论文部分内容阅读
为了验证土壤氮(N)素和大气二氧化碳(CO2)浓度的增高是交互或者累加性地控制“植物-土壤”系统中的碳(C)分配这一假设,同时为了揭示这种作用是否随着植物种类而变化,在不同的CO2浓度下的高氮和低氮土壤中种植豆科植物紫花苜蓿(Medicago truncatula)和非豆科植物燕麦(Avena sativa),并对植物的生长和土壤微生物等特性在这些条件下的变化进行了测定．结果表明,植物物种和土壤N素的交互作用对土壤微生物和植物的生长有着重要的作用．对于紫花苜蓿而言,CO2和土壤N素的交互作用对土壤可溶性C和土壤微生物生物量有重要影响,但对燕麦则并非如此．尽管CO2和土壤N素都显著影响植物的生长,但它们对植物的影响并不存在交互性,也就是说CO2和土壤N素对植物生长的影响是累加的．豆科植物的固氮特性与CO2的交互作用可能掩盖了土壤N素与CO2的交互作用对豆科植物生长的影响．在低N土壤中,燕麦的冠根比从初期的2．63±0．20降低到后期的1．47±0．03,表明燕麦在生长受到土壤N素的抑制时,分配了更多的能量到根部以加强植物对养分元素的吸收(如N素);在高氮土壤中,紫花苜蓿的冠根比随时间延长显著升高(从2．45±0．30到5．43±0．10),说明当土壤N素不是植物生长限制因子时,更多的能量被分配到地上部分以加强植物对C的同化．在不同土壤N素水平上,大气CO2浓度对植物的冠根比的影响均不显著．
In order to verify that the increase of soil N and atmospheric CO2 concentration is the hypothesis of controlling carbon (C) distribution in the plant-soil system interactively or cumulatively, (Medicago truncatula) and non-legumes (Avena sativa) were planted in high-nitrogen and low-nitrogen soils under different CO2 concentrations. The effects of plant growth and soil micro-organism Changes under these conditions were determined. The results showed that the interaction between plant species and soil N element played an important role in the growth of soil microorganisms and plants. For alfalfa, the interaction of CO2 with soil N content has a significant effect on soil soluble C and soil microbial biomass, but not on oats. Although CO2 and soil N all significantly affect plant growth, their effects on plants are not interdependent. That is to say, the effects of CO2 and soil N on plant growth are cumulative. The interaction between nitrogen fixation of leguminous plants and CO2 may obscure the effect of soil N interaction with CO2 on the growth of leguminous plants. In low N soil, the crown-root ratio of oats decreased from 2.63 ± 0.20 in the initial stage to 1.47 ± 0.03 in the later stage, indicating that the oats allocated more Energy to the roots to enhance plant absorption of nutrients (such as N); crown algae crown-root ratio increased significantly over time (from 2.45 ± 0.30 to 5.43 ± 0 .10), indicating that when soil N is not a limiting factor for plant growth, more energy is allocated to aerial parts to enhance plant assimilation of C. In different soil N levels, the effect of atmospheric CO2 concentration on plant crown-root ratio was insignificant.