| To study intensively the mechanism of Trichoderma promoting woody plant growth,improving stress resistance and enhancing photosynthetic capacity,this paper used potted Shanxin poplar aged 30 d as plant materials,the untreated group named "CK" and treated with Trichoderma group named After 60 days,the effects of Trichoderma treatment on growth traits,stress tolerance-related physiological indicators,photo synthetic characteristics and hormone levels of Shanxin poplar had stuided.The main findings were as follows:1.Biomass index measurements found that after Trichoderma treatment,the plant height,leaf number and stem diameter in group T were all higher than CK.And the plant height and stem diameter were significantly different at 40 d,while leaf number was significantly different at 30 d.The results showed that Trichoderma could promote the growth of Shanxin poplar.2.The results of stress tolerance-related physiological indicators showed that the content of malondialdehyde in group T was lower than CK at 30 d,but there was no significant difference;when treated for 60 d,the malondialdehyde content in group T was 1.06 times of that in group CK,showing a significant difference.Moreover,the determinations of active enzyme at 30 d found that the POD activity in group T was significantly higher than CK;the SOD,CAT,APX and PPO activity in group T were all slightly higher than CK,but there were no obvious difference.At 60 d,the SOD,CAT and APX activity in group T were all slightly higher than that of CK,and there was no significant difference;while the POD and PPO activity in group T were lower than CK,and there were also no significant difference.The free radical content increased at 60 d,inducing enhanced SOD and CAT activity in the leaves,resulting in resistance,which precisely illustrated that Trichoderma could enhance the resistance to certain extent by increasing the related defense enzyme activity of Shanxin poplar.But the resistance enhancement was not obvious because there was no external inducing factors.3.Photo synthetic correlation index detections found that the chlo-a,chlo-b and total chlorophyll content in group T were all significantly higher than CK at 30 d after Trichoderma treatment.At 60 d,total chlorophyll content in group T were also significantly higher than CK.The results showed that Trichoderma could effectively promote the accumulations of photo synthetic pigment of Shanxin poplar.Besides,at 30 d,the Amax,AQE,Cond,Ci and Tr of leaves in group T were all higher than CK,but the differences were not significant,but the Pn in group T was significantly higher than CK.And at 60 d,all indexes were significantly higher than CK,which showed that Trichoderma could improve the photosynthetic ability of plants and the utilization rates of weak light to promote their growth.Through the analysis of chlorophyll fluorescence parameters,it was found that after Trichoderma treatment,the both Fo values were lower than CK,whether at 30 d or at 60 d,which indicated that the PSII reaction center activity in the leaves of Shanxin poplar was stable and not destroyed in the later stage of transplanting.In this experiment,the maximum fluorescence(Fm)of different treatments was not significantly affected.The ETR,qP,NPQ,?PSII index were all increased,and the ?NO index was decreased.The above results showed that Trichoderma could enhance the activity of leaf PSII and enhance the ability of light protection.4.The endogenous hormone related index detections found that after 30 d of application of Trichoderma to rhizosphere soil of Shanxin poplar,the endogenous hormone content in leaves changed significantly.For example,the content of IAA in group T was significantly lower than CK;the content of SA in group T was significantly higher than CK;the content of JA,GA3 and ABA in group T were higher than CK,but the differences were not significant.After 60 d,the content of IAA in group T was slightly lower than CK,and the difference was not significant;the content of SA and GA3 in group T were significantly higher than CK;the content of JA and ABA in group T were higher than CK,and the differences were not significant.The results of this study showed that the levels of five endogenous hormones in plants could be changed after the rhizosphere of Shanxin poplar was irrigated with Trichoderma,and with the extension of time,the change of the content of five endogenous hormones changed from the trend of improving resistance to the trend of promoting plant growth,which was consistent with the rule of the change of growth index measured by us. |
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