大气CO2浓度升高对玉米非结构性碳水化合物和籽粒品质的影响

本试验利用改进的开顶式气室(OTC)在黄土高原长武农业生态试验站田间模拟大气CO₂浓度升高环境,设置3个处理:CK(田间环境,自然大气CO₂浓度)、OTC(OTC气室,自然大气CO₂浓度)、OTC_e(OTC气室,CO₂浓度700 μmol·mol^-1),探讨春玉米在不同生育期各器官非结构性碳水化合物(NSC)及籽粒品质(可溶性糖、淀粉和粗蛋白)对大气CO₂浓度升高的响应,为揭示旱作区春玉米对大气CO₂浓度升高的适应机理提供科学依据。结果表明: 大气CO₂浓度升高对玉米NSC含量、积累量的影响因器官和生育期不同而异。与CK和OTC相比,OTC_e促进了生殖生长阶段叶、茎和根NSC的活化再分配,提高了叶片、茎秆和根系NSC转运到籽粒的量(ATM_NSC)、向籽粒的转运率(AR_NSC)以及对籽粒的贡献率(AC_NSC);与CK相比,OTC带来的增温效应抑制了茎和根NSC的活化再分配,促进了叶NSC的活化再分配,显著提高了玉米叶ATM_NSC、AR_NSC、AC_NSC。在两年试验中,大气CO₂浓度升高对玉米籽粒可溶性糖、淀粉和粗蛋白含量无显著影响。

Effects of elevated atmospheric CO2 concentration on nonstructural carbohydrates and grain quality of maize

We used open-top chambers (OTCs) to simulate the conditions of elevated atmospheric CO₂ concentration at the Changwu State Key Agro-Ecological Experimental Station of the Loess Plateau. There were three treatments, CK (maize grown under field conditions with natural atmospheric CO₂ concentration), OTC (maize grown in the open-top chamber under natural atmospheric CO₂ concentration), and OTC_e (maize grown in the open-top chamber under elevated atmospheric CO₂ concentration of 700 μmol·mol^-1).We explored the responses of non-structural carbohydrate (NSC) and grain quality (soluble sugar, starch and crude protein) of spring maize to elevated CO₂ at different growth stages, aiming to provide scientific basis for revealing the adaptation mechanism of maize to elevated CO₂. The results showed that the effects of elevated CO₂ on NSC content and accumulation in maize varied across organs and growth periods. Elevated CO₂ promoted the activation and redistribution of NSC in leaves, stems and roots during reproductive growth period, and significantly increased the amount of NSC conversion to the grains (ATM_NSC), as well as the conversion rate to the grains (AR_NSC) and the contribution to the grains (AC_NSC) in leaves, stems and roots. Compared with CK, the warming effect of OTC inhibited the activation and redistribution of NSC in stems and roots, but promoted the activation and redistribution of NSC in leaves, significantly increased the ATM_NSC, AR_NSC, and AC_NSC of maize leaves. Elevated CO₂ did not affect the contents of soluble sugar, starch, and crude protein in maize grains.