| The regional climate change trend of warming and drying in North China obviously affects the growth of forest trees.Rhizosphere fungi can promote tree growth and improve stress resistance.In this study,Larix principis-rupprechtii and Pinus tabulaeformis as the typical afforestation tree species in North China were studied.Through indoor pot experiment,two main processes of Trichoderma spp.inoculation or not were set up to study effects of rhizosphere fungi on seedling growth,antioxidant system and osmotic adjustment system of two coniferous species under different drought stresses(control,CK;light drought,LD;moderate drought,MD;severed rought,SD).The main conclusions are as follows:1.Compared with P.tabulaeformis,the infection rate of Trichoderma spp.to L.principis-rupprechtii seedlings roots were higher,with the increasing drought stress,the infection rate of Trichoderma spp.to the two conifer was falling gradually,vaccination contribution rate of biomass of the two conifer under drought stress is bigger than that under normal water,the maximum of L.principis-rupprechtii was in SD,the maximum of P.tabulaeformis was in MD,in contrast with P.tabulaeformis,inoculation effect of Trichoderma spp.to L.principis-rupprechtii seedlings was more stronger.2.Inoculation of Trichoderma spp.can significantly promote the growth of underground and overground parts of both conifers,especially the root.With the intensification of the drought stress,the root-crown ratio of inoculated and non-inoculated seedlings of L.principis-rupprechtii gradually increased,and the change range of root-crown ratio of inoculated seedlings of L.principis-rupprechtii was moderate,causing less damage to them.The root-crown ratio of both inoculated seedlings and non-inoculated seedlings of P.tabulaeformis showed a trend of "rising first and then falling",both reaching the maximum value at LD(0.29 and 0.26,respectively).The root-crown ratio of inoculated seedlings of P.tabulaeformis increased by 11.54% compared with that of non-inoculated seedlings.3.With the aggravation of drought stress,SOD activity of inoculated seedlings and non-inoculated seedlings of the two conifers showed a trend of "rise first and then fall".The accumulation of MDA content increased,and POD activity increased gradually.Under drought stress,SOD,POD activity and MDA content of inoculated seedlings and non-inoculated seedlings of the two conifers were higher than those under normal water.Under the same drought stress,the activity of SOD and POD of inoculated seedlings of the two conifers were higher than that of non-inoculated seedlings of the two conifers,but the content of MDA of inoculated seedlings was lower than that of non-inoculated seedlings.Under the same treatment,the MDA content of P.tabulaeformis seedling needles was lower than that of L.principis-rupprechtii.4.With the increasing drought stress,the proline content of inoculated seedlings and non-inoculated seedlings of the two conifers increased gradually,and the proline content of inoculated seedlings of P.tabulaeformis under CK,MD and SD increased more than that of L.principis-rupprechtii inoculated seedlings.Under drought stress,the proline content of the inoculated seedlings of the two conifers was more than the non-inoculated seedlings.5.With the aggravation of drought stress,compared with the CK,the soluble sugar content of inoculated seedlings and non-inoculated seedlings of the two conifers were higher,the whole shows the trend of "first" lowered later,the soluble sugar content of L.principis-rupprechtii inoculated seedlings and non-inoculated seedlings were maximum respectively in MD,LD;the soluble sugar content of inoculated seedlings and noninoculated seedlings of P.tabulaeformis were both maximum in MD;That is,the inoculated seedlings of L.principis-rupprechtii were more conducive to the accumulation of soluble sugar content.6.Through the dimensionality reduction analysis and comprehensive evaluation of of various physiological indexes of L.principis-rupprechtii and P.tabulaeformis seedlings using principal component analysis method,it was found that Trichoderma spp.had the most significant inoculation effect on L.principis-rupprechtii seedlings under SD,content of starch,MDA,soluble sugar and POD activity were the most suitable physiological indexes to test the inoculation effect.Trichoderma spp.had the most significant inoculation effect on P.tabulaeformis seedlings,content of starch,proline,soluble sugar and SOD activity were the most suitable physiological indexes to test the inoculation effect. |
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