灌溉與蓮霧(Syzygium samarangense Merr.＆Perry)裂果的關係

Abstract

臺灣目前栽培的蓮霧於春夏季節裂果嚴重，故擬以不同灌溉量造成植株水勢不同，進而觀察裂果與果實品質。連續兩年分別在屏東縣佳冬鄉及枋山鄉蓮霧產區進行試驗。果實生育期間，佳冬試區分成每天灌溉（對照組）及停止灌溉，枋山試區每隔2-3天灌溉一次（對照組）及每天灌溉。植株水勢變化，佳冬停止灌溉與對照組無顯著差異，枋山每天灌溉與對照組亦無顯著差異；佳冬停止灌溉會增加裂果率但枋山則無顯著差異。裂果果實的總可溶性固形物高於完整果。當果實的果梗端、中間及果萼端等三部位的總可溶性固形物開始出現顯著差異時，即開始裂果。雖然利用停止灌溉甚至每天灌溉來造成植株樹體水勢差別，進而探討對蓮霧裂果的影響，但憾未對試區樹體水勢造成顯著差異，以致無法觀察不同土壤水分含量對裂果的影響一致性的影響;但在目前栽培狀況下，也可能係其他因子調控蓮霧裂果，尚待解決。

With the advance of technology in production-season adjustment, the fruits of waxapple can be produced in the winter, spring and summer. Unfortunately, those fruits mature in warm season crack seriously. The experiment was done in the commercial orchards at Jia-Dong and Fang-Shan townships of Ping-Dong County to investigate the effects of changing water potentials of trees by adjusting the irrigation frequency on the fruit cracking and quality. During the period of extensive fruit growth irrigation was withheld and daily-irrigation was acted as control at Jia-Dong. At the same period irrigation was implemented daily compared with control which irrigation was done every 2-to-3-day interval at Fang-Shan. Tree water potentials, either predawn or mid-day, were not significantly different between treatment and control with two sequential years of experiment. The percentage of fruit cracking of water-withheld trees was higher than that of daily-irrigated ones at Jia-Dong but no significant difference at Fang-Shan. Cracked fruits had higher total-soluble-solid content than intact ones. Once the total-soluble-solid contents in the fruits between stem-end and stylar-end became significantly different the fruits began to crack. Regrettably water potential of trees did not differ after adjusting soil water content and hence did not result in the clear response on fruit cracking. Alternatively, other factors, instead of soil water content, may be involved in fruit cracking of waxapple under current cultural condition in Taiwan and is worthwhile for further study.