Dissertations / Theses on the topic 'Pak choi (Brassica chinensis L.)'

The overall aim of the study was to assess the risk of gene flow from Brassica crops by insectmediated pollen transport. I measured the viability of pollen in Brassica flowers throughout crop development and compared this with the viability of pollen transported by insects inside and outside one early- and one late-season crop. In order to evaluate the relative importance of different species in pollen transport, I measured abundance of flower visitors during crop development, and measured the foraging behaviour of five key pollinator species throughout the growing season, in relation to variation in microclimate, crop phenology and the relative abundance of other pollinator species competing for flower resources. Flower visiting insects of Brassica rapa crops were highly diverse, and their abundance and diversity changed with crop phenology. I found similar abundances at the family level for both crops studied, although capture rates were greater in the early- than in the late-season crop. Across flowering development, the greatest numbers of insects were captured at the peak of flowering for both crops. During the flowering period, Diptera was the most abundant order collected, followed by Hymenoptera. The most abundant family in Hymenoptera was Apidae which tracked crop development in both fields, with greater numbers of insects captured inside than outside the field. Standardized-count pollen loads were smaller in Diptera than in Hymenoptera. Of the five key pollinator species sampled, Lasioglossum sordidum (Hymenoptera: Halictidae), Apis mellifera (Hymenoptera: Apidae) and Bombus terrestris (Hymenoptera: Apidae) transported similar pollen loads, which were much greater than those carried by Eristalis tenax (Diptera: Syrphidae) and Melangyna novae-zealandiae (Diptera: Syrphidae). The numbers of insects captured outside of the crop were 10% and 33% of the totals captured inside for the early- and the late-season crop, respectively. The proportion of insects entering versus leaving the crop varied considerably across species, crops and trap location (i.e., whether traps were inside or 50 m outside the border of the crop). However, it is worth noting that not uncommonly more insects were attracted into the crop early in the season, staying there rather than leaving, and then when flowers started to disappear there was a massive escape of insects leaving. This research provides evidence for the influence of crop age on the foraging behaviour of key pollinators and for species-specific variation in the foraging behaviour of Brassica visitors with crop development. Temporal variation in the rate and variability of movement between flowers, and the duration and variability in time spent on each flower, throughout the growing season differed markedly between pollinator species. Flower density, plant density, and the abundance of other insects contributed to the observed variation in pollinator behavioural activity for A. mellifera, E. tenax, M. novae-zelandiae and L. sordidum. Bombus terrestris had the greatest rates and variability of movement, and the greatest rates of flower visitation among all key pollinators studied. Therefore B. terrestris might contribute to gene flow to a greater extent than other key pollinators. Additionally B. terrestris had the greatest variability in the rate of movement, increasing the risk of pollen movement over long distances. In summary, I found that (i) insect abundance and diversity changed with crop phenology and Diptera was the most abundant order collected, (ii) flower density, plant density, and the abundance of other insect pollinators were important factors explaining pollinator behaviour for all key pollinators, except B. terrestris, (iii) B. terrestris might contribute to gene flow to a greater extent than other key pollinators, because it has a greater rate of flower visitation and a greater flight distance between flowers than other pollinators, and (iv) pollen viability tended to decrease with crop development and declined sharply even just 50 m outside the edge of the crop.

碩士
國立中興大學
園藝學系所
101
Pak-Choi is one of the most important leafy vegetables in Taiwan. Pak choi is easy and fast to grow which makes it an ideal vegetable for summer season. It can be grown all year round in Taiwan. Utilization of Pak-choi as bioreactors not only can produce high economic product and increase the additional values, but also can take advantage of its cultural characteristic to produce large amount of target protein for industry, food, forage, and medical application. Transglutaminase (TGase) can catalyze the formation of ε-(γ-glutamyl) lysine covalent bond within molecules and between molecules and form 3D structure by cross link between proteins. On the basis of the gelatinize ability of protein concentrate, TGase has great application potential in food industry. Expression of target genes via chloroplast genomes not only enhances the level of expression without epigenetic effects, but also prevents out crossing of the introduced target genes via pollen grain. In this study, chloroplast transformation vectors harboring the selective marker gene (AlaR, daao, and aadA) and target genes (tga, gus, and egfp) constructed outside and of homologus recombination sequences, respectively, were transferred into the chloroplast of Pak-Choi via biolistic bombardment. After occurring twice of DNA recombination with chloroplast genome, only target gene will remain in the chloroplast genome and the selective gene and vector residues will be eliminated. The purpose of this study is to develop selective maker gene-free technique of Pak-choi chloroplast transformation for the production of TGase. In this study, 4 vectors pMT91EP-sRA, pMT91EP-sDA, pMT92GP-sDA, and pMT92GP-sRA, harboring the tga gene were transferred into the chloroplast of Pak-Choi ''Tainung No.3'' via biolistic bombardment. The regenerated plantlets were primary selected by 100~200 ppm D-alanine or 25~50 ppm spectinomycin. T0, T1, and T2 trasplastomic Pak-Choi plants were obtained from pMT91EP-sRA and pMT92GP-sRA constructs. The results of PCR, RT-PCR and western blots analyses indicated that the tga gene was integrated in the chloroplast genome of transplastomic Pak-Choi and expressed tga mRNA as well as TGase protein, while selective marker genes, AlaR, and aadA, were not detectable in the transplastomic Pak-Choi. Our results showed that the possibility of production of tga gene transplastomic Pak-Choi with maker gene-free technique.

