Influence of Shading on Flower Forcing in Wax Apple (Syzygium samarangense Merr. et Perry)

Abstract

Off-season production and flower forcing due to shading system was conducted in this study. 3-year-old pot planted wax apple with secondary shoots were covered with 50% or 95% shading net for 40 days, and flower forcing treatment then were treated. The results was showed that the 95% shading treatment resulted in decreasing number and length of new shoots, decreased number of fine roots, and their dry matter weight. However, flower cluster and flower number were significantly more than those of low shading and unshading treatments. The water content of shoot, leaf, were increased after shading treatment. In the observation of leaf tissue, cells of palisade tissue were shorter and snongy tissue were less developed than unshading treatment in the new shoots. Photosynthetic rate and photosynthetic prodution accumulation decreased significantly. Meanwhile, root growth and shooting were inhibited. The data also showed that the carbohydrate content decreased and total nitrogen content had increasing tendency at the end of shading. The C/N ratio had not direct implication for wax apple flowering.為探討催花前的遮光對蓮霧植株生育及生理之反應，本研究以3年生盆栽植株，在5~7月間經過修剪培育兩次梢後，在9~10月間以遮光率95%及50%的黑網遮光40日，然後進行催花，調查遮光對植株生長及開花之影響。由試驗結果可知強遮光使植株抽梢數減少，新梢較短，新梢及細根乾物種均顯著減少。有遮光的處理在催花後，萌發的花穗數及花數顯著地高於不遮光的植株，其新梢數與催花後花數成負相關。經過遮光處理之枝條、葉的水分含量均呈現增加。由葉片的厚度亦減少。幼梢葉之單位葉面積葉綠素的含量隨著遮光程度增加而增加，而熟梢葉在遮光前後葉綠素含量變化較小。遮光期間葉片光合成速率明顯下降，遮光結束時枝條的碳水化合物含量減少，全氮含量則有增加的趨勢，該碳氮比與蓮霧之開花並無直接的關聯