Effect of establishment methods and irrigation scheduling on leaf area, leaf area index and leaf area duration of wet season rice

Rice cultivation plays a crucial role in global food security but is increasingly constrained by labor shortages and water scarcity. Conventional puddled transplanted rice (TPR) is highly resource-intensive, necessitating the need for efficient crop establishment methods and optimized irrigation strategies. This study aimed to evaluate the effect of different establishment methods and irrigation scheduling on key leaf growth indices viz., leaf area (LA), leaf area index (LAI) and leaf area duration (LAD) which are critical indicators of canopy development and productivity. The field experiment was conducted during kharif 2022 and 2023 at the ICAR-Indian Institute of Rice Research (IIRR), Hyderabad, using a strip-plot design with four replications and nine treatment combinations. Three rice establishment methods were assigned to horizontal strips: normal transplanting (NTP-M1), mechanized SRI (MSRI-M2) and direct-seeded rice in raised beds (DSR-M3). Three irrigation scheduling treatments were assigned to vertical strips: AWD with 10 cm depletion (I1), AWD with 5 cm depletion (I2) and continuous submergence ±5 cm (I3). Results revealed that MSRI (M2) consistently recorded the highest LA, LAI and LAD, followed by DSR (M3), while NTP (M1) showed the lowest values. The superior performance of MSRI was attributed to the use of younger seedlings, wider spacing, uniform mechanical transplanting and intensive cono-weeding, which enhanced canopy expansion, tiller survival and root anchorage. Among irrigation regimes, AWD with 5 cm depletion (I2) sustained higher LA, LAI and LAD than AWD with 10 cm depletion (I1) and performed comparably with continuous submergence (I3), indicating its potential to conserve water without compromising canopy growth. The interaction effect between establishment methods and irrigation scheduling was non-significant; however, individually, MSRI and AWD with 5 cm depletion emerged as the most effective practices. These findings highlight their potential to improve canopy growth indices, enhance water-use efficiency and sustain productivity, offering a viable strategy for sustainable rice cultivation under water-limited environments.