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对日光温室内栽培的五叶一心白菜分别叶面喷施2、5、10和15mmol·L-1亚硫酸氢钠(NaHSO3),以喷施清水为对照,分别在处理后0、4、8、12和16d测定植株生物量、叶片的硝酸盐含量(NO3-)和硝酸还原酶(Nitrate reductase,NR)活性,同时测定叶片的光合参数和叶绿素荧光参数。结果表明,10mmol·L-1NaHSO3处理后12d时的效应最为显著,与对照相比,叶片NO3-含量降低44.85%,NR活性提高51.26%,且株高和地上部干质量均明显增加;同时显著提高其净光合速率(Pn)、羧化效率(CE)、最大羧化速率(Vcmax)、PSⅡ的原初量子效率(Q)和最大电子传递速率(ETRmax)。由此说明,对白菜叶面喷施NaHSO3,一方面能够在一定程度上提高NR活性,拉动氮素的还原同化,降低NO3-的累积;另一方面能够通过提高PSⅡ电子传递能力和羧化反应速率,促进光合碳同化效率,可在碳骨架和能量供应上拉动氮代谢的还原同化。
The leaves of five-leaf cabbage cultivated in solar greenhouse were sprayed with NaHSO3 (2, 5, 10 and 15 mmol·L-1), respectively. Sprayed with water as control, The plant biomass, nitrate content (NO3-) and nitrate reductase (NR) activity of leaves were measured on 12th and 16th day. The leaf photosynthetic parameters and chlorophyll fluorescence parameters were also measured. The results showed that the effect of 10 mmol·L-1NaHSO3 on the 12th day was the most significant. Compared with the control, the content of NO3- in leaves was reduced by 44.85% and the activity of NR was increased by 51.26%, and the plant height and shoot dry weight were significantly increased (Pn), carboxylation efficiency (CE), the maximum carboxylation rate (Vcmax), the primary quantum efficiency (Q) and the maximum electron transfer rate (ETRmax) of PSⅡwere increased. Thus, spraying NaHSO3 on cabbage leaves could not only increase NR activity to a certain degree, but also promote the reduction and assimilation of nitrogen and reduce the accumulation of NO3-. On the other hand, NaHSO3 could enhance the electron transport ability of PSⅡ and the carboxylation reaction Rate, promoting photosynthetic carbon assimilation efficiency, and reducing nitrogen assimilation in carbon skeleton and energy supply.