遮荫对红叶桃叶片光合生理的影响

研究了夏秋季全光照（对照）和连续遮荫条件下（中度遮荫、重度遮荫）红叶桃叶片光合生理特性的变化。结果表明：在夏秋两季，红叶桃叶片相对含水量（RWC）均随遮荫程度的增加而升高，而比叶重（SLW）、净光合速率日积分值（DIV of Pn）、光补偿点（LCP）和羧化效率（CE）变化趋势则相反；遮荫下红叶桃表观量子效率（AQY）夏季高于对照而秋季低于对照，水分利用效率日积分值（DIV of WUE）则与之相反；遮荫的红叶桃叶绿素（Chl.）含量极显著高于对照，夏季遮荫使红叶桃叶片花色素苷（Ant.）含量高于对照；遮荫条件下花色素苷含量/叶绿素含量（Ant./Chl.）始终低于对照；全光照下净光合速率（Pn）日变化均表现双峰曲线，存在光合“午休”，而遮荫下“午休”现象消失。因此，遮荫可减轻红叶桃光抑制，但不利于光合积累和叶片彩色的呈现，红叶桃更适于栽植在全光照条件下。

Effects of Shading on Photosynthetic Characteristics of Red-leaf Peach

The changes of photosynthetic characteristics in leaves of red-leaf peach under natural condition（control）and under continuous shading condition（moderate shading and severe shading）were studied respectively. The results showed that relative water content（RWC）of leaves of red-leaf peach increased while specific leaf weight（SLW），diurnal integral value of photosynthesis（DIV of Pn），light compensation point (LCP) and carboxylation efficiency (CE) decreased with the dilute of light intensity in summer and autumn. Furthermore，the apparent quantum yield（AQY）of red-leaf peach under summer shading condition was much higher than that in autumn while diurnal integral value of water use efficiency（DIV of WUE）was reverse. The content of chlorophyll（Chl.）in leaves of red-leaf peach under shading condition was significantly higher than that under the control in the two seasons and the similar result appeared on the content of anthocyanin（Ant.）in summer. In addition，Ant./Chl. of red-leaf peach was always significantly lower than the control. The diurnal variation of photosynthesis in leaves of red-leaf peach in full illumination showed the two-peak curve in summer and autumn but the phenomenon disappeared when it was under shading. This article concludes that the photoinhibition can be abated by appropriate shading treatment but it goes against photosynthetic accumulation and color appearance. Sored-leaf peach should be planted in full illumination.