Response Of Mycorrhizal Pinus Massoniana Seedlings To Aluminum Stress

Pinus massoniana Lamb.is a major afforestation and timber species in southern China.It has the characteristics of fast-growing,high-yield and adaptability.It is also a typical ectomycorrhizal tree species.The ectomycorrhizal fungi and host plants form dense bacteria.The wire mesh enlarges the absorption of water and nutrients in the soil by the roots of the plants,which is beneficial to the growth and development of the plants and enhances the resistance of the plants.Three different ectomycorrhizal fungi,Suillus luteus?L.:Fr.?Gray,referred to as Sl),Suillus bovinus?Sb?,and Amber bovine bacterium?Suillus?were selected.The placidus abbreviated as Sp)is the research object.Under the condition of pure liquid culture,the effects of Al³⁺ectomycorrhizal fungal growth,antioxidative enzyme activity,nitrogen,phosphorus,potassium and aluminum absorption are studied to screen out the antibiotics with strong anti-Al³⁺.Fungus-bronching Boletus?Sl?,and then growing mycorrhizal seedlings of Pinus massoniana.The hydroponic method was used to analyze the mycorrhizal and non-mycorrhizal Pinus massoniana seedlings by adding different concentrations(0,0.2,0.4,0.8,1.2 mmol·L^-1)of AlCl₃to the Hogland nutrient solution.Aluminum stress test to study the effects of aluminum stress on the growth characteristics,physiological characteristics and tissue nutrient content of mycorrhiza and non-mycorrhizal seedlings,and theoretically reveal the mycorrhizal/non-mycorrhiza masson pine stress The physiological and biochemical response mechanism provides technical measures for alleviating aluminum toxicity on acidic soils,and provides theoretical and technical guidance for the cultivation of mycorrhizal seedlings.Initially obtained the following research results:1.Al³⁺concentration has a significant effect on the growth characteristics of exogenous mycorrhizal fungi?1?Aluminum treatment significantly affected the growth of ectomycorrhizal fungi.The aluminum concentration(<0.8mmol·L^-1)promoted the accumulation of biomass of the three strains,and the maximum promotion effect was 0.8mmol·L^-1.At 1.6mmol·L^-1,the mycelial biomass accumulation of the three strains was inhibited,and the biomass accumulation was S1>Sb>Sp.Under aluminum treatment,the pH of the Sb and Sp cultures was significantly higher than that of the Sl strain.?2?Aluminum treatment at a low concentration(?0.4 mmol·L^-1)increases the nitrogen content in the hyphae.At 0.4mmol·L^-1,the nitrogen content of Sl,Sb and Sp strains increased by42.65%,61.85%and 49.84%,respectively,compared with the treatment without aluminum.The aluminum treatment also significantly increased the phosphorus in the hyphae.And the content of aluminum.The aluminum treatment of 0.2 mmol·L^-11 promoted the absorption of potassium by hyphae,and then showed an inhibitory effect with the increase of aluminum concentration.The absorption of NPK by the three strains was generally S1>Sb>Sp,and the absorption of aluminum was reversed.Aluminum treatment significantly reduced the activity of POD and SOD in the strain and increased the content of MDA.The overall activity of the enzyme activity was Sl<Sb<Sp,and the MDA content was reversed.It indicates that the more aluminum ions absorbed by the strain,the lower the enzyme activity of the strain and the stronger the aluminum resistance.2.Al³⁺concentration has significant effects on the growth and physiological characteristics of two species of Pinus massoniana seedlings.?1?The treatment of 0.2mmol·L^-11 aluminum promoted the growth,root growth and biomass accumulation of Pinus massoniana seedlings.When the aluminum concentration was>0.4mmol·L^-1,it exhibited an inhibitory effect,and at 0.8 mmol·L^-1,the inhibitory effect was the greatest.Aluminum treatment significantly reduced the root vigor of the two species of Pinus massoniana seedlings.The root activity of the seedlings of Sl seedlings was higher than that of non-inoculation.The content of malondialdehyde?MDA?increased with the increase of aluminum treatment time and the increase of aluminum concentration.The content of MDA in the needles treated with 0.2mmol·L^-11 aluminum was the lowest.Aluminum treatment promoted the content of osmotic adjustment substances such as soluble sugar,soluble protein and proline?Pro?in the mycorrhizal and non-mycorrhizal Pinus massoniana seedlings,and reached the maximum at1.2mmol·L^-1.value.The content of proline reached the maximum at 60d.Compared with 0d,the proline content in the seedlings of S.sinensis was increased by 0.45⁷.11 times and 0.03⁷.14times,respectively.When the concentration of Al³⁺was less than 0.4mmol·L^-1,the activities of SOD and POD in the mycorrhizal and non-mycorrhizal needles of Pinus massoniana were significantly increased,and reached the maximum at 30 days.?2?In the range of 0⁰.4mmol·L^-1,aluminum treatment promoted the synthesis of chlorophyll a and chlorophyll b from mycorrhizal and non-mycorrhizal needles,and the maximum effect was promoted at 0.2mmol·L^-1.When the aluminum concentration is greater than 0.8mmol·L^-1,the synthesis of chlorophyll a and chlorophyll b is inhibited,and the inhibition is enhanced with the increase of aluminum concentration.3.Al³⁺concentration has significant effects on the absorption of aluminum and nutrients in two species of Pinus massoniana seedlings.?1?Aluminum treatment promoted the absorption and accumulation of nitrogen by two species of Pinus massoniana roots.The promotion effect was the highest at 0.2mmol·L^-1,and the nitrogen content in the stem of S1 seedlings increased by 20.85%compared with the non-inoculated seedlings.When the aluminum concentration is greater than 0.8mmol·L^-1,the nitrogen content in stems and leaves is inhibited,and the inhibition is enhanced with the increase of concentration.In addition,the inoculation of Sl significantly increased the content of N in the roots and leaves of Pinus massoniana seedlings,and the size was root>leaf>stem.?2?Aluminum treatment promoted the absorption and accumulation of phosphorus in the roots of two Pinus massoniana seedlings.The phosphorus content in stems and leaves showed a promoting effect only at 0.2mmol·L^-1,and then the inhibitory effect was enhanced with the increase of aluminum concentration.The size is expressed as root>stem>leaf.?3?Low concentration(0.2mmol·L^-1)of aluminum promoted the absorption of potassium by roots and leaves of two species of Pinus massoniana seedlings,and then showed inhibition.And the inoculation of ectomycorrhizal fungi has a stronger ability to absorb potassium.The main absorption of aluminum in the roots of Pinus massoniana is in the root system,and it is rarely transported to the aboveground part.When the aluminum concentration is greater than 0.8mmol·L^-1,the transport of aluminum in the roots to the stems and leaves is increased,in which the stems are More aluminum is transported than in the leaves.