Soybean plants, receiving nitrate-N or dependent on nitrogen fixation, were subjected to
progressive water deprivation under controlled environmental conditions in a growth room.
Comparative studies were carried out with respect to well-watered, control plants. Stressed,
nitrate-fed plants had relatively greater root development, higher transpiration rates per unit
leaf area, lower threshold values of leaf water potential for stomatal closure and osmotic
adjustment in upper leaves. Therefore, these plants were adopting mechanisms to achieve …

The effect of nitrogen (N) source (nitrogen fixation or nitrate assimilation) and progressive
water stress on pigment content, carbon assimilation and changes in the activity of certain
photosynthetic (Rubisco and phosphoenol pyruvate carboxilase) and photorespiratory
enzymes (glutamate synthetase and glycolate oxidase) during vegetative development of
soybean plants was studied. Glycolate oxidase declined by 13% in nitrogen-fixing plants
under water deficit, and increased in nitrate-fed ones. Nodulated plants were less sensitive …