Mulching and Greenhouse Structure Significantly Impact Spinach Production during Winter in Trans-Himalayan Ladakh, India

Abstract

A winter greenhouse experiment was conducted during 2024-2025 in the trans-Himalayan cold-arid region of Leh, Ladakh, to evaluate the combined effects of protected structure type and black polyethylene mulching on the growth and yield of spinach (Spinacia oleracea L.). The study compared four protected cultivation systems: a large Ladakh passive solar greenhouse, a small Ladakh greenhouse, a polycarbonate trench greenhouse, and a polyethylene trench greenhouse, each under mulched and non-mulched conditions. Spinach cv. Pusa Vilayati Palak was harvested through three successive cuttings taken at the marketable leaf stage, with harvest intervals varying among protected structures due to differences in microclimatic conditions, and key growth and yield parameters were recorded. The large Ladakh greenhouse combined with mulch consistently outperformed other structures, producing the highest cumulative yield (223.4 g plant-¹; 9.9 kg m-²), representing a 53% increase over the corresponding non-mulched treatment. Mulching significantly enhanced plant growth, chlorophyll index, and regrowth capacity across structures, and advanced the first harvest by 2-3 days. In the polycarbonate trench greenhouse, mulch increased cumulative yield by up to 72%, enabling three successive cuttings. In contrast, the polyethylene trench greenhouse failed to support regrowth beyond the first cutting due to inadequate thermal insulation under peak winter conditions. Overall, mulching increased total spinach yield by 37.5-69.7%, depending on the greenhouse structure and cutting stage from I to III. The results demonstrate that structure-specific protected cultivation combined with mulching is a highly effective strategy for enhancing winter spinach productivity in high-altitude, sub-zero environments