Vessey J K, Henry L T, Raper C D
Dep. of Plant Sci., Univ. of Manitoba, Winnipeg, Canada.
Crop Sci. 1990 Mar-Apr;30(2):287-94. doi: 10.2135/cropsci1990.0011183x003000020009x.
Plants grown on porous media at elevated CO2 levels generally have low concentrations of tissue N and often appear to require increased levels of external N to maximize growth response. This study determines if soybean [Glycine max (L.) Merr. Ransom'] grown hydroponically at elevated CO2 requires increases in external NO3- concentrations beyond levels that are optimal at ambient CO2 to maintain tissue N concentrations and maximize the growth response. This study also investigates temporal influences of elevated CO2 on growth responses by soybean. Plants were grown vegetatively for 34 d in hydroponic culture at atmospheric CO2 concentrations of 400, 650, and 900 microliters L-1 and during the final 18 d at NO3- concentrations of 0.5, 1.0, 5.0 and 10.0 mM in the culture solution. At 650 and 900 microliters L-1 CO2, plants had maximum increases of 31 and 45% in dry weight during the experimental period. Plant growth at 900 microliters L-1 CO2 was stimulated earlier than at 650 microliters L-1. During the final 18 d of the experiment, the relative growth rates (RGR) of plants grown at elevated CO2 declined. Elevated CO2 caused increases in total N and total NO3(-)-N content and leaf area but not leaf number. Enhancing CO2 levels also caused a decrease in root:shoot ratios. Stomatal resistance increased by 2.1- and 2.8-fold for plants at the 650 and 900 microliters L-1 CO2, respectively. Nitrate level in the culture solutions had no effect on growth or on C:N ratios of tissues, nor did increases in CO2 levels cause a decrease in N concentration of plant tissues. Hence, increases in NO3- concentration of the hydroponic solution were not necessary to maintain the N status of the plants or to maximize the growth response to elevated CO2.
在高浓度二氧化碳环境下生长在多孔介质上的植物，其组织氮浓度通常较低，且往往似乎需要增加外部氮水平才能使生长反应最大化。本研究旨在确定在高浓度二氧化碳环境下进行水培的大豆[Glycine max (L.) Merr. Ransom']是否需要将外部硝酸根离子浓度提高到高于在环境二氧化碳浓度下的最佳水平，以维持组织氮浓度并使生长反应最大化。本研究还调查了高浓度二氧化碳对大豆生长反应的时间影响。植物在大气二氧化碳浓度分别为400、650和900微升/升的水培环境中进行营养生长34天，在最后18天，培养液中的硝酸根离子浓度分别为0.5、1.0、5.0和10.0毫摩尔。在650和900微升/升二氧化碳浓度下，植物在实验期间干重最大增幅分别为31%和45%。在900微升/升二氧化碳浓度下植物的生长比在650微升/升二氧化碳浓度下更早受到刺激。在实验的最后18天，高浓度二氧化碳环境下生长的植物的相对生长率（RGR）下降。高浓度二氧化碳导致总氮和总硝酸根离子 - 氮含量以及叶面积增加，但叶片数量未增加。提高二氧化碳水平还导致根冠比下降。在650和900微升/升二氧化碳浓度下，植物的气孔阻力分别增加了2.1倍和2.8倍。培养液中的硝酸盐水平对生长或组织的碳氮比没有影响，二氧化碳水平的升高也未导致植物组织氮浓度降低。因此，增加水培溶液中的硝酸根离子浓度对于维持植物的氮状态或使对高浓度二氧化碳的生长反应最大化并非必要。
