Optimizing morpho-physiological traits and yield potential in Indian mustard [Brassica juncea (L) Czern] through irrigation frequency, humic acid and sulphur application

The depleting of water resources and poor nutrient availability during crop growth pose significant stress, adversely affecting the vegetative and reproductive growth of mustard crops. This stress extends its negative impact to the reproductive stage and on oil content. Consequently, morpho-physiological traits were targeted for evaluation under varying irrigation frequencies and the application of humic acid and sulphur, both individually and in combination, using a split-plot design.The results demonstrated that the treatment involving three irrigations (I3) and the combination of humic acid and sulphur (T3) were consistently the most effective and statistically significant at p = 0.05 for most parameters. The interaction effect of these treatments was observed specifically for absolute growth rate (AGR), crop growth rate (CGR), relative growth rate (RGR), total number of branches per plant, seed yield (kg/ha), and total chlorophyll content (mg/g).Furthermore, I3 exhibited the highest percentage increase over the control for parameters such as plant height (9.3%), dry matter accumulation (35.5%), number of leaves (65.24%), leaf area (24.97%), leaf area index (36.01%), absolute growth rate (23.42%), crop growth rate (15.34%), net assimilation rate (37.08%), relative growth rate (56.93%), total number of branches (10.85%), seed yield (kg/ha), and total chlorophyll content (10.85%). Similarly, T3 recorded increases of 12.1%, 31.3%, 22.46%, 12.63%, 31.93%, 12.41%, 4.02%, 34.17%, 50.70%, and 12.75% for these same parameters, respectively.This study highlights the significant potential of combining three irrigations at critical growth stages with the application of humic acid and sulphur to mitigate the adverse effects of water stress on morpho-physiological traits in Indian mustard (Brassica juncea (L) Czern). Such interventions demonstrate promise in improving growth, yield, and physiological performance under induced water stress conditions.