博士
國立中興大學
園藝學系所
94
The objectives of this study were to: 1. develop an in vitro tissue regeneration system for Pak-choi (Brassica campestris L. ssp. chinensis L. Makino), 2. explore the possibility for improving the in vitro tissue regeneration derived from mature or aging explants of Pak-choi, 3. establish the Agrobacterium transformation system of Pak-choi, 4. establish the gene-gun transformation system of Pak-choi, and 5. explore the possibility for improvement of Pak-choi with stresses resistance via Agrobacterium-mediated and gene-gun transformation. The sources of explants of Pak-choi and the components of culture medium were studied to develop a tissue culture system for Pak-choi. The results indicated that the MS basal medium (Murashige and Skoog, 1962) supplemented with 2% sucrose, 1 mg/L BA, 0.5 mg/L NAA, 0.25mg/L GA3, 3mg/L AgNO3 and 5mg/L putrescine was the best components of culture medium for the explants regeneration of ''Tainung No. 1'' and ''Tainung No. 2'' Pak-choi, and 66.7% to 70% of regeneration rate could be achieved. Higher regeneration rates were obtained from the explants derived from the cotyledons than those of from hypocotyls. In general, calli were first regenerated from the explants of Pak-choi, and then adventitious shoots and roots were regenerated on the regeneration medium subsequently, ie. via “organogenesis pathway”. However, embryoids rather than calli were regenerated on the regeneration medium supplemented with polyamines (e.g. putrescine or spermidine), ie. via “somatic embryogenesis pathway”. The effects of types, ages, and positions of explants of ''Tainung No. 1'' and ''Tainung No. 2'' Pak-choi on in vitro tissue regeneration were performed. Effects of plant growth regulators, amino acids, polyamines, casein hydrolysate, and silver nitrate on shoot regeneration and root formation derived from the 15-days-old and 21-days-old explants of Pak-choi was also conducted. The highest rates of shoot regeneration and root formation were found in the 3-days-old explants. As the ages increased, the rates of shoot regeneration and root formation decreased. However, the high differentiation capacity was also found in the 27-days-old explants. Significantly increased the rates of shoot regeneration and root formation was found in the 15-days-old explants cultivated in the regeneration medium of Pak-choi (MS basal medium containing 2% sucrose, 1 mg/L BA, 0.5 mg/L NAA, 0.25mg/L GA3, and 3mg/L AgNO3) supplemented with 50 ml/l coconut juice. Improving the in vitro tissue regeneration of 21-days-old explants could be achieved by addition of 0.1 mg/L ABA into the regeneration medium of Pak-choi. Nevertheless, the efficient regeneration medium for 27-days-old explants was the same culture medium as the 3-days-old and 9-days-old explants.Attempts had been made to co-transfer the superoxide dismutase (sod62), and catalase (cat78) genes of Chinese cabbage into the ''Tainung No.1'' and ''Tainung No.2'' Pak-choi. Cotyledon and hypocotyl explants of Pak-choi were co-infected with two Agrobacterium carrying a distinct disarmed T-DNA containing rbcS-sod62 (pKrScn) and rbcS-cat78 (pKrCcn) genes, respectively. Results indicate that regenerated rates of Pak-choi were 16%. After 20 mg/L of kanamycin selection, the survival rate was 1.6%, and co-transformation rate of two genes was 0.075%. The results of PCR and Southern bolt hybridization indicated that the rbcS-sod62 and rbcS-cat78 genes had been transferred into Pak-choi, and inserted into their genomes. Two co-transformed plants of ''Tainung No.2'' Pak-choi were obtained. Increases in the transformation efficiency were obtained in the co-culture medium supplemented with the emery or 200µM acetosyringone (AS). Cotyledon and hypocotyl explants of Pak-choi were co-infected with two Agrobacterium carrying a distinct disarmed T-DNA containing rbcS-TP-sod62 (pKrTScn) and rbcS-TP-cat78 (pKrTCcn) genes, respectively. Results indicate that regenerated rates of Pak-choi were 18%. After20 mg/L of kanamycin selection, the survival rate was 2.2%, and co-transformation rate of two genes was 0.202%. The results of PCR and Southern bolt hybridization indicated that the rbcS-TPsod62 and rbcS-TPcat78 genes had been transferred into Pak-choi, and inserted into their genomes. Two and four co-transformed plants of ''Tainung No.1'' and ''Tainung No.2'' Pak-choi were obtained, respectively. T0 plants of rbcS-TP-sod62 and rbcS-TP-cat78 genes transformed Pak-choi were allowed to self-pollinated, and seeds were collected at maturity. T0 seeds were germinated on MS medium containing 20 mg/L of kanamycin for two weeks. Survival T1 seedlings were subjected to PCR and Southern bolt hybridization analysis. The results of genetic analysis indicated that the transformed rbcS-TP-sod62 and rbcS-TP-cat78 genes had been stably inherited in T1 progeny plants. Significant higher SOD and CAT activities were detected in the T1 transgenic progeny of Pak-choi than those of control plants. Following settings were suggested when Pak-choi explants was bombarded with Biolistic PDS-1000/He (Bio-Rad) particle gun apparatus: gold particle size less than 1.0 μm in diameter, 4mm spacer ring in thickness, 4mm spacer bar in diameter, 4.5cm for distance of bombardment, 3cm for distance from microcarrier launch assembly to the recipient explants. High transformation efficiency was achieved from the 6-days old Pak-choi explants bombarded with 650psi~900psi rupture disks. Cotyledon and hypocotyl explants of Pak-choi were bombarded with two plasmids containing sod62 (pASCCSOD) and cat78 (pASCCCAT) genes, respectively. After 10 mg/L of spectinomycin selection, the survival rate was 3.86%, and co-transformation rate of two genes was 0.43%. The results of PCR and Southern bolt hybridization indicated that the sod62 and cat78 genes had been transferred into Pak-choi, and inserted into their genomes. Two and twenty-nine co-transformed plants of ''Tainung No.1'' and ''Tainung No.2''Pak-choi were obtained, respectively. T0 plants of sod62 and cat78 genes transformed Pak-choi were allowed to self-pollinated, and seeds were collected at maturity. T0 seeds were germinated on MS medium containing 10 mg/L of spectinomycin for two weeks. Survival T1 seedlings were subjected to PCR and Southern bolt hybridization analysis. The results of genetic analysis indicated that the transformed sod62 and cat78 genes had been stably inherited in T1 progeny plants. Significant higher SOD and CAT activities were detected in the T1 transgenic progeny of Pak-choi than those of control plants.

