Soil Moisture Stress and Nitrogen Supply Affect the Growth Characteristics and Yield of Upland Rice Cultivars

Abstract

To assess the effect of soil moisture stress and nitrogen fertilizer application on the growth characteristics and yield of upland rice cultivars. Study Design: Completely randomized design in a factorial arrangement. Place and Duration of Study: National Crops Resources Research Institute, Namulonge, Uganda between March and July 2015. Methodology: The experiment comprised four nitrogen (N) application levels (0 as control, 40, 80 and 120 kg N/ha) as main plots and four soil moisture levels (25% as control, 15, 10 and 5%) as sub-plots. Results: Plant heights for stressful moisture levels (15, 10 and 5%) at all N levels were lower (P < .001) than those of the control treatments at the respective N levels. Also, rice plants under stressful treatments at each N level took longer (P < .001) to mature when compared with the control treatments at the respective N levels. Subjecting rice plants that were supplied with 0 kg N/ha to moisture stress did not significantly (P > .05) affect the number of panicles produced when compared with the control. Under the 40 kg N/ha level, number of panicles produced by rice plants subjected to 15 and 10% moisture stress levels (3.56 and 4.00) were significantly lower than those of the control (6.00). For the 80 and 120 kg N/ha levels, number of panicles decreased significantly at all moisture stress levels when compared with the respective control treatments. Subjecting rice plants to moisture stress at the 40, 80 and 120 kg N/ha levels significantly (P < .001) reduced the grain yield when compared with the respective control treatments. Conclusion: Namche-3 rice cultivar performed optimally when subjected to 15% moisture stress and 120 kg N/ha application rate. Thus, farmers growing Namche-3 rice in areas with limited soil moisture may apply N at 120 kg/ha if they are to realize better grain yields.