|Title:||水稻對褐飛蝨抵抗性研究：特別論及寄主與生物小種間之相互作用||Other Titles:||Studies on Varietal Resistance to the Brown Planthopper in Rice with Special Emphasis on the Interaction Between Host and Biotypes||Authors:||鄭清煥
|Keywords:||水稻;褐飛蝨||Issue Date:||Dec-1984||Publisher:||農業試驗所||Related Publication(s):||稻作區域性與期作性低產及增產措施之研究||Start page/Pages:||293-322||Source:||農業試驗所特刊;第16號||Abstract:||
The brown planthopper (BPH) is the most destructive insect pest of rice in Taiwan especially in the second rice crop. A cultivation of resistant varieties is considered as the most economic measures for control of the hopper. During past decade, a program for breeding rice resistance to the hopper have been well established in Taiwan and six resistantt varieties have been named and released for commercial cultivation. Recently, in view of the occurrence of biotypes of BPH in southeast Asia only two to three years after resistant variety JR 26 was cultivated extensively. In order to avoid a monoculture of monogenic resistant varieties to induced the occurrence of virulent bio-types of the hopper as which have happened in southeast Asia, it is considered importance to breed rice for resistance in diverse genetic basis. For this purpose, three hundred and ninety eight variety (lines) with different resistance genes were introduced from the International Rice Research Institute (IRRI) and identified both in laboratory and field in this study. Among them 32 improved resistant lines with Bph-3, bph-4, or genes combination of Bph-3 or bph-4 with Bph-1 or bph-2, and the progenies of Ptb 33 (with two unidentified reistance genes) were selected as good sources for breeding resistance to BPH (Table 1). In addition, three “field resistance” varieties (resistance is possibly conditioned by polygenes), Triveni, Utri-Rajapan and Kencana were also introduced from the IRRI, and a method for identification of such type of resistance was also established by infestation of 30-day-old seedings planting in a plate and infestation with a density of 4 seedlings per mated-female of BPH. By using this method, the ¡§field resistance¡¨ varieties could be identified from the susceptible varieties during the nymphal stage of following generation.
The interactions between varieties with different resistance genes and four biotypes of BPH. were also investigated at present study. It indicated that the host preference, survival rate, population development and degree of damage of different biotypes on varieties with different resistance genes differed significantly. The biotypes developed from varieties with Bph-1 and Bph-3 . resistance genes were more virulent than that was developed from variety with bph-2. No mechanical barrier was observed in the tissues of rice plant to disturb the feeding of biotypes from resistant varieties. However, when every biotpye was caged to feed on resistant variety, the insect changed feeding sites frequently, and more branch of stylet sheath produced in each feeding was observed. A significantly less amount of honeydew excreted when the insect caged on resistant varieties, that is considered as mainly due to a lack of feeding stimulant involved in the resistant varieties.
The ability and inability of biotypes to survive and infest on varieties with different resistance genes was observed to be polygenic in nature. The results of reciprocal crosses between biotypes I and II, and between biotypes I and III showed that the inability of biotype I to survive on Mudgo was partial dominant to those of biotype II, and the inability of biotype I to survive on H 105 was partial dominant to those of biotype III. Reciprocal crosses between biotype II and III indicated that the inability of biotype III in survival and infesting Mudgo was over dominant to those of biotype II.
The experiment conducted to assess whether or not the evolution of new biotypes can be prevented or retarded by use of a rotative or mixed planting of resistant varieties with different resistance genes, the survival rate of the nymphs of BPH on such planting systems was compared with those which were reared continously on a fixed resistant variety. The results showed that BPHs were easy to shift their ability to survive on resistant variety when they were forced to feed on the variety continously for more then 6 generations. However, when the resistant varieties with different resistance genes were grown in rotation or grown in mixture, then the survival of BPHs on a particular resistant variety were evidently lower than that was forced to feed on a particular resistant variety continously. This indicate that rotative or mixed cultivation of resistant varieties having different resistance gene in an area could slow down the evolution of new biotypes.
The resistant varieties having released for commercial cultivution in Taiwan are all with bph-2 resistance genes and belong to moderate resistant ones. These varieties tested in an outbreak of BPH conditions showed that the resistant varieties alone could not suppress the BPH population below the level of economic threshold. However, by cultivation of resistant varieties could reduce more than a half of insecticidal application. Since the selection pressure of these varieties to BPH are lower than that of 1R26, they migh not overcome by the new virulent biotypes as easy as that of 1R26 in southeast Asia countries. In addition, a cultivation of morderate resistant varieties were observed to be compatible with biological control since they did not reduce the natural enemies of the pest inhabiting on them. Accordingly, the varieties with bph-2 resistance-gene were considered as an important element of an integrated rice-insect pests manager-ment program. Nervethiess, as mention above when resistant varieties are planted extensively in a big area, planting resistant varieties with different resistance genes would be more effeictve in preventing the prevalence of virulence biotypes of the BPH than that of monoculture with monogenic resistant varieties. Therefore, breeding for resistance to BPH in diverse gonetic basis is urgent needed.
|Appears in Collections:||植物保護系|
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