裔芽重量及定植時間、遮陰與氮肥施用對鳳梨冬季自然開花之影響

Abstract

台灣冬季低溫可促使鳳梨冬季自然開花，會使產期過度集中於夏季，減少秋季產量，降低整體產值，因此自然開花為台灣鳳梨產業之嚴重問題。本試驗之目的主在探討，裔芽重量、定植時間、遮陰與氮肥施用對鳳梨冬季自然開花之影響，以了解鳳梨開花所需的條件，並依此調整定植時間、定植苗重，並於冬季時遮陰或施加氮肥，以期避開冬季低溫導致之開花。 植株重量530 g以上，電石處理之開花率可達50%以上，且除定植1個月之植株外，中、大苗定植愈久，開花率愈低。低溫處理之結果與電石處理相異，其植株愈重、葉片數愈高，處理後之開花率愈高，並非所有處理經低溫處理後皆會開花；小苗定植時間少於3個月，經低溫處理後不開花，中、大苗定植時間小於1個月，經低溫處理後之開花率僅有10%，故較晚定植植株或定植小苗，其植株重量較輕，可減少冬季低溫造成的開花。 植株以70%與90%遮陰處理，對鳳梨生長速率影響不大，但可有效延遲鳳梨自然開花之時間，且延遲之時間與遮陰程度成正比。70%遮陰處理最多可延遲自然開花時間達2週，並可使25%之果實延遲2週採收；90%遮陰處理則可達4週，並90%遮陰處理所有果實延遲2週採收。種遮陰處理與對照組之果實重量無顯著差異，但90%遮陰處理之果實糖度稍高於其他兩處理。 施用尿素可促進鳳梨葉片生長。葉片數約40-50片之植株，於自然低溫前施用40 g以上之尿素，再配合給水可有效抑制自然開花。

Pineapple flowering could be induced naturally by low temperature during winter in Taiwan. Natural flowering makes it difficult for growers to schedule harvest time and yield, and decrease price of pineapple. The object of this thesis is to study the effect of slip weight, planting time, shading and nitrogen application on inhibiting pineapple natural flowering caused by low temperature of winter. In calcium carbide treatment, the flowering percentage of middle and large slips were decreased as planting time delayed, excluded plants planted only one month. The flowering percentage reached 50% when plant weight was heavier than 530 g. In low temperature treatment, the flowering percentage increases as the planting time being advanced and slip weight increased. Small slips planted less than three months did not flower after low temperature treatment. Flowering percentage was only 10% after treated with low temperature same for middle and large slips planted only one month. Planting small slips or planting near winter, could decrease the flowering percentage after winter. Pineapple natural flowering could be delayed with 70% and 90% of shading, and had little effect on growth rate. Time to flowering was delayed with increase shading level. Flowering was delayed for 2 and 4 weeks by 70% and 90% shading treatment, respectively. Harvest time of 25% of fruits in70% shading treatment were delayed for 2 weeks, and all fruits in 90% shading treatment were delayed for two weeks. Fruit weight of each treatment did not have significant difference. Applying urea could accelerate leaf growth in pineapple. Apply of 40 g urea on pineapple with 40-50 leaves and watering every two weeks could inhibit natural flowering effectively.