根系分隔方式对间作玉米大豆根际红壤磷组分及磷吸收的影响

Effects of Root Barriers Mode on Red Soil Rhizosphere Phosphorus Fractions and Phosphorus Absorption Under Intercropping Maize and Soybean

【目的】明确不同根系分隔方式对间作玉米大豆根际红壤Hedley磷组分与作物磷吸收的影响,为理解间作模式下红壤磷高效利用机制提供理论依据。【方法】以玉米大豆间作为研究对象开展盆栽模拟试验,设置根系塑料分隔(SB)、尼龙网分隔(MB)和不分隔(NB)3种方式,研究在不同磷水平下(P_(2)O_(5),0、50、100、150、200 mg/kg土,分别用P0、P1、P2、P3、P4表示)玉米和大豆生物量、磷吸收量及根际土壤活性、中活性和稳定性磷组分的变化。【结果】相比SB,NB显著提高间作玉米和大豆的生物量,间作系统生物量LER随施磷水平增加而降低,在P2水平达到最大。NB玉米磷吸收量显著提高,NB大豆在P1-P3水平磷吸收量显著提高。间作系统磷吸收优势随施磷水平先增加后下降,在P3水平达到最大。相比SB,NB玉米根际土壤活性磷组分提高,中活性磷组分降低;大豆根际土壤活性磷和中活性磷组分显著降低。NB玉米根际土壤活性无机磷含量相比SB显著提高,大豆根际土壤活性和中活性无机磷、活性和中活性有机磷含量均低于SB。冗余分析表明,NaHCO_(3)-Pi是玉米和大豆根际土壤速效磷含量和植株磷吸收量、生物量变化的最主要因素(分别可解释49.5%、27.2%)。随机森林模型发现,大豆和玉米根际土壤中活性磷组分对间作系统磷吸收优势的贡献最大,分别为14.65%和10.52%。【结论】间作玉米大豆根系不分隔处理可提高作物生物量与磷吸收量,提高玉米根际土壤活性无机磷组分,降低大豆根际土壤活性磷组分、中活性磷组分,其中大豆根际土壤中活性磷组分是提高间作系统磷吸收优势的最主要原因。

【Objective】The purpose of this study was to investigate the effects of different root barriers pattern on rhizosphere soil phosphorus(P)fractions and crop P absorption under maize and soybean intercropping,and further to provide theoretical basis for understanding the mechanism of efficient P utilization in intercropping mode.【Method】The effects of different P levels on the biomass,P absorption,labile P fraction,moderate labile P and non-labile P fraction in rhizosphere soil of maize and soybean were studied by using plastic barrier(SB),nylon mesh barrier(MB)and non-barrier(NB)between maize and soybean roots.【Results】Biomass of maize and soybean in intercropping system without root barrier was significantly increased compared with that of SB.The biomass LER of intercropping system decreased with the increase of P application level and reached the maximum at P2 level.The NB significantly increased the P uptake of maize,and the NB soybean significantly increased the P uptake between P1 and P3 levels.Compared with no P application and high P application,there was no significant change of P absorption in SB soybean roots.The advantage of P uptake in intercropping system increased first and then decreased with P application level,and reached the maximum at P3 level.Compared with SB,the labile P fractions of maize were increased in the NB rhizosphere soil,while the moderate labile P fractions were decreased in rhizosphere soil.The contents of rhizosphere labile and moderate labile P in soybean treated with NB were significantly lower than those treated with SB.The content of labile inorganic P in NB maize rhizosphere soil was significantly higher than that in SB,while the content of labile inorganic P and labile organic P in soybean rhizosphere soil was lower than that in SB.The redundancy analysis showed that NaHCO_(3)-Pi was the main factor affecting the content of available P in maize and soybean rhizosphere soil,and the variation of phosphorus uptake and biomass(explained variance 49.5%and 27.2%,respectively).According to the random forest model,moderate P fraction in soybean and maize rhizosphere had the largest contribution to the advantage of P uptake in intercropping system,which were 14.65%and 10.52%,respectively.【Conclusion】Intercropping system with no roots barriers could increase crop biomass and P uptake,labile inorganic P content in maize rhizosphere soil could be increased while labile and moderate P fraction in soybean rhizosphere could be decreased without root barrier,and moderate P of soybean rhizosphere had the most influence to system P uptake.