基于空间分析法研究温室番茄优质高产的水氮模式

【目的】本文通过设置不同灌水施氮水平处理,研究温室盆栽条件下,不同水氮供应组合对番茄产量品质和水氮利用效率的影响,分别提出单一指标最大和兼顾产量品质最优时的灌水施氮组合。【方法】试验于2013年在西北农林科技大学旱区农业水土工程教育部重点实验室的灌溉试验站日光温室内进行,供试番茄品种为金鹏M6088,在盆栽条件下设置3个灌水上限:低水W1(70%θf)、中水W2(80%θf)和高水W3(90%θf),θf为田间持水率;3个施氮量:低氮N1(N 0.24 g·kg~(-1)土)、中氮N2(N 0.36 g·kg~(-1)土)和高氮N3(N 0.48 g·kg~(-1)土),试验采用完全随机区组设计,共9个处理,每个处理重复15次。运用多元回归分析和空间分析相结合的方法,寻求单一指标最大时的灌水施氮组合,以及综合评价产量品质的水肥调控效应,提出兼顾产量品质最优时的灌水施氮范围。【结果】番茄产量、灌溉水生产率、氮肥偏生产力和品质受灌水量和施氮量的影响显著。番茄单株产量随着灌水量和施氮量的增加而先增加后降低(低氮和低水除外),低氮下增加灌水量可弥补缺氮造成的减产,低水下增施氮肥可缓解干旱对产量的抑制作用。产量与水氮供应量之间呈较好的二元二次关系,当灌水量和施氮量分别为62.3 L/株和0.3864 g·kg~(-1)土时,番茄单株产量有最大值(1 599.4 g/株),但灌水量和施氮量超过其峰值时,产量反而会减少。减小灌水量和增大施氮量时,灌溉水生产率增加;增大灌水量和降低施氮量时,氮肥偏生产力增加。番茄各品质指标受灌水量和施氮量的影响极显著。可溶性固形物和有机酸随着施氮量的增加而增加,维生素C、番茄红素、可溶性糖和糖酸比则先增大后降低。随着灌水量的增加,可溶性固形物和维生素C(中氮除外)呈降低趋势,番茄红素、可溶性糖和糖酸比呈先增加后降低的趋势(低氮除外)。采用熵权法计算得出番茄单一品质指标对不同水氮处理的敏感度排序为:番茄红素可溶性糖糖酸比有机酸维生素C可溶性固形物。【结论】通过多元回归分析和空间分析得出,番茄产量和品质同时达到大于等于95%最大值的灌水上限为田间持水率的80%,施氮区间约为0.34—0.44 g·kg~(-1)土。

An Investigation on Optimal Irrigation and Nitrogen Rates of Greenhouse Tomato Based on Spatial Analysis for High Yield and Quality

【Objective】The objectives of the study were to investigate the effects of different water and nitrogen supply rates on fruit yield and quality of tomato (M6088), irrigation water and nitrogen use efficiency，and to obtain the best combination of irrigation and nitrogen for maximum tomato production when a single indicator was considered and the optimal range of water and nitrogen rates for high yield and quality tomato production. 【Method】A pot experiment was conducted in greenhouse at the Key Laboratory of Agricultural Soil and Water Engineering in Arid and Semiarid Area of Ministry of Education in Northwest A&F University in 2013. The treatments comprised three irrigation upper limitations (W1, 70%θ_f; W2, 80%θ_f; W3, 90%θ_f, θ_f is the field capacity), and three nitrogen rates (N1, N 0.24 g·kg^-1; N2, N 0.36 g·kg^-1; N3, N 0.48 g·kg^-1). And the treatments were replicated fifteen times in random complete block designs. The multivariate regression analysis was used to obtain the best combination of irrigation and nitrogen for maximum tomato production when a single indicator was considered. The spatial analysis method was further used to comprehensively evaluate the tomato yield and quality to seek optimal range of water and nitrogen rates.【Result】The amount of irrigation and rate of nitrogen significantly affected the fruit yield, fruit quality, irrigation water productivity (IWP, in kg·m^-3, kg fruit produced per cubic metre water irrigated) and partial factor productivity of nitrogen (PNP). The fruit yield per plant increased first and then decreased with the irrigation and nitrogen rates were increased (except for N1, W1 treatments). Increasing irrigation amount remedied production reduction caused by nitrogen deficiency under N1 condition; increasing nitrogen rate relieved restrain from drought on fruit yield under W1 condition. Yield and the water and nitrogen supply exhibited a binary quadratic regression relationship. The maximum yield (1 599.4 g/plant) was achieved when the irrigation and nitrogen rates were 62.3 L/plant and 0.3864 g·kg^-1 soil, respectively. When the irrigation and nitrogen rates increased constantly, the tomato yield decreased. The IWP increased with the decreasing irrigation amount and increasing nitrogen rate, while the PNP was in contrast. The rates of water and nitrogen significantly influenced fruit quality parameters. With the increasing of nitrogen rate, soluble solids and organic acid content increased while vitamin C, lycopene and soluble sugar content and sugar acid ratio first increased and then decreased. Soluble solids and vitamin C content decreased with increasing irrigation amount (excepted for N2 treatment). Lycopene and soluble sugar content and sugar acid ratio first increased and then decreased with increasing irrigation amount (except for N1 treatment). The entropy weight method was used to determine the subjective weight of single tomato quality attributes. Results indicated that the attributes were ranked based on their importance by lycopene＞soluble sugar＞sugar-acid ratio＞organic acid＞Vc＞soluble solids. 【Conclusion】Through the multivariate regression analysis and the spatial analysis methods, the results showed that acceptable yield and quality of tomato (≥95% of corresponding maximum values) were obtained within the range of irrigation upper limitation 80% θ_f and nitrogen rate 0.34-0.44 g·kg^-1 soil.