, and John M. Vella. "Floral morphogenesis and proliferation in Poa labillardieri (Poaceae)." Australian Journal of Botany 57, no. 7 (2009): 602. http://dx.doi.org/10.1071/bt08071.
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Inflorescence and spikelet development in Poa labillardieri Steud. were investigated by scanning electron microscopy. Thirteen developmental stages were described in detail, starting with the vegetative shoot apex which was shown to be of the short type (stage zero), followed by a conversion from vegetative to floral meristem at Stage 1 and ending at Stage 12, with a mature panicle consisting of a variable number of florets at anthesis within each spikelet. The occurrence of short-type vegetative apices in this perennial grass adds further support to the view that there is no correlation between life span and the apex type. The branches of the P. labillardieri panicle are formed in acropetal succession; however, it is the upper branches that first bear rudiments of the spikelets, starting at the tip of the branches. In contrast differentiation of florets within each spikelet occurs in acropetal succession, so that the basal floret is farthest advanced and each successively upper floret less advanced. P. labillardieri occasionally produces inflorescences containing spikelets in which some or all of the florets are replaced by a plantlet that is structurally similar to a vegetative tiller. Proliferous development ranged from a situation where all florets were converted to vegetative propagules that can be detached and rooted readily in soil, to cases where proliferation extended only as far as an enlargement of the lemma, with either functional or non-functional sexual organs in its axil. Under greenhouse conditions, there was a shift from occasional cases of partially proliferating spikelets that occur in the wild to complete vigorous proliferation stimulated by unknown factor(s). Departure from the normal sexual pattern took place from early Stage 5 (initiation of spikelet primordial) to late Stage 6 (differentiation of florets).
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SIM, L. C., R. J. FROUD-WILLIAMS, and M. J. GOODING. "The influence of winter oilseed rape (Brassica napus ssp. oleifera var. biennis) canopy size on grass weed growth and grass weed seed return." Journal of Agricultural Science 145, no. 4 (January 16, 2007): 313–27. http://dx.doi.org/10.1017/s0021859606006721.
Full textAbstract:
SUMMARYFour experiments conducted over three seasons (2002–05) at the Crops Research Unit, University of Reading, investigated effects of canopy management of autumn sown oilseed rape (Brassica napus L. ssp. oleifera var. biennis (DC.) Metzg.) on competition with grass weeds. Emphasis was placed on the effect of the crop on the weeds.Rape canopy size was manipulated using sowing date, seed rate and the application of autumn fertilizer. Lolium multiflorum Lam., L.×boucheanum Kunth and Alopecurus myosuroides Huds. were sown as indicative grass weeds.The effects of sowing date, seed rate and autumn nitrogen on crop competitive ability were correlated with rape biomass and fractional interception of photosynthetically active radiation (PAR) by the rape floral layer, to the extent that by spring there was good evidence of crop: weed replacement.An increase in seed rate up to the highest plant densities tested increased both rape biomass and competitiveness, e.g. in 2002/3, L. multiflorum head density was reduced from 539 to 245 heads/m2 and spikelet density from 13 170 to 5960 spikelets/m2 when rape plant density was increased from 16 to 81 plants/m2. Spikelets/head of Lolium spp. was little affected by rape seed rate, but the length of heads of A. myosuroides was reduced by 9% when plant density was increased from 29–51 plants/m2.Autumn nitrogen increased rape biomass and reduced L. multiflorum head density (415 and 336 heads/m2 without and with autumn nitrogen, respectively) and spikelet density (9990 and 8220 spikelets/m2 without and with autumn nitrogen, respectively). The number of spikelets/head was not significantly affected by autumn nitrogen.Early sowing could increase biomass and competitiveness, but poor crop establishment sometimes overrode the effect. Where crop and weed establishment was similar for both sowing dates, a 2-week delay (i.e. early September to mid-September) increased L. multiflorum head density from 226 to 633 heads/m2 and spikelet density from 5780 to 15 060 spikelets/m2.
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Price, Steven C., James E. Hill, and Robert W. Allard. "The Morphological and Physiological Response of Slender Oat (Avena barbata) to the Herbicides Barban and Difenzoquat." Weed Science 36, no. 1 (January 1988): 60–69. http://dx.doi.org/10.1017/s0043174500074464.