碩士
國立中興大學
土壤環境科學系所
99
Phosphite (HPO3-2, Phi) is a reduced form of phosphorus, having a similar structure to phosphate (PO4-3, Pi). The former is a diprotic acid, but phosphate is a triprotic acid. Phosphite salts have been used as a fungicide for some diseases control. Some plants can used it as phosphorus fertilizer, but no phosphorus fertilizer effect for other plants, after the long-term use it even caused ecological problem. This study using hydroponic system to investigate the effect of phosphite/phosphate ratio in the nutrient solution on the growth, nitrate reductase, phosphatase, nutrient uptake of Pak-choi (Brassica chinensis L.,Cultiva). Screening Phi using bacteria from soil and inoculated into nutrient solution to evaluate their effect on the growth of Pak-choi. Results showed that increased the phosphite/phosphate ratio in nutrient solution decreased weights of shoot and root in fresh and dry, concentrations of extractable phosphate, total phosphorus, and magnesium, activities of leaf nitrate reductase and phosphatase, and the chlorophyll index. Evidence showed phosphate contributes a partial function as phosphorus fertilizer. Although the fresh weight and dry weight of Pak-choi root of 100％ phosphate treatment was 56 %, and 67 % decreased, respectively, compared to no phosphorus treatment. The fresh weight and dry weight of Pak-choi shoot was 69 % and 9 % increased, respectively, compared to the no phosphorus treatment. The inoculation of the top three most effective phosphate using bacteria, increased the Pak-choi shoot and root fresh weights by 37-93 % and 27-62 %, respectively, compared to no inoculation treatment

