Moisture stress reduces stomata conductance, growth and yield of soybean

Soybean [Glycine max (L) Merrill] yield amongst smallholder farmers in Kenya is low and range from 445-1200 kg ha-1. These low yields are attributed to various factors including moisture stress and use of poor agronomic practices. Optimization of soybean production would help reduce food, nutrition and income insecurity at household level in Kenya. An experiment was conducted to determine the effect of varying soil moisture regimes on stomata conductance, growth and yield of selected soybean cultivars under greenhouse conditions. The experiment was conducted as a randomized complete block design (RCBD) in a 4 by 6 factorial treatment arrangement with moisture regimes (80%, 60%, 40% and 20% of field capacity) as first factor and cultivars (Gazelle, Nyala, EAI 3600, DPSB 8, Hill and DPSB 19) as second factor. Collected data on stomata conductance, leaf area, root nodulation, grain yield and seed protein content were subjected to Analysis of Variance (ANOVA) using Linear Mixed Model in GENSTAT. Significantly different treatment means were separated using Tukey’s test at (p≤0.05). Moisture stress significantly reduced stomata conductance, leaf area, grain yield, protein content and root nodulation of all tested soybean cultivars. The degree of stress response however varied amongst soybean cultivars tested. Cultivar DPSB 19 is recommended for production under low moisture levels.