Postharvest physiology of Curcuma alismatifolia flowers

Flowering stems of Curcuma alismatifolia (Zingiberaceae) cv. Chiang Mai Pink contain small flower buds and open flowers, surrounded by large pink bracts. Vase life is limited by browning at the bract tips. This browning may relate to ethylene production as it was hastened by treatment with exogenous ethylene. Browning was apparently not due to lack of carbohydrates, as sugar treatment had no effect, and was also apparently not due to xylem plugging with microbes because antimicrobial compounds (8-hydroxyquinoline sulphate (HQS) and dichloroisocyanuric acid (DICA)) were ineffective. The stems had a very short vase life after 3 days of dry storage. When stored in water, the optimum temperature for storage was 7 degreesC. After 3 or 6 days of storage at 7 degreesC the vase life was not different from that of unstored controls (about 18 days). However, if flowers were held at 5 degreesC for 3 days they had a vase life of only 2 days. It is concluded that C. alismatifolia is an attractive cut flower with a considerable length of vase life (usually more than 2 weeks, in freshly harvested stems). The flowers are chilling-sensitive, and cannot be stored dry but they can be stored in water at 7 degreesC for about 6 days. Since vase life is rather long, it is also possible to store the flowers in water for a few days at ambient temperatures. (C) 2004 Elsevier B.V. All rights reserved

Ethylene production and post-pollination development in Dendrobium flowers treated with foreign pollen

Dendrobium ‘Pompadour’ flowers fade early following pollination. This is associated with increased ethylene production and early epinasty. These effects are also produced by application of 1-aminocyclopropane-1-carboxylic acid (ACC) on the stigma. Pollen (one anther each) from Ruellia tuberosa L. (Acanthaceae) and Caesalpinia pulcherrima (L.) Sw. (Fabaceae) also increased ethylene production and caused early epinasty and fading. Pollen of Hibiscus schizopetalus (Mast.) Hook.f. (Malvaceae), in contrast, had no effect. R. tuberosa pollen increased ACC concentration and ACC synthase activity of the orchid flowers. Aminooxyacetic acid (AOA) pretreatment prior to R. tuberosa pollination prevented early fading, epinasty and the increase in ethylene production. It also prevented the increase in ACC concentration, and ACC synthase activity. Ovary growth was stimulated by Dendrobium ‘Pompadour’ pollinia, not by any of the incompatible pollen. Applied ACC did not promote ovary growth. It is concluded that incompatible pollen can hasten senescence and epinasty by increasing ACC synthase activity and ethylene production. Ovary growth, in contrast, is apparently not primarily regulated by ethylene

High floral bud abscission and lack of open flower abscission in Dendrobium cv. Miss Teen: rapid reduction of ethylene sensitivity in the abscission zone

We studied the abscission of floral buds and open flowers in cut Dendrobium inflorescences. Abscission of floral buds was high and sensitive to ethylene in all cultivars studied. Many open flowers abscised in most cultivars, but cv. Willie exhibited only small amount of floral fall and cv. Miss Teen none. Applied ethylene (0.4 ¿L L¿1 for 24 h at 27°C) greatly hastened abscission of open flowers in most cultivars, but had only a small effect in cv. Willie and no effect in cv. Miss Teen. Flower fall, if it occurred, was completely inhibited by 1-methylcyclopropene (1-MCP), showing that it was regulated by endogenous ethylene. Ethylene production from the abscission zones was low in all cultivars studied. In cv. Miss Teen the abscission zone changed from highly ethylene sensitive to completely insensitive in ~30 h, coinciding with floral opening. Removal of the floral buds somewhat reduced abscission in open flowers, but the lack of open flower abscission in cv. Miss Teen could not be explained by higher bud fall. The ovary did not grow in the (unpollinated) flowers, showing that lack of abscission in cvv. Willie and Miss Teen was not due to parthenocarpy. Flower removal in cv. Miss Teen had no effect on ethylene sensitivity of the abscission of the remaining pedicel. However, removal of the distal 2 cm of the 3-cm-long pedicels dramatically increased ethylene sensitivity. This suggests that the pedicel is important for the low ethylene insensitivity of abscission, in this cultivar. It is concluded that the abscission zones in the cvv. Willie and Miss Teen, in contrast with the other cultivars investigated, became rapidly insensitive to ethylene at the time of flower opening. At least part of the ethylene sensitivity in Miss Teen seems to be due to a factor in the pedicel