碩士
國立中興大學
園藝學系
92
Abstract The objectives of this study were to evaluate the feasibility of using medium film culture techniques in automatic conveyer system for short season vegetable production. ‘San-Feng’ pak-choi (Brassica campestris L. Chinensis Group) was used as plant materials and peat moss (PM), golden mushroom compost (GMC), rice hull (RH), and perlite (PR) as soilless mediums. Media either from commercial or from self-designed formulas were tested in different thickness for pak-choi growth. Results indicated that as the material Florafleur-001H medium thickness decreased from 3 cm to 1 cm, medium temperature, electrical conductivity (EC) increased, and leaf turgor decreased also during the early growth stage. Plant heights, stem diameters, leaf numbers, leaf sizes, and dry weights were decreased significantly also as medium thickness decreased. The best yields of 3.70 kg/m2 was obtained on the medium thickness at 3 cm. Since the air filled porosity (AFP) of mediums decreased from 10% to 14.9% at 1 cm thick. This caused great inconvenience in cultivation management. Commercial medium amendment by adding 10~30% of RH or 20~40% of PR could increase AFP by 1.5% to 2.5%. Among the physical characteristics analysis of GMC, PM, RH, PR, and soil, the container capacity (CC) of GM and PM were 58-67% and 67-77%, respectively, and were significantly higher than all other materials. As the height of container increased, CC decreased, AFP increased. Although the easily available water (EAW) content was not significant different among tested medium materials, the EAW of all materials in taller containers were found higher than those in shorter one. In the contrary, the water buffer capacity (WBC) in shorter containers was significantly less than that of taller containers. RH and PR had the highest portion of particle size above 2 mm thus had the highest AFP at 80-86% and 44-51%, respectively. Three different medium formulas were designed according to the physical and chemical characteristics of tested medium materials. The best plant growth and highest final yield was obtained from the formula of PM: GMC: RH = 3:2:1 (v/v) which had TP, AFP, CC, EAW, WBC, and BD for 94.7%, 39.6%, 55%, 23.5%, 7.7%, and 0.12g/cm3, respectively.

碩士
國立中興大學
園藝學系
81
Two cultivars of Pak Choi(Brassica campestris L. var. chinensis) ere used to study the physiology and growth of the vegetable cultured in solution with supraoptimal temperatures.

Vermicompost leachate (vermiliquer) is the liquid obtained from frequent washing of worms, organic inputs and casts. It is rich in nutrients for plants. The aim of this study was to evaluate the potential of vermiliquer as an alternative to inorganic nutrient sources in hydorponics.

碩士
國立屏東科技大學
熱帶農業暨國際合作研究所
93
Bamboo vinegar was produced by three to five years old moso bamboo (Phyllostachys pubescens) from Jwu-Shan, the carbonization temperatures each were 400(deg)C, 600(deg)C, and 800(deg)C and the collection temperatures were from 150(deg)C which at least over six months stable sinking and distillation methods and the commercial product D, were prepared to analyze its valid components including the pH value, electric conductivity, and the element contents of phosphorus, potassium, calcium, and magnesium etc. in this experiment. The original vinegar which diluted with distilled water in the concentration of 100, 300 , and 500 times were each foliar spray and direct irrigation treated in field and the commercial culture medium to investigate the effect of moso bamboo vinegar on pak-choi plant (Brassica rapa L. Chinensis Group cv. Feng-Shan Pak-choi). In the foliar spray test of different concentration solution of bamboo vinegar A on pak-choi showed an promotional effect that were 1.4 times in plant weight and 1.1 times in plant height increasing. Foliar spray test by bamboo vinegar solution diluted with distilled water 100 times in four seasons showed that vinegar A and B promoted plant weight of pak-choi each to 2.6 and 4 times increasing in summer period, each 1.68 and 1.61 times increasing in autumn and each 1.48 and 1.40 times increasing in winter, and then each 1.49 and 1.45 times increasing in spring period separately. The direct bamboo vinegar irrigation on commercial medium culture of pak-choi plant showed that vinegar diluted with distilled water under 100 and 300 times concentration solution promoted plant weight each to 1.43 and 1.40 times increasing separately. Direct bamboo vinegar irrigation treatment in field showed that diluted vinegar A and B solution each in the concentration of 500 times could promote to 1.75 and 1.65 times increasing of plant weight in pak-choi separately, while there were 1.5 and 1.55 times increasing of plant weight in the diluted 300 times concentration solution of vinegar A and B each. Moso bamboo vinegar A and B also had the plant weight promoted effect of pak-choi plant in 2.5 times increasing when tested at 100 times diluted solution each.

