营养元素对豆科牧草-根瘤菌共生系统牧草生长及结瘤能力的影响

Effects of nutrient elements on the grass growth and nodulation ability of legume-rhizobia symbiosis system

为了探究营养元素对豆科牧草-根瘤菌共生系统牧草生长及结瘤能力的影响,试验选用贵州天然豆科牧草红三叶(Trifolium pratense L.)、白三叶(Trifolium repens L.)分别与根瘤菌伯克氏菌(Burkholderia phytofirmans)R63-1、拉格雷根瘤菌(Rhizobium laguerreae)R87-4共生,设不同浓度(100,200,300,500 mg/L)的氮肥、磷肥、钾肥3种肥料,另设不配施根瘤菌液、不配施肥料在自然状态下生长的牧草作为空白对照(CK1、CK2),同时设只配施根瘤菌液、不配施肥料的牧草作为对照(CK3~6),共60个处理,每个处理3个重复,测定牧草农艺性状和结瘤能力,解析营养元素对固氮共生体系的影响。结果表明:红三叶+根瘤菌的株高、根际直径及单株鲜重与CK1、CK2相比,分别最高增加了90.93%、242.55%、714.47%,白三叶+根瘤菌分别最高增加了65.92%、69.06%、334.21%。红三叶+R63-1+200 mg/L氮肥处理的根长、干物质含量均最高,根瘤数最多,分别为29.03 cm、22.94%、202.78颗/株,比CK3分别增加63.92%(P<0.05)、41.17%(P<0.05)、87.85%(P<0.05)。红三叶+R63-1+500 mg/L磷肥处理的根际直径、单株鲜重均最高,根瘤数最多,分别为10.01 mm、16.13 g、271.67颗/株,比CK3分别高24.35%(P>0.05)、67.50%(P>0.05)、151.66%(P>0.05)。红三叶+R87-4+300 mg/L钾肥处理的株高、单株鲜重、鲜重冠根比均最高,分别为23.70 cm、16.16 g、1.51,但与CK4相比均差异不显著(P>0.05),且根瘤数最多,达424.11颗/株,比CK4高485.87%(P<0.05)。白三叶+R87-4+100 mg/L氮肥处理的株高、根长、根际直径、单株鲜重均最高,根瘤数最多,分别为39.28 cm、26.25 cm、5.96 mm、13.13 g、121.33颗/株,比CK6分别高14.75%(P<0.05)、12.32%(P>0.05)、33.04%(P<0.05)、13.68%(P>0.05)、6.18%(P>0.05)。白三叶+R87-4+300 mg/L磷肥处理的株高、根长、单株鲜重均最大,分别为56.64 cm、27.67 cm、23.73 g,比CK6分别高65.47%(P<0.05)、18.40%(P>0.05)、105.45%(P<0.05),且根瘤数为508.67颗/株,比CK0高345.15%(P<0.05),但较大根瘤体积比CK6低62.70%(P<0.05)。白三叶+R87-4+500 mg/L钾肥处理的根长、根际直径、单株鲜重均最大,根瘤数最多,分别为24.67 cm、6.82 mm、33.34 g、375.33颗/株,比CK6分别高5.56%(P>0.05)、52.23%(P<0.05)、188.66%(P<0.05)、228.46%(P<0.05)。红三叶、白三叶在氮磷钾肥各浓度处理下,除结瘤率外,红三叶、白三叶在各指标变异系数分别在15.75%~99.32%、17.83%~90.43%之间。说明加施菌液可以让两种牧草形成根瘤,且促使两种牧草的株高、根际直径、单株鲜重增加;以单株鲜重为主进行分析,R87-4的促进作用强于R63-1,菌液对红三叶的促进作用强于白三叶。对两种牧草分别加施氮、磷、钾肥后,部分浓度对红三叶、白三叶的农艺性状和结瘤能力有抑制作用,部分浓度有促进作用,以变异系数为主进行分析,肥料对白三叶的影响大于红三叶。

