Academic literature on the topic 'Rice grassy stunt disease'

The brown plant hopper (BPH) is a major pest of rice and as a vector of Rice ragged stunt virus (RRSV) and Rice grassy stunt virus (RGSV). Curently, numerous rice yellow stunt disease symptoms are found in the field that caused by the single and simultaneous infection of these two viruses. Brown plant hopper population correlate with the incidence and severity of the disease. Misuse of insecticides, would cause of BPH resistances to imidacloprid. This study aimed to investigate the ability of BPH imidacloprid-resistant and susceptible to transmit of rice yellow stunt disease on rice plants. The variables tested were the acquisition period, inoculation period, number of infesting BPH, and lifespans of the viruliferous BPH that used in this research. Experiments were set as separated Completely Randomized Design with 10 replications for each treatment within an experiment. The results showed that both resistant and susceptible BPH to imidacloprid was able to transmit the virus to healthy plants. The acquisition and inoculation period test showed the BPH could transmit the virus with the shortest acquisition time for 30 minutes followed 24 hours of inoculation, as well as the acquisition time of 10 days with the shortest inoculation time for 30 minutes. Based on the incubation time, symptoms variation, and disease severity, susceptible BPH were more effective in transmitting rice yellow stunt disease than imidacloprid-resistant BPH. Single imidacloprid-resistant or susceptible BPH was proven able to transmit rice yellow stunt disease to healthy plants during its lifespan. Lifespans BPH viruliferous of imidacloprid-resistant were shorter than susceptible, which was 16 days for resistant BPH and 21 days for susceptible BPH.

Most rice protection methods have currently used toxic chemicals to control pathogens and pests, which leads to environment pollution. Systemic acquired resistance (SAR) taking advantage of natural defence reaction of plants could be proposed as an alternative, ecologically friendly ap-proach for plant protection. Its application into rice production could minimize the chemicals quantity used, and could contribute to the decrease of environmental pollution and the development of sustainable agriculture. The research was conducted to select the best effective chemical and method to improve the health of rice plants infected by grassy stunt disease in net-house of Cantho University. SAR chemicals were used at very low concentrations (in mM). Results showed that the height of rice plants treated with SAR chemicals was higher than that of plants untreated. Besides, the number of diseased plant was reduced and the ratio of firm grain and yield increased when plants were applied by SAR. Among them, oxalic acid was the best systemic acquired resistance. With oxalic acid, seed soaking was better than seed coating in systemic acquired resistance against rice grassy stunt disease.
 Hầu hết các phương pháp sản xuất lúa hiện nay đều sử dụng các hóa chất độc hại trong việc phòng trừ bệnh và côn trùng gây hại, nên dẫn đến ô nhiễm môi trường. Kích thích tính kháng lưu dẫn giúp kích hoạt cơ chế tự nhiênkháng bệnh của cây có thể là giải pháp bảo vệ thực vật thay thế an toàn với môi trường. Việc ứng dụng tiến bộ này vào trong sản xuất lúa có thể làm giảm lượng hóa chất sử dụng, đóng góp vào việc giảm thiểu ô nhiễmmôi trường và sự phát triển của một nền nông nghiệp bền vững. Nghiên cứu đã được thực hiện tại nhà lưới trường Đại học Cần Thơ để tuyển chọn hóa chất và phương pháp sử dụng hóa chất để tăng cường sức khỏe giúp cây lúa vượt qua bệnh vàng lùn. Hóa chất kích kháng được sử dụng ở một nồng độ rất thấp (đơn vị là mM). Kết quả cho thấy chiều cao cây lúa khi xử lý chất kích kháng tốt hơn so đối chứng không xử lý. Bên cạnh đó, số cây lúa nhiễm bệnh giảm, tỉ lệ hạt chắc và năng suất tăng khi cây lúa được xử lý với chất kích kháng. Trong số các chất kích kháng đã sử dụng, acid oxalic cho hiệu quả vượt trội. Với chất acid oxalic, phương pháp ngâm hạt cho hiệuquả kích kháng tốt hơn phương pháp áo hạt.

