Soil-plant-water relations, growth and nutrient uptake patterns of field-grown soybeans under moisture stress

Soil-moisture stress effects on reproductive and vegetative components of soybeans

“…Leaf-area distribution in their canopies showed that most of the leaves were concentrated in the top layers of the canopy. The apparent differences in leaf-area distribution appeared to be mediated by moisture stress effects more dominantly than the effects of the variation in photosynthetically active radiation (Sivakumar, 1977).…”

“…A reduction in soybean leaf-water potential to less than -8 bars was associated with a large reduction in leaf enlargement and, at a leaf-water potential of -12 bars, growth was completely halted (Sivakumar, 1977).…”

“…Moisture-stress effects on leaf area could be brought about by influ encing leaf size, leaf number, and leaf senescence (Sivakumar, 1977).…”

“…Working with soybeans, Sivakumar (1977) showed that relative growth rate and relative leaf growth rate declined with age of the plant because the level of self-shading increased. In the same experiment, he concluded that net assimilation rate and crop growth rate, calculated by using the regression procedure for the uncovered plots, had a marked increase in the late part of the season due to a combination of decreasing leaf area and increasing dry weights.…”

“…In the same experiment, he concluded that net assimilation rate and crop growth rate, calculated by using the regression procedure for the uncovered plots, had a marked increase in the late part of the season due to a combination of decreasing leaf area and increasing dry weights. Classical methods of analysis failed to show this feature because of the nonlinear relationship between leaf area and dry weight (Sivakumar (1977). Koller et al (1970) concluded that at any given time the most recently initiated soybean plant fraction had the greatest relative growth rate.…”