红壤水分调节对柑桔叶片叶绿素和光合特性的影响

Effects of Red Soil Moisture on Chlorophyll Content and Photosynthesis of Orange (Citrus Unshiu Marc.) Leaves

通过调节柑桔根际土壤含水量,研究了红壤不同水分处理对柑桔叶片叶绿素含量、净光合速率(Pn)、胞间CO2浓度(Ci)、进出气室CO2的浓度差(△Ca)、气孔导度(Gs)、蒸腾速率(Tr)和羧化效率(CE)的影响。结果表明,红壤相对含水量在75%时,柑桔叶片叶绿素a、叶绿素b和类胡萝卜素含量都达到了最大值;Tr与土壤含水量变化趋势一致(R2=0.9625**),而Pn(R2=0.9388*)、△Ca、CE在土壤相对含水量75%以下时,与土壤含水量呈正相关,说明红壤相对含水量在75%以上时柑桔叶片的部分蒸腾与Pn无关;Pn与Ci呈负相关,土壤相对含水量在30%时的Gs与其他水分处理间的差异达到极显著,表明红壤水分含量所引起的柑桔叶片光合速率变化在土壤相对含水量30%以下时主要是由非气孔因素所引起,而在土壤相对含水量30%以上时主要是由气孔因素所引起。

The effects of red soil moisture on the chlorophyll content, net photosynthetic rate （Pn）, intercellular CO2 concentration （Ci）, difference of CO2 eoncentrations（△Ca） passing in and out CO2 chamber, stomatal conductance （Gs）, transpiration rate （Tr）, and earboxylation efficiency （CE） of orange leaves under different soil relative moisture treatments were studied. The results showed that when the soil relative moisture was 75%, the contents of chlorophyll a, chlorophyll b and carotinoid of orange leaves reached the maximum, and there was a positive correlation between Tr and soil relative moisture （ R^2 = 0.9625＊＊ ）; but when the soil relative moisture was lower than 75%, there were positive correlations between Pn, △Ca, CE and soil moisture, this indicated that no relation between Pn and the transpiration of orange leaves when the soil relative moisture over 75%. There was negative correlation between Pn and Ci. There were significant differences between Gs at the treatment of soil moisture equal to 30% and those of other treatments, this indicated that Pn change of orange leaves was mainly caused by non-stomatie inhibition when soil relative moisture was lower than 30%, but mainly caused by stomatic factors when the soil relative moisture over 30%.