碩士
國立中興大學
園藝學系所
107
This study focused on the physiological reactions of pak choi (Brassica chinensis L. cv. ''Quanzhou'') and edible amaranth (Amaranthus tricolor L. cv. ''White leaf '') under different flooding days (2, 4, 6, and 8 days). After 2-day flooding treatment, the edible amaranth was affected earlier than the pak choi, and it is above-ground and root fresh/dry weight, plant height and root length were significantly decreased compared to the control. The concentration of macronutrient and micronutrient in pak choi and edible amaranth decreased to varying degrees. Especially when after 8-day flooding treatment, the roots of pak choi and edible amaranth may be damaged due to lack of oxygen, thus the absorption of large macronutrient and micronutrient was reduced making the plants less nutritious. After 6-day flooding treatment, the photosynthetic rate, stomatal conductance and transpiration of pak choi and edible amaranth were significantly reduced, indicating that 6-day flooding has imposed a serious stress on pak choi and edible amaranth. After 2-day flooding treatment, the TPC(total phenolic contents) and DPPH (1,1-diphony-2-picrythydrazyl) of the pak choi significantly increased, indicating that its antioxidant capacity was increased. The TPC and DPPH of the edible amaranth increased significantly after 6-day flooding. The TPC and DPPH measured in pak choi and edible amaranth significantly increased after the 8-day flooding. After flooding plus 5-day recovery treatment, the pak choi showed a recovery mechanism during the recovery period. For example, the reduction rate of its root length was 40.5% after 6-day flooding treatment, but decreased to 30.8% after the recovery period, indicating that the roots have been repaired during the recovery period, and the reduction rate of leaf area and above-ground fresh weight were also reduced after recovery. The reduction rate in above-ground phenotypes of edible amaranth after flooding plus recovery treatment was higher than those investigated immediately after flooding, indicating that the edible amaranth leaves may have suffered from irreversible damage during flooding. After 4-day flooding plus recovery treatment, the leaves of both pak choi and edible amaranth began to turn yellow, become dehydrated and withered, and the yellowing sympom started from the lower part of leaves, and after 6-day flooding plus recovery treatment, the survival rate of pak choi and edible amaranth began to decrease, especially in number of pak choi. Our results showed that the higher flooding days, the stronger negative effects it has on pak choi and edible amaranth, indicating the higher number of flooding days, the more negative to plant growth. Temperature increase due to global warming together with annual increment of atmospheric CO2 concentration may have impacts on future crop growth. In this study, root growth, above-ground phenotype and leaf nutrient status of greenhouse-grown pak choi and edible amaranth were monitored at 500 ppm and 1000 ppm CO2 concentrations under a high temperature (35/30℃, day/night) condition. Results from this study indicated that pak choi shows higher root and shoot fresh and dry weight, stem diameter, plant height, total number of leaves and leaf area but lower P, Ca and Fe concentrations in leaves at 1000 ppm CO2 concentration compared to those at 500 ppm. In contrast, edible amaranth displayed no significant difference in its above-ground phenotype when cultivated at different CO2 concentrations, however, significantly less number of lateral roots and P, Mg and Fe concentrations in leaves were observed at high CO2 concentration. Taken together, our results suggested that under high temperature conditions, C3 plants may benefit more from increased atmospheric CO2 concentration than C4 plants.

碩士
國立中興大學
園藝學系所
94
The objectives of this study were to evaluate the effects of applying NH4Cl at concentration of 0, 50, 100 and 200 ppm on the growth and nitrate contents in two leafy vegetables, lettuce ‘Hsing Nong No.1’ and pak-choi ‘San Feng’, hydroponicly cultured in Hoagland solution. Results indicated that supplement of NH4Cl in Hoagland solution had significant effects on increasing NH4+ contents, glutamine synthetase activity and total protein contents in both lettuce and pak-choi leaves. Chlorophyll contents and photosynthetic rates were found also increased, and consequently, the plants with NH4Cl supplement showed significant increases in plant height, leaf area and other horticultural characteristics as compared to the control. Supplement of NH4Cl to hydroponic solution showed quadratic effects on the decrease of NO3- contents in the leaves of both vegetables. The most effective concentration of NH4Cl were found at 50 ppm on lettuce and at 100 ppm on pak-choi, and the NO3- contents were 20.7% and 16.8% lower than the control, respectively. The trends of the decrease in NO3- in both vegetables were found similar in winter season and in summer season. Further experiments showed that the presence of Cl- in the solution was possibly the main reason that caused the reduction in NO3- concentration. It is postulated that the anion competition between Cl- and NO3- inhibited the absorption of NO3- and subsequently decreased the NO3- contents in the leaves of both lettuce and pak-choi. The decrease of NRA activity as observed in this study may due to the decrease in NO3- because NRA is a substrates activate enzyme. In conclusion, the supplement of NH4Cl at 50 ppm or at 100 ppm to hydroponic solution had dramatic effects not only on the decrease of nitrate contents in lettuce and in pak-choi but also on the increase of growth and yield. It is worthy of further study for the commercial production of vegetables of high yield and safety.

