International Journal of Plant & Soil Science

Lettuce (Lactuca sativa L.), a cool-season leafy vegetable of high nutritional and medicinal value, is globally recognised as a premier salad crop. The study aims to investigate the effect of brassinolide and plant spacing on morphological and yield attributes of Lettuce. The present study was conducted during the Rabi seasons of 2023–24 and 2024–25 at SHUATS, Prayagraj, to evaluate the effect of Brassinolide (BR) application and plant spacing on growth and yield attributes of lettuce. The experiment followed a factorial randomised block design comprising five Brassinolide levels (0, 4, 8, 12, and 16 ppm) and three plant spacings (45×30 cm, 45×45 cm, and 45×60 cm), with 15 treatment combinations replicated thrice. Results revealed that Brassinolide application at 12 ppm (B₄) significantly enhanced plant growth and productivity across both years and pooled data. This treatment recorded the highest plant height (30.21 cm), number of leaves per plant (27.39), leaf length (21.34 cm), width (20.12 cm), fresh (16.28 g) and dry (0.84 g) leaf weights, and maximum yield (251.72 q/ha). Plant spacing of 45×30 cm (S₁) also led to superior growth and yield, with the highest values observed across most parameters. Interaction effects between BR levels and spacing were also significant. The findings suggest that the combined application of Brassinolide @ 12 ppm with a spacing of 45×30 cm optimises vegetative growth and yield of lettuce. This highlights the potential of BRs in enhancing physiological performance and productivity, especially under intensive cultivation systems. In conclusion, the application of Brassinolide improves the attributes to Brassinolide's role in promoting cell division, elongation, chlorophyll synthesis, and nutrient uptake, which collectively boost overall plant vigour and biomass accumulation.