蚕豆根分泌物对紫色土有效养分及微生物数量的影响

为培育紫色土肥力和合理利用蚕豆资源,本研究首先通过溶液培养法收集到蚕豆根系分泌物后,并通过真空旋转蒸发仪得到浓缩液,然后通过室内土壤培养试验,即分别在3种60 g紫色土(酸性紫色土、碱性紫色土和中性紫色土)添加2个水平6 m L(低量)和12 m L(高量)]的蚕豆根系分泌物浓缩液,并置于25℃恒温箱中黑暗培养15 d,从而探索蚕豆根系分泌物对不同紫色土有效养分和微生物数量的影响。结果表明:在3种紫色土上,与对照相比,添加低量和高量蚕豆根系分泌物浓缩液后,土壤碱解氮含量和p H均显著降低;而土壤有效磷、速效钾、有效铁、有效锌含量和微生物数量均显著增加,且此趋势随根系分泌物浓缩液添加量增加而增强。与其他两种紫色土相比,酸性紫色土添加蚕豆根系分泌物浓缩液对于土壤碱解氮含量和p H的降低效应最明显,对土壤中细菌和真菌数量增加效应更为显著,与对照相比,增幅分别为-32.00%、-4.51%、3.51倍和9.00倍。与其他两种紫色土相比,碱性紫色土添加高量蚕豆根系分泌物浓缩液对土壤有效磷、速效钾、有效锌和有效铁含量活化效应最强,分别是对照的4.48倍、2.04倍、147.10%和128.00%。在中性紫色土上,添加高量蚕豆根系分泌物浓缩液对以上土壤有效养分和土壤微生物数量的影响介于酸性紫色土和碱性紫色土之间。总之,蚕豆根系分泌物对不同紫色土土壤有效养分(土壤碱解氮和p H除外)和土壤微生物活性有不同促进效应,这对于紫色土肥力培育有深远影响。

Effects of faba bean (Vicia faba L.) root exudate on soil available nutrients and microbial population in different purple soils

In order to improve the fertility of purple soil and make reasonable use of faba bean, this study collected faba bean root exudates by solution cultivation and obtained the concentrated solution by vacuum rotary evaporator. Then a soil cultivation experiment was carried out with 2 levels (low level of 6 mL and high level of 12 mL) of concentrated solutions of faba bean root exudates added separately to three types of 60 g purple soils (acid purple soil, alkaline purple soil and neutral purple soil) in constant temperature box. The aim of the study was to determine the effects of faba bean root exudates on soil available nutrients and microbial population in different purple soils. The results showed that compared with the control, both alkali-hydrolysable N and pH decreased significantly while available P, K, Zn and Fe along with microbial population increased significantly in the three types of purple soil after adding concentrated solutions of faba bean root exudates to the soil. Moreover, the above trends increased with increasing level of the root extrudates. The decreasing effects of high amount of faba bean root exudates on soil alkali-hydrolysable N and pH were most obvious in acid purple soil compared with in alkali and neutral purple soils. However, the most significant increasing effect on soil bacteria and fungi amounts was also observed in acid purple soils. The above four indicators in acid purple soils with high level faba bean root exudates addition were respectively 68.00%, 95.49%, 4.51 times and 10.00 times those of the control. In alkali purple soils, the addition of high amount of concentrated faba bean root exudates showed most significantly increasing effects on soil available P, K, Zn and Fe contents, which were 4.48 times, 2.04 times, 147.00% and 128.00% of those of the control, respectively. In conclusion, there were different effects on soil available nutrients and soil microbial activity after faba bean root exudates addition to different types of purple soils. This had a profound effect on the fertility of cultivated purple soils in the study area.