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The morphological and physiological response of the slender oat (Avena barbataPott ex Link # AVEBA) to the herbicides barban (4-chloro-2-butynyl 3-chlorophenylcarbamate) and difenzoquat (1,2-dimethyl-3,5-diphenyl-1H-pyrazolium) in conjunction with decreased water availability was determined for seven populations, representing three ecotypes, under greenhouse conditions. Generally, within the range of sublethal herbicide doses, with increasing herbicide rates, phytotoxicity ratings increased, but plant dry weight, tiller height, and number of spikelets were decreased. Also, the number of juvenile tillers decreased, while that of fertile tillers increased. Flag leaf area increased and flowering was delayed. The ratio of number of spikelets to plant dry weight and seed weight was influenced the least. Under the highest rates of difenzoquat, the within-plant variance of spikelet number decreased, indicating that there may have been a more equal partitioning of resources amongst tillers for spikelet production. The general influence of water stress was to amplify the effect of the herbicide. For example, the dry treatment reduced dry weight and tiller height, and delayed flowering. Within a particular herbicide treatment, the effect of the water stress was to cause reduced within-plant variance for days to flowering, flag leaf area, and number of spikelets. Three reactions were observed that could have helped buffer decreases in spikelet production: 1) An increased fraction of the dry weight of the plants was partitioned into the spikelets at the expense of other vegetative matter, 2) the increased leaf area of the primary tiller may have helped counterbalance any reduction in photosynthesis caused by herbicide action, and 3) an increased number of juvenile tillers was converted into fertile tillers resulting in an increased number of mature tillers. These data indicate that the slender oat has a remarkable “phenotypic plasticity,” which enables it to maintain reproductive structures under sublethal herbicide doses.
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Gladman, Nicholas, Yinping Jiao, Young Koung Lee, Lifang Zhang, Ratan Chopra, Michael Regulski, Gloria Burow, et al. "Fertility of Pedicellate Spikelets in Sorghum Is Controlled by a Jasmonic Acid Regulatory Module." International Journal of Molecular Sciences 20, no. 19 (October 8, 2019): 4951. http://dx.doi.org/10.3390/ijms20194951.
Full textAbstract:
As in other cereal crops, the panicles of sorghum (Sorghum bicolor (L.) Moench) comprise two types of floral spikelets (grass flowers). Only sessile spikelets (SSs) are capable of producing viable grains, whereas pedicellate spikelets (PSs) cease development after initiation and eventually abort. Consequently, grain number per panicle (GNP) is lower than the total number of flowers produced per panicle. The mechanism underlying this differential fertility is not well understood. To investigate this issue, we isolated a series of ethyl methane sulfonate (EMS)-induced multiseeded (msd) mutants that result in full spikelet fertility, effectively doubling GNP. Previously, we showed that MSD1 is a TCP (Teosinte branched/Cycloidea/PCF) transcription factor that regulates jasmonic acid (JA) biosynthesis, and ultimately floral sex organ development. Here, we show that MSD2 encodes a lipoxygenase (LOX) that catalyzes the first committed step of JA biosynthesis. Further, we demonstrate that MSD1 binds to the promoters of MSD2 and other JA pathway genes. Together, these results show that a JA-induced module regulates sorghum panicle development and spikelet fertility. The findings advance our understanding of inflorescence development and could lead to new strategies for increasing GNP and grain yield in sorghum and other cereal crops.
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Lazarides, M., J. Lenz, and L. Watson. "Clausospicula, a new Australian genus of grasses (Poaceae, Andropogoneae)." Australian Systematic Botany 4, no. 2 (1991): 391. http://dx.doi.org/10.1071/sb9910391.
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Clausospicula, a new monotypic genus from the Darwin and Gulf District, Northern Territory, Australia, is described and illustrated. Its diagnostic characters include cleistogamous spikelets, reduced panicles, racemes and spikelets, and pedicelled spikelets which are poorly developed and deciduous, or suppressed. Also, the glumes of the bisexual spikelet are awned and slightly keeled or without keels. A prominent feature is the extension of the peduncle into an appendage to which the callus of the bisexual spikelet is attached. The epidermis is notable for its distinct costal and intercostal zones, rectangular intercostal long-cells with tessellated, pitted cell walls, stomata inserted beneath the overlapping interstomatals and arranged in definite rows bordering the costal zones, the presence of macrohairs, narrow microhairs 39–46.5 µm long, silica-celllcork-cell pairs with dumbbell-shaped silica bodies costally and butterfly-shaped silica bodies intercostally. The transverse section shows a distinct midrib with the vascular bundles arranged in a conventional arc abaxially and colourless tissue adaxially, and a symmetrically ordered lamina. The primary vascular bundles are accompanied by sclerenchyma as girders abaxially and adaxially; the adaxial epidermis is extensively bulliform and the abaxial epidermis is of bulliform-like cells.
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Gunawardena, T. A., and S. Fukai. "The interaction of nitrogen application and temperature during reproductive stage on spikelet sterility in field-grown rice." Australian Journal of Agricultural Research 56, no. 6 (2005): 625. http://dx.doi.org/10.1071/ar04099.
