Physiological Responses Of Kidney Bean To CO₂ Enrichment And Water Regulation

In investigate the effects of elevated CO₂ concentration and water regulation on the growth and physiological metabolism of kidney bean,the experiment was conducted with "Chaozaoyichixiu" kidney bean variety as material,and high CO₂ concentration（800±50 μmol·mol-1 C1）was set as control in the greenhouse,the water conditions were divided into 4 gradients: 95-100%（slightly increased W1）,70-75%（CK W2）,45-50%（moderate drought W3）and 20-25%（severe drought W4）,respectively,the effects of CO₂ enrichment and water regulation on agronomic traits,photosynthesis-ralated parameters during the whole growth period and osmotic regulators,membrane lipid peroxidation,anti-stress enzyme activity and quality were investigated during pod setting of kidney bean.The main findings are as follows:1.The effect of individual water regulation: under normal atmospheric conditions,compared to the control W2,W1 treatment reduced 68.57% for the leaf area,the activity of SBPase and CAT was respectively increased 25.80% and 39.73% at the seedling stage;W3 treatment reduced 30.18% for the activity of TPI and increased 59.84% for the activity of SOD;W4 treatment reduced Pn at seedling stage and extension stage,increased Chla,Chlb and Chl contents at flowering stage,increased Gs and Tr at podding stage which also increased 62.72% for the content of MDA but reduced 22.67% for the activity of FBPase,the activities of SOD and CAT were improved to alleviate membrane lipid peroxidation and increase soluble sugar content to adjust osmotic potential.Severe drought reduces yield per plant,the water treatment had no significant effect on the quality of kidney bean.2.The effect of CO₂ enrichment treatment alone: under normal water conditions,compared with the control C0,CO₂ enrichment reduced 55.74% of the leaf area at the seedling stage,increased Pn and Ci at the extension stage,Ci and the content of Chla and Chl at the flowering stage,and the content of Chla and Chl and photosynthesis and the activities of key carbon assimilation enzymes during the podding stage,increase the activities of SOD,CAT,and the content of As A.Long-term CO₂ enrichment inhibits the soluble protein content of osmotic regulators,there was no significant effect on the quality of kidney bean and improve yield per plant.3.The effect of CO₂ enrichment on water regulation: Under W1 water conditions,CO₂ enrichment increases Pn and Ci from the extension stage to the podding stage,and increases the Chla,Chlb and Chl content in the flowering and podding stages;Under the W3 water condition,CO₂ enrichment increases Pn and Ci,Chla and Chl content at flowering stage,and increases photosynthesis,Chla and Chl content,TPI and SBPase activities at podding stage;Under W4 water conditions,CO₂ enrichment increase Pn and WUE at seedling and extesion stage,increases Pn and Ci but reduce the content of Chla,Chlb and Chl at flowering stage,increase the activity of TPI and SBPase at podding stage,reduce 43.30% for the content of MDA,and reduce 65.66% for the content of O2-,increase the activity of SOD and CAT,the content of As A and soluble protein to relieve membrane lipid peroxidation.CO₂ enrichment improves the activities of FBPase,CA and TK under each water treatment,there was no significant effect on quality indexes under each water treatment.The kidney bean plant itself has certain ability to resist water stress.CO₂ enrichment promoted the growth and development of kidney bean plants,and also alleviated membrane lipid peroxidation reaction of kidney bean leaves under severe drought treatment to a certain extent.