Differential response of rabi sorghum (Sorghum bicolor L. Moench) genotypes todrought stress in the northern zone of Karnataka

Abstract

Sorghum is a major cereal crop well adapted to the semi-arid and arid climatic conditions found in northernKarnataka, Maharashtra, Andhra Pradesh, Telangana and other similar regions. The sorghum crop is known for its droughtadaptability while being classified as a major millet for its nutritional benefits. A field experiment was conducted usingeighteen rabi sorghum genotypes in the rabi of 2021-22 at the Vijayapura under the All India Coordinated SorghumImprovement Project. The genotypes were collected from various locations in India. These genotypes were evaluated fortheir physiological performance in the northern dry zone of Karnataka. The highest assimilation rate was achieved by RSV1876 (31.1 μmol m-2s-1 at flowering and 16.77 μmol m-2s-1 at physiological maturity) under the water stressed regimefollowed by Phule Anuradha (29.98 μmol m-2s-1 at flowering and 17.14 μmol m-2s-1 at physiological maturity). PhuleAnuradha transpired 5.13 mmol m-2s-1 of H2O at flowering and 3.647 mmol m-2s-1 of H2O at the physiological maturity closeto RSV 1876 with 5.130 mmol m-2s-1 of H2O and 3.602 mmol m-2s-1 of H2O at flowering and physiological maturityrespectively. The RSV 1876 outperformed other genotypes by accumulating 2.519 mmol proline per gram fresh weight ofleaf already at the flowering which increased the accumulation to 2.938 mmol proline per gram fresh weight of leaf under thewater stress condition. The genotype CRS 99 (89.4 % in the non-stress and 89.65 % in the stress regime) had highest leafRWC followed by RNTN-13-39 (88.5 % in the non-stress and 88.7 % in the stress regime). The genotype RSV 1876 hadthe highest chlorophyll content of 4.33 mg g-1 leaf fresh weight at flowering degrading to 3.506 mg g-1 leaf fresh weight underthe stress condition. The genotype RSV 1876 was able to achieve the highest yield of 53.65 gram of seed yield per plantinsignificantly followed by Phule Anuradha producing 52.09 gram of seed yield per plant when subjected to the stresscondition