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Increased grain yield in response to high rates of application of nitrogen (N) fertiliser is often limited by increased spikelet sterility, particularly under low temperature conditions in the New South Wales (NSW) rice industry. In 3 field experiments, different N rates were applied for different sowing dates to investigate the interaction between N rate and temperature during microspore development on spikelet sterility and grain yield. In one experiment the effect of water depth on spikelet sterility was also investigated. Engorged pollen production, spikelet sterility, and yield and its components were recorded. Application of N affected a few different processes that lead into spikelet sterility. Application of N at both pre-flood (PF) and panicle initiation (PI) significantly reduced the number of engorged pollen grains per anther, which was negatively correlated with spikelet sterility. Application of N and low temperature during microspore development with the absence of deep water also decreased pollen engorgement efficiency (the percentage of pollen grains that were engorged). Application of N further increased spikelet density, which, in turn, increased both spikelet sterility and grain yield. The combined effect of spikelet density and low temperature during microspore development explained the 44% of variation in the number of engorged pollen grains per anther. Grain yield was decreased by low temperature during microspore development in the shallow water when N was applied. Spikelet sterility as a result of late sowing was strongly correlated with minimum temperature during flowering. It is concluded that N application reduced pollen number per anther as a result of increased spikelet density, and this made the spikelets more susceptible to low temperature, causing increased spikelet sterility.
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Sung, Shi-Jean S., Gerald R. Leather, and Maynard G. Hale. "Development and Germination of Barnyardgrass (Echinochloa crus-galli) Seeds." Weed Science 35, no. 2 (March 1987): 211–15. http://dx.doi.org/10.1017/s0043174500079078.
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Barnyardgrass [Echinochloa crus-galli(L.) Beauv. # ECHCG] spikelets were collected from greenhouse-grown plants at various developmental stages. Caryopses contained in a single spikelet were dormant at maturity, but dormancy was overcome when the spikelets were dry afterripened at 23 C or were treated with high temperatures, acid scarification, or punctured with a scalpel. The season at which anthesis occurred affected the length of time for afterripening. Enhanced germination due to puncturing and scarification was not related to removal of a restriction to water entry. The effectiveness of puncturing in overcoming dormancy depended on moisture content of the spikelets at the time of puncturing. Above 18% moisture content germination percentage was low regardless of the dormancy-releasing treatment.
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He, Dong, Rui Liang, Tuan Long, Ying Yang, and Changyin Wu. "Rice RBH1 Encoding A Pectate Lyase is Critical for Apical Panicle Development." Plants 10, no. 2 (January 30, 2021): 271. http://dx.doi.org/10.3390/plants10020271.
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Panicle morphology is one of the main determinants of the rice yield. Panicle abortion, a typical panicle morphological defect results in yield reduction due to defective spikelet development. To further elucidate the molecular mechanism of panicle abortion in rice, a rice panicle bald head 1 (rbh1) mutant with transfer DNA (T-DNA) insertion showing severely aborted apical spikelets during panicle development was identified and characterized. The rbh1-1 mutant showed obviously altered cell morphology and structure in the degenerated spikelet. Molecular genetic studies revealed that RBH1 encodes a pectate lyase protein. Pectate lyase-specific activity of Rice panicle Bald Head 1 (RBH1) protein assay using polygalacturonic acid (PGA) as substrates illustrated that the enzyme retained a significant capacity to degrade PGA. In addition, immunohistochemical analysis showed that the degradation of pectin is inhibited in the rbh1-1 mutant. Further analysis revealed that a significant increase in reactive oxygen species (ROS) level was found in degenerated rbh1-1 spikelets. Taken together, our findings suggest that RBH1 is required for the formation of panicle and for preventing panicle abortion.
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Fuller, Dorian Q., Aleese Barron, Louis Champion, Christian Dupuy, Dominique Commelin, Michel Raimbault, and Tim Denham. "Transition From Wild to Domesticated Pearl Millet (Pennisetum glaucum) Revealed in Ceramic Temper at Three Middle Holocene Sites in Northern Mali." African Archaeological Review 38, no. 2 (March 16, 2021): 211–30. http://dx.doi.org/10.1007/s10437-021-09428-8.
