日光温室秋冬茬番茄氮素供应目标值的研究

通过连续两年的田间试验,以寿光当地的传统施肥处理为对照,通过对日光温室秋冬茬番茄主要生育时期土壤无机氮素供应水平的调控,确定番茄在第一穗果膨大期、第二穗果膨大期和第四穗果膨大期合理的无机氮素供应水平(追肥前根层土壤Nmin+追施化肥氮量)分别为N237、173和153kg/hm2。在3次追肥期间土壤有机氮矿化数量分别为N53、13和21kg/hm2;有机肥矿化提供的氮素量分别为N41、8和-17kg/hm2;灌溉水带入氮素量分别为N11、5和5kg/hm2。因此,若考虑土壤Nmin、土壤有机氮矿化、有机肥矿化、化肥氮及灌溉水带入的氮素等来源的氮素供应,则日光温室秋冬茬番茄在第一穗果膨大期、第二穗果膨大期和第四穗果膨大期时的氮素供应目标值分别为N342、199和162kg/hm2。目标产量为73t/hm2的番茄全生育期的氮素供应目标值为N481kg/hm2。

Studies on the target value of nitrogen supply for greenhouse tomato growth during autumn-winter season

Continuously excessive nitrogen input in greenhouse is one of the major problems in Shouguang, the famous vegetable production base in China, and this led to deteriorated product quality, high risk of nitrate leaching, secondary soil salinization, and low fertilization profit, etc. The main reason for these problems is that there is no effective N recommendation technique for greenhouse vegetable production. The objectives of the present study were to develop a nitrogen topdressing recommendation system and related target values of nitrogen supply at different growth stages for greenhouse tomato grown in autumn-winter season in Shouguang. Two field trials from 2002 to 2003 were conducted to determine the critical target value of nitrogen topdressing for greenhouse tomato at three growth stages in Shouguang, using (real-time) nitrogen control index, i.e. nitrate in petiole sap, fruit expanding rate, marketable yield and quality, and recommending techniques of nitrogen balance method for nitrogen topdressing (Nc), in comparison with farmer's conventional practice (Nt), on the basis of enough basal fertilizer application. Based on the results in 2003 autumn-winter season, with 80% of N supply level determined in the experiment of 2002, it could be concluded that the optimum mineral N supply levels (N_(min) content in effective root zone fertilizer N supply level at topdressing) were N 237, 173 and 153 (kg/hm~2) at the first, the second, and the fourth cluster fruit expanding stage, respectively. Besides the N supply from soil mineral N in effective root zone and chemical fertilizer N at topdressing, soil organic N, organic manure, and irrigation water also provided some available N for crop growth in greenhouse. The apparent N mineralization amounts from soil (organic) N pool in effective root zone were N 53, 13 and 21(kg/hm~2)at the first, the second, and the fourth cluster fruit (expanding) stage, respectively. Similarly N 41, 8 and -17(kg/hm~2) were supplied from apparent organic manure mineralization, and irrigation water provided N 11, 5 and 5(kg/hm~2) during the three topdressing stages. Considering the above-mentioned N input components, target values of N supply were N 342, 199 and 162(kg/hm~2) at the first, the second, and the forth cluster fruit expanding stage for greenhouse tomato grown in autumn-winter season in Shouguang. Total N target value for the whole growth stage of tomato was N 481(kg/hm~2) in order to achieve the target yield of 73(t/hm~2) in the (region.) These target values of N supply are useful for N topdressing recommendation of greenhouse tomato grown in (autumn-winter) season.