不同氮素水平对西瓜幼苗生长及叶绿素荧光特性的影响

Effect of nitrogen on watermelon seedling growth and chlorophy11 fluorescence parameters of watermelon leaves

以早春红玉西瓜品种为试验材料,通过砂培试验,研究了不同氮水平对西瓜幼苗生长和叶片叶绿素荧光参数的影响,结果表明,氮浓度在16.67 mmol.L-1时,西瓜幼苗干物质积累显著高于其他处理,最适宜植株的生长;氮浓度在16.67和20.83 mmol.L-1时,西瓜幼苗叶片的初始荧光(Fo)均达到最小值,PSⅡ潜在活性(Fv/Fo)、PSⅡ实际光化学量子产量(ΦPSⅡ)达到最大值,而PSⅡ最大光化学量子产量(Fv/Fm)变化规律不明显。从整体变化看,非光化学猝灭(qN)值的变化幅度大于光化学猝灭(qP),且随着氮浓度的增加,qP先上升后下降,而qN的变化规律却与之相反。在本试验条件下,当纯氮浓度为16.67～20.83 mmol.L-1时,即能满足西瓜幼苗较佳光合作用和生长需要,氮浓度过高或过低均会抑制植株的生长。

The sand culture was used to investigate the changes of watermelon seedlings growth and chlorophyll fluorescence parameters of ZaoChunHongYu after the application of different concentrations of nitrogen.The results showed that the dry matter accumulation of watermelon seedlings was the biggest under the treatment of nitrogen 16.67 mmol·L-1.Fo reduced to the minimum,Fv/Fo and ΦPSⅡ increased to the maximum,but Fv/Fm did not show obvious change when nitrogen supply was from 16.67 mmol·L-1 to 20.83 mmol·L-1.From the whole change,qN varied stronger than qP which rised up first and then fell down as the nitrogen increased,but the change of qN was opposite.The results suggested that the application concentration of nitrogen from 16.67 to 20.83 mmol·L-1 could improve the watermelon seedling photosynthesis and growth,but more or less N could inhibit the seedling growth.