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AbstractImprints of domesticated pearl millet (Pennisetum glaucum (L.) R. Br.) spikelets, observed as temper in ceramics dating to the third millennium BC, provide the earliest evidence for the cultivation and domestication process of this crop in northern Mali. Additional sherds from the same region dating to the fifth and fourth millennium BC were examined and found to have pearl millet chaff with wild morphologies. In addition to studying sherds by stereomicroscopy and subjecting surface casts to scanning electron microscopy (SEM), we also deployed X-ray microcomputed tomography (microCT) on eleven sherds. This significantly augmented the total dataset of archaeological pearl millet chaff remains from which to document the use of the wild pearl millet as ceramic temper and the evolution of its morphology over time. Grain sizes were also estimated from spikelets preserved in the ceramics. Altogether, we are now able to chart the evolution of domesticated pearl millet in western Africa using three characteristics: the evolution of nonshattering stalked involucres; the appearance of multiple spikelet involucres, usually paired spikelets; and the increase in grain size. By the fourth millennium BC, average grain breadth had increased by 28%, although spikelet features otherwise resemble the wild type. In the third millennium BC, the average width of seeds is 38% greater than that of wild seeds, while other qualitative features of domestication are indicated by the presence of paired spikelets and the appearance of nondehiscent, stalked involucres. Nonshattering spikelets had probably become fixed by around 2000 BC, while increases in average grain size continued into the second millennium BC. These data now provide a robust sequence for the morphological evolution of domesticated pearl millet, the first indigenous crop domesticated in western Africa.
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Prieto, Paula, Helga Ochagavía, Simon Griffiths, and Gustavo A. Slafer. "Earliness per se×temperature interaction: consequences on leaf, spikelet, and floret development in wheat." Journal of Experimental Botany 71, no. 6 (December 26, 2019): 1956–68. http://dx.doi.org/10.1093/jxb/erz568.
Full textAbstract:
Abstract Wheat adaptation can be fine-tuned by earliness per se (Eps) genes. Although the effects of Eps genes are often assumed to act independently of the environment, previous studies have shown that they exhibit temperature sensitivity. The number of leaves and phyllochron are considered determinants of flowering time and the numerical components of yield include spikelets per spike and fertile floret number within spikelets. We studied the dynamics of leaf, spikelet, and floret development in near isogenic lines with either late or early alleles of Eps-D1 under seven temperature regimes. Leaf appearance dynamics were modulated by temperature, and Eps alleles had a greater effect on the period from flag leaf to heading than phyllochron. In addition, the effects of the Eps alleles on spikelets per spike were minor, and more related to spikelet plastochron than the duration of the early reproductive phase. However, fertile floret number was affected by the interaction between Eps alleles and temperature. So, at 9 °C, Eps-early alleles had more fertile florets than Eps-late alleles, at intermediate temperatures there was no significant difference, and at 18 °C (the highest temperature) the effect was reversed, with lines carrying the late allele producing more fertile florets. These effects were mediated through changes in floret survival; there were no clear effects on the maximum number of floret primordia.
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Joshi, Bal K., Laxmi P. Subedi, Santa B. Gurung, and Ram C. Sharma. "Pollen and Spikelet Analysis in F1 Rice Hybrids and their Parents." Nepal Agriculture Research Journal 8 (November 24, 2014): 120–26. http://dx.doi.org/10.3126/narj.v8i0.11605.
Full textAbstract:
Pollen analysis can be used to discriminate between different species, identify possible interspecies hybrids, identify restorer and maintainer lines, useful to study genetics of restorer gene, interaction between chromosome and cytoplasm and relationship between parents. Pollen abortion system of male sterility is an important tool in hybrid rice production and spikelet is the major yield components. Nine improved cultivars, six landraces and three wild aborted cytoplasmic-genetic male sterile (CMS) lines were used to analyze pollen and spikelet in F1 rice hybrids and their parents. The frequency of pollen categories and its relationship to spikelet fertility were investigated. Pollen sterility of the F1s was determined by staining pollen grains in 1% potassium iodide-iodine (I-KI) solution. Spikelet fertility was determined by counting the total number of seed set in proportion to the total number of spikelets. Correlation and regression coefficients for some traits were computed. In hybrids, pollen fertility ranged from 0.5 to 82% and spikelet fertility from 0 to 87%. Pollen fertility varied from 28 to 97%, while spikelet fertility from 73 to 91% in pollen parents. The highest and the lowest percentages of pollen fertility were found in Chaite-6 and Chiunde cultivars respectively. Spikelet fertility percentage varied widely among hybrids and many hybrids had lower spikelet fertility percentage than their parents. Therefore, it is of practical importance to understand the causes of high spikelet sterility in hybrids for possible increase in spikelet fertility. Highly significant positive correlation was found between stained round fertile (SRF) pollen and spikelet fertility. The positive value of correlation and regression coefficient on SRF and spikelet fertility were found between F1 and mid parent, and F1 and male parent. High fertility of cross may be due to the presence of a wide compatibility gene or restorer genes in the cultivar. Lower pollen and spikelet fertility of the crosses was attributed to effect of the genetic background of the tester parent. Nepal Agric. Res. J. Vol. 8, 2007, pp. 120-126 DOI: http://dx.doi.org/10.3126/narj.v8i0.11605
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Panda, B. B., A. K. Badoghar, K. Das, R. Panigrahi, E. Kariali, S. R. Das, S. K. Dash, B. P. Shaw, and P. K. Mohapatra. "Compact panicle architecture is detrimental for growth as well as sucrose synthase activity of developing rice kernels." Functional Plant Biology 42, no. 9 (2015): 875. http://dx.doi.org/10.1071/fp14363.
