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Pod Set Related to Photosynthetic Rate and Endogenous ABA in Soybeans Subjected to Different Water Regimes and Exogenous ABA and BA at Early Reproductive Stages
FULAI LIU, CHRISTIAN R. JENSEN and MATHIAS N. ANDERSEN
Annals of Botany
Vol. 94, No. 3 (September 2004), pp. 405-411
Published by: Oxford University Press
Stable URL: http://www.jstor.org/stable/42759222
Page Count: 7
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• Background and Aims The physiological reasons for reduced pod set in soybean (Glycine max) caused by drought during anthesis are not established. The objective of this study was to investigate the involvement of photosynthetic rate (A), pod endogenous abscisic acid (ABA) and exogenously applied ABA and 6-benzylaminopurine (BA) in regulating pod set in soybean during drought. • Methods Two pot experiments were done in a controlled-environment glasshouse. In expt I, soybeans were either well-watered (WW) or draughted by withholding water from 4 d before to 4 d after anthesis (DAA). In expt II, soybeans were drought-stressed (DS) from –4 to 4 DAA. From –2 to 4 DAA, some of the WW and DS plants were treated with 0·1 mM ABA or 1 HIM BA. • Key Results Drought stress decreased A, but increased pod ABA concentration ([ABA]). Pod set decreased only when A had decreased by 40 %, and pod [ABA] had increased 1·5-fold. Beyond the thresholds, pod set correlated positively with A and negatively with pod [ABA]. Exogenously applied ABA decreased A and pod set in WW plants, whilst it increased A and pod set in DS plants; exogenous BA had opposite effects. In these plants, pod set correlated linearly with A. • Conclusions Drought-induced decrease in A is significant in inducing pod abortion, probably as a consequence of carbohydrate deprivation. The effects of ABA and BA on pod set may be partially due to their effects on photosynthate supply.
Annals of Botany © 2004 Oxford University Press