Effect of irrigation levels and mulching on growth and yield performance of nigella (Nigella sativa L.)

The present study evaluated the interactive effects of irrigation scheduling and mulching on growth, physiological traits, and yield of Nigella sativa under semi-arid conditions of central India. The experiment was conducted in a split-plot design with four irrigation regimes (IW/CPE ratios of 1.0, 0.8, 0.6, and 0.4) as main plots and four mulching treatments (silver-black polythene, black polythene, organic mulch, and no mulch) as subplots. Results revealed that the highest plant height (66.71 cm), number of branches (8.21), and LAI (2.00) at harvest were recorded under IW/CPE 1.0 + silver-black mulch (T₂), closely followed by IW/CPE 0.8 + silver-black mulch (65.92 cm, 8.03 branches, and 1.97 LAI, respectively). The corresponding LAD values were 60.36 (T₂) and 58.60 (T₆) compared to only 27.89 under severe water deficit (IW/CPE 0.4 without mulch, T₁₆). Reproductive parameters also followed a similar trend, with maximum capsules per plant (37.86) and seeds per capsule (90.54) in T₂, whereas the lowest values (23.24 capsules and 77.76 seeds) occurred in T₁₆. Seed yield was markedly influenced, ranging from 1160.71 kg/ha in T₂ to 640.87 kg/ha in T₁₆, while harvest index varied from 33.04% (T₂) to 26.99% (T₁₆). The study clearly demonstrated that optimum irrigation (IW/CPE 0.8–1.0) coupled with reflective polythene mulches, particularly silver-black mulch, significantly enhanced water conservation, canopy longevity, and assimilate partitioning, thereby improving seed yield by 45–50% over deficit irrigation without mulch. These findings confirm that integrated irrigation–mulch management is a practical strategy for maximizing productivity and sustainability of nigella cultivation in semi-arid regions.