In order to explore the effects of nutritional elements on the growth and nodulation ability of legume-rhizobia symbiotic system,Trifolium pratense L.and Trifolium repens L.were selected from natural leguminous grasses in Guizhou province for symbiosis with Burkholderia phytofirmans R63-1 and Rhizobium laguerrea R87-4,respectively.Three different concentrations of N,P,and K fertilizers(100,200,300,500 mg/L)were applied.In addition,a blank control(CK1,CK2)was set up for grass growing under natural state without the application of rhizobium solution or fertilizer.At the same time,a grass control(CK3-6)was set up with only rhizobium solution and no fertilizer,with a total of 60 treatments and 3 replicates for each treatment,and the agronomic traits and nodulation ability of the grass were measured to analyze the effects of nutrients on the nitrogen fixation symbiotic system.The results showed that the plant height,rhizosphere diameter,and fresh weight in the red clover+rhizobia increased by 90.93%,242.55%and 714.47%,respectively,compared with CK1 and CK2,while white clover+rhizobia increased by 65.92%,69.06%and 334.21%,respectively.The root length,dry matter content,and the number of root nodules in the red clover+R63-1+200 mg/L N fertilizer treatment were the highest,which were 29.03 cm,22.94%and 202.78 per plant,respectively,which increased by 63.92%(P<0.05),41.17%(P<0.05)and 87.85%(P<0.05)compared to CK3.The rhizosphere diameter,fresh weight per plant,and the number of root nodules in the red clover+R63-1+500 mg/L P fertilizer treatment were the largest,which were 10.01 mm,16.13 g and 271.67 per plant,respectively.It was increased by 24.35%(P>0.05),67.50%(P>0.05)and 151.66%(P>0.05)compared to CK3,respectively.The plant height,fresh weight per plant,and crown to root ratio in the red clover+R87-4+300 mg/L K fertilizer treatment were the highest,which were 23.70 cm,16.16 g and 1.51,respectively,but there was no significant difference compared to CK4(P>0.05).At this concentration,the number of root nodules was the highest,reaching 424.11 per plant,which was 485.87%higher than CK4(P<0.05).The plant height,root length,rhizosphere diameter,fresh weight per plant,and the number of root nodules in the white clover+R87-4+100 mg/L N fertilizer treatment were the highest,which were 39.28 cm,26.25 cm,5.96 mm,13.13 g and 121.33 per plant,respectively.They were increased by 14.75%(P<0.05),12.32%(P>0.05),33.04%(P<0.05),13.68%(P>0.05)and 6.18%(P>0.05)compared to CK5,respectively.The plant height and fresh weight per plant in the white clover+R87-4+300 mg/L P fertilizer treatment group were the highest,which were 56.64 cm,27.67 cm and 23.73 g,respectively.They were increased by 65.47%(P<0.05),18.40%(P>0.05)and 105.45%(P<0.05)compared to CK6,respectively.At this concentration,the number of nodules was 508.67 per plant,which was 345.15%higher than CK6(P<0.05),but the volume of larger nodules was 62.70%lower than that in the CK6(P<0.05).The root length,rhizosphere diameter,fresh weight per plant,and the number of root nodules in the white clover+R87-4+500 mg/L K fertilizer treatment were the highest,which were 24.67 cm,6.82 mm,33.34 g and 375.33 per plant,respectively.It was increased by 5.56%(P>0.05),52.23%(P<0.05),188.66%(P<0.05)and 228.46%(P<0.05)compared to CK6 group,respectively.Under different concentrations of N,P,and K fertilizers,the variation coefficients of each index for red and white clover ranged from 15.75%to 99.32%and 17.83%to 90.43%,respectively,except for nodulation rate.The results indicated that the addition of bacterial solution could induce the formation of root nodules in both types of forage,and promote an increase in plant height,rhizosphere diameter,and fresh weight per plant.From the perspective of fresh weight per plant,R87-4 had a stronger promoting effect than R63-1,and the bacterial solution had a stronger promoting effect on red clover than white clover.After applying N,P,and K fertilizers to two types of forage separately,some concentrations had an inhibitory effect on the agronomic traits and nodulation ability of red clover and white clover,while some concentrations had a promoting effect.From the coefficient of variation,the effect of fertilizer on white clover was greater than that on red clover.