Ectomycorrhizal Fungi Enchance Drought Resistance Of Populus Ussuriensis

In this paper, the growth and nutrition metabolism of three kinds of ECMF(Boletus luridus, Suillus bovinus, Suillus luteus) were studied under the drought stress which was formed by PEG. We inoculate B.l and S.b which were able to resistant drought esistance into Populus ussuriensis, then, the changing of physiological index and Chlorophyll fluorescence of the mycorhizal plants were studied under drought stress. Reveal the mechanism of ECMF promote drought resistance of their host. The major results were as follow:1. Effects of drought stress on the growth and nutrition metabolism of ECMFThe diameter growth of three ECMF remain keeping S-Tape under drought stress which was formed by PEG, and exponential phase of every mycelial was postponed 1-2 days under stronger drought stress (the water potential≤-0.49 MPa), and there was no significant different between three kinds of ECMF and CK with weak drought stress(.P>0.05); Under stronger drought stress (the water potential≤-0.49 MPa), the Mycelial growth and biomass accumulation of three ECMF was inhibited with significant differences(P<0.05). Variance analysis showed that B.l and S.b were similar in the colony growth trends under the drought stress, which has no significant difference between strains (P> 0.05). The colony growth of S.l has no significant difference with B.l and S.b (P<0.05), under the less drought stress (water potential≥-0.15 MPa). The mycelial growth of S.l was strongly inhibited compared to B.l and S.b, and there are significant differences between strains (P<0.05)The consumption trends of nutrient were more or less the same under drought stress. there was no significant effects on the consumption of C, N, P under weak drought stress (the water potential≥-0.15 MPa), but under stronger drought stress, the consumption of macroelement for mycelia growth was decreased, on the contrary, the consumption of microelement K was significantly promoted with the increase of drought stress. The relative consumption nutrient of 3 each ECMF differed significantly between strains (P<0.05). The consumption rate of each species odered as follow:S.b>B.l>S.l. The consumption rate of nitrogen, phosphorus and potassium odered as follow:B.l>S.b>S.l.The effects of drought stress on the three ECMF was different, the tolerance to drought stress of B.l and S.b was higher than S.l in aspects of mycelial growth and nutrition metabolism, therefore, B.l and S.b can be used as a dominant species. B.l and S.b can be used as dominant species in breeding species with drought resistant.2. Effects of ECMF on the physiological index of P. ussuriensis under drought stress.The stem length and diameter of P. sussuriensis was significantly promoted after B.l and S.b was inoculated, and the effect of S.l was stronger than B.l. The infection rate was positive correlated with growth-promoting.The Leaf Water Content decreased, SOD, CAT activity, free Pro and MDA contents increased under drought stress. But in P. ussuriensis inoculated with B.I and S.b, Leaf Water Content, SOD, CAT activity, free Pro was significantly higher than CK (P<0.05), MDA content was significantly lower than CK (P<0.05), therefore, the drought resistance of P. ussuriensis was promoted, and the effect of S.l was stronger than B.l (P<0.05).3 ECMF the relative consumption of each nutrient was significant difference between strains (P<0.05), various species of carbon consumption rate between the order of:Sb> Bl> Sl, nitrogen, phosphorus and potassium consumption rate of the order of:Bl> Sb> Sl.3. Effects of ECMF on the photosynthesis of P. ussuriensis under drought stressChlorophyll Content of P. ussuriensis decreased under drought stress, but in the same time and same water stress, the Decrease of Chlorophyll Content in P. ussuriensis inoculated ECMF was significantly lower than CK (P<0.05), thus a high absorption capacity was maintained and the drought resistance was promoted.Chlorophyll fluorescence parameters—Fv, Fv/Fm, Fv/Fo was significantly decreased under water stress, which showed that the PSⅡaction center in P. ussuriensis seedlings was taking damaged, thus the primary reaction of photosynthesis was inhibited, but in the same time and same water stress, the decrease of Fv, Fv/Fm, Fv/Fo in P. ussuriensis inoculated ECMF was significantly lower than CK (P<0.05), therefore the mischief of PSⅡwas decreased, the drought resistance was promoted, and the effect of S.l was stronger than B.l (P<0 .05).4. In a word, S.b was the most helpful fungi for P. ussuriensis to resistent drought stress in the 3 species of Ectomycorrhizal fungi.