水分和氮素供应对菠菜硝酸盐累积和钾素吸收的影响

研究了水分和氮素供应对露地秋菠菜的硝酸盐累积和钾、氮吸收的影响。结果表明：与传统的水氮管理措施相比，采用水分平衡法和氮素专家系统进行的水氮供应并没有造成作物减产，但对钾、氮元素的吸收却有明显的影响，同氮素吸收相比，作物对钾素的吸收数量更高；并且作物对钾、氮的吸收比例随氮素供应水平的增加而降低，试验还动态监测了菠菜最新展开叶的叶柄汁液中的硝酸盐和K^ 浓度在一天内的变化情况。结果表明，不同水氮处理的菠菜叶柄汁液的硝酸盐浓度在白天均没有发生显著变化；叶柄汁液中的K^ 浓度和NO3^-／K^ 的浓度比在白天受氮素供应水平的影响很大，供氮量高，K^ 浓度和NO3^-／K^ 浓度比的变化也大，但受灌水量影响不大。图3表2参17。

EFFECTS OF EXOGENOUS SUPPLY OF WATER AND NITROGEN ON NITRATE ACCUMULATION AND POTASSIUM UPTAKE OF SPINACH (SPINACIA OLERACEA L.)

Effects of different water and nitrogen supply on nitrate accumulation and potassium uptake by autumn spinach (Spinacia oleracea L.) were studied in the field experiments in 1999 and 2000. The results showed that there was no yield reduction in recommended water and nitrogen treatments in comparison to conventional water and nitrogen treatments, but significant differences were observed in nitrogen and potassium uptake. Compared to nitrogen uptake, more proportion of potassium accumulated in the above-ground part of spinach. The ratio of potassium and nitrogen uptake by spinach decreased with N supply increasing. The concentrations of nitrate and potassium ions in the petiole sap extracted from the latest expanded leaf were monitored in the daytime with sunshine. No significant change of nitrate concentration occurred in petiole sap during the investigated period, but K+ concentration and the concentration ratio of NO 3-/K+ were strongly affected by N supply level other than irrigation regimes. Fig 3, Tab 2, Ref 17