分次施氮对菠萝产量和品质的影响

针对果农对施肥次数比较困惑的现状，开展分次施氮对菠萝产量和品质的影响研究。试验选用巴厘品种，采用农民传统施氮量N 400 kg/hm2作为固定水平，根据菠萝生长阶段，设计缓慢生长期1次性全部施入， 缓慢生长期和加速生长期2次均施， 缓慢生长期、 加速生长期和快速生长期3次分别施N 80、 200和120 kg/hm2， 缓慢生长期、 加速生长期、 快速生长期和催花前4次分别施N 80、 70、 150和100 kg/hm2 4个处理和不施肥（对照），研究了大田种植条件下分次施氮对果重、 产量和果实品质的影响。结果表明，施肥2次以上可显著提高菠萝叶片叶绿素和类胡萝卜素含量，增加叶片和植株重量，提高菠萝单果重和产量，且随着分施次数的增加，菠萝的单果重和产量均有升高的趋势。施肥2次以上，单果增重达10%以上，分4次施肥比1次性施肥显著提高单果重和菠萝产量。但对果实的品质而言，随施肥次数增加，可滴定酸、 含糖量和Vc含量呈下降趋势，其中Vc含量下降最为明显，降幅可达14%~26%。因此，如果要提高菠萝产量，氮肥最少需要分2次施用，而要保持较好的品质，施肥次数不要超过2次。

Effects of split application of nitrogen on yield and quality of pineapple

With farmers confused by frequency of split fertilization status, this research was carried out to study the effects of frequency of N fertilizer application on yield and quality of pineapple. Ananas comosusr cv. Yellow Mauritius and N 400 kg/ha as a fixed rate which is the farmers’ traditional fertilization rate were selected for the study. It was designed as single application, splitting in 2 equal dosages during the slow and accelerating growth stages, splitting in 3 applications with N 80, 200 and  120 kg/ha during the slow, accelerating and fast growth stages, splitting in 4 applications with N 80, 70, 150 and 100 kg/ha during the slow, accelerating, fast growth stages and before the forcing stage, respectively. The contrast was no N fertilization. The aim was to study effects of increasing frequency of split application on weight, yield and quality of pineapple fruits. The results show that the splitting in more than 2 applications significantly improve leaf chlorophyll contents, carotenoid contents, leaf weights, plant weights, fruit weights and yields of pineapple, and pineapple fruit weights and yields both have the  increased trends with the increase of the fertilization frequency. With the splitting in more than 2 applications, a single fruit would be increased by more than 10%. The splitting in 4 applications improves pineapple yield significantly compared with the single application. However, the qualities of the pineapple are different. The titratable acidity, sugar content and vitamin C content have downward trends when adding the N fertilization frequency, and the vitamin C content reduction is most obvious and is decreased by 14%-26%. This study concludes that frequency of the splitting application should be more than 2 to achieve high yields. On the contrary, it should be less than 2 to maintain good fruit quality. The research provides a reference for farmers engaged in pineapple cultivation.