Identification of Drought Tolerant Genotypes in Backcross Inbred Lines of Rice using Drought Indices

Abstract

The experimental material for the present investigation consisted of 101 Backcross Inbred Lines (BILs) developed by two parents viz., Norungan (drought resistant, recurrent) and TKM 9 (drought susceptible, donor). The present investigation was envisaged to identify the drought tolerant BILs through drought indices like Drought Susceptibility Index (S) proposed by Fischer and Maurer (1978) based on the relationship of the change in relative yield (yield in drought / yield in absence of drought) of an individual cultivar to change in relative yield across a range of stress intensities on comparison and Drought Response Index (DRI) using linear regression on yield potential and days to 50% flowering given by Bidinger et al. (1987). Descriptive statistics revealed that the range of DSI and DRI values varied from -11.07 to 3.78 and -1.84 to 2.48 respectively. In general, the result of the investigation exhibits that, the cultures CB-07-701-283, CB-07-701-98, CB-07-701-280, CB- 07-701-174 and CB-07-701-156 recorded the lowest values of DSI and the cultures CB-07-701-161, CB-07-701-174, CB-07-701-268, CB-07-701-147 and CB-07-701-255 recorded the highest DRI values which ultimately indicates that these genotypes were highly tolerant to drought stress situa- tions and produced the highest grain yield. On comparing the DSI and DRI values, the culture CB- 07-701-174 (DSI: -7.69 and DRI: 2.33) was present in both the indices which strongly reveals that this genotype was highly resistant in nature and had significant higher grain yield under stress when compared to irrigated condition. It was suggested that, these genotypes are suitable for drought stress conditions and are appropriate for hybridization with the aim of increasing drought tolerance in further breeding programs.