限制根群對蓮霧生長發育之影響

Root Restriction Affects Growth and Development of Wax-Apple (Syzygium samarangense Merr. et Perry)

蓮霧為生長旺盛之熱帶果樹，每年抽梢5~6次，因此如何控制枝梢營養生長，是產期調節成功的關鍵所在。本試驗以一年生粉紅種蓮霧（Syzygium samarangense Merr. Et Perry）之高壓苗為材料，以二份田土、一份泥炭土及一份樹皮堆肥充分混合成栽培介質，將根群分別限制在40、90、200、730及1700公升五種的栽培盆中，以探討限制根群對蓮霧枝梢與根部生長之影響，期能建立一簡便的產期調節模式。經三年的生育調查結果顯示，株高與樹冠寬度隨栽培盆體積增加而增加，但730及1700公升二處理間無顯著差異；主幹橫截面積的增加量則隨栽培盆體積的增加而呈二次曲線式的增加。生長一、二或三年後，地上部總乾物重及地下根部乾物重，均隨栽培盆體積增加而增加。各處理之枝／根比，均隨樹齡的增加而逐漸降低，在同一年度，各處理間則無顯著差異。調查二年的產量結果顯示，單株產量及產量效率均有隨栽培盆體積增大而增加的趨勢，但730與1700公升二處理間，在統計上則差異不顯著；顯示在二年半生育期間，730公升以下之根域範圍，栽培盆的大小是限制產量的重要因素之一。綜合本試驗結果顯示，限制根群為一有效抑制蓮霧枝梢及根部生長之方法。

The wax-apple (Syzygium samarangense) is a vigorous tropical fruit tree species that has five to six growth flushes per year. Therefore, controlling vegetative growth is the key to a successful forcing culture of this species in Taiwan. In this study, one-year-old, own-rooted wax-apple trees were grown in different- sized containers filled with a synthetic potting mixture, to test if root restriction inhibits shoot and/or root growth, and thereby, lends itself to forcing culture. After 3 years growth, plant height and canopy width of wax-apple trees were increased as container volume increased. However, there was no statistical significance in plant height and canopy width between plants grown at 730 litter's containers and those of 1700 litter's containers. The increase in trunk cross-sectional area (TCSA) at 15 em above the soil, increased quadratically with container volume. At the end of the first, the second and the third year, totals shoot dry weights and root dry weights were positively correlated with container volume. The shoot/root ratios decreased as the plants grown older. However, there was no difference in shoot/root ratios among treatments in the same year. Increases in yield per plant and yield efficiency were resulted in responding to increase in the container volume. However, there was no statistical significance in yield per plant and yield efficiency between plants grown at 730 litter's containers and those of 1700 litter's containers. We conclude that container size below 730 litter is one of the important limiting factors for wax-apple yield after two and half yeas of cultivation, and root restriction is an effective means of reducing shoot and root growth of the wax-apple.