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以弱光敏感的菊花品种‘清露’为试材,采用分析光合参数的方法,在自然光照(对照)和30%光照(弱光处理)2个条件下,研究了不同光强梯度(1 500、1 200、1 000、800、600、400、200、150、100、50、20、0μmol·m~(-2)·s~(-1))下植株在0、5、10、15、20d各时间点的光合特性变化,以探讨弱光对菊花光合特性影响规律,为苗期管理提供参考。结果表明:随着光合有效辐射(PAR)的提高,净光合速率呈上升趋势,在弱光条件下也是如此,对照净光合速率(Pn)最大值达到15.31CO_2μmol·m~(-2)·s~(-1),而弱光下最大值仅达到7.94CO_2μmol·m~(-2)·s~(-1);光饱和点(LSP)最大值分别为1 061.00、825.00μmol·m~(-2)·s~(-1);光补偿点(LCP)最大值分别为58.7、76.42μmol·m~(-2)·s~(-1);对气体交换参数进行分析,发现弱光下植株通过增大气孔导度(Gs),减少胞间二氧化碳浓度(Ci),来减缓因光照不足而造成的光合速率下降;然而弱光下菊花虽然通过自身调节来适应环境变化,但低光照仍会造成其光合速率的下降,影响植株的正常生长。这种效应既与气孔限制有关,又受非气孔因素的影响。
Using the method of analyzing the photosynthesis parameters under the condition of natural light (control) and 30% light (low light treatment), we studied the effects of different light intensity gradients (1 500,1 200,1 000,800,600,400,200,150,100,50,20,0 μmol · m -2 s -1) , 20d photosynthetic characteristics at different time points to explore the weak light on the photosynthetic characteristics of chrysanthemum, providing reference for the seedling management. The results showed that the net photosynthetic rate increased with the increase of photosynthetically active radiation (PAR) under low light conditions, and the maximum value of Pn reached 15.31CO_2μmol · m -2 · s ~ (-1), while the maximum under low light reached only 7.94CO_2μmol · m ~ (-2) · s ~ (-1) and the maximum value of light saturation point (LSP) was respectively 1 061.00 and 825.00μmol · m ~ -2) · s ~ (-1) and the maximum value of light compensation point (LCP) were 58.7 and 76.42μmol · m -2 · s -1, respectively. The gas exchange parameters were analyzed, The lower plantlet could reduce the decrease of photosynthetic rate due to insufficient illumination by increasing the stomatal conductance (Gs) and reducing the intercellular carbon dioxide concentration (Ci). However, although the chrysanthemum adapts itself to environmental changes through low light, low light Still can cause the decline of its photosynthetic rate, affect the normal growth of the plant. This effect is not only related to stomatal limitation but also to non-stomatal factors.