| We collected the roots and rhizosphere soil samples from four different sites (Ganquan, Suide, Mizhiand Yulin) on the Loess Plateau in Shaanxi. The spatial distribution of AMF colonization, spore density andglomalin in the rhizosphere of Amorpha fruticosa were investigated, and their relationships with soil factorswere analysed. Then, under pot condition, an experiment was conducted to study the effects of AMF on thegrowth and drought resistance of Amorpha fruticosa under water stress. The main conclusions included asfollows:1. The average AMF colonization rate from Suide was the highest of all the samples, which was up to100%, and the lowest colonization rate was75.02%from Mizhi. The spore density from Mizhi was higherthan that of other samples, and it was5.91/g. The lowest spore density was from Yulin, and it was1.57/g.The highest spore density existed in the0-10cm layer of all samples, and with the soil depth increasing, thespore density decreased. In different regions, the difference of AMF colonization rate and spore densitywere notable. The rate of AMF colonization did not significantly correlate with the spore density. SOC,ammonia-N, olsen-P, urease and alkaline phosphatase from Yulin were significantly higher than those ofother samples. Except for the sucrase from Mizhi and Suide and alkaline phosphatase from Ganquan, in0-10cm layer, the activity of most soil enzymes and glomalin reached the maximum, and declined with theincreasing soil depth, which had a significant difference among the different layers.2. AMF colonization had a significant positive correlation with SOC, nitrate-N, olsen-P, and it had avery significant positive correlation with pH, TEG and EEG. Spore density had a significant positivecorrelation with olsen-P, sucrase, urease, and had a negative correlation with ammonia-N. TEG had a verysignificant positive correlation with EEG. Principal component analysis showed that the cumulativevariance proportion of PCA1and PCA2were up to56.4%. PCA1contained glomalin, AMF colonizationrate and spore density. PCA2contained pH and some soil factors. Therefore, the soil environment wasmainly decided by these factors. 3. Under30%of soil relative water content, the root activity of Amorpha fruticosa inoculating AMFwhich was reached up to0.66mg g-1 h-1 was significantly higher than that without inoculating AMFwhich was0.49mg g-1 h-1. With soil relative water content decreasing, plant height, root activity, shootdry mass and root dry mass were decreased, and AMF colonization rate was significantly increased from43.99%to88.47%. Under the different soil relative water content, contents of proline, soluble sugar andsoluble protein were significantly increased by inoculating AMF, especially the content of proline thatinoculating AMF was2.31times as much as that without inoculating AMF, and the content of MDA wasdecrease with soil relative water content increased. Inoclulating AMF could promote the activities of threekinds of anti-oxidative enzymes included SOD, POD and CAT, which were1.47,1.48and1.37times that ofthose without inoculating AMF, and keep them at a high level.4. Under water stress, Fv/Fm of the plant inoculating AMF was significantly higher than thatwithout inoculating AMF. Under30%of soil relative water content, Fv/Fm of the plant without inoculatingquickly decreased from0.76to0.70, when the water stress reached to the middle and later period. But frombeginning to the end, Fv/Fm with inoculating AMF was at the level about0.78. At the early period of waterstress, ETR was at the same level among the different treatment. With the days lasting, ETR was higher thanthe level of early period. Under30%of soil relative water content, the plant without inoculating AMFdecreased by a largest margin which was from9.8to6.0in middle period, and it could not get recover tothe original level at the later period. But the plant inoculating AMF could get recover. qL increasedsignificantly with the increasing of soil relative water content, and the plant inoculating AMF was higherthan that without inoculating AMF. At the middle of water stress, qL decreased significantly from0.86to0.73under30%of soil relative water content. The plant without inoculating AMF continueded to drop to0.6,but the plant inoculating AMF get recover to original level about0.84. At the early period of waterstress, NPQ increased with the decreasing of soil relative water content. With the days lasting, NPQ of alltreatments increased slowly, and the plant of inoculating AMF was lower than that without inoculatingAMF. |
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