水肥耦合下西芹生育期内硝酸盐含量变化规律分析

为了探索水肥耦合对西芹生育期内硝酸盐含量的变化规律,采用三因素五水平二次通用旋转组合设计,在冀西北高寒半干旱区开展了旱棚试验研究.试验表明:随生育期延长西芹硝酸盐含量先升后降,且收获期最低:水肥高中低不同组合下西芹生育期硝酸盐含量除低肥低水和对照因缺水在收获前期有波峰出现外,其他水肥不同组合下,硝酸盐曲线均表现为先升后降.从卫生学角度评价,只有处理7(N109.5P36W5692)和处理20(N270P90W4500)即低肥高水和中水中肥处理西芹硝酸盐含量符合安全标准.不同因子组合下各效应(单因子效应、双因子效应及3因子效应)的西芹生育期硝酸盐动态变化规律表明,氮、磷、水对西芹硝酸盐主效应分析依次表现为增加、不确定性和减少.结果表明:不合理的氮、磷、水施用是限制西芹正常生长,造成西芹硝酸盐积累的主要原因.

Variation law of nitrate content of celery during growth period under water and fertilizer coupling

In order to determine the effect of water and fertilizer coupling on the variation law of nitrate content in celery at the growth stage, a 3×5 orthogonal block design experiment was conducted under rain-free condition in the semiarid cold region of Northwest Hebei Province. Results show that celery nitrate content increases at early growth stage and then decreases at late growth stage, reaching its lowest at harvest under different combinations of high, moderate and low water and fertilizer. However, the nitrate content order is different for low water and fertilize treatment and also in the control treatment. Of all the treatments, only 7 (N_109.5P₃₆W₅₆₉₂) and 20 (N₂₇₀P₉₀W₄₅₀₀) treatments, low fertilizer and high water treatment, and moderate fertilizer and water treatments meet safe standards for public health. The one-factor, two-factor and three-factor effect on nitrate content under different combinations show that the effect of N increases, that of P is uncertain while that of water decreases. Unreasonable N, P, water combination restricts normal growth of celery, increases nitrate accumulation.