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Photosynthesis and dry matter production in Tibet of China, and the effect of CO_2 enrichment for them

西藏光合作用和干物质生产及CO_2富集对其的影响

基本信息

批准号：
12575018
负责人：
IWAMA Kazuto
金额：
$ 6.34万
依托单位：
Hokkaido University
依托单位国家：
日本
项目类别：
Grant-in-Aid for Scientific Research (B)
财政年份：
2000
资助国家：
日本
起止时间：
2000 至 2001
项目状态：
已结题

来源：
https://kaken.nii.ac.jp/en/grant/KAKENHI-PROJECT-12575018/
关键词：
China CO_2 enrichment dry matter production grain yield open top chamber photosynthesis Tibet wheat 気孔光合成速度 CO_2増加窒素濃度チベット高原蒸散速度二酸化炭素濃度バレイショ

项目摘要

Climatic condition of Tibet plateau (3500-4000 m in sea level) holds a unique position for agriculture. Contents of CO_2 and O_2 are 60 to 70 % relative to flats of 0 m sea level, the solar radiation in summer is very high usually beyond 2000 μ mol m^<-2> sec^<-1> and the temperature difference between day and night is often beyond 20℃. The aim of the present research was to clarify these particular conditions for the photosynthesis and dry matter production of crops cultivated in this area in the present and the future. The experiment was conducted at the experimental farm in Lhasa (3700 m in sea level), located by Chinese Academy of Science, with open top chambers of enriched (1.55 times higher) and control (normal air) CO2 content growing a local variety of spring wheat. Mean net photosynthetic rate during the growing season was increased by CO2 enrichment, 19.5μ mol m^<-2> sec^<-1> in the control chamber and 26.9μ mol m^<-2> sec^<-1> in the enriched chamber. However, the total dry weight at the heading stage and the grain yield at the harvesting stage were almost the same in the two chambers, 1401〜1472 g m^<-2> and 610〜702 g m^<-2>, respectively. It was mainly due to higher rate of blighted tillers before heading stage in the enriched CO_2 plants relative to the control plants. The results indicated that main limiting factor for grain yield in this region was not low CO_2 content, but low soil nutrient condition.

西藏高原（海拔3500-4000米）的气候条件对农业具有独特的地位。CO_2和O_2的含量为60 ~ 70%（相对于0 m海平面），夏季太阳辐射很高，通常超过2000 μ mol·m ~<-2>（-2）·s ~（-1）<-1>，昼夜温差通常超过20℃。本研究的目的是阐明这些特殊条件下的光合作用和干物质生产在这一地区种植的现在和未来。实验在中国科学院位于拉萨的实验农场（海拔3700米）进行，采用开顶式富气室（高1.55倍）和对照（正常空气）CO2含量种植当地春小麦品种。生长季节的平均净光合速率通过CO2富集而增加，对照室为19.5μ mol m^<-2>sec^<-1>，富集室为26.9μ mol m^<-2>sec^<-1>。然而，抽穗期的总干重和收获期的籽粒产量在两个室中几乎相同，分别为1401 × 1472 g/m2<-2>和610 × 702 g/m2<-2>。这主要是由于富CO_2植物抽穗前的枯萎率高于对照植物。结果表明，该地区粮食产量的主要限制因子不是低CO_2含量，而是低土壤养分状况。