碩士
國立中興大學
土壤環境科學系所
97
The concerns of healthy life and healthy environments have been increasing all over the world. People are looking for vegetables containing low nitrate. The hydroponic culture is a good system to produce the concentration of nitrate of vegetables under control. However, an efficient use of water in hydroponic system is also very concerned. The aims of this thesis were to develop a hydroponic system that supplies the daily required nutrient with the daily required water for evapotranspiration and to know the best nutrient supplying time for lowering the nitrate concentration of vegetables without the loss of vegetable production. The seedling of Pak-chio (Brassica Chinensis L.) was growing in a normal nutrient solution for three weeks then growing in different treatments for one week. There were 7 treatments (Ck, D1, D2, D3, DN1, DN2, and DN3) designed in this study and conducted twice, one in 2006 and other one in 2007, with 4 replications for each time. Plants were growing in a container with 24000 ml nutrient solution for CK treatment. The nutrient used for treatments of D1, D2, and D3 was prepared in the estimated consuming water and supplied only once in each morning. The consuming waster was divided into two parts one supplied in the morning and the other in the evening, with 30 % and 70 % for each, respectively. The nutrient used for DN1 was supplied in the morning water, for DN2 was evenly divided in the morning and in the evening water, and for DN3 was supplied in the evening water. The elemental concentration of plant shoot was digested with HCl and HNO3 solution then determined by ICP-AES. The concentration of anions was extracted with hot water and determined by IC instrument. The DPPH radical scavenging activity and ferrous ion chelating power as the indicator for antioxidant were also determined. The water consumption of the system developed in this study was less than 25% of the original system, and the production of Pak-chio was higher than those of control, even reached significant level in the experiment conducted in 2006 under fully sunshine days. The sunshine length in 2007 was low due to long rainy days, which causes the production among treatments did not reach significant level. The nitrate concentration of shoot was lowest for D1 and DN1 treatments, and significantly lower than those of CK and DN3 in 2006. The nitrate concentration of shoot of those in 2007, under low sunshine days, were 2 to 4 times of those in 2006, under fully sunshine days. Results showed that the DPPH radical scavenging activity and ferrous ion chelating power of the first culture and ferrous ion chelating power of the second culture are positively related to the dry weight of the Pak-chio. In addition, the DPPH radical scavenging activity in the second culture is negatively related to the ferrous ion chelating power. This may indicate that the ability of antioxidant was affected by the dry matter content, the dry matter content of the first crop was higher than those of the second crop, and other plant qualities may be also envolved. The results supported that the daily required nutrient supplied daily in the morning with low ratio of water, and remaining the high ratio of water supplied in the evening will make the Pak-choi in high production with low nitrate concentration in eatable part.

Phytochemicals are defined as biologically active, non-nutrient (i.e. not essential for the maintenance of life), plant compounds. They are present in all fruits, vegetables, grains, and other plant foods, and have been shown to be beneficial to human health. Flavonols are a group of phytochemicals present in a variety of different vegetables including broccoli, Brussels sprouts, cabbage, cauliflower, kale and bok choy. Flavonols have been shown to exhibit powerful antioxidant activity as well as possess potential protective properties against certain cancers. The aim of this research was to measure the levels of the major flavonols in bok choy and to assess the antiproliferative activity of crude bok choy extracts, selected fractions, and individual flavonol compounds on human colon cancer cells (HT-29) in vitro. The flavonol composition of three bok choy cultivars (Sumo, Karate, and Miyako) was determined after acid hydrolysis by HPLC-PDA/ESI-MSn . Kaempferol (85.5 – 122 mg/100 g DW), isorhamnetin (38.3 – 66.7 mg/100 g DW), and quercetin (10 – 20.6 mg/100 g DW) were the main flavonols present. The Miyako variety contained the highest levels of both quercetin and isorhamnetin, however, the levels of kaempferol were comparable in all three cultivars. The total flavonol aglycone content in the three bok choy cultivars did not vary significantly (183.3 mg/100 g DW, 159.9 mg/100 g DW, and 197.3 mg/100 g DW for Sumo, Karate, and Miyako respectively), therefore, no conclusions were made as to whether one bok choy cultivar may contain more health-promoting flavonols than another. Several glycoside and hydroxycinnamic acid derivatives of quercetin, isorhamnetin, and kaempferol were identified in the alkaline and hydroalcoholic bok choy extracts by HPLCPDA/ESI-MSn . Two flavonol-3-sophoroside-7-glucosides and three flavonol-3,7-diglucosides were identified in the bok choy after alkaline hydrolysis, and six complex flavonol glycosidehydroxycinnamic acid derivatives, two flavonol di-glycosides, and one flavonol mono-glucoside were identified in the hydroalcoholic extracts. Kaempferol-3-O-sophoroside-7-O-glucoside was purified by preparative HPLC and SPE and fully characterised by NMR, UV and MSn . The ability of crude bok choy extracts, selected fractions, and individual flavonol compounds to inhibit cell proliferation of the human colon adenocarcinoma cell line, HT-29, in vitro was assessed using the MTT assay. The antiproliferative effects on HT-29 cells was evident for all extracts/fractions/compounds examined, however, the crude bok choy extracts were found to be the most potent. The IC50 values for the three bok choy cultivars ranged between 1.58 – 4.01 mg/L after 72 hours of exposure. Preliminary results suggested that bok choy has the potential to positively influence human health, both from a chemopreventive perspective as well as a chemotherapeutic.

