摘要
在不同郁闭度巨桉林下间作鸭茅、多年黑麦草和扁穗牛鞭草,对3种牧草叶绿素含量、叶绿素荧光参数、光合日进程和生物量进行测定分析,并探讨各牧草在不同郁闭度的巨桉林分下生长状况。结果表明,1)随着林分郁闭度的增加,3种牧草的叶绿素(Chl)含量增大,间作下牧草的Chl含量和叶绿素b(Chlb)都高于对照(CK),鸭茅和多年黑麦草叶绿素a/b(Chla/Chlb)值随郁闭度增加而显著降低(P<0.05);2)随着林分郁闭度的增加,鸭茅和多年黑麦草光系统Ⅱ的光化学效率(Fv/Fm)先增加后下降,下降时的林分郁闭度为0.60;鸭茅和多年黑麦草Fv/Fm值大于扁穗牛鞭草,但在间作条件下其Fv/Fm值增加程度小于扁穗牛鞭草;3)3种牧草在对照和间作条件下的光合日进程都是单峰曲线;鸭茅在林分郁闭度小于0.53时,多年黑麦草在林分郁闭度小于0.42时,其日平均净光合速率(Pn)都高于对照,间作条件下扁穗牛鞭草的Pn低于对照;4)扁穗牛鞭草对照的生物量最高,随着林分郁闭度的增加,其生物量逐渐减小,但在不同郁闭度下的生物量均比其他牧草对应郁闭度下的生物量高,在郁闭度为0.56时,扁穗牛鞭草生物量仍大于其他牧草的最大生物量。从总体来看,3种牧草对弱光环境的响应方式不同,鸭茅和多年黑麦草主要表现在提高Chlb含量,而扁穗牛鞭草主要表现在提高Fv/Fm值,3种牧草的耐荫性为鸭茅>多年黑麦草>扁穗牛鞭草。鸭茅在林分郁闭度小于0.54时,多年黑麦草在林分郁闭度小于0.34时,其生物量随郁闭度增加而增加,表明适度的遮荫有助于提高这2种牧草的生物量。
Dactylis glomerata , Lolium perenne and Hemarthria compressa were inter-cultivated in Eucalyptus grandis forest with different canopy densities. Chlorophyll content, chlorophyll fluorescence, daily photosynthesis, biomass of three herbage species were studied to analyze their growth under different shading, The results showed that： 1） As canopy densities increased, both total chlorophyll contents（Chl） and chlorophyll b （Chlb） of three herbage species were higher than their CK （without shading）, and chlorophyll a/b （Chla/ Chlb） of the former two species significantly decreased （P〈0.05）. 2） As canopy density increased, PSⅡ efficiency （Fv/Fm） of D. glomerata and L. perenne increased at first, and then decreased when the canopy density reached about 0.60. The Fv/Fm values of D. glomerata and L. perenne were higher than that of H. compressa, but under shading, the increment of the value was lower than that of H. compressa. 3） Daily photosyn-thesis of the three herbage species demonstrated a curve with one peak. When the canopy densities were below 0.53 for D. glomerata and below 0.42 for L. perenne, daily average net photosynthesis rates （Pn） were higher than their CK. While the Pn of H. compressa in inter-cultivated systems was smaller than CK. 4） The biomass of H. compressa in the CK was the highest, but it gradually decreased as the canopy density increased. When canopy density reached 0.56, the biomass of H. compressa was still higher than the highest biomass of the other two herbages. As a whole, the response of three herbages to a faint light environment is different. Under shading conditions, D. glomerata and L. perenne mainly exhibited an increase of Chlb, but for H. compressa, the increase of Fv/Fm. The shading tolerance of the three herbages was D. glomerata〉L, perenne〉H. compressa. The results suggested that when the canopy density was below 0.54 for D. glomerata and below 0.34 for L. perenne, shading can promote their growth.
出处
《草业学报》
CSCD
2008年第1期58-65,共8页
Acta Prataculturae Sinica
基金
国家科技部"十五"重大科技攻关项目(2001BA606A)
四川省重点学科建设项目(SZD0419)资助
关键词
巨桉
林草间作
郁闭度
叶绿素
叶绿素荧光
光合速率
生物量
Eucalyptus grandis
inter-cultivation of forest and herbage
canopy density
chlorophyll
chlorophyll fluorescence
photosynthetic rate
biomass
