巨桉林草间作模式中牧草的耐阴生理适应性

Physiological bases of herbages shade-tolerance in Eucalyptus grandis and herbage inter-cultivated system

研究了不同郁闭度巨桉林下鸭茅、多年生黑麦草和扁穗牛鞭草的耐阴生理适应性.结果表明:随着林分郁闭度的增加,3种牧草的光饱和点(LSP)、光补偿点(LCP)、叶绿素a/b(Chla/Chlb)、游离脯氨酸(Pro)、可溶性糖(SS)和可溶性蛋白(SP)含量呈下降趋势,表观量子效率(AQY)、叶绿素(Chl)含量、丙二醛(MDA)含量和超氧化物歧化酶(SOD)活性有不同程度的提高;随着林分郁闭度的增加,扁穗牛鞭草的日均净光合速率(Pn)呈下降趋势,鸭茅和多年生黑麦草的Pn先增加后下降,且在林分郁闭度分别小于0.54和0.27时,二者的Pn均高于对照;3种牧草的11项生理指标与郁闭度的相关性均达到显著水平(P<0.05);运用平均隶属函数法对3种牧草的耐阴适应性进行排序,结果为鸭茅>多年生黑麦草>扁穗牛鞭草.

The study on the physiological bases of the shade-tolerance of Dactylks glonerata, Lolium perenne, and Hemarthria compressa inter-cultivated in Eucalyptus grandis forests with different canopy densities showed that with increasing canopy density, the light saturation point （ LSP）, light compensation point （LCP）, chlorophyll a/b （Chla/Chlb）, and the contents of proline （Pro）, sol- uble sugar （SS） and soluble protein （SP） of the three herbages decreased gradually, but the apparent quantum yield （ AQY）, chlorophyll content （ Chl）, malondialdehyde （ MDA ） content, and superoxide dismutase （SOD） activity were in adverse. The daily average net photosynthesis rates （P,） of H. compressa decreased gradually, while that of D. glomerata and L. perenne increased first and decreased then. When the canopy density was below 0. 54 for D. glomerata and below 0.27 for L. perenne, the P. of the two herbages was higher than CK. There existed significant correlations （P 〈 0. 05 ） between 11 physiological indices of the three herbages and canopy density, and the shade-tolerance of the three herbages was in the order of D. glomerata 〉 L. perenne 〉 H. compressa, based on the ordination with average subjection function method.