Water relations of cut flowering branches of Thryptomene calycina (Lindl.) Stapf. (Myrtaceae)

Abstract

Cut flowering branches of Thryptomene calycina (Lindl.) Stapf. placed in water showed a decrease in water uptake, transpiration, hydraulic conductivity, fresh weight (FW), water content of flowers and water potential within 2 days of harvest. Flowers started to close approximately 3 days after harvest, and flower buds did not open throughout vase life. The longevity of the branches averaged 6–9 days and was determined by the wilting of flowers. Hydraulic conductivity, FW and longevity were increased by measures that removed or prevented the formation of occlusions in the stems, such as recutting the stems underwater or by inclusion of anti-bacterial compounds (citric acid at 250–500 mg l−1, or dichloroisocyanuric acid (DICA) at 50 mg l−1 in the vase solution. Hydraulic conductivity, FW and longevity were also significantly improved by the inclusion of the surfactant nonylphenolpolyglycol ether (Agral-600, at 160 μl l−1) in the vase solution. Agral-600 did not reduce the number of bacteria in the vase solution, and may act by bypassing bacterial occlusions. The inclusion of sucrose (10 g l−1) with an adequate anti-microbial compound, improved longevity, stimulated bud opening and further delayed flower closure. The results indicate that the longevity of T. calycina is limited by a vascular occlusion in the stem base.