Assessment of Multiple Tolerance Indices to Identify Rice Lines Suitable for the Aerobic System of Cultivation

Climate resilience is the most concentrated subject in the current scenario for rice improvement. The aerobic system of rice cultivation involving direct seeding with need-based irrigation in non-puddled soil is gaining ground with respect to a current scenario of water scarcity. The selection of lines suitable and stable under aerobic along with irrigated conditions without any yield penalty is one of the focus areas of the breeding programme for resource use efficiency. In the present study, we have screened a panel of 118 rice lines under aerobic i.e. limited water conditions and irrigated conditions at ARS Dhadesugur Karnataka to identify ideal selection indices viz. STI, TOL, SSI, YSI, YR, YI, PYR, MP and GMP for selecting the best high-yielding and stable lines under both rice cultivation methods. The deployment of selection indices here only pertains to finding the differences in yield per plant under aerobic and irrigated conditions. According to the results of multivariate analysis (correlation and PCA), STI, YI, MP and GMP exhibited a strong correlation with YP and YS. Therefore, they appear to be the most effective stress indices for the selection of lines with good yield potential under water-limited and irrigated conditions. These indices serve as valuable selection criteria for the identification of aerobic-tolerant cultivars from both water-limited and normal conditions. These indices identified lines, DB 5 (Swarna × Oryza nivara (IRGC 81848)) and NPK-40 (Swarna × Oryza nivara (IRGC81832)) wild introgression lines. GNV-14-96-1 (BPT-5204 × Nerica line) Advanced breeding line. JBB 631-1 ((Swarna*2/ IRGC 4105) (RP 5405-JBB-631-1-1-1-1-1-1)) Tropical japonica × indica introgression line. KR-209 (Wazuhophek × ISM) and KR-262 (Wazuhophek × ISM) recombinant introgression lines. TI-36 and TI-124 Ethyl Methane Sulfonate (EMS) mutants of BPT-5204. WB-10 (Langphou) and WB-16 (Phouoibi) North-Eastern Landraces were promising for both environments. These lines are suitable because of low grain yield loss under aerobic conditions and can be further considered for cultivation.