Impact of water stress on reproductive development in sweet pepper (Capsicum annuum L.). III. Inhibition of water stress-induced ethylene production by silver thiosulphate

H. Z. Jaafar, J. G. Atherton, C. R. Black and J. A. Roberts

Abstract

The supposition that ethylene mediates the impact of water stress on flower abscission was supported by the experiment involving the use of silver thiosulphate (STS) to block ethylene-induced abscission. Foliar application of STS at 1 mM was highly effective in blocking the increase of endogenous ethylene evolution and preventing flower abscission in severely water stressed plants from day six onwards. As much as 11.7% of the secondary flowers had abscinded 6 days after experiencing water stress and this increased to 53.3% on day 10, which accounted for more than eightfolds greater than the non-stress condition. Concurrently, there was also a sixfold increment (p <0.05) of ethylene evolution in these flowers from 0.06 to 0.37 ηL/g FW/h as compared to the nonstress condition. A further increase of the ethylene evolution to 0.89 ηL/g FW/h was observed on day 10, which was about 3 times greater than the non-stress condition. However, flowers from water stressed plants treated with STS did not experience any marked increase in their endogenous ethylene evolution which registered from 0.07 to 0.10 ηL/g FW/h neither was there any flower abscission. Comparison in the characteristics of flower development as influenced by the application of STS was clearly marked by the visual observation. These findings confirmed that ethylene has a major role in promoting flower or bud abscission in water stressed sweet pepper and that foliar application of STS one day after imposing water stress and repeated every 3 days proved highly effective in blocking abscission.

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