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The increase of spikelet number in the panicles of modern super rice has made the architecture compact, as the extra spikelets are accommodated mostly on secondary branches than on primary branches. However, the grain yield did not improve because of poor grain filling, which was more visible in the basal spikelets than apical spikelets. The objective of this study was to examine the effect of the compactness and positional difference of spikelets in the panicle on grain filling by comparing the activity and genetic expression of starch synthesising enzymes in the developing kernels of lax-(Upahar and CR3856–45–11–2-7–2-5 (CR-45)) and compact-(Mahalaxmi and CR3856–29–14–2-1–1-1 (CR-29)) panicle cultivars. Upahar and Mahalaxmi are genetically related, whereas CR-45 and CR-29 are recombinant inbred lines. The grain carbohydrate concentration and activity of sucrose synthase (SUS) enzyme were estimated during the active period of grain filling. Further, expression of isoforms of SUS, ADP glucose pyrophosphorylase (APL and APS for large and small units respectively) and starch synthase (SS and GBSS for soluble and granule bound starch synthases respectively) were also assayed through PCR studies. The genotype approach used revealed grain SUS activity and starch concentration high and sugar concentration low in the lax- compared with compact-panicle cultivars and in the apical spikelets compared with basal ones. The margin of variation between apical and basal spikelets was higher in the compact- than the lax-panicle cultivars. Genetic expression of most of the isoforms of the enzymes was higher in the lax- than the compact-panicle cultivars as seen in RT–PCR studies. A quantitative appraisal of transcript levels of isoforms in the qRT–PCR identified greater expression of SUS3 in the basal spikelets of Upahar than that in Mahalaxmi and in CR-45 over CR-29, most prominently during the active period of grain filling. We conclude that proximal location as well as increased density of spikelets on panicles affected SUS3 expression in the basal spikelets. The metabolic dominance of a spikelet in rice panicle is dependent on the expression of the genes for different isoforms of starch synthesising enzymes, but the expression of SUS3 could be more specific than the others. SUS3 expression is most active during grain filling of the lax-panicle cultivars, but its dominance is reduced significantly in the kernels of the compact-panicle cultivars.
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Giunta, Francesco, Rosella Motzo, and Adriana Virdis. "Development of durum wheat and triticale cultivars as affected by thermo-photoperiodic conditions." Australian Journal of Agricultural Research 52, no. 3 (2001): 387. http://dx.doi.org/10.1071/ar00034.
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The understanding of the interaction between thermo-photoperiodic conditions and the genetic control of anthesis date is fundamental in explaining the environmental adaptation of durum wheat and triticale cultivars. The development of 8 durum wheat (Triticum turgidum L. var. durum) and 2 triticale (×Triticosecale Wittmack) cultivars was studied at 3 sowing dates (September, November, and March) by observations on apex development, number and rate of leaf appearance, spike fertility, and number and length of elongated internodes. Variation in anthesis date was mostly explained by the total number of leaves, which ranged between 8.3 and 15, and hence by the duration of the phase of leaf primordium production. Total leaf number also affected the length ofthe subsequent phase until flag leaf appearance. The phyllochron was influenced by both sowing date and genotype, and was minimum in the March sowing (87 degree-days). The genotypic variability in phyllochron was due either to the variations in leaf number or to genotypic intrinsic differences. Time to terminal spikelet stage was related to the number of spikelets per spike and to the number of elongated internodes, although stem length depended more on internode length than on internode number. The number of spikelets per spike was associated with leaf number, but their relationship was affected by the thermal conditions during spikelet primordium initiation. No differences were observed between wheat and triticale cultivars, apart from the number of spikelets per spike.
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Souza, Natalia M. de, Rubens Marschalek, Luis Sangoi, and Francieli S. Weber. "Spikelet sterility in rice genotypes affected by temperature at microsporogenesis." Revista Brasileira de Engenharia Agrícola e Ambiental 21, no. 12 (December 2017): 817–21. http://dx.doi.org/10.1590/1807-1929/agriambi.v21n12p817-821.
