椪柑之藥劑疏果及合理產量評估

Abstract

為改善碰柑隔年結果現象，進行藥劑（NAA）疏果與隔年結果強度之研究，並評估其合理產量。疏果試驗分別以0、200、300、400及500 ppm NAA溶液於5月上旬，約盛花後50日之生理落果中期施用。噴施NAA者，有極顯著的疏果效果，產量則相對減少。落果率隨NAA濃度之增加而增加，二者呈極顯著之正相關。施用NAA以疏果，可增加果重與大果之比率，但樹冠外圍取樣分析結果，果實之糖、酸含量在處理問未達顯著差異。連續四年單株產量分析，顯示隔年結果強度與前一年之產量因子，包括果實數、產量及平均果重均有不同程度之相關。各年之產量因子問彼此亦具相關性。本研究結果顯示，由隔年結果強度與前一年結果數之迴歸分析，可用以推算一椪柑園單株之合理產量，做為疏果之依據，以減少隔年結果現象。 To adjust the alternate bearing of ‘Ponkan’ mandarin (Citrus reticulata Blanco), experiments were conducted in two commercial orchards located in Chia-yi and Tong-shih. Five single-tree replicates were sprayed with NAA at rate 0, 200, 300, 400 and 500 ppm in early May, and fruit drop, yield and fruit quality were investigated. The fraction of fruit thinned was significantly correlated with the concentration of NAA. Fruit weight and the percentage of larger fruit increased in treated trees, but sugar and acid content of the fruit sampled from the outer skirt of canopy varied insignificantly for various treatments. The alternate bearing intensity (ABI) of succesive years was correlated with the yield, fruit weight and number of fruit of the previous year. The yield to diminish alternate bearing(ABI=0) was calculated by regression analysis of ABI and the number of fruit of the previous year. The result showed that optimum yield to alleviate alternate bearing may be estimated by this model.