水氮钾耦合对火龙果产量和品质的调控效应

【目的】系统研究火龙果的水肥耦合效应，制定适宜的灌水施肥方案，为其高产优质和可持续发展提供技术依据。【方法】以紫红龙（Hylocereus polyrhizus，Zihonglong）为试验材料，以田间持水量、施氮量和施钾量为试验因素，采用3因素5水平二次回归通用旋转组合设计，共设20个处理，进行2018—2019连续2年的定株水肥耦合试验，统计火龙果周年产量和各批次单果重，测定果实可溶性糖、可溶性蛋白等品质指标并进行综合评分，探究水、氮、钾对火龙果产量和品质的调控作用，采用频率分析法对产量和品质数学模型进行优化分析，以获取高产优质下的灌水施肥方案。【结果】不同处理水氮钾的供应对火龙果果实可溶性蛋白、糖酸比等品质指标影响显著（P<0.05，下同），处理10（田间持水量40%、N 300 kg/ha、K2_O 375 kg/ha）和处理15（田间持水量60%、N 300 kg/ha、K2_O 375 kg/ha）的果实蛋白质含量相对于其他处理有所提升，处理4（田间持水量72%、N 122 kg/ha、K2_O 152 kg/ha）相对于其他处理明显降低火龙果果实中可滴定酸含量，提升糖酸比值，改善果实风味，但也降低果实中总酚含量。整体来看，产量和综合品质均随田间持水量、施氮量和施钾量的增加表现为先增后减的变化趋势；因素对产量和综合品质的影响程度均表现为田间持水量>施氮量>施钾量，田间持水量、施氮量和施钾量对于火龙果产量的交互效应存在差异，其中田间持水量与施氮量对产量的交互作用显著。在田间持水量52.43%~70.86%、N 215.17~511.00 kg/ha、K2_O 148.99~565.47 kg/ha时，火龙果产量可达22500 kg/ha以上；在田间持水量48.25%~64.68%、N 247.89~404.48 kg/ha、K2_O 247.30~581.51 kg/ha时，火龙果综合品质评分达80分以上。【结论】田间持水量、施氮量和施钾量水平显著影响火龙果的产量和主要品质指标，适宜的灌水和充足的氮钾供应可提高火龙果的产量和品质，增加其商品性和经济效益，综合考虑三者对火龙果产量和品质的影响，滴灌条件下，火龙果高产优质的灌水施肥方案为:田间持水量52%~65%，N 247.89~404.48 kg/ha，K2_O247.30~565.47 kg/ha。该优化方案可供同等肥力水平火龙果园水肥一体化模式下的管理参考。

Effects of irrigation and nitrogen,potassium fertilizer coupling on yield and quality of pitaya

【Objective】To systematically study the coupling effect of water and fertilizer on pitaya,and formulate suitable irrigation and fertilization plans,so as to provide technical basis for its high yield,high quality and sustainable development.【Method】With Hylocereus polyrhizus(Zihonglong)as the experimental material,field capacity,nitrogen application and potassium application as experimental factors,a three-factor and five-level quadratic regression general rotation combination design was adopted,and a total of 20 treatments were set to conduct a two-year(2018-2019)water and fertilizer coupling experiments on fixed plants. The annual yield and single fruit weight were counted,and the fruit soluble sugar, soluble protein and other quality indicators were measured in a comprehensive evaluation to investigate the effect of water,nitrogen and potassium on the yield and quality of H. polyrhizus. The frequency analysis method was used to optimize the mathematical model of yield and quality to obtain the irrigation and fertilization scheme under efficient production.【Result】Different treatments of water,nitrogen and potassium supply had a significant effect on fruit soluble protein, sugar-acid ratio and other quality indicators(P<0.05,the same below). Compared with other treatments,the pitaya under treatment 10(field water holding capacity 40%,N 300 kg/ha,K₂O 375 kg/ha)and treatment 15(field capacity 60%,N 300 kg/ha,K₂O 375 kg/ha)had higher protein content compared to that under other treatments. Treatment 4(field capacity 72%,N 122 kg/ha,K₂O 152 kg/ha),compared with other treatments,could reduce the titratable acid content,raise the ratio of sugar to acid,thus,improving the fruit flavor,at the same time it also reduced total phenolic content. Overall,the yield and comprehensive quality of the fruit increased first and then decreased with the increase of field water holding capacity,nitrogen and potassium supply. The effect of each factor on yield and comprehensive quality was in the order:Field capacity>nitrogen application>potassium application. There were differences in the interaction effects of water,nitrogen and potassium on the yield of H. polyrhizus. The interaction effect of field water holding capacity and nitrogen supply on yield was significant. When the field capacity was 52.43%-70.86%,N 215.17-511.00 kg/ha,K₂O 148.99-565.47 kg/ha,the yield could reach more than 22500 kg/ha;when the field water holding capacity was 48.25%-64.68%,N 247.89- 404.48 kg/ha,K₂O 247.30-581.51 kg/ha,the comprehensive quality score of dragon fruit was above 80 points.【Conclusion】The level of field capacity,nitrogen application and potassium application significantly affects the yield and quality indicators of H. polyrhizus. Appropriate irrigation and sufficient nitrogen and potassium supply can improve the fruit yield and quality,and increase its commerciality and economic benefits it could bring. Considering the effects of field capacity, nitrogen and potassium fertilizer supply on yield and quality,the irrigation and fertilization plan for efficient production of H. polyrhizus under drip irrigation is as follows:field capacity 52%-65%,N 247.89-404.48 kg/ha,K₂O 247.30-565.47 kg/ha. This optimized irrigation and fertilization plan can be used as a reference for the management of the water and fertilizer integration mode in the same fertility level of pitaya orchards.