Prof. J. P. LalSaumya Awasthi2016-09-212016-09-212014http://krishikosh.egranth.ac.in/handle/1/77967The present study, “Genetic enhancement for drought tolerance in rice (Oryza sativa L.) Through Marker Assisted Selection” was undertaken with a view to estimate the nature and magnitude of gene effects contributing to yield and its traits under moisture – stress (rainfed) and moisture non stress (irrigated) environments. Isolated and identified high yielding lines through MAS. Six elite diverse genotypes (three drought susceptible and high yielding and three drought tolerant varieties) of rice were selected. Among the six genotypes three were used as Testers (HUR – 3022, HUR – 105 and Sarjoo - 52) as females while the remaining three genotypes were used as testers (Nagina – 22, Anjali and Birsa Gora) as males for making the crosses following line × tester design. The experiments were carried out at Agricultural research farm, Institute of Agricultural Sciences, Banaras Hindu University, Varanasi, during Kharif (rainy season) of 2009 to 2011 and off season crop during 2009-10 at Central Rice Research Institute, Cuttack, Odisha. Three drought susceptible varieties were crossed with three drought tolerant varieties to produce nine F1’s (excluding reciprocals) in line × tester fashion during kharif, 2009. F1’s along with their parents were grown during off season, 2009 – 2010. Fresh crosses were attempted to make F1’s, BC1 and also F1’s were selfed to produce F2 seeds. The seeds of F1, BC1F1 along with the parents were grown in compact family randomized block design in three replications during Kharif 2010. Fresh crosses were also made to get F1 seeds whereas F1, F2 and BC1F1 plants were selfed to get F2, F3 and BC1F2 seeds. Five generations P1, P2, F1, F2 and F3 from each of the nine crosses were grown in Randomized block design with three replications under two environments i.e. moisture stress (rainfed) and moisture non – stress (irrigated) during kharif, 2011. There exist highly significant differences among the parents and their crosses for all the traits studied during Kharif, 2011 under rainfed and irrigated conditions. Observations were recorded on 20 plants for parents F1 and 50 plants for F2 and F3 per replication were selected randomly from each crosses for 11 quantitative traits including drought traits viz., seedling height, plant height, stomatal count, leaf rolling, stay green, panicle weight, per cent filled grains, number of spikelets per panicle, 1000-seed weight, grain yield per plant and proline content. All the crosses were subjected to C & D scaling tests as suggested by Mather (1949) to examine whether epistatic gene effects exists in the material under study, and if so what is the relative importance. Accordingly in interacting crosses all the five – parameters (m, d, h, i and l) were estimated. Presence of epistasis/ gene interaction varied with the crosses as well as traits, most of the crosses exhibited presence of epistasis. The generation mean analysis for most of the characters showed the importance of both additive and dominance types of gene effects. However, additive gene effect, in general was higher than dominance gene effects under both the conditions. In presence of epistasis, almost all the crosses showed duplicate type of gene interaction. On the basis of drought parameters, line SA – B – 10 – 35 derived from the cross (HUR 3022 × Birsa Gora) × HUR – 3022 was identified/ selected as drought tolerant which might be expected to give high yielding drought tolerant plant in segregating generation, under irrigated condition. In case of rainfed condition, line SA – D – 10 -9 derived from the cross (Sarjoo 52 × Birsa Gora) × Sarjoo – 52 performed well. The component traits such as, proline content, stomatal behaviour, leaf rolling, stay green, percent filled grains, 1000 seed weight and yield per plant singly or in combinations appear to be most important towards enhancing seed yield and drought tolerance in transgressive segregants. From the cross (HUR – 3022 × Nagina - 22) × HUR – 3022, plant numbers, SA- A – 2, SA – A – 5, SA – A – 13, SA – A – 16, SA- A – 24, SA- A – 32, and SA – A – 56 were found to have drought tolerant gene qDTY2.3. In case of (HUR – 3022 × Birsa Gora) × HUR – 3022, two drought tolerant genes were incorporated. Only those plants were therefore selected which showed polymorphism for the genes qDTY2.3 and qDTY3.2. Thus, plant number SA – B – 7, SA- B – 11, SA – B – 14 and SA – B – 16, SA – B – 22, SA – B – 28, SA – B 32 were selected. Cross (Sarjoo – 52 × Nagina - 22) × Sarjoo – 52 exhibited polymorphism for the presence of a single gene for drought tolerance i.e. MQTL1.1. Plant number SA – C – 4, SA – C – 10, SA – C – 12, SA – C – 15, SA – C – 22, SA – C – 23, SA – C – 24, SA – C – 29, SA – C – 56, SA – C – 60 and SA – C – 75 were selected on the presence of gene responsible for the drought tolerance. In case of (Sarjoo - 52 × Birsa Gora) × Sarjoo - 52, two drought tolerant genes were incorporated. Only those plants were therefore selected which showed polymorphism for the genes MQTL1.1 and qDTY3.2. Thus, plant number SA – D – 1, SA – D – 7, SA- D – 8, SA – D – 9, SA – D – 13, SA – D - 27 and SA – D – 56 were selected.enRice, drought tolerance, marker assisted selection, Morpho-physiological characterizationThesis