Reproductive allocation and seed production in Bromus madritensis ssp rubens at elevated atmospheric CO2
Reproductive allocation and seed production in Bromus madritensis ssp rubens at elevated atmospheric CO2
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DOI：
10.1046/j.1365-2435.1999.00366.x
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发表时间：
1999-12-01
影响因子：
5.2
通讯作者：
Smith, SD
中科院分区：
文献类型：
--
作者：
Huxman, TE;Hamerlynck, EP;Smith, SD
1.植物对CO2浓度升高的响应有两个趋势：叶片含氮量下降和光合作用气体交换增加。虽然这两种模式对于了解植物和生态系统对气候变化的反应非常重要，但很少有研究评估这些模式对生殖分配和种子生产的影响。因此，无芒雀麦Bromus madritens SSP.分别在常温(360 mU/m ol~(-1))、x 1.5 m o l/m ol(-1)和高CO_2浓度(700 m u/m o l/m o l)环境中生长，比较不同CO_2生长环境对生长和生殖分配的影响。在不同的CO2生长环境下，最终总生物量或生殖量没有差异。当生长CO_2浓度从360增加到700亩时，单位总质量和单位营养质量的生殖质量显著下降，但单位叶面积(LSA)的下降不明显。尽管有这些下降，但与环境二氧化碳相比，单位LSA在高二氧化碳条件下产生的种子数量显著增加。这些结果可能是由于在大气CO2.4水平升高的情况下，与繁殖相比，营养生长的分配转向了更大的投资。在生殖前，不同CO2处理的叶片碳吸收没有显著差异。相比之下，生长在高二氧化碳环境中的植物在种子灌浆期间没有表现出光合作用速率的下降，这表明氮素可能没有像周围植物中明显发生的那样从叶片重新转移到种子中。这里测量的模式可能部分解释了在无芒雀麦中表现出的二氧化碳环境的亲本效应。与生长在环境中的双亲种子相比，亲本二氧化碳生长条件升高产生的种子产生的幼苗产生的叶片较小，发育迟缓，根较小。由于无芒雀麦的成功部分归功于其产生大量可存活种子的能力，这些生殖分配和随后的苗木在高二氧化碳环境中生长表现的变化可能会对莫哈韦沙漠的群落组成产生影响。
1. Two trends are consistent across the response of plant species to growth at elevated CO2: decreased leaf nitrogen content and increased photosynthetic gas exchange. While both of these are very important to the understanding of plant and ecosystem responses to climate change, little research has evaluated the consequences of these patterns on reproductive allocation and seed production.2. For this reason, Bromus madritensis ssp. rubens was grown in ambient (360 mu mol mol(-1)), x 1.5 ambient (550 mu mol mol(-1)) and elevated (700 mu mol mol(-1)) CO2 environments to compare the relationship between allocation to growth and reproduction as a function of CO2 growth environment.3. There were no differences in final total biomass or reproductive mass between CO2 growth environments. There were significant decreases in reproductive mass per unit total mass and per unit vegetative mass, but not per unit leaf surface area (LSA), as growth CO2 environment increased from 360 to 700 mu mol mol(-1) CO2. Despite these decreases, the number of seeds produced per unit LSA in elevated CO2 significantly increased as compared to ambient CO2. These results may be owing to a shift in allocation to greater investment in vegetative growth as compared to reproduction under elevated levels of atmospheric CO2.4. Prior to reproduction, there were no significant differences between CO2 treatments in carbon uptake by leaves. In contrast, plants grown in elevated CO2 did not show a decline in photosynthetic rate during seed filling, suggesting that nitrogen may not have been re-translocated from leaves to seeds as apparently occurred in ambient plants.5. Patterns measured here may partially explain the parental effect of CO2 environment exhibited in Bromus. Seeds produced from elevated parental CO2 growth conditions lead to seedlings that produce smaller leaves that are delayed in development and smaller roots as compared to structures produced by seeds from ambient-grown parents.6. Because the success of Bromus is partially owing to its ability to produce large numbers of viable seeds, these changes in reproductive allocation and subsequent seedling performance with respect to growth in an elevated CO2 environment may have impacts on community composition in the Mojave Desert.