遮阴对日光温室柑橘生长及生理特性的影响

Effects of shading on the growth and physiological characteristics of Citrus in solar greenhouse

以4年生枳砧砂糖橘为试材,研究不同遮阴处理对温室柑橘树冠微环境、柑橘生长及叶片生理特性的影响。结果表明:未遮阴的日光温室条件下,中午光合有效辐射强、温度高、相对湿度低,柑橘叶片净光合速率日变化呈"双峰型",有明显的光合"午休"。遮阴可显著降低光合有效辐射,降低柑橘树冠温度,增加树冠相对湿度,柑橘叶片净光合速率日变化表现为"单峰型"。遮阴处理对新萌发夏梢生长表现出抑制作用,随着透光率的降低,柑橘枝长、枝粗、枝条数降低。遮阴处理使柑橘叶片单叶面积增大,叶片变薄。遮阴使叶绿素b含量增加,随着透光率的降低,叶绿素a/b值变小。一层遮阴柑橘幼果坐果率比对照提高了16.44%,二层遮阴处理坐果率为0。

In order to study the effects of different shading treatments on the canopy microclimate condition, shoot growth and some leaf physiological metabolism of citrus under solar greenhouse, 4-year-old seedlings of Shatangju tangerine （Citrus reticulate‘Shatangju’） on the stock of trifoliate orange （Poncirus trifoliata Raf.） was selected as materials. Results showed that the PAR and temperature of greenhouse were high, the relative humidity was very low, and the curve of diurnal variation of net photosynthetic rate （ Pn ） was demonstrated two peaks with midday depression of photosynthesis under un-shading treatment. Shading markedly decreased canopy PAR and temperature, increased the relative humidity. The curve of diurnal variation of net photosynthetic rate （ Pn ） was demonstrated single peak with shading. Shading inhibited the growth of new germination summer shoot. With the transmittance reducing, new shoot number, diameter and length decreasing. Shading markedly increased leaf area and decreased leaf thickness. Compared with CK, the Chl b of leaves declined and Chl a/b decreased under shading. The young fruit set with a layer of shading treatment increased 16.44%, while the young fruit set was 0 under two layers of shading treatment.