结球甘蓝氮素营养快速诊断及最佳用量研究

应用Merck RQflex 2型反射仪和硝酸根试纸条研究了氮肥施用数量和施用方式对宁夏银川平原结球甘蓝产量和品质的影响,并探讨了结球甘蓝硝酸盐与氮肥用量的相关性和速测指标.结果表明:结球甘蓝的产量随施肥量的增加而增加,表现出线性-平台关系;施氮肥促进结球甘蓝产量的增加和净菜率提高;根据关键需肥期进行追肥比传统的基肥加追肥具有显著的增产效果,且收获时体内硝酸盐水平降低;结球甘蓝心叶外第一片完全展开叶叶柄硝酸盐含量随施氮量增加而显著增加,但随生育期延长而下降.结球甘蓝最佳经济施氮量为528 kg/hm2,叶柄硝酸盐适宜含量为3 172.20mg/kg.

Paper Test-Strips for Rapid Determination of Nitrate Content in Cabbage to Diagnose Nitrogen Nutrition and Its Application

Paper test - strip for rapid determination of nitrate content were used in testing nitrate content of Cabbage at growth durations with the application of different amount and method of N fertilizer in Yinchuan plain. The coeffident between nitrate and N application rate in Cabbage and its rapid diagnostic indicator were also studied. The results showed that the gross and net production of Cabbage was increased with the increased N application rate. A linearity-flat rela- tionship was observed between N amount and Cabbage yield. N fertilizing according to key growth periodic requirement not only can increase cabbage yield, but also can decrease nitrate content. Nitrate on inner leafstalk was significantly increased with the increased N application rate, but was decreased along with cabbage growth. The optimum application amount of N was 528kg/hm^2. Yet for nitrate diagnose, the feasible quantity was 3 172. 20 mg/kg in leafstalk of cabbage. It indicated that the method could replace the total nitrogen analysis method to the nitrogen nutritional diagnose.