Effect of water stress on soybean metabolism

Effect of water stress on soybean metabolism

Rev. ed.

Shanhua AVRDC Taiwan

1986

p.373-382

SB205.S7A85

The effect of water stress on carbohydrate metabolism, absorption of nitrate, protein metabolism, and the source of the nitrogen of proline in soybean plants were studied with 15N tracer technique. Insoluble sugar content rapidly decreased with the advent of water stress, but soluble sugars, mainly sucrose, gradually increased. These results indicate a water-stress induced reduction in photosynthesis and a decreased translocation of soluble sugars and/or a cessation of plant growth. Nitrate absorption was sensitive to water stress and the flow of nitrate into the leaves ceased completely under severe stress conditions. Net protein loss from water-stressed leaves was attributed to both a decrease in synthetic activity and a stimulated degradation of protein. Proline and asparagine accumulated in severely water-stressed plants. From the water-stressed leaves, 35% of the nitrogen loss was compensated for by a gain in nitrogen in the free amino acids, especially proline and asparagine. Total proline content (free + protein - bound) increased under severe stress conditions to 130% of the non-stress plants. The increase in the 15N content of free proline was three times more than the decrease in the 15N content of the leaf-protein-bound proline. These results indicate that the accumulation of free proline in response to water stress was caused by overproduction of free proline derived from the leaf protein. [AS]

Soybean in tropical and subtropical cropping systems; Proceedings of

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