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ABSTRACT This study evaluated the effect of temperatures during the phase of microsporogenesis on spikelet sterility of paddy rice and identified genotypes tolerant to low temperatures at this growth stage. The inbreds SC681, SC491, and SC676 and the cultivars Epagri 109 and SCS116 Satoru were assessed. The genotypes were submitted for three days in a growth chamber to five temperatures at microsporogenesis: 9, 12, 15, 18, and 21 oC. For each tested temperature, a control was kept in the greenhouse under environmental conditions. After harvest, full and empty spikelets were counted and weighed and the percentage of spikelet sterility was determined. Data were evaluated by variance analysis using the F test. Averages were compared by Tukey’s test and regression analysis. The highest spikelet sterilities were observed when the genotypes were exposed to the temperatures of 9 and 12 oC. Genotype spikelet sterility was similar to that of the control at 21 ºC. The inbred SC 676 presented higher tolerance to lower temperatures is therefore potentially suited to generate a cultivar with adequate agronomic performance in rice growing areas prone to cold conditions at microsporogenesis.
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Gunawardena, T. A., S. Fukai, and F. P. C. Blamey. "Low temperature induced spikelet sterility in rice. I. Nitrogen fertilisation and sensitive reproductive period." Australian Journal of Agricultural Research 54, no. 10 (2003): 937. http://dx.doi.org/10.1071/ar03075.
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Low temperature during panicle development in rice increases spikelet sterility. This effect is exacerbated by high rates of nitrogen (N) application in the field. Spikelet sterility induced by low temperature and N fertilisation was examined in glasshouse experiments to clarify the mechanisms involved. In two glasshouse experiments, 12-h periods of low (18/13�C) and high (28/23�C) day/night temperatures were imposed over periods of 5–7 days during panicle development, to determine the effects of low temperature and N fertilisation on spikelet sterility. In one experiment, 50% sunlight was imposed together with low temperature to investigate the additive effects of reduced solar radiation and low temperature. The effect of increased tillering due to N fertilisation was examined by a tiller removal treatment in the same experiment. Pollen grain number and spikelet sterility were recorded at heading and harvest, respectively. Although there was no significant effect of low temperature on spikelet sterility in the absence of applied N, low temperature greatly increased spikelet sterility as a result of a reduction in the number of engorged pollen grains per anther in the presence of applied N. Spikelet sterility was strongly correlated with the number of engorged pollen grains per anther. Low temperature during very early (late stage of spikelet differentiation–pollen mother cell stage) and peak (second meiotic division stage–early stage of extine formation) microspore development caused a severe reduction in engorged pollen production mainly as a result of reduced total pollen production. Unlike low temperature, the effect of shading was rather small. The increased tillering due to application of high rates of N, increased both spikelet number per plant and spikelet sterility under low temperature conditions. The removal of tillers as they appeared reduced the number of total spikelets per plant and maintained a large number of engorged pollen grains per anther which, in turn, reduced spikelet sterility. The number of engorged pollen grains per anther determined the numbers of intercepted and germinated pollen grains on the stigma. It is concluded that N increased tillering and spikelet number per plant and this, in turn, reduced the number of engorged pollen grains per anther, leading into increased spikelet sterility under low temperature condition.
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Soni, Sandeep Kumar, VK Yadav, N. Pratap, VP Bhadana, and T. Ram. "Selection Criteria, Yield Relationship with Component Traits and Grouping of Tropical Japonica, Indica Lines and Derived Hybrids of Rice (Oryza sativa L.)." SAARC Journal of Agriculture 11, no. 2 (March 20, 2014): 17–32. http://dx.doi.org/10.3329/sja.v11i2.18399.