Detection and Transmission of rice stunt virus on Ciherang and Situ Bagendit Varieties. The explosion of brown planthoppers recently has caused reduction of rice production in Indonesia. Brown planthoppers do not only act as pest, but also transmit Rice grassy stunt virus (RGSV) and Rice ragged stunt virus (RRSV). Detection of the existence of the two viruses in rice plants and vector insects is important to be done to ensure that the virus is infected with the vector. The aim of this research is to detect the existence of virus in varieties of Ciherang and Situ Bagendit as a result of transmission in the laboratory and to find out the ability of brown planthoppers to transmit stunt virus to both of the varieties. This research was compiled using Completely Randomized Design (CRD) with 4 treatments, namely healthy rice plants of Ciherang and Situ Bagendit varieties, Ciherang and Situ Bagendit varieties which were infested by brown planthoppers each with 5 repetitions. The parameters observed were incubation period, symptoms, plant height, number of leaves and incidence of disease. The data on plant height, number of leaves and incidence of disease were analyzed using ANOVA and continued with the Least Significant Difference (LSD) test at the level of 5%. The results showed that Ciherang and Situ Bagendit varieties were only positively infected by Rice ragged stunt virus. The results of the rice transmission showed that Ciherang variety had a faster incubation period of 10 DAI while Situ Bagendit was 14 DAI, but the two varieties showed an inhibition of growth in plant height and number of leaves compared to healthy plants with each incidence of 51.3% and 46.3%.

Yellow leaf disease (YLD) with phytoplasmal aetiology is a serious disease of arecanut palm in India. The present study was undertaken to characterize the 16S rRNA and secA gene sequences of the Indian arecanut YLD phytoplasma for ‘Candidatus Phytoplasma ’ species assignment and 16Sr group/subgroup classification. Phytoplasma 16S rRNA genes were amplified using three sets of semi-nested/nested primers, 1F7/7R3–1F7/7R2, 4Fwd/3Rev–4Fwd/5Rev and P1/P7–R16F2n/R16R2, producing amplicons of 491, 1150 and 1250 bp, respectively, from diseased samples. The amplicons were cloned and sequenced. A blast search showed that the sequences had 99 % similarity with sugar cane white leaf phytoplasma (16SrXI) and Napier grass stunt phytoplasma (16SrXI). Phylogenetic analysis based on the 16S rRNA gene revealed the clustering of YLD phytoplasma with the rice yellow dwarf and Bermuda grass white leaf groups. The YLD phytoplasma F2nR2 sequence shared 97.5 % identity with that of ‘Candidatus Phytoplasma oryzae ’ and 97.8 % identity with that of ‘Candidatus Phytoplasma cynodontis ’. Hence, for finer differentiation, we examined the secA gene-based phylogeny, where the YLD phytoplasma clustered with Napier grass stunt and sugar cane grassy shoot phytoplasmas, both belonging to the rice yellow dwarf group. Hence, we are assigning the Indian arecanut YLD phytoplasma as a ‘Candidatus Phytoplasma oryzae ’-related strain. Virtual RFLP analysis of a 1.2 kb fragment of the 16S rRNA gene (F2nR2 region) identified the Indian arecanut YLD phytoplasma as a member of 16SrXI-B subgroup. We name the phytoplasma Indian yellow leaf disease phytoplasma, to differentiate it from the Hainan YLD phytoplasma, which belongs to group 16SrI.

