Die invloed van preservering op sommige metaboliese prosesse in verouderende swaardleliebloeiwyses

Abstract

Pulsing of Gladiolushybrida (L. )(cv. Striking Horn) inflorescences for four hours with preservatives containing silverthiosulphate (STS), 8-HQC or 8-HQ-potassiumbilsulphate, citrate or aluminiumsulphate and/or sucrose, resulted in increased longevity and florets of better quality. Water absorption and respiration rates were decreased and senescence was postponed after treatment. Although fl ore ts of Gladiolus inflorescences do not normally produce significant amounts of ethylene during their post-harvest life, ethylene synthesis can be induced by treatment with certain preservatives. How= ever, this ethylene has no effect on the longevity of the florets. The 1-aminocylopropane-1-carboxylic acid (ACC) content of the perigone tissue was determined. The results indicate that the activity of the ethylene forming enzyme (EVE) of the perigone was very low during the entire post- harvest life of the florets. Treatment with exogenous ethylene showed that the florets were not very sensitive to ethylene. The postharvest life of the florets decreased with only 31% after treatment with 100 mm 3 ethylene .dm- 3 • Pulsing inflorescences with STS and aminooxyacetic acid (A0A) before treatment with ethylene resulted in a decreased sensitivity to ethylene, indicating that senescence in Gladiolus is related to ethylene synthesis and ethylene action. Pollination induces an increase in ethylene production and enhances senescence of individual florets. Basal application of 2 mmol ACC.cm- 3 markedly increased ethylene production and enhanced senescence of pollinated florets, indicating a pollinated induced increase in the ability to convert ACC to ethylene and an increase in sensitivity to ethylene. Treatmen t with 2 mmol STS.dm- 3 (ethylene antagonist) and 2 mmol A0A.dm- 3 (inhibitor of ACC synthase) slightly enhanced senescence of unpollinated florets. This decrease in longevity could be the result of a toxic effect exerted by AOA · and STS. Pollination of the STS- and AOA-treated florets resulted in an increase in longevity compared to nontreated pollinated florets. This indicates that pollination induced senescence is related to ethylene production as well as ethylene action. The results of the study indicate that the effect of ethylene on Gladiolus inflorescences is a function of its sensitivity to ethylene rather than the amount of ethylene produced.