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

Aims: 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.