再生水加氯对滴灌系统堵塞及番茄产量与氮素吸收的影响

加氯处理是防止再生水滴灌系统生物和化学堵塞的常用方法，但有关加氯处理对作物生长影响的研究尚不充分。通过在日光温室内的田间试验，研究了加氯浓度和加氯频率对再生水滴灌灌水器堵塞特性、番茄产量和品质的影响；建立了土壤硝态氮含量随土壤电导率、含水率和温度变化的多元回归模型，分析了加氯处理对根区土壤硝态氮变化动态和氮素吸收的影响。结果表明，加氯处理能够有效防止再生水滴灌引起的灌水器流量降低；再生水滴灌增加了硝态氮在土壤表层（15 cm深度）的累积，促进了作物对氮素的吸收；加氯处理使植株吸氮量明显降低，加剧了硝态氮在土壤表层的累积，累积量随着加氯浓度和加氯频率的增大而增大；再生水滴灌的番茄产量略高于地下水滴灌，而再生水加氯处理会使产量有所降低；再生水滴灌使番茄口感指标（可溶性糖和水溶性总酸）显著提高、营养指标（Vc含量和可溶性固形物）显著降低，加氯处理能够有效缓解营养指标的降低趋势。采用浓度低于50 mg/L、频率低于两周1次的加氯处理对作物的氮素吸收有一定的抑制作用，但不会对作物生长造成明显不利影响。

Effect of chlorination on yield and nitrogen uptake of tomato and emitter clogging in a drip irrigation system with sewage effluent

Chlorination is a common practice used in prevention and treatment of emitter clogging caused by algae and bacteria, but the effect of chlorination on crop growth has not been adequately addressed. Field experiments were conducted in a solar-heated greenhouse to investigate the effects of chlorine concentration and injection frequency on emitter clogging of drip system with sewage effluent and tomato yield, quality and nitrogen uptake. A multiple regression equation to predict nitrate content in soil from the measured soil bulk electrical conductivity, water content and temperature was derived. Then the equation was used to investigate the effects of chlorination on nitrate dynamics and nitrogen uptake. The results demonstrated that chlorination is an effective method for preventing the reduction of emitter discharge in drip systems applying sewage effluent. Drip irrigation with sewage effluent increased nitrate content in upper 15 cm layer of soil and nitrogen content of plant stem and produced a greater nitrogen uptake than irrigation with groundwater. Chlorination decreased the total nitrogen content of plant stem and nitrogen uptake, and increased the accumulation of nitrate in upper layer of soil. The increase of chlorine concentration and injection frequency led to a significant increase of nitrate accumulation. A slightly greater yield of tomato was observed for drip irrigation with sewage effluent than irrigation with groundwater, while chlorination resulted in a decreased yield. Irrigation with sewage effluent increased soluble sugar and water-soluble acid of tomato fruits, but decreased ascorbic acid and soluble solids. Chlorination might alleviate the decreasing trends of ascorbic acid and soluble solids resulted from sewage application. The results obtained from this study suggested that injection of chlorine with an input concentration of less than 50 mg/L and an interval of larger than two weeks do not impose a negative influence on tomato growth, although the injection of chlorine may restrain the nitrogen uptake of plant.