Effects of three Trichoderm aasperellum strains on the growth and photosynthetic characteristics of tissue-cultured Populus davidiana×P. alba var. pyramidalis seedlings

In order to collect Trichoderma asperellum strains which could promote the growth of woody plants, pot experiment was carried out with one-year-old tissue-cultured seedlings of Populus davidiana×P. alba var. pyramidalis to study the effects of three strains of T. aspereullm: ACCC32492 (Ta492), ACCC30536 (Ta536) and T4(Ta4) on the growth, the chlorophyll contents, diurnal variation of photosynthesis and light response curve characteristic parameters. The results showed that the height, basal stems diameter and biomass yields of the poplar seedlings inoculated with these T. asperellum strains were higher than those of the control (CK) at different levels. At most of the time points, the chlorophyll contents and chlorophyll a/b ratios in the leaves of the inoculated poplars were significantly higher (P<0.05) than those of CK which laid material foundation for the improvement of photosynthetic rate. The net photosynthetic rate (Pn), stomatal conductance (Gs) and transpiration rate (Tr) of the poplars inoculated with these T. asperellum strains increased compared with those of CK, but their respective time-course changing trends were the same as CK. The maximum net photosynthetic rate (Pn max), the light saturation point (LSP) and the apparent quantum efficiency (AQY) of the poplars inoculated with T. asperellum strains were higher than those of the CK. All the above results indicated that inoculation of the three T. asperellum strains could significantly improve the photosynthetic efficiency and growth of poplar seedlings. T. asperellum ACCC30536 strain had the best effects on the growth of poplar seedlings.