大气中CO₂浓度升高以及由此所引起的温室效应已成为人们普遍关注的议题。在未来的世界里,CO₂浓度将持续上升。预计到21世纪中叶,CO₂浓度可能达到700ppm。一些试验结果表明;CO₂浓度升高对多数植物的个体生长发育有促进作用,其中包括种子的发芽率提高,幼苗生长加快,叶面积增大,根系数量增多,气孔数量减少,茎干生长轮加宽,开花期提早,种子产量提高等。但是,CO₂浓度升高对植物也有不利影响。在高CO₂浓度环境中,由于过量产生的碳水化合物在叶片中的积累和矿物质的不平衡,许多植物在生长后期生长缓慢或出现负增长;个体生长发育规律的变化将导致一些增长种群逐渐向衰退种群过渡;C₃类杂草的加速生长将引起农业欠收;群落结构与组成的变化将促使一些植物走向绝灭;植物残渣中碳氮比的改变将引起生态系统生产力的下降等。因此,对于今后大气中CO₂浓度升高的影响还要做大量的研究。

Changes in the atmospheric concentration of CO, has brought about great concern. It was noticed that the global concentration of CO₂, would steadly increase and it was further predicted that the concentration might reach 700 ppm by the middle of next century. Some initial studies indicated that an elevation of this gas would seriously enhance plant growth. For most species in a high-CO₂ environment, seeds germination percentage higher, seedlings grew faster, leaf area became larger, number of roots increased, stomata1 number reduced, growth rings of stems became wider. flowering turned earlier and seed yield increased comparing with the condition in ambient air. Nevertheless, elevated CO₂ will not necessarily benefit plants. The excess accumulation of starch in the chloroplasts and unequilibium of mineral recycling resulting from a CO₂-rich world will slow down plants growth rate or turn it negative over time. In addition, dramatic changes in the growing rhythm of individual plant will lead some increasing populations to decreasing populations. The outgrowth of C₃ grasses will disproportionately cause agricultural crops less productive ; Continuing changes in the structure and composition of communities will alter the existence of some species, rendering them vulnerable to extinction. Increasing C/N ratio of plant residue will also lessen ecosystem productivity. Therefore, it is essential to further studies for assessing the effects of elevated CO₂ on plants.