International Journal of Horticulture, 2026, Vol.16, No.4, 206-213 http://hortherbpublisher.com/index.php/ijh 209 temperatures that accelerate meristematic activity and shorten plastochron intervals, thereby increasing leaf production rates (Tarara, 2000; Lamont, 2005). Rice straw mulch was statistically comparable to plastic mulch at 90 and 120 DAT, suggesting its nutrient-release profile increasingly supports rapid leaf development as the crop approaches the grand growth phase. These trends mirror findings of Kabir et al. (2013), who reported plastic mulch superiority for early-stage leaf development with straw mulch increasingly competitive at later stages. Table 2 Effect of mulching treatments on number of leaves per plant of onion (Allium cepa L.) at 30, 60, 90, and 120 days after transplanting (DAT) Treatments Number of leaves per plant 30DAT 60DAT 90DAT 120DAT Control 4.13b 5.67c 7.13c 7.47b Banana leaf mulch 4.27ab 6.00bc 7.87bc 7.93ab Sawdust mulch 4.20b 6.13b 8.07b 8.20ab Rice straw mulch 4.53ab 6.67ab 8.80ab 8.73a Plastic mulch 4.73a 7.00a 9.27a 9.00a LSD(p≤0.05) 0.51 0.57** 0.75** 0.84** CV(%) 6.32 5.14 5.51 6.87 Grandmean 4.37 6.29 8.23 8.27 Note: Means in a column followed by different lowercase letters differ significantly at p ≤ 0.05 (DMRT). ** p ≤ 0.01. DAT: days after transplanting; LSD: least significant difference; CV: coefficient of variation 3.3 Leaf length Leaf length increased from transplanting through 90 DAT before declining at 120 DAT as assimilates were redirected to bulb storage organs (Table 3). Rice straw mulch consistently produced the longest leaves at all stages (25.88, 46.32, 58.14, and 42.37 cm at 30, 60, 90, and 120 DAT). Plastic mulch was statistically at par at all stages. The enhancement under rice straw mulch is attributed to improved nitrogen availability from mineralizing organic matter, which elevates leaf chlorophyll content and photosynthetic efficiency, sustaining leaf expansion (Baten et al., 1995; Nair and Ngouajio, 2012). The control consistently produced the shortest leaves, reflecting competitive water stress and nutrient immobilization associated with soil crusting in unmulched plots. Table 3 Effect of mulching treatments on leaf length (cm) of onion (Allium cepa L.) at 30, 60, 90, and 120 days after transplanting (DAT) Treatments Leaf length (cm) 30DAT 60DAT 90DAT 120DAT Control 22.53b 38.91c 46.07d 30.44d Banana leaf mulch 23.94ab 41.72bc 49.53c 34.88c Sawdust mulch 24.27ab 43.46ab 52.71bc 37.08bc Rice straw mulch 25.88a 46.32a 58.14a 42.37a Plastic mulch 25.17a 45.53a 55.92ab 41.14ab LSD(p≤0.05) 2.21* 3.14* 3.88*** 4.31*** CV(%) 5.24 4.33 3.97 6.22 Grandmean 24.36 43.19 52.47 37.18 Note: Means in a column followed by different lowercase letters differ significantly at p ≤ 0.05 (DMRT). * p ≤ 0.05; *** p ≤ 0.001. DAT: days after transplanting; LSD: least significant difference; CV: coefficient of variation 3.4 Yield and yield-associated parameters All yield parameters except root length were significantly affected by mulching treatments (Table 4). The absence of a statistically significant mulch effect on root length (p > 0.05) likely reflects high intra-block variability and the sensitivity of onion root architecture to micro-scale irrigation uniformity (Larkin, 2020).
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