碩士
國立臺灣大學
園藝暨景觀學系
106
In Taiwan, 70% of all consumed water was agriculture irrigation water, in which 60% was used in surface irrigation during 2015. However, water use efficiency of surface irrigation is low due to the irrigation water applied is more than plant requirement. In present study, rape ‘Qing Long’ (Brassica rapa) and pak-choi ‘Feng-Jing’ (Brassica rapa var. chinensis) were used as the materials for experiments of (1) water dis-supply and (2) re-water after water dis-supply, for 3 replications. In water dis-supply experiment, non-destructive physiological characters including SPAD, chlorophyll fluorescence FV/FM, NDVI and PRI, and destructive physiological characters including fresh weight, dry weight and dry matter ratio of shoots, leaf water potential and antioxidant enzymes activities, as well as volumetric water content (VWC) of peat medium were investigated after water dis-supply to select suitable character as irrigation indicator. In re-water after water dis-supply experiment, shoot fresh weight and dry weight of 2 crops were investigated under different irrigation treatments. Peat VWC was also measured to select suitable indicator for re-watering. In rape experiment replication I, the suitable non-destructive physiological character is chlorophyll fluorescence FV/FM. The recommended peat VWC for harvest is 30% and for re-watering 38%. In rape experiment replication II, any non-destructive physiological character was not suitable as an irrigation indicator. The recommend peat VWC for harvest is 20% and for re-watering 18%. In rape experiment replication III, the plants did not face drought stress. In pak-choi experiment replication I, no non-destructive physiological character was suitable as an irrigation indicator. The recommended peat VWC for harvest is 20% and for re-watering 39%. In pak-choi experiment replication II, the suitable irrigation indicator for non-destructive physiological character is chlorophyll fluorescence FV/FM and NDVI. The recommended peat VWC for harvest is 20%, and for re-watering 22%. In pak-choi experiment replication III, no non-destructive physiological character was suitable as an irrigation indicator. The recommend peat VWC for harvest is 20%, and for re-watering 18%. In conclusion, chlorophyll fluorescence FV/FM has the potential to be an irrigation indicator, but is still not stable. The recommended peat VWC for irrigation is 30% during sunny days or unstable weather, and 20% during rainy days. Peat VWC never below 40% is conservatively suggested. Artificial neural network was also used to predict classification of pak-choi yield. The accuracy rate is 31%. More experimental units are needed to increase the accuracy of predicting the classification of pak-choi yield and reach intelligence agriculture.

碩士
國立中興大學
園藝學系
90
Three cultivars of Pak-choi were sown in 72,128 and 288-cell plug trays, their plant fresh weight, dry weight, leaf number, leaf area, root fresh weight, root dry weight and root length showed no significant difference among different cell size after 9 to 12 days of sowing. However, the difference would increase gradually as days after sowing increased. Seedlings in 72-cell plug showed best growth. The root shoot ratio of cultivar ‘Dai Tokyo’ in 288-cell was higher than seedlings sowed in 72 and 128 cell plug. Relative growth rate of fresh weight and dry weight had the highest value in early seedling growth, but gradually increased as sowing days increased. Plants sowed in 288-cell showed less in relative growth rate at 21 days after sowing in comparison to seedlings in 72 and 128-cell but difference become less in later growth. Testing of root vigor indicated that seedling in 128-cell had higher TTC in fresh weight unit and seedlings in 72-cell were the lowest. Using PI value for measuring vigor affected by seedling age and cell size in plant growth after transplanting showed that both plants in 128 and 72-cell had higher PI value than the 288-cell. There were significant difference among cultivars, seedling age and cell size on fresh weight, dry weight, leaf number and plant height after transplanting into field. Cultivar ‘Feng Jing’ had the highest shoot fresh weight, dry weight and plant height. Among seedling age of 12, 15 and 18 days, the higher seedling age of the 18 day seedling had the best growth after transplanting. Plants in difference cell size showed that 72-cell plug seedling had the best shoot fresh weight, dry weight, leaf number and plant height, but the 4-unit of 128 cell was the lowest. Plants in 18-cell plug showed lower growth rate at 12 days after transplanting but growth rate increased with number of planting days. It was only less than plant in 72-cell when harvested at the 18th day. Relative growth rate after transplanting was highest in cultivar ‘To Pak-choi’ or those directly transplanting from 128-cell plug and 18 day seedling were lower in early growth than increased later which indicated that young seedlings had higher vigor. There were significant differences on fresh weight of the largest leaf, leaf area, position of leaf among cultivars, seedling age and plug size. The single leaf fresh weight and leaf area were positive correlated with single plant fresh weight which can be used as index for predicting yield.

