冠层下部遮荫和修枝对红锥苗木生长和光合特征的影响

Effects of Shading and Pruning in Lower Canopy on Growths and Photosynthetic Characteristics of Castanopsis hystrix Seedlings

为了解冠层下部枝叶遮荫和修枝对红锥(Castanopsis hystrix)的影响,以2年生红锥苗木为试材,在红锥苗木1/3冠层下部进行遮荫和修枝处理,测定红锥株高、地径、不同器官生物量和光合特征等指标,研究冠层下部遮荫和修枝对红锥苗木生长和光合特征的影响。结果表明,随遮荫度增加,株高和地径均呈先升后降的趋势;冠层上部和下部各部位生物量及总生物量均呈先升后降的趋势;冠层上部和下部叶生物量分配比及冠层上部茎和地上部分生物量分配比均呈先升后降的趋势;冠层下部枝条、茎和地上部分生物量分配比均呈下降趋势;冠层上部枝条和根生物量分配比及根冠比均呈先降后升的趋势;叶片净光合速率、气孔导度、蒸腾速率和水分利用效率均呈先升后降的趋势;胞间二氧化碳浓度呈先降后升的趋势。45%遮荫和修枝处理下,红锥苗木的生长指标、大部分器官生物量及其分配比和光合特征指标均较高,70%和85%遮荫处理下均较低。

In order to understand effects of shading and pruning in lower canopy on Castanopsis hystrix,taking 2-year-old C.hystrix seedlings as test materials,different shading and pruning treatments were carried out on 1/3 lower canopy of C.hystrix seedlings,and indexes of plant height,ground diameter,biomass of different organs and photosynthetic characteristics were determined.Effects of shading and pruning in lower canopy on growths and photosynthetic characteristics of C.hystrix seedlings were studied.Results showed that with increase of shading degree,plant height and ground diameter showed trends of firstly increase and then decrease.Biomass of different parts in upper and lower canopies and total biomass showed trends of firstly increase and then decrease.Biomass allocation ratios of leaves in upper and lower canopies,and biomass allocation ratios of stems and above-ground parts in upper canopy showed trends of firstly increase and then decrease.Biomass allocation ratios of branches,stems and above-ground parts in lower canopy showed trends of decrease.Biomass allocation ratios of branches in upper canopy and roots and root to shoot ratio showed trends of firstly decrease and then increase.Net photosynthetic rate,stomatal conductance,transpiration rate and water use efficiency of leaves showed trends of firstly increase and then decrease.Intercellular carbon dioxide concentration showed trend of firstly decrease and then increase.Growth indexes,most of organ biomass and allocation ratios,and photosynthetic characteristics were higher in 45% shading and pruning treatments,and lower in both 70% and 85% shading treatments.