<p>Brown plant hopper (BPH) is one of the main pest of rice in Indonesia and it occurred every years with fluctuate acreage. BPH is also vector of Rice Ragged Stunt Virus (RRSV) and Rice Grassy Stunt Virus (RGSV). Green Super Rice (GSR) was designed to have resistance to major pests and diseases so that it need less pesticides and thus save ro environment. GSR was developed in IRRI and China and was tested in Indonesia since 2009 until now (2019). This research was aimed to study the genetic variability and heritability of 26 selected GSR lines to RRSV and RGSV along with four check varieties. The experiment was conducted in ICRR Sukamandi and Pusakanagara Experimental Station. The experiment was arranged following randomized complete block design with three replications. Transplanting was done into 21 days old seedling into 25 cm x 25 cm planting space of 1 m x 1 m plot. BPH and virus investation was occured narturally due to BPH outbreak along the season (DS 2010). Percentage of plant showing RRSV and RGSV symtom was measured as consideration the resistance of plant to the viruses. The results showed that the tested genotypes had high genetic variability and heritability classified as medium in the resistance to RGSV. The genotypes showed low genetic variability and heritability in the resistance to RRSV. It implies that breeder effort is feasible to develop resistant lines to RGSV. HUANGHUAZHAN and HHZ 12-Y4-Y3-Y1 are consistently resistant to RGSV and can be used as donors in further plant breeding activities. The selection of resistant individuals in populations of plant breeding material recommended to be done on earlier generations for RGSV and further generation for RSSV.</p>

<p>Development of Rice Core Collection. Tiur S. Silitonga and Andari Risliawati. Rice genetic resources have been collected from almost all of the district in the provinces of Indonesia. Presently, the collection of rice genetic resourses are totally 4.200 accessions. The purpose of these activities were to test, select and grouping of rice genetic resources to develop core collection. Various activities have been conducted such as characterization and selection of rice genetic resources to agronomic performance and yield, evaluation to brown plant hopper and grassy stunt virus and their resistance/tolerance to bacterial leaf blight, blast, and drought. Development core collection with various traits such as morphology and agronomy characteristics, yield component, seed quality, resistance to pest and diseases and tolerance to abiotic stresses will increase the use of rice genetic resources to create high yielding varieties with various traits. The availability of various rice varieties with traits needs could cover all the areas including lowland, upland, swampy areas, and marginal land areas with endemic attacked by pest and diseases. All rice genetic resources have been characterized to agronomic performance and yield in Sukamandi experimental farm, evaluated their resistance to brown plant hopper and bacterial leaf blight in Sukamandi and Cianjur, and drought tolerance in Jakenan, Central Java. The results of the experiment have developed core collection by grouping varieties with their traits such as 55 accession (accs.) of varieties with long panicle (>30 cm), 25 accs. short duration (<115 days), 32 accs. of dwarf plant (<115 cm), 25 accs. of short to medium duration (<130 days) with yielded 4.7-5.9 t/ha, 35 accs. have low to medium amylose content, 20 accs. resistant to brown plant hopper and grassy stunt virus, 33 accs. resistant to bacterial leaf blight, 23 accs. resistant to blast and 30 accs. tolerant to drought.</p><p> </p><p><strong>Abstrak</strong></p><p>Koleksi plasma nutfah padi saat ini lebih dari 4.200 aksesi yang dikumpulkan dari hampir seluruh provinsi di Indonesia. Untuk meningkatkan pengelolaan dan pemanfaatan sumber daya genetik padi telah dilakukan pengujian, seleksi, dan pengelompokan varietas dalam bentuk koleksi inti. Tersedianya koleksi inti plasma nutfah padi dengan sifat agronomis, morfologis, komponen hasil terutama mutu gabah, kadar amilosa, dan ketahanan terhadap hama dan penyakit akan mempermudah pemanfaatannya dalam perakitan varietas unggul padi umur genjah, produksi tinggi, dengan mutu beras dan rasa nasi yang enak. Penelitian ini bertujuan untuk membentuk koleksi inti dengan cara menyeleksi dan mengelompokkan sumber daya genetik padi pada berbagai sifat penting seperti umur genjah, tanaman pendek, hasil tinggi, toleran terhadap cekaman biotik dan abiotik, bentuk beras, dan kadar amilosa. Tersedianya beragam varietas dalam koleksi inti dengan berbagai sifat yang diinginkan akan mempermudah akses dan pemanfaatan oleh para pengguna, terutama pemulia, dalam perakitan varietas baik padi sawah, padi gogo, dan padi lahan rawa pasang surut. Hampir seluruh plasma nutfah padi telah dikarakterisasi dan diseleksi terhadap sifat agronomis dan hasil di KP Sukamandi. Seleksi terhadap hama wereng coklat dan penyakit hawar daun bakteri dilakukan di Sukamandi dan Cianjur, dan pengujian toleransi kekeringan di KP Jakenan, Jawa Tengah. Dari hasil pengujian telah dibentuk koleksi inti plasma nutfah padi dengan sifat penting, antara lain sebanyak 55 aksesi dengan malai panjang (>30 cm), 25 aksesi berumur genjah (<115 hari), 32 aksesi tanaman pendek (<115 cm), 25 varietas memiliki potensi hasil antara 4,7-5,9 t/ha dan umur genjah sampai sedang (<130 hari), 35 aksesi kadar amilosa rendah sampai sedang, 20 aksesi tahan terhadap hama wereng coklat dan virus kerdil rumput, 33 aksesi tahan terhadap penyakit hawar daun bakteri, 23 aksesi tahan penyakit blas, dan 30 aksesi toleran kekeringan.</p>

