长期大气CO_(2)浓度升高对大豆磷吸收及根际磷转化的影响

Long-term effects of elevated atmospheric CO_(2) concentration on soybean phosphorus acquisition and soil phosphorus transformation in the rhizosphere of soybean

磷(P)作为第二重要的植物营养元素,能够调节作物对气候变化的适应性。东北不同地区黑土有机质含量存在着较大差异,对作物营养吸收产生较大影响。然而,长期大气CO_(2)浓度升高对不同有机质含量黑土大豆生长、土壤磷组分以及相关微生物机制的影响鲜有研究。本研究利用开顶式生长室(OTC)重点探究了气候变化对不同有机质黑土大豆根际土壤磷组分和相关磷转化微生物功能基因的影响。结果表明,不同有机质含量的黑土大豆磷吸收对长期大气CO_(2)浓度升高的响应一致,既先升高后降低。然而,大豆根际磷组分的响应存在差异性。大气CO_(2)浓度升高降低了高有机质黑土中大豆根际NaHCO_(3)-P_(o)含量,但增加了低有机质黑土中大豆根际有机磷库(NaHCO_(3)-P_(o)和NaOH-Po)的含量,而降低了无机磷库(NaOH-Pi)的含量。同时,大气CO_(2)浓度升高使高有机质黑土根际土壤基因拷贝数增加53.0%,低有机质黑土中大豆根际土壤基因拷贝数增加44.4%。因此,长期气候变化条件下,高有机质含量黑土通过有机磷矿化功能微生物来满足大豆对磷素的需求;而在低有机质含量黑土中,长期高CO_(2)浓度主要影响无机磷组分以及相关功能基因。

Phosphorus(P),the second important plant nutrient,regulates crop adaptation to climate change.The organic matter content of Mollisols in different areas of Northeast China is quite different,which greatly influences crop nutrient absorption.How-ever,few studies have investigated the long-term effects of elevated CO_(2) concentration on soybean growth,soil phosphorus fraction and relevant microbial mechanisms with different organic matter content of Mollisols.The study used open-top growth chambers to mainly investigate the effects of elevated CO_(2) on soil phosphorus fractions and relevant functional genes in Mollisols with different organic matter content.The results showed that the response of P uptake of soybean to the long-term elevated CO_(2) was the same change with different organic matter content,increasing first and then decreasing,while differences existed on P fractions in rhizo-sphere of soybean.Elevated CO_(2) decreased NaHCO_(3)-P_(o) fraction in high-SOM(H-SOM)soil,however,elevated CO_(2) favored the accumulation of organic fraction(NaHCO_(3)-P_(o) and NaOH-P_(o)),reduced inorganic fraction(NaOH-Pi)in low-SOM(L-SOM)soil.In addition,elevated CO_(2) concentration increased the copy numbers of phoC by 53.0%in H-SOM,but increased the copy numbers of pstS by 44.4%in L-SOM.Therefore,under long-term climate change,soybean can meet the P demand through organic P mineraliza-tion by soil microorganisms in H-SOM,while inorganic P and relevant functional genes are affected in L-SOM.