碩士
國立中興大學
園藝學系
92
Abstract Effects of plastic mulch color on root temperature, photosynthetic photon flux density (PPFD) reflection and growth of leaf lettuce (Lactuca sativa L.) cv. ‘No. 3’ and pak-choi (Brassica campestris L.) cv. 'Feng Jing' and cv. 'Brisk Green' were investigated in greenhouse at different climates in three croppings of plants transplanted in September, 2003, November, 2003 and January, 2004. Five plastic mulches including aluminum polyethylene, clear plastic, green plastic, red plastic, and yellow plastic were compared to the nonmulch control. The significant difference in PPFD between control and mulched treatments was shown in Sept. crop but not in Nov. and Jan. crops. The PPFD tended to increase on mulch surfaces, except red plastic, during three croppings. The highest PPFD were measured on aluminum polyethylene and yellow plastic which were 6-21% higher than in control. Root temperature under mulches was higher than in control during three croppings. The highest root temperature was shown under aluminum polyethylene and clear plastic which was 2.6 to 3.1oC higher than the control at midday. Green, red and yellow plastics had similar effect on root temperature. Plant growth and yield as well as physiology parameters of leaf lettuce and pak-choi were affected by color mulching. The effect of mulch varied during croppings. Yields decreased in mulched treatments compared to control by 17-28% in Sept. crop but increased in clear and yellow plastics by 27-71% in Nov. and Jan. crops except pak-choi cv. 'Feng Jing' in Nov. crop which was not influenced by the color mulching. Aluminum polyethylene enhanced root growth in Nov. and Jan. crops but did not affect plant fresh weight and yield. Aluminum polyethylene increased chlorophyll contents of leaf lettuce and pak-choi cv. 'Brisk Green' grown in Sept. crop but not in Nov. and Jan. crops. Although the significant difference was not constant, the highest chlorophyll contents were shown in green plastic and the lowest contents was in red and yellow plastics. Photosynthetic rate of the three crops decreased in aluminum polyethylene and clear plastic by 15-40% or 18-43%, respectively, as compared to control in Sept. crop but it responded less to color mulching in Nov. and Jan. crops. Yellow plastic increased carbohydrate levels in leaves and roots of plants grown in Nov. and Jan. crops while aluminum polyethylene increased carbohydrate level in roots. The lowest nitrate content in leaves of the three crops were shown in control and yellow plastic in Sept. or Jan. crop, respectively. In Nov. crop, nitrate content in leaves of pak-choi cv. 'Feng Jing' grown in green plastic was higher than in yellow plastic but there were no differences among treatments in leaf lettuce and pak-choi cv. 'Brisk Green'. Percentage of pak-choi leaves injured by diamond-back moth (Putella xylostella L.) generally decreased in mulched treatments during the three crops, however, yellow plastic was the most efficient mulch to reduce the leaf injury.

碩士
國立中興大學
土壤環境科學系所
103
As the world population booming, food problem has been concern for a long time. Recently, different natural disasters, such as global warming, tsunami attack and sea level rising, and also man-made problem, like human activities, excessive use of fertilizer and water pollution, lots of arable land has been salt-affected. Farmers in Taiwan often over supply fertilizers, in addition, irrigate low quality water and greenhouse effect which create salt-affected soil problem. Phytoremediation is a cheap method to solve salt-affected problem and friendly to environment. In this study, Egyptian clover (Trifolium alexandrinum L.), Pak choi (Brassica rapa L Chinese Group.), Arucola (Eruca sativa) and Sesbania (Sesbania canabia (Retz.) Pers.) were grown under soils adjusted into different EC levels with NaCl. Part one of this study Egyptian clover and Pak choi were cultivated under EC levels at 4, 6, 8 and 12 dS m-1. Results showed that both of Egyptian clover and Pak choi could lower the soil sodium concentration remarkably under 4 and 6 dS m-1 treatments. As the higher biomass and Na accumulation of Pak choi made it became a better choice for it reducing soil sodium concentration to 35 and 26% under 4 and 6 dS m-1 treatments, respectively, and the corresponding values for Egyptian clover were 20 and 12%. The values of soil EC lowered from initial 4.01 to 3.15 and 3.55 dS m-1 for Pak choi and Egyptian clover, respectively. However, as the growth period increased of Pak choi, the K:Na of plant tissue quickly decreased from 1.76, 2.09, and 0.39 at 30 DAS 0.39 to 0.94, 0.92, and 0.19 at 40 DAS for 4, 6, and 8 dS m-1 treatments, respectively. This indicated that an extra K fertilizer may be needed to support Pak choi for lasting its Na removing potential. In the second part, two different salt tolerant rhizobia(Rhizobium pusense) were inoculated for Sesbania and growing under solution EC at 3, 6, 9 and 12 dS m-1 hydroponic systems. Results showed that rhizobium inoculation do not make any differences of the growth of sesbania among different EC treatments. At the last part of this study, the biomass of Pak choi and Sesbania grown applied back to their produced pot as green manure for treatments with soil EC adjusted to 4 and 12 dS m-1. Though Pak choi reduced soil sodium concentration to 60% in previous cultivation, the soil EC recovered back to their initial values for most salt elements Pak choi tissue released back to soil during growing periods for the crop tissue having easily decomposed character. The decomposition of Sesbania is much slower with the lower ratio of sodium in the tissue released back to soil during growing period. Accordingly, both of Pak choi and Sesbania are suitable for salt removing from the salted soil, Pak choi tissue should be moved out of the sites. Sesbania can be used as green manure for the following crops.