Auxins對蓮霧新梢生長與果實品質之影響

Effect of Auxins on Shoot Growth and Fruit Quality of Wax-apple

以七年生蓮霧園為材料，自十二月初起至六月底止，每半個月噴一次下列四種auxins：2,4-D, 5, 10, 20 ppm; 2, 4, 5-T 5, 10, 20 ppm; 4-CPA 5, 10, 20 ppm; SNA 25, 50, 100 ppm各計14次。自一月起至六月底止共調查抽梢情形及品質分析各五次，部步結果顯示抽新梢蓮霧果實之影響甚大，尤以大量抽梢後，尚呈紅嫩狀態時，因搶奪養分，致果皮顏色不紅，糖度低降，品質差。及至新梢生長停止，葉呈淺綠色後，皮色及糖度漸恢復正常。四種auxins對抑制蓮霧抽梢及提高品質之效果，依使用濃度而異，在抑制抽梢方面，以2,4,5-T 5 ppm及SNA之頂梢數及枝幹梢數最少，新梢長度最短，尤以2,4,5-T 5 ppm及SNA 25 ppm對抑制蓮霧抽梢之效果最佳；2,4-D 5 ppm效果雖亦不錯，但有藥害，會造成嫩葉捲曲畸形，幼花序掉落，果皮色不紅，糖度低降。在果重、果長及果寬方面，初期各藥劑均有顯著增進之效果，但後期則相反。在糖度及果皮色方面，4-CPA及SNA均有提高糖度及增加色澤之效，2,4,5-T效果不顯著，2,4-D反比對照差。就早花寒害落果之防止效果言，四種藥劑均甚有效，尤以2,4,5-T效果最好，可減少落果78.7%，其次為4-CPA及2,4-D可減少64.5～69.3%，再次為SNA可減少23.7%；在濃度方面，2,4-D、2,4,5-T及4-CPA均以10 ppm為最佳，SNA則以50 ppm為佳。

Seven-year-old wax apple trees were treated 11 times with the following auxins: 1).2,4-D 5,10,20ppm; 2). 2,4,5-T 5,10, 20ppm;3). 4-CPA 5,10,20 ppm; 4). SNA 25, 50, 100 ppm; at half-month intervals during December-June period. The shoot growth of trees and fruit quality were investigated 5 times during January-June peirod. The preliminary results showed that the growing shoots affected the fruit quality. The fruits borne on trunks or shoots without significant elongation growth had better color and higher total soluble solid content than those on trunks or shoots with extensive sprouting and elongation. The effect of auxins on the growing shoots and fruit quality depends on their concentrations. In respect of inhibition of growing shoots, 2,4,5-T and SNA showed less and shorter terminal shoots as well as trunk shoats. Five ppm of 2, 4, 5-T and 25 ppm of SNA showed the best results for controlling shoot growth. Five ppm of 2,4-D inhibited shoot growth but it resulted in the injury of young expanding leaves, dull fruit color and low sugar content of fruits. In respect of fruit weight, length and width, all the chemicals showed beneficial effect in the initial period but deleterious afterward. In respect of fruit color and total soluble-solid content, 4-CPA and SNA showed beneficial effect, 2, 4, 5-T showed no significant effect and 2, 4-D showed deleterious effect. All the chemicals prevented fruitlet abscission due to chilling injury, 2, 4, 5-T showed the best result and reduced 78.7% of fruit abscission. In respect of the concentration of chemicals 10 ppm of 2,4-D, 2,4,5-T and 4-CPA showed the best result.