滴灌条件下氮肥用量对火龙果果实的影响

通过田间试验，研究了滴灌条件下不同施氮量（0，315，450，585，800 kg·hm?2）对火龙果果实生长和品质的影响。结果表明:合理的施氮量能促进火龙果果实的生长，不同生长期果实需氮量不同。施氮量一定程度上影响果实横径的生长，对纵茎影响较小。施氮量对果实中氮钾含量影响较大，二者均随施氮量的增加先增加后降低，但各处理间氮素含量差异不显著，施氮量对磷素含量影响较小。火龙果果实和花中氮磷钾含量均为K>N>P，其中，果实中N∶P∶K=1.00∶0.20∶1.12，花中N∶P∶K=1.00∶0.15∶2.13。不同采收期，氮肥用量对果实中可溶性固形物，可滴定酸和可溶性糖及抗坏血酸等含量的影响存在差异。综合考虑，实际生产中应以T2处理（450 kg·hm?2）施氮量为基础，根据不同采收期来调整施氮量。

Effects of Different Nitrogen Treatments on Pitaya Fruit Growth and Quality under Drip Irrigation

Red-flesh pitaya (Hylocereus polyrhizus) was treated with nitrogen fertilizer at the respective levels of 0, 315, 450, 585, 800 kg·hm?2 under drip irrigation to analyze the effects of different nitrogen treatments on the growth and quality of pitaya fruit. The results showed that judicious nitrogen application rate promoted the growth of pitaya fruit, and that the amount of nitrogen needed for the fruit growth was different at the different growth stages. The amount of nitrogen applied to some extent affected the growth of fruit transverse diameter, but had little effect on the fruit longitudinal diameter. The effect of nitrogen application on the content of nitrogen and potassium in fruit increased firstly and then decreased, but there was no significant difference in nitrogen content among different treatments, but the effect of nitrogen application on phosphorus content was relatively small. The nitrogen, phosphorus and potassium contents in the fruit and flowers were in the order of K > N > P, of which the ratio of N∶K was 1∶.20∶.12 in pitaya fruit and N∶P∶K = 1.00∶0.15∶2.13 in flowers. Nitrogen fertilizer application rate had different effects on the contents of soluble solids, titrable acids, soluble sugar and ascorbic acids in fruit at different harvest stages. It is recommended that in pitaya production pitaya should be applied with nitrogen at a rate based on Treatment 2 (450 kg·hm?2) and harvest stages.