Most rice protection methods have currently used toxic chemicals to control pathogens and pests, which leads to environmental pollution. Systemic acquired resistance (SAR) taking advantage of natural defence reaction of plants could be proposed as an alternative, ecologically friendly approach for plant protection. Its application into rice production could minimize the chemicals quantity used and could contribute to the decrease of environmental pollution and the development of sustainable agriculture. The research was conducted to select the most effective chemical and suitable method to improve the health of rice plants infected by grassy stunt disease in net-house of Can Tho University. SAR chemicals were used at very low concentrations (in mM). Results showed that the height of rice plants treated with SAR chemicals was higher than that of plants untreated. Besides, the number of diseased plants was reduced and the ratio of firm grain and yield increased when plants were applied by SAR. Among the used substances, oxalic acid provided the best systemic acquired resistance. With oxalic acid, seed soaking was better than seed coating in systemic acquired resistance against rice grassy stunt disease<br>Hầu hết các phương pháp sản xuất lúa hiện nay đều sử dụng các hóa chất độc hại trong việc phòng trừ bệnh và côn trùng gây hại, nên dẫn đến ô nhiễm môi trường. Kích thích tính kháng lưu dẫn giúp kích hoạt cơ chế tự nhiên kháng bệnh của cây có thể là giải pháp bảo vệ thực vật thay thế an toàn với môi trường. Việc ứng dụng tiến bộ này vào trong sản xuất lúa có thể làm giảm lượng hóa chất sử dụng, đóng góp vào việc giảm thiểu ô nhiễm môi trường và sự phát triển của một nền nông nghiệp bền vững. Nghiên cứu đã được thực hiện tại nhà lưới trường Đại học Cần Thơ để tuyển chọn hóa chất và phương pháp sử dụng hóa chất để tăng cường sức khỏe giúp cây lúa vượt qua bệnh vàng lùn. Hóa chất kích kháng được sử dụng ở một nồng độ rất thấp (đơn vị là mM). Kết quả cho thấy chiều cao cây lúa khi xử lý chất kích kháng tốt hơn so đối chứng không xử lý. Bên cạnh đó, số cây lúa nhiễm bệnh giảm, tỉ lệ hạt chắc và năng suất tăng khi cây lúa được xử lý với chất kích kháng. Trong số các chất kích kháng đã sử dụng, acid oxalic cho hiệu quả vượt trội. Với chất acid oxalic, phương pháp ngâm hạt cho hiệu quả kích kháng tốt hơn phương pháp áo hạt