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Forty-five rice lines comprising of thirty derived hybrid lines obtained from ten tropical Japonica, three Indica and two national checks viz. Pusa Basmati 1121 and Sarjoo-52 were evaluated for selection parameters, yield contributing components and genetic divergence. Fifteen quantitative and three qualitative traits were studied from experimentation with randomized block design during Kharif 2011. The phenotypic coefficient of variability was higher than genotypic coefficient of variability for all of the traits. The highest estimates of broad sense heritability coupled with genetic advance in per cent of mean was recorded for spikelets per panicle, plant height followed by L:B ratio, spikelets per panicle, grains per panicle, biological yield per plant, flag leaf area, days to 50% flowering, plant height which might be due to the additive nature of gene action. Such results indicated that these traits will be reliable for the effective selection. Highly positive and significant correlation was observed at both phenotypic and genotypic level between grain yield per plant and biological yield per plant, followed by panicle bearing tillers per plant, spikelet fertility, panicle length, 1000- grain weight, grains per panicle, panicle weight, flag leaf length, spikelet per panicle, flag leaf area, kernel length, flag leaf width, days to 50% flowering, and harvest index. This relationship reflected that grain yield and aforesaid economic traits can be increased simultaneously in breeding programme to develop high yielding Indica as well as Tropical Japonica rice varieties. Whole genotypes grouped in 8 non-overlapping clusters exhibited maximum genetic diversity between clusters III i.e., TJ- 64897 × NDR-359, TJ-64897 × CSR36, TJ-64897 × PB-1 and VIII i.e., TJ-11010 × NDR359, TJ-11010 × PB-1, TJ-16081 × NDR-359, TJ-16081 × PB-1. These clusters also stand for early days to flowering, short slender, second highest harvest index and panicle bearing tillers per plant, spikelets per panicle, grains per panicle, spikelet fertility, 1000- grain weight, long bold slender, biological yield per plant, and grain yield per plant. These genotypes showing higher mean performance for aforesaid traits can be exploited for enhancing hybrid vigour of desired New Plant Type with higher number of panicle bearing tillers per plant, spikelet per panicle and grains per spike in Indica as well as Tropical Japonica rice varieties for achieving higher yield. DOI: http://dx.doi.org/10.3329/sja.v11i2.18399 SAARC J. Agri., 11(2): 17-32 (2013)
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DAS, SMRUTI, P. KRISHNAN, MONALISA NAYAK, and B. RAMAKRISHNAN. "CHANGES IN ANTIOXIDANT ISOZYMES AS A BIOMARKER FOR CHARACTERIZING HIGH TEMPERATURE STRESS TOLERANCE IN RICE (ORYZA SATIVA L.) SPIKELETS." Experimental Agriculture 49, no. 1 (December 12, 2012): 53–73. http://dx.doi.org/10.1017/s0014479712001056.
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SUMMARYHigh temperature stress at flowering can adversely affect rice yield, largely due to failure of fertilization. Oxidative damage can be a major reason inducing spikelet sterility in rice. In the present study, the effect of high temperatures on antioxidant metabolism in rice spikelets was characterised using nine different genotypes. Exposure to different temperatures at flowering stage revealed significant differences among various antioxidant enzymes in spikelets, both quantitatively and qualitatively. Spikelets of susceptible genotypes withstood temperature stress of up to 35 °C, those of moderately tolerant between 35 °C and 38 °C and those of tolerant genotypes up to 40 °C. Presence or absence, and changes in the isozyme intensities were consistent with alterations in their activities. Superoxide dismutase (SOD) isozymes II and III were present after exposure at 30 °C and 35 °C, while SOD I appeared above 40°C. Intensities of catalase isozymes I and III and the only isozyme of ascorbate peroxidase altered, while the only isozyme of guaical peroxidase and two (III and IV) of the four isozymes of catechol peroxidase disappeared after high temperature exposure of 45 °C. Thus, this work provides an evidence of the role of antioxidant metabolism in spikelets under high temperature stress conditions. Hence, changes in antioxidant isozymes in rice spikelets can be used as a biomarker for characterizing high temperature stress tolerance in rice spikelets.
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Mohapatra, Pravat Kumar, Pradeep Kumar Naik, and Rajesh Patel. "Ethylene inhibitors improve dry matter partitioning and development of late flowering spikelets on rice panicles." Functional Plant Biology 27, no. 4 (2000): 311. http://dx.doi.org/10.1071/pp99057.
Full textAbstract:
Primary branch development of the rice panicle was in the order of a basipetal sequence from the top to the bottom at the time of anthesis. Delayed development of spikelets on the proximal branches of the panicle resulted in reduced grain filling. Two experiments were carried out to manipulate growth and development of the proximal spikelets with exogenous application of chemicals regulating formation or action of ethylene. In the first experiment, inhibitors of ethylene synthesis (cobalt) and action (silver) improved grain biomass and specific gravity of the basal spikelets, while 2-chloroethylphosphonic acid (CEPA) depressed these parameters significantly. In the second experiment, the ethylene synthesis inhibitor 1-aminoethoxyvinylglycine (AVG) promoted spikelet development on the basal primary branches and improved their survival and grain biomass. On the contrary, the ethylene precursor 1-aminocyclopropane-1- carboxylic acid (ACC) inhibited growth and development of these spikelets. The action of AVG was reversed when ACC was applied in combination with AVG. In both experiments, the chemicals did not influence growth and development of the superior spikelets on the apical primary branches of the panicle. Depression of growth and development by CEPA or ACC coincided with a concomitant rise in soluble carbohydrate concentration of the spikelets, whereas treatments with ethylene inhibitors decreased the concentration of the materials. The role of ethylene in metabolic dominance of the apical spikelets and its impact on grain yield of rice panicles is discussed.
