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Water use efficiency of three common subsistence legume crops in relation to soil type under controlled environment conditions.

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Water scarcity in agriculture is the primary reason for poor crop yield and quality. The study's primary aim was to determine the effect of water stress on the growth and development of grain legumes in relation to the type of soil used for their production. A pot trial was used to grow three legume varieties (Gadra bean, Lima bean, and Peas) in five different soil types. The growing conditions were controlled for similarity, except for water availability. Adequate (75%FC), moderate (50%FC), and poor (30%FC) levels of water availability were imposed. Field capacity was measure by weight by filling a bare soil area with excess water inducing drainage, cover the wet soil with a plastic cover, wait about 2-3 days, collect a soil sample, weigh moist soil, dry in an oven at 105°C till to constant; weigh (after about 24 hours) and weigh the dry soil then moisture at field capacity was calculated. Crop response to water availability was determined by plant growth indices of time to flowering and plant size during growth. Crop performance was initially monitored in terms of crop establishment capacity as indicated by emergence. Chlorophyll content index and stomatal conductance were used to determine plants' general physiological response during the vegetative phase of growth. Biomass accumulation and grain yield were determined at harvest by separating them into the aboveground total plant mass, root mass, and grain mass, respectively. Also, the availability of calcium (Ca), potassium (K), phosphorus (P), sodium (Na), Manganese (Mn), and magnesium (Mg) was determined in plant tissue after harvest. The results showed that plant height, number of leaves, number of seeds, dry grain weight, and plant dry weight of the three legumes responded significantly to water stress conditions. Chlorophyll content index and stomatal conductance showed significant differences in water availability. Calcium, P, and Mn increased with increased field capacity, but Mg and K decreased. Regardless of soil type and variety, crop performance declined with a decrease in water availability. Water stress was shown to have a rapid effect on legume performance, as indicated by highly significant differences between water availability levels during plant growth. Soil type has substantial interaction with water availability, mainly due to structural and chemical characteristics influencing water availability. Root mass is the most sensitive legume plant part of water stress than vegetative parts and grain responses to water stress's adverse effects.


Masters Degree. University of KwaZulu-Natal, Pietermaritzburg.