Investigation of soybean leaf area influenced by water supply

Soybean leaf area observations were carried out in two levels of water supply using two different varieties (Sinara and Sigalia) in Hungary. Half of the crops was grown using unlimited watering in evapotranspirometers, while the others received only 50% of their water requirements from the R1 (beginning bloom) stage (stressed crops). Out of four meteorological variables, the air temperature, the most easily accessible meteorological variable impacted the LAI (leaf area index) the most, irrespective of water supply. To obtain the variation in the vertical leaf area distribution, the LAI(max) was selected and analyzed, when leaf area remained relatively invariable. Water deprivation in the reproductive phase significantly reduced the LAI, irrespective of the studied variety. The water stress condition significantly lowered the level-wise trifoliate area of Sigalia above the sixth leaf level but did not lower it in the case of Sinara. Increase of 1.5 in the number of leaf levels could be contributed to the higher LAI of crops with unlimited watering in comparison to water stressed ones. The area of the middle leaflet was significantly higher compared to the outer ones at the bottom and the top of the plant, but they were of about the equal size around the center of the plant height irrespective of the variety. According to our best knowledge, this morphological phenomenon has not been described yet.