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Chuck, G., R. B. Meeley, and S. Hake. "The control of maize spikelet meristem fate by the APETALA2-like gene indeterminate spikelet1." Genes & Development 12, no. 8 (April 15, 1998): 1145–54. http://dx.doi.org/10.1101/gad.12.8.1145.
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Evans, C. K., W. Xie, R. Dill-Macky, and C. J. Mirocha. "Biosynthesis of Deoxynivalenol in Spikelets of Barley Inoculated with Macroconidia of Fusarium graminearum." Plant Disease 84, no. 6 (June 2000): 654–60. http://dx.doi.org/10.1094/pdis.2000.84.6.654.
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This research examined the biosynthesis of deoxynivalenol (DON) and 15-acetyldeoxynivalenol (15-ADON) in barley spikelets inoculated with macroconidia of Fusarium graminearum (Group-II). Investigations were conducted to determine if these toxins were present in macroconidia of the pathogen prior to inoculating barley spikelets. Extracts of macroconidia cultured from mung bean agar were analyzed using gas chromatography-mass spectrometry. Neither DON or 15-ADON was detected in three isolates' macroconidia when compared with macroconidia-DON-matrix standards adjusted to 100, 200, 300, and 400 ng/g with a detection limit of 100 ng/g. Mean recovery of DON that was added to macroconidia was 89.5%. The same isolates were pathogenic on barley cultivars Robust (moderately susceptible) and Chevron (moderately resistant) and produced DON (0 to 3.69 ng/g) and 15-ADON (detected but not quantified) when grown in rice culture. Greenhouse experiments were performed to determine when DON and 15-ADON were detectable after inoculation and to quantify their amount in inoculated barley spikelets. The three isolates of F. graminearum were separately inoculated to a central spikelet on heads of barley cultivars Robust and Chevron. Both toxins were detected in spikelets 48 h postinoculation (PI). DON increased dramatically after 72 h and did not diminish thereafter. Accumulation of 15-ADON peaked at 72 to 120 h and decreased by 240 h PI. There were no statistical differences between cultivars or among fungal isolates for accumulation of either toxin when averaged over the time intervals. Differences of toxin accumulation at each sampling interval were significant (P < 0.0001) when averaged over isolates and cultivars. Spikelets of six cultivars and lines were sampled at inoculation and 18, 36, 54, 72, and 90 h PI. DON and 15-ADON were detected at 36 h PI, but differences among the cultivars and lines were not significant. Yield of DON in inoculated spikelets of 31 barley cultivars and lines at 72 h PI ranged from 0.14 to 1.26 μg per spikelet, and differences among the cultivars and lines were significant (P < 0.002). The data demonstrate a useful range of variability for toxin accumulation in inoculated spikelets among germ plasm in the Minnesota breeding program. Macroconidia with no detectable DON or 15-ADON could be used for in vitro studies of toxin biosynthesis. Establishing when DON and 15-ADON are synthesized facilitates studying the effects of promising fungicides, biocontrol organisms, and new or novel genetic resistance mechanisms and if or how they may prevent or delay the biosynthesis of toxins.
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Malumpong, C., S. Cheabu, C. Mongkolsiriwatana, W. Detpittayanan, and A. Vanavichit. "Spikelet fertility and heat shock transcription factor (Hsf) gene responses to heat stress in tolerant and susceptible rice (Oryza sativa L.) genotypes." Journal of Agricultural Science 157, no. 04 (May 2019): 283–99. http://dx.doi.org/10.1017/s002185961900056x.
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AbstractThe reproductive stage of rice is the most sensitive to heat stress, which can lead to spikelet sterility. Thus, heat-tolerant and heat-susceptible genotypes were used to investigate their differences in terms of phenotypic responses and expression changes of Hsf genes at the pre-flowering stage under heat stress. Results clearly showed that panicles had the highest temperature compared with other plant parts under both natural and heated conditions. However, the temperatures of tolerant and susceptible genotypes were not significantly different. In terms of spikelet fertility, the tolerant lines M9962 and M7988 had high seed set because their anther dehiscence, pollen viability and pollen germination were only slightly affected. In contrast, the susceptible line Sinlek showed severe effects at all steps of fertilization, and the pollen viability of M7766 was slightly affected under heat stress but was more affected in terms of anther dehiscence and pollen germination. Both susceptible lines showed dramatically decreased seed set. In addition, the expression of six HsfA genes in the flag leaves and spikelets at the R2 stage of plants under heat stress showed different responses. Notably, expression of the HsfA2a gene was predominantly upregulated in the flag leaf and spikelets under heat stress in M9962. Therefore, it can be concluded that heat stress has severe effects on the stamen, and that different genotypes have different susceptibilities to heat stress.