K. JAYALALITHAR. PAVANI2023-11-302023-11-302023-11-30D6398https://krishikosh.egranth.ac.in/handle/1/5810201985Root study and the field experiment were conducted for the “Evaluation of pigeonpea [Cajanus cajan (L.) Millsp] genotypes for high root mining, morpho-physiological and yield parameters under rainfed situation” during kharif 2019 and 2020 at RARS farm and Dryland farm, S.V. Agricultural college, Tirupati. Ten treatments consisting of ten genotypes out of which four were mid-early duration genotypes (V1- PRG-176, V2- CO-6, V3- AKTE 12-04, V4- ICPL 8863), four were medium duration genotypes (V5- MPV 106, V6-RVSA 16-1, V7-LRG 133-33, V8-LRG-52) and remaining two were long duration genotypes (V9-ICPL 15062, V10- ICPL 17103) were selected for the study purpose. Root Mining studies were carried out under specially raised rectangular soil beds of size i.e; 15m x 2m x 1.5m (Lx B x H) in completely randomized block design and replicated twice, whereas the field study was carried out in randomized block design and replicated thrice. Significant genotypic variation was observed among the mid-early, medium and late duration genotypes with respect to root traits, growth, photosynthesis, WUE traits, heat tolerance traits, crop weather relations, biochemical and yield parameters. In the root study, the mid-early duration genotype, CO-6 and the medium duration genotype, LRG-52 exhibited superior performance by recording 66.0 and 57.0 per cent increase in root length over the late duration genotype, ICPL 15062. LRG-52 increased the number of primary and secondary roots by 64.0 and 57.0 per cent, and CO-6 by 50.0 and 45.6 per cent, respectively, over the late duration genotype, ICPL 17103. Higher root: shoot ratio was recorded in the genotype LRG 52 (0.41) and the lesser root: shoot ratio was recorded in ICPL 8863 (0.23) at 65 DAS in simulated raised soil bed conditions. Among the ten genotypes evaluated under field study, the maximum total plant drymatter production was recorded significantly in the genotypes LRG-52 and CO-6 and the increase was 1.5 folds over the late duration genotype ICPL 17103. These two genotypes recorded 1.6 and 1.4 folds increase in pod drymatter, xvii respectively, over ICPL 15062 at harvest. Hence these two genotypes were considered as efficient total dry matter partitioning ones under rainfed conditions. LRG-52 and CO-6 exhibited less leakage of solutes and increased the membrane thermo stability index by 27.4 and 24.6 per cent, respectively over ICPL 15062 and decreased the canopy temperature by 20.7 and 17.2 percent, respectively, over ICPL 17103 and by 18.7 and 15.1 per cent, respectively over ICPL 15062. CO-6 and LRG-52 recorded higher heat use efficiency and increased by 107.0 and 96.5 per cent, respectively over ICPL 17103. Hence these two genotypes with higher MSI and lesser canopy temperature were considered as heat tolerant genotypes compared with the late duration genotypes under rainfed situation. The maximum SCMR was recorded in LRG-52 and CO-6 genotypes and increased the value by 42.1 and 41.0 per cent, respectively, over ICPL 17103 and 41.8 and 40.6 per cent, respectively, over ICPL 15062. These two genotypes recorded 31.3 and 26.6 per cent increase in RWC over ICPL 15062. LRG-52 and CO-6 recorded 15.4 and 20.0 per cent decrease in SLA over the late duration genotype ICPL 15062 at flowering and pod formation stage of the crop (120 DAS). Hence these two genotypes with high RWC, SCMR and lesser SLA were considered as higher WUE genotypes under rainfed conditions. In the current investigation, genotypic variation was observed with respect to photosynthetic attributes. The genotypes LRG-52 and CO-6 recorded 49.6 and 42.4 per cent increase in photosynthetic rate over ICPL 17103. With respect to crop weather relations under rainfed conditions, at maturity, the late duration genotypes recorded the highest GDD of 3389.8 oC day followed by the medium duration genotypes, recorded the GDD value of 3076.6 oC day. The lowest GDD of 2724.0 oC day was recorded by the mid-early duration genotypes. At harvest, LRG-52, a medium duration genotype recorded maximum number of pods per plant and increased by 70.1 per cent and CO-6 by 64.5 per cent over ICPL 17103. This might be due to increase in number of branches plant-1 where balance was maintained between vegetative and reproductive phase. LRG-52 recorded the maximum 100 seed weight of 12.93 g which was at par with CO-6 (11.48 g). The minimum 100 seed weight of 9.53 g was recorded in ICPL 17103 which was at par with ICPL 15062 (10.11 g). LRG 52, a medium duration genotype exhibited superior performance and increased the seed and stalk yield by 74.3 and 18.8 per cent, respectively, and CO-6 by 63.0 and 23.1 per cent, respectively over the long duration genotype ICPL 17103. LRG-52 recorded higher HI of 28.44 % and the lesser HI was recorded in ICPL 17103 (21.16%). Correlation studies revealed that there is high positive correlation between growth and yield attributes. Medium and late duration genotypes exposed to terminal moisture stress (i.e., 2 to 3 continuous dry spells) during flowering and pod formation stages in both the years of study. The medium duration genotype LRG-52, eventhough faced with moisture stress, performed better over other maturing groups (i.e., late duration genotypes) in the present study. However, the mid-early duration genotype CO-6 was also comparable with that of medium duration genotype LRG-52 with regards to seed yield due to its early maturing character, and it is considered to use where early maturity of the crop is required, especially under rainfed conditions to escape the terminal moisture stress. The genotypes ICPL 15062 and ICPL 17103 were xviii late maturing and encountered moisture stress during flowering and pod formation stages during both the years of study that resulted in lesser seed yield and its components in the present study. Based on the results obtained, it can be concluded that the medium duration genotype LRG-52 has the capacity to withstand terminal drought situations and can be recommended as a drought tolerant one especially under rainfed conditions. Along with this, the mid-early duration genotype CO-6 can also be recommended to rainfed areas as it possess drought escape nature because of its earliness character. Hence these two genotypes may be popularized due to their noteworthy performance under rainfed conditions in Southern zone of Andhra Pradesh.EnglishThesis