Climate-smart mechanized rice transplanting: from nursery innovations to site-specific irrigation strategies in tropical conditions

Abstract

Abstract

Introduction Rice production faces increasing challenges due to climate variability and water scarcity, requiring integrated approaches that combine mechanized crop establishment with climate-smart management strategies. Methods This study, conducted in the department of Huila, Colombia, comprised three complementary phases: (i) historical climate analysis over a 30-year period using the Oceanic Niño Index to quantify precipitation and temperature anomalies associated with El Niño and La Niña events; (ii) optimization of nursery management through the evaluation of three rice genotypes (H-57, FEDEARROZ-67, and FEDEARROZ-2020), four substrate compositions, and four seeding rates under a split-split-plot design; and (iii) field evaluation of alternative irrigation strategies under mechanized transplanting, comparing MIRI+AWD with conventional gravity irrigation across three genotypes and two planting densities. Results Climate analysis revealed a bimodal precipitation regime, with El Niño associated with precipitation deficits of 33–36% during December–February and La Niña generating surpluses of up to 54% in July. In the nursery phase, H-57 showed higher emergence than FEDEARROZ-67 and FEDEARROZ-2020 by 35% and 12%, respectively, whereas substrate C (2/4 silt + 1/4 humus + 1/4 rice hull) achieved the highest mat stability values, particularly for FEDEARROZ-2020. Optimal seeding rates ranged from 60–90 g tray -1 for H-57 and 90–120 g tray⁻¹ for the commercial varieties. Under field conditions, MIRI+AWD consistently reduced water consumption per unit yield (WCY) compared with conventional irrigation, achieving reductions of 56.32%, 47.91%, and 44.23% for FEDEARROZ-2020, H-57, and FEDEARROZ-67, respectively, although these responses were strongly influenced by local edaphoclimatic conditions. Discussion The integration of climate characterization, optimized nursery management, and site-specific irrigation strategies provides a comprehensive framework for enhancing the resilience, resource-use efficiency, and sustainability of mechanized rice transplanting systems under tropical conditions.