中文摘要：

为探讨CO2浓度升高能否减缓高浓度NH4^＋-N对番茄根系的毒害作用,本试验在营养液栽培条件下,以番茄为材料,在CO2生长箱中研究2个CO2浓度与5个不同NH4^＋/NO3^-配比的交互作用对生长介质的pH、根系生长及根系活力的影响。结果表明,随着生育期的推进与CO2浓度的升高,pH变化幅度增大。两个CO2浓度均表现为全NO3^- -N含量营养液的pH呈上升趋势,其它处理营养液的pH均呈现出不同程度的下降趋势,下降的幅度随NH4^＋/NO3^-比例的增加而增加;而且全NH4^＋-N引起pH值下降的程度大于全NO3^- -N引起pH增加的程度。CO2浓度升高增加了低NH4^＋/NO3^-比例供应处理的蕃茄幼苗冠干重、根干重、根系活力、根系总吸收面积、活跃吸收面积。这些指标对CO2的响应随NH4^＋/NO3^-比例的降低而加强,冠干重、根干重、根系活力、根系总吸收面积、活跃吸收面积增加分别高达65.8%、78.0%、18.9%、12.9%与18.9%。说明在CO2浓度升高条件下,番茄幼苗根生长潜力在全NO3^- -N处理中最大,但不能减弱全NH4^＋-N对番茄根系的毒害作用。

英文摘要：

In order to understand whether the elevated CO2 does alleviate the toxic effect on tomato root system due to high NH4^＋ -N concentration in nutrient solutions, a growth chamber experiment was conducted to determine the influence of NH4^＋/NO3^- ratio and elevated CO2 concentrations on the pH in nutrient solution, growth and root vigor system of tomato seedling roots. Tomato （Lycopersicon esculentum Mill var. Hezuo 906） was grown in pots with nutrient solutions varying in NH4^＋ ：NO3^- ratio （0： 1, 1：3, 1 ： 1, 3：1 and 1：0） in growth chambers with ambient （360μL/L） or elevated CO2 concentrations （720μL/L）. It enhanced the changes of pH with promotion of growth time and CO2 enrichment. At two CO2 levels, pH increased with whole NO3^- -N in nutrient solution and decreased in other treatments and enhanced the decrease of pH with increasing proportion of NH4^＋ -N in nutrient solutions. The decrease in pH value with only NH4^＋ -N in nutrient solution was higher than the increase in pH with only NO3^- -N in nutrient solution. Elevated CO2 increased the dry weight of shoots and roots, root vigor system, total absorbing area, active absorbing area of tomato seedlings. All measurement indices above of tomato seedlings were increased in the elevated CO2 treatment with increasing proportion of NO3^- in nutrient solutions and the dry weight of shoots, dry weight of roots, root vigor system, total absorbing area and active absorbing area were up to 65.8%, 78.0%, 18.9%, 12.9% and 18.9% higher at elevated than at ambient CO2 concentration, depending on NH4^＋/NO3^- ratio. The results indicated that tomato seedling roots may benefit best from CO2 enrichment when 100% NO3^- -N in nutrient solutions is supplied, and elevated CO2 did not inhibit the adverse effects on tomato seedling roots when 100% NH4^＋-N in nutrient solution is supplied.