Ecophysiology of drill-seeded rice under reduced nitrogen fertilizer and reduced irrigation during El Niño in Central Colombia

Abstract

Improvement of efficiencies of N fertilizer and irrigation water is needed for large-scale market-oriented rice cultivation without puddling practice as in American continents. Effects of reductions of N fertilizer and irrigation water on grain yield of drill-seeded rice on zero-leveled fields were quantified across five N levels (220, 180 [two sources with 5 or 3 splits], 140, and 0 kg N ha−1) and three irrigation strategies (irrigating every 3, 6, or 8 days; W1, W2, and W3, respectively) in dry and wet seasons during an El Niño event in Central Colombia. Reducing the N application rate from 180 kg N ha−1 to 140 kg N ha−1 (22% reduction) did not reduce yield in either season in spite of slightly reduced N uptake, owing to increased N use efficiency in all irrigation strategies. Three split of N fertilizer with slow release urea (180 kg N ha−1) and with basal organic amendment did not reduce yield compared with the conventional 5 split method. Yield in dry season reduced under the 2 water-saving strategies (W2, W3) almost proportionally to the reduced water supply (irrigation + rainfall) by flowering. In wet season, yield in mild water saving (W2, with 26% water saving) was similar to conventional irrigation management (W1), leading to its highest water productivity. Physiological parameters (e.g. stomatal conductance, total N uptake) were greater in wet season than in dry season. This study showed potential reduction of N fertilizer and conditions of climate for water-saving in drill-seeded rice production in Colombia.

Keywords

• rice
• direct seeding
• n uptake
• grain yield
• water-saving
• seasonal effect