Study On The Effect Of Growth, Physiology, Yield And Quality Of Soybean To Increasing CO₂ Concentration

The plant height,stem diameter,net photosynthesis rate,transpiration,water use efficiency,solar-energy utilization efficiency,yield and yield composing elements, chlorophyll contents,fat contents,protein and amino acid contents of soybean were measured under ambient and elevated CO₂ levels conditions,and their responses to elevated CO₂ were analyzed.The results showed that,Compared with CK,the hight increased from 6.50%to 21.91%,the stem diameter from 3.51%to 14.65%under four high CO₂ concentration(450μmol·mol^-1,550μmol·mol^-1,650μmol·mol^-1and 750μmol·mol^-1). With the enrichment of CO₂ concentration,the net photosynthesis rate,water use efficiency and solar-energy utilization efficiency increased,but the transpiration decreased.Compared with CK,the net photosynthesis rate increased from 5.41%to 23.69%;water use efficiency increased from 9.84%to 49.22%;solar-energy utilization efficiency increased from 6.64% to 26.32%;transpiration decreased from 7.33%to 22.97%under four high CO₂ concentration.The midday depression of photosynthesis was taken on when CO₂ concentration was low,but this phenomena abated whit elevated CO₂ concentration. Midday depression of photosynthesis disappeared when CO₂ concentration rise to 750μmol·mol^-1.The chlorophyll a,chlorophyll b,total chlorophyll contents and carotenoid contents of soybean trend to increased when elevated CO₂ concentration.Compared with CK, chlorophyll a contents increased from 1.72%to 11.64%;chlorophyll b contents increased from 2.00%to 20.00%;total chlorophyll contents increased from 5.45%to 13.78%; carotenoid contents increased from 7.63%to 24.58%.But the ratio of chlorophyll a to b was reduced under four high CO₂ levels.Compared with CK,the yield increased from 8.80%to 39.81%respectively.Among the yield composing elements,the influence of the number of pods per plant on yield was obviously;The flowing was hundred-seed-weight;And the influence of the number of seeds per pod was indistinctive.With the enrichment of CO₂ concentration,the content of kalium,iron,molybdenum,cuprum and cobalt decreased.Among them,the content of kalium and iron decreased obviously.Compared with CK,kalium contents declined from 1.40mg·g^-1to 2.69 mg·gm^-1,and iron contents drop from 2.33μg·g^-1to 16.09μg·g^-1.The content of calcium,magnesium,zincum,manganese,natrium and selenium increased with elevated CO₂ concentration.When CO₂ concentration elevated,the fat contents increase.Compared with CK,the fat acid contents rose from 2.58%to 8.50%.The content of kitool acid and stearic acid of saturation fatty acid trended to decline with CO₂ concentration elevation.Among unsaturation fatty acid,oleic acid contents increased obviously;sub-oleic acid contents vary irregularly with elevated CO₂ concentration.Flax acid contents trend to decreased with elevated CO₂ concentration.The protein contents of soybean decrease with elecated CO₂ concentration.Compared with CK,protein contents decrease from 0.5%to 3.3%under four high CO₂ concentration leves.The amino acid contents and amino acid composition also changed,the content of Thr,Gys,Tyr and Met increased,the content of Ile and His had no significant change; meanwhile,the other 12 amino acids decreased differently.When CO₂ concentration elevated,the gross amino acid and gross necessary amino acid decreased.Compared with CK,the gross amino acid decreased from 0.14%to 3.55%,the gross necessary amino acid decreased from 0.59%to 3.58%under different CO₂ leves.