修剪時期對臺灣低海拔‘新興’梨(Pyrus pyrifolia Nakai.) 之花芽形成與休眠性之影響

Abstract

寄接梨生產，需每年更新嫁接接穗，所需之梨穗來自台灣高海拔地區及國外進口，惟進口梨穗數量變動大，且存在檢疫等疑慮，故需研討因應之道。本研究探討‘新興’梨寄接於橫山梨後，其營養生長、花芽形成、休眠狀態等表現，以了解寄接‘新興’梨在中低海拔之生長發育習性與季節性生育狀況。於2014年2月標定橫山梨徒長枝以‘新興’梨寄接後，存活但萌發為營養芽及開花未結果之接穗，並於3月起逐月將基部3個芽以上之枝條剪除，修剪後觀察再萌發枝條之萌芽表現、花芽形成、內容物變化，以研究萌發枝條之花芽形成與休眠性。試驗結果顯示，3月修剪處理者，其枝條生長長度最長，於生長停滯前可達到118 ± 15.23 cm；6月以前修剪之處理，枝條均於7月達生長停滯、枝條長度不再增加。枝條萌發率於5月修剪開始下降，6月修剪枝條萌發率降至3成以下，7月後修剪之處理，其枝條均不再萌發，顯示此時卓蘭地區‘新興’基部三片葉以下部位已進入休眠。卓蘭地區‘新興’梨，新生枝條上花芽形成在8月之後，3月與4月修剪者於9月時約有8成以上的芽已為花芽，較梨山地區早1個月；惟3月修剪與4月修剪之處理，於9月之後有花芽褐化、敗育情形，而卓蘭地區5月及6月修剪新興枝條，花芽褐化不明顯；顯示過早形成之花芽易受環境等因素而影響品質表現。修剪後萌發枝條冷藏6週後進行扦插，結果顯示3月及4月修剪後萌發枝條其萌芽率較高，可達5成以上；5月處理後萌發枝條萌發率則下降。內容物分析的結果顯示，3月及4月修剪處理之枝條氮含量變動趨勢接近，5月後氮含量逐漸下降，至8月含氮量上升，9月後氮含量減少。分析碳水化合物總量結果，3月及4月修剪處理之枝條澱粉含量於9月急遽增加；80%乙醇可溶性醣含量，則是6月採樣最高；碳水化合物含量，3月及4月修剪處理並不會影響含量變化，趨勢與卓蘭地區‘新興’枝條含量相似，而碳水化合物總量增加，主要增加量為澱粉。5月後修剪枝條可改善花芽褐化問題，而萌發率下降可能與修剪部位有關，未來可嘗試其他修剪部位。卓蘭地區‘新興’可利用修剪來避開生長期高溫，於低海拔地區生產‘新興’寄接用梨穗，增加國產梨穗數量，本研究未來可作為低海拔地區高需冷性梨穗生產之參考。

In top-grafting pear production, pear scions would be renew every year. Most pear scions are imported from Japan and some from high altitude area in Taiwan. It is concerned that the source, quality and quarantine of the imported pear scion in doubt. In this research, we investigated the relationship of flower bud development, budburst, and shoot content with dormancy in shoot of ‘Shinko’ (pyrus pyrifolia Nakai). Vegetative buds and nonbearing shoots of the Top-grafted ‘Shinko’ pear were labeled in February 2014. Shoots were pruned to shoots with three 3 buds every months after March. We investigated the development of shoot and bud to study floral formation and dormancy of the shoots. We hope to directly produce ‘Shinko’ pear scion in lowland area. The shoots pruned in March grown to 111.8±32.4 cm in length. The new shoot length gradually reduced with the delayed of pruning time. The shoots pruned after July did not form any floral bud. It shows that the buds were turned into dormancy after July. The ratio of reproduction buds was about 27-33% in August, and 84% in September. In the same time, the ration of floral bud was lower in Lishan area, about 60%. Shoots pruned in March and April formed floral buds in August. The tip of small flower buds on the inflorescence began browning in September. The shoots pruned in May formed floral buds in September and the flowers on the inflorescence were not turned brown. It showed that flower buds quality affected by environment in lowland area. The percentage of bud break of one-eye cutting of ‘Shinko’ shoots in March was 63.75%, and 54.78% in April. The percentage of bud break of one-eye cutting of ‘Shinko’ shoots in May reduced, about 25%. It shows that the buds accumulated dormancy inductuion hormone after May. The leaf nitrogen contents of pruned in March and April shoot gradually decrease with the delayed of pruning time. Before buds were turned into dormancy, leaf nitrogen moved into shoot, and transformed into amino acid for cold torlence. Carbohydrates of pear shoots were composed of starch and with 80% ethanol soluble as minor after September. The starch content of shoots pruned in March and April dramatically raise in September. The content of 80% enthanol soluble was about 17 mg/g dw in June, higher than other collections.Carbohydrates was not affected by the pruning time. Shoots pruned after May might avoid necrosis improving bud flower quality. Furture, it is possible that using shoots purning in May to produce pear scions in lowland in Taiwan.