植物有性生殖对大气CO2浓度变化响应的研究进展

 比较详细地概述了过去数十年关于在大气CO₂浓度升高条件下,植物有性生殖特性发生变化的主要研究成果。随着植物相对生长速率加快,植株达到有性生殖所需形体大小的时间变短,开花期提前,生殖器官的生物量也相应提高,其主要表现为开花数量、花粉和花蜜产量、果实数量与大小、种子大小与产量等均有不同程度的增加。对大多数农作物而言,种子产量的增加主要通过种子数量的增加,而与种子大小变化关系不大。通常,高浓度CO₂对豆科植物种子含氮量影响比较小, 却能显著地降低非豆科植物种子含氮量。不同类型植物的生殖生物量增加趋势存在一定的规律性,如不定型植物>定型植物,豆科植物>C₃非豆科植物>C₄植物,栽培植物>野生植物。针对国内外对CO₂浓度升高影响植物有性生殖特性的研究中存在的不足,该文提出了今后研究应该注意的问题。

A REVIEW ON RESPONSES OF PLANT SEXUAL REPRODUCTION TO ELEVATED CO2

Plant reproductive traits are key characteristics for predicting the impacts of global changes on plant community, agro_ecosystem and plant ecological fitness. This review seeks to integrate current results about the effects of elevated CO_2 on plant reproductive traits in detail based on the existing experimental data in the past few decades. Earlier investigations demonstrate that elevated CO_2 advances the flowering time through increasing relative growth rate and accelerating developmental process. All the numbers of flowers, fruits, and seeds, the mass of seed as well as the production of pollen and nectar of plants have been found to be stimulated by CO_2 enrichment. It is further revealed that the increase in plant yields results largely from an increase in seed number rather than from individual seed mass. Elevated CO_2 concentrations have little effect on seed N] of legumes, but significantly reduce seed N] of most nonlegumes. Contents of proteins, amino acids, and some mineral ions usually decrease in seeds of most nonlegumes. Different functional groups of plants are often found to differ markedly in their reproductive responses to elevated CO_2: 1) crops allocate more mass to reproduction and produce more fruits and seeds than do undomesticated species; 2) indeterminate plants have stronger responses to elevated CO_2 in comparison with determinate species; 3) legumes are most responsive to elevated CO_2, followed by nonlegume C_3 species, then C_4 species. Based on the data available, it seems rational to believe that changes in plant reproductive traits resulting from elevated CO_2 may alter the competitive hierarchy, the species composition, and hence the functioning of plant community. Finally, some issues noteworthy for future researches in this field are also put forward with reference to the existing unsolved questions.