Indra DeoRather, Shoukat Ahmad2018-11-262018-11-262017-12http://krishikosh.egranth.ac.in/handle/1/5810084378Brown planthopper (BPH) is one of the destructive insect pests causing significant yield losses in rice. BPH causes direct damage to the rice plants by sucking the sap from phloem, causing hopper burn and transmitting viral diseases like grassy and ragged stunt viruses. Several resistant donors have been identified from time to time, but the new biotypes of the pest arise to defeat the extended use of resistance genes in a single variety. This necessitates the regular identification of new resistant donors along with their characterization at genetic and molecular level. Such characterization facilitates their easy and efficient utilization in crop improvement programmes. Keeping this in view, the present investigation was carried out at G.B. Pant University of Agriculture & Technology, Pantnagar, Uttarakhand, India to identify and genetically analyze the new BPH resistance sources using classical and molecular tools. In addition, some other objectives like characterization of advanced breeding lines of rice and assessment of relative efficiency of different emasculation methods were also undertaken. The phenotypic evaluation of advanced and stable lines of rice using standard seed box screening technique revealed that genotypes PHS 29, MRST 3 and RP 2068-18-3-5 were resistant to BPH whereas, all the advanced lines were susceptible except for UPR 3943-8-1-1, UPR 3947-23-2-2, UPR 3871-8-1-2-2, UPRI 2013-10, UPR 3906-18-2-1, UPR 3951-1-1-2-1, UPR 3957-5-2-2 and UPR 3960-2-1-1, which were moderately susceptible. The molecular analysis of mapping populations (F2:3) derived from TN 1 x PHS 29 and Pusa Basmati 1 x MRST 3 crosses revealed that putative SSR markers RM3355 and RM50 were associated with BPH resistance. Primer RM50 was also confirmed to be associated with the trait using a representative pool of advanced breeding and stable lines for molecular analysis. The inheritance studies carried out on the basis of goodness of fit of segregation ratios of BPH resistant and susceptible plants in F2 generation revealed that the resistance in PHS 29 and MRST 3 genotypes is conditioned by one and two recessive genes, respectively. The gene action of BPH resistance in PHS 29 was found to be additive in nature. Whereas, in MRST 3 genotype, it was found to be dominance in nature. As far as analysis of yield and yield contributing traits is concerned, genotypes reflected significant differences and superior grain yield per plant was recorded in genotypes UPR 3906-18-2- 1, UPR 3837-7-2-1-1, UPRI 2013-4 and UPR 3819-9-1-1-1 over the years. Among various emasculation methods, hand emasculation was found to be the most efficient with pooled mean efficiency of 84.05%. Suction method was identified as the second most efficient emasculation technique after hand emasculation with pooled mean efficiency of 75.74%. The results also indicated that emasculation efficiency is genotype- independent. Concluding the results of the present endeavour, the new resistance donors can be very useful in tackling BPH attacks on rice, especially in this part of the world. However, there is a need to conduct allelic tests of the identified resistant lines by crossing them with already characterized BPH resistant sources in order to know whether the identified BPH resistant sources in the investigation are different from previous sources. Furthermore, fine mapping analysis of these possibly new genes of resistance can be carried out using the linked markers identified during the present study.ennullThesis