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Control of weeds and shrubs by the short-term intensive clearing on natural regeneration sites as related to their physiological properties of photosynthesis

通过对自然更新地点的短期集中清理来控制杂草和灌木，与其光合作用的生理特性相关

基本信息

批准号：
11660136
负责人：
HASHIMOTO Ryoji
金额：
$ 2.5万
依托单位：
Iwate University
依托单位国家：
日本
项目类别：
Grant-in-Aid for Scientific Research (C)
财政年份：
1999
资助国家：
日本
起止时间：
1999 至 2000
项目状态：
已结题

项目摘要

1.Physiology of photosynthetic system1) Measurements of pulse-modulated chlorophyll fluorescence were useful for stress-diagnosis of regenerated leaves of weeds and shrubs after clearing. Diurnal drops in photosynthetic quantum yield were associated with photo-inhibition linked to water deficit ; water and nutrient conditions in leaves seemed to closely relate to photo-inhibition. 2) Establishment of photosynthetic system in cotyledons of tree seedlings was examined throughout changes in total-N and Rubisco contents after germination. Although photosynthetic system was established in a few weeks by rapid activation of N metabolism followed by germination, photosynthetic activity immediately decreased probably due to translocation of N to other organs and therefore highly stable stage was not observed. Nutrition condition in soil greatly influenced photosynthetic activity in cotyledons through effect of N contents.2.Vegetative propagation types for shrub speciesSeedlings of seven shrub species which had occurred after the cutting of a deciduous broad-leaved forest was investigated. Vegetative propagation by underground organs was divided into four types ; single sprouting, mulch-sprouting, horizontal root sprouting, subterranean stem sprouting ones. First subterranean stem sprouting types and secondarily horizontal root sprouting ones would act as tough competitors for tree seedlings because they are able to occupy the living space quickly at extremely high phytomass density.3. Ground treatment by machineryGround treatment by a small-sized excavator was made to reduce the regeneration of weeds and shrubs on a natural reproduction site. The mechanical treatment kept the reproduction site at low coverage condition for several months, delayed the bamboo grass development for a year, and restricted the shrubs development. Out of these three effects, the first one was considered to contribute most largely to the seedling establishment of objective tree species.

1.光合系统生理1）脉冲调制叶绿素荧光技术可用于杂草和灌木清除后再生叶片的逆境诊断。光合量子效率的日下降与水分亏缺引起的光抑制有关;叶片中的水分和营养条件似乎与光抑制密切相关。2)通过观察萌发后子叶中总氮和Rubisco含量的变化，研究了树木幼苗光合系统的建立。虽然光合系统建立在几个星期内迅速激活的N代谢，然后发芽，光合活性立即下降，可能是由于氮转运到其他器官，因此没有观察到高度稳定的阶段。土壤营养状况通过N含量的影响，对子叶的光合活性产生显著影响。2.灌木植物的无性繁殖类型对7种灌木植物的落叶阔叶林采伐后的幼苗进行了调查。利用地下器官进行无性繁殖可分为单芽、覆盖芽、水平根芽、地下茎芽四种类型。首先地下茎芽类型和其次水平根芽类型能够在极高的植物量密度下迅速占据生存空间，是苗木的坚韧竞争者.采用机械处理的方法对一个自然繁殖地进行了小型挖掘机处理，以减少杂草和灌木的再生。机械处理使繁殖地在低覆盖条件下维持数月，使竹草发育延迟一年，并限制了灌木的发育。在这三种效应中，第一种效应被认为对目标树种的成苗贡献最大。