不同稻茬土壤对紫云英根瘤生长特性的影响研究

Impacts of different paddy soils on nodule growth characteristics of Chinese milk vetch

紫云英根瘤生长特性对不同土壤理化指标变化的响应存在一定的差异性,尤其是在稻茬条件下相关研究较少。为全面分析水稻-紫云英轮作模式下紫云英根瘤生长特性与土壤理化指标之间的关系,试验通过野外调查与室内分析相结合的形式,采取相关分析和通径分析等方法,对苏南太湖流域和宁镇丘陵2个稻作区不同土壤条件下稻茬紫云英根瘤生长特性的差异性进行比较研究。结果表明:不同采样地生长的紫云英单株根瘤数、根瘤重量及固氮酶活性也不同。其中昆山采样地的紫云英单株根瘤数和固氮酶活性均达到最大值(分别为86.24·plant-1,1362.73 nmol C2H4·min-1·g-1),而丹阳采样地单株根瘤数和固氮酶活性均最低(分别为1.13·plant-1,9.25 nmol C2H4·min-1·g-1);根瘤数量与土壤理化性质的相关性分析,根瘤数量与全氮、有机质、硝态氮极显著相关(P<0.01),与含水量、有效磷显著相关(P<0.05);通过土壤理化性质与根瘤数量的通径分析发现,硝态氮、全氮、有机质、有效磷、土壤pH综合作用依次降低,其中有机质、硝态氮、有效磷的直接通径系数为正值(P2=1.629,P1=0.633,P4=0.448),是促进紫云英结瘤的主要因子,土壤全氮的直接通径系数为负值(P5=-1.138),是结瘤的主要限制因子。紫云英根瘤生长特性与土壤环境之间存在相互影响、相互协同关系,所以,在实际生产中,稻茬紫云英生长应增施一定数量的有机肥与磷肥,并酌减氮肥用量,以充分提高紫云英结瘤固氮能力。

Nodule growth characteristics of Chinese milk vetch(CMV)differ in response to different soil physical and chemical properties,especially in different paddy soils.This study aimed to analyze the relationship between nodule characteristics of CMV and soil physical and chemical properties in CMV used in crop rotations with rice in Taihu and Ning-zhen rice growing regions.Correlation analysis and path analysis were used to associate differences in nodule characteristics with particular soil conditions in rice stubble.It was found that root nodule number,nodule weight and nitrogenase activity of milk vetch in rice-CMV crop rotations were affected by soil conditions.Nodule number per plant and the nitrogenase activity in Kunshan sample point were high(86.24·plant-1,1362.73 nmol C2H4·min-1·g-1,respectively),while corresponding values for Danyang sample point were low(1.13·plant-1,9.25 nmol C2H4·min-1·g-1,respectively).Path coefficients for nitrate nitrogen,total nitrogen,organic matter and available phosphorus were generally strongly correlated with nodule number,and organic matter,nitrate nitrogen and available phosphorus were positively correlated(P2=1.629,P1=0.633,P4=0.448)but total nitrogen negatively correlated(P5=-1.138,P represents direct path coefficient of factors).Soil organic matter,nitrate nitrogen and available phosphorus had the greatest positive influence on nodule number,whereas high soil total nitrogen reduced nodule number.There is a synergistic relationship between root nodule characteristics and the soil environment.In practice,appropriate organic fertilizer and phosphate fertilizer should be used to improve the nitrogen fixation capacity in CMV,rather than nitrogen fertilizer.