Weighted Geometric Mean Index to identify drought tolerant Post-rainy sorghum [Sorghum bicolour (L.) Moench] lines

Abstract

Twenty five genotypes were evaluated along with four checks viz., M35-1, Phule Anuradha, CSV 22, and CSV 26during post-rainy season 2016-17 under three water regimes at Centre on Rabi Sorghum farm, Solapur (1.) Well watered -irrigated throughout the crop season, 2. Limited water stressed i.e irrigated till GS2 growth stage and 3. Severe water stressed i.e. irrigated till GS1 growth stage. The experiment was conducted in split plot design with three replications. Plot size was 3 rows of 3m length for each genotypes and spacing 45x15cm. Drought tolerant and susceptible genotypes were categorised on the basis of Weighted Geometric Mean Index (WGMI). To calculate WGMI, different weights were assigned to the treatments according to experimental mean yield difference between severe drought (yield under GS1 environment ) and well watered (non-drought) environment. The experimental mean grain yield under GS1, GS2 and well watered conditions were 230.60, 802.23, and 1160.39 g/plot, respectively hence weights 5.03, 3.47, and 1 were assigned to these treatments accordingly. Genotypes having higher WGMI than summation of mean WGMI and standard deviation of WGMI were categorized as tolerant, higher than mean WGMI as moderately tolerant and lower than mean WGMI as susceptible. Based on these criteria genotypes under GS1 environment CRSDT 10, CRSDT 3, CRSDT 4, and CRS 58 were categorized as drought tolerant and CRS 57, CRS 52, CRS 7, CRSDT 7, Phule Anuradha, and M35-1as moderately tolerant. Under GS2 environment genotypes CRSDT 4, CRS 60, Selection 3, Phule Suchitra and CRS 58 as tolerant and IC 343586, CRSDT 5, CRS 52, CRSDT 12, IC 392137, M35-1, CRSDT 3, and CRSDT 8 as moderately tolerant. For GS 1 as well as GS 2 environments CRSDT 4, CRSDT 3, CRS 58, CRSDT 10 and CRS 52 as tolerant and CRS 57, CRS 7, Phule Anuradha, Phule Suchitra, M35-1, Selection 3, CRSDT 12, CRSDT 7, and IC 343586 moderately tolerant. The experimental mean fodder yield under GS1, GS2 and well watered conditions were 1969.33, 2292.00, and 2525.33 g/plot, respectively hence weights 1.28, 1.16, and 1 were assigned to these treatments. Under GS1 environment for fodder yield CRS 48, IC 392156, IC 392137 and CRS 60 as drought tolerant and CRS 20, IC 343586, IC 392155, CRS 59, CRS 7, CSV 26, CRSDT 6, Selection 3, CRSDT 4 and Phule Suchitra as moderately tolerant. Under GS 2 environment CRS 20, CRS 60, IC 392156, CRS 48 as tolerant and IC 343586, IC 392137, Phule Suchitra, CRS 59, CRSDT 4, CRSDT 12, Selection 3, CRSDT6, CRS 57 and phule Anuradha categorized as moderately drought tolerant. For GS 1 as well as GS 2 environments CRS 48, IC 392156, CRS 60, and IC 392137 tolerant and CRS 20, IC 343586, IC 392155, CRS 59, CSV 26, CRS 7, CRS DT6, Phule Suchitra CRSDT 4 and Selection 3 moderately tolerant.