铵态氮抑制向日葵生长的作用机制初步探讨

Preliminary study on the mechanism of ammonium nitrogen inhibiting the growth of sunflower

采用营养液培养方法,研究了细胞膨压的下降与铵态氮(NH+4 N)抑制向日葵生长的关系。结果表明,与硝态氮(NO-3 N)相比,铵态氮明显抑制了向日葵的生长,表现在生物量明显降低,顶部展开叶的叶面积显著下降,地上部和顶部展开叶的含水量下降。同时还发现,虽然铵态氮处理向日葵叶片的渗透势与硝态氮处理间差异不显著,但其水势和膨压明显低于硝态氮处理;铵态氮供应使向日葵最大展开叶中K+,Ca2+,NO-3等离子浓度显著下降。说明细胞膨压的下降是铵态氮导致向日葵生长受阻的主要原因之一。

Solution culture was conducted to study the relationship between decrease in tougor pressure in top leaf and ammonium nitrogen on inhibition of sunflower growth. The results showed that compared with nitrate supply, ammonium nutrition led to the significant decrease in biomass, leaf area of top expanded leaves and water content of shoot and top expanded leaves. No difference in osmotic potential between nitrate and ammonium treatments was found, while the water potential and tougor pressure in top expanded leaves supplied with nitrate were obviously higher than those of ammonium treatment. In addition, the K^+,Ca^(2+),NO^-_3 concentration in top expanded leaves fed with ammonium was lower than that of nitrate treatment. In conclusion, the decrease in tougor pressure in top expanded leaves was one of the main mechanisms leading to biomass decline of sunflower plants under the conditions of this experiment.