Biomass, growth and matter partitioning in soybean [Glycine max] plants under long-term moisture deficit
2000
Ghosh, A.K. (Kagawa Univ., Miki (Japan). Faculty of Agriculture) | Ishijiki, K. | Toyota, M. | Kusutani, A. | Asanuma, K.
Information on growth, matter partitioning and yield response of soybean plants[Glycine max (L.) Merr.] grown at different levels of moisture stress imposed from the early stage until harvest seems to be insufficient. In this experiment, a determinate cultivar 'Akiyoshi' was grown in a greenhouse at optimal (80% of field capacity) and three sub-optimal soil moisture levels (65%. 50% and 40% of field capacity). Moisture stress significantly decreased root length, plant height, leaf area and the number of branches, flowers, pods and seeds. Moisture deficiency resulted in smaller leaves and a slower rate of leaf expansion but higher weight per unit area. Increasing moisture deficit significantly decreased the dry matter weight of all the plant organs and also the shoot:root ratio at all stages of growth. With decreasing soil moisture levels, plants accumulated a greater proportion of dry matter in the main stem leaves and roots but a lower proportion in their branches and the whole shoot. Nonsignificant differences in assimilate partitioning to the pods suggest that the seed yield depends on the dry weight of the whole plant. Moisture deficiency decreased the weight per seed and also seed yield per plant. Continuous moisture deficiency reduced the number of branches per plant and the seed yield per branch. Hence, the significant yield decrease per plant resulted from the reduced dry matter production of plant and low productivity of branches in conjunction with the smaller
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