日光温室番茄的氮素追施与反馈调控

在施用足量有机肥的基础上,以山东寿光当地的常规氮肥追施措施为对照,通过结合硝酸盐速测技术对日光温室秋冬茬番茄不同生育时期的氮素供应进行实时动态调控,以确定合理的追肥数量。结果表明,同当地农民的常规处理相比,采用实时调控处理的氮素投入总量减少了N170kg.hm2,但对番茄的生长(株高、茎粗、果实发育速度等)、产量和品质等指标没有任何影响。根据追肥前根层土壤氮素的供应水平(0—30cm土壤NO3--N含量+氮素追施数量)的监测,可初步确定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最多为N296kg.hm2、216kg.hm2和191kg.hm2。与此同时,将每个时期所确定的目标值应用在同期生长的其它3个日光温室的番茄氮素追施调控,结果发现与相应的农民常规处理相比,实时调控处理对作物的生长同样没有影响,这表明在日光温室秋冬茬番茄生产过程中,结合植株和土壤硝酸盐速测技术,通过施肥调控满足作物在不同生长时期的氮素供应水平是可行的。

Nitrogen topdressing and feedback control in greenhouse tomato

The trial of real-time control for nitrogen topdressing in protected-field tomato was conducted in autumn-winter season in Shouguang,Shangdong province using the technique of nitrate quick-testing under enough organic manure application at preplanting. Farmer's conventional practice in N topdressing was used as control in the trial. Nitrogen recommendation in topdressing was based on the results of nitrate quick-testing in the rooted soil layer and petiole sap before topdressing. The results showed that compared with conventional topdressing practice the amount of applied N in topdressing reduced by N 170 kg/hm~2 without any negative effects on shoot height, fruit developing rate, and marketable yield. Based on soil nitrate measurement and applied N rate in topdressing it was suggested at least N recommendation in topdressing of greenhouse tomato production should meet the target values of N 296 kg/hm~2, 216 kg/hm~2, and 191 kg/hm~2 at the first, the second, and the forth cluster fruit expanding stage, respectively. Successful results were also collected from the validating trials in the other three greenhouses using these target values at the same time. It means that no yield reduction using these real-time control for N topdressing was investigated in the validating trials with different nitrate content at preplanting stage, in comparison with conventional N topdressing practice. Although the N target values were not "critical" value, this suggested it was still very useful in N management for sustainable vegetable production.