ABSTRACT Guar ( Cyamopsis tetragonoloba L.) is a drought‐tolerant crop and an important source of gum and bioactive compounds. The present study was conducted to investigate the response of 15 different guar genotypes under three soil moisture levels (100%, 70%, and 45% FC). The results indicated that drought stress caused significant reductions in physiological traits such as relative water content (RWC), seed gum (SG), viscosity, and dry matter digestibility (DMD). For instance, mean RWC decreased from 85.96% under non‐stress conditions to 79.58% at 70% FC and 64.23% at 45% FC, whereas genotypes showed considerable variation in their responses (at 70% FC, the lowest reduction was observed in S6673 with −2.0%, and the highest reduction in RGC‐1066 with −13.6%). SG decreased from 28.17 at 100% FC to 25.63 and 21.11 at 70% and 45% FC, respectively, and DMD declined from 46.96 to 43.63 and 37.1. Viscosity also decreased from an average of 2645 under non‐stress conditions to 1906 and 1603 at 70% and 45% FC, respectively. In contrast, bioactive compounds and antioxidant indices increased under drought stress. Reductions in protein and carotenoids were also observed; protein content decreased from 28.07 to 24.2 and 16.29, and carotenoids declined from 2.12 to 1.58 and 1.25. Based on the MGIDI, genotype RGC‐986 showed the highest similarity to the ideal genotype and was identified as the superior genotype with high performance in physiological and biochemical traits. Genotypes RGC‐1031, Saravan, and S6566 also exhibited acceptable performance under drought stress, whereas genotypes such as S‐5885 and BR‐99 showed the lowest adaptability. These results demonstrated that despite reductions in some quantitative and nutritional traits, drought stress enhanced phenolic compounds, tannins, flavonoids, and antioxidant capacity, and these findings can be utilized in breeding programs and targeted cultivation of guar in water‐limited regions.
ShariffAl‐Sheikh et al. (Thu,) studied this question.