施氮量对滴灌甜菜中后期叶片叶绿素荧光特性的影响

Effect of nitrogen application on chlorophyll fluorescence characteristics in beet leaves at middle and late stage under drip irrigation

氮肥对甜菜叶片光合作用和碳同化具有重要作用,利用PAM-2500研究了4种施氮水平(0、5、150、225 kg·hm^-2)下甜菜块根膨大期和糖分积累期叶片叶绿素荧光量子产量以及快速光曲线相关参数。结果表明,甜菜生育中后期PSⅡ潜在最大光化学效率F v/F m均在0.8左右,处理间无显著差异,糖分积累期N 150处理的实际光化学效率YⅡ高于其它处理。增施氮肥可以提高甜菜叶片相对电子传递速率,两个生育时期甜菜叶片相对电子传递速率均表现为随施氮量增加不断升高的趋势。甜菜生育中后期N 150的最大相对电子传递速率和半饱和光强均高于N 0和N 75处理,但与N 225无显著差异。150 kg·hm^-2的施氮量可以提高甜菜叶片相对电子传递速率,最大相对电子传递速率以及对强光的耐受能力,提高滴灌甜菜叶片光合能力的同时,达到减氮增效的目的。

Nitrogen fertilizer plays an important role in photosynthesis and carbon assimilation of beet leaves.The chlorophyll fluorescence quantum yield and fast light curve related parameters of leaves at root expansion stage and sugar accumulation stage under four nitrogen application levels(0,75,150,225 kg/hm^2)were studied by using PAM-2500.Results showed that the PSⅡpotential maximal photochemical efficiency Fv/Fm are around 0.8 during later growth stage and no significant differences between treatments.Actual photochemical efficiency YⅡof N 150 is higher than other treatments at sugar accumulation period.Nitrogen fertilizer increased the relative electron transfer rate of beet leaves during the two growth periods.The maximum relative electron transfer rate,semi-saturation and light intensity of N 150 were higher than those of N 0 and N 75,but there was no significant difference between them and N 225.Appropriate nitrogen application can improve relative electron transfer rate,maximum relative electron transfer rate and tolerance to strong light in beet leaves.Chlorophyll fluorescence parameters can be used to indicate nitrogen nutrition status in beet leaves under drip irrigation.