Effect of paclobutrazol growth retardant applied at different growth stages on plant growth and seed yield of soybean cvs. SJ4 and SK1
1992
Chanprasert, W.
Main objective of this study was to evaluate whether paclobutrazol which its effect can retard soybean vegetaive growth during reproductive phase, can diuert photoassimilate to increase pod set and seed growth or not. Paclobutrazol at the rate of 1 kg ai/3, 125 litre of water/ha was directly sprinkled onto the SJ.4 and SK1 soybean plants at different growth stages, i.e. R1, R3 and R5. The results revealed that treated plants reached growth stage R6 before the untreated plants possibly due to the higher rate of seed filling. Paclobutrazol reduced plant height, branch number, node number and flowering period. The earlier the soybean plants were given the growth retardant, the more deleterious effect occurred. Paclobutrazol also reduced pod number per plant, but had no effect on potential seed yield due to the compensation of seed number per pod and seed weight. The concentration of 1 kg ai/ha of paclobutrazol may be too high to promote reproductive growth in these two soybean cultivars.
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