Effect of calcium and pod removal on reproductive abcission, senescence, and yield of soybean [Glycine max (L.) Merr.] plants
1998
Oro, F.H.
Reducing the rate of reproductive abscission and delaying senescence to lengthen photosynthetic activity and pod-filling are considered as two approaches for maximizing soybean yield. Experiments using calcium chloride in varying concentrations as spray on the leaves of podded and depodded soybean plants (variety UPL Sy-8) were done with the following objectives: 1.) to determine the effect of exogenous calcium on the reproductive abscission of soybean, and 2.) to determine if chemical treatment with calcium could alter the senescence pattern of soybean in such a way as to improve seed yield. Data obtained revealed that calcium treatment at 0.06 M CaCl2 reduced reproductive abscission but did not increase seed yield. Calcium delayed loss of leaf chlorophyll in podded as well as depodded plants whereas early pod removal slowed down the rate of leaf yellowing. Partial pod removal at an early stage allowed plants to make some compensatory adjustments so that yield was not affected relative to control or podded plants. Late pod removal led to reduced seed abortion and heavier seeds but these did not contribute much to total seed yield. The study showed that pods do not regulate the onset and rate of senescence in soybean UPL Sy-8. It also demonstrated that calcium could promote regrowth and rejuvenation - an indication that monocarpic senescence can be reversed, and soybean plants can be made to bear fruit more than once
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