Evaluation Of Aluminum Tolerance And Aluminum Tolerance Mechanism Of Cynodon Dactylon Germplasm Resources

Bermudagrass, the most important member of the gramineous genus Cynodon,is a world-famous warm-season turfgrass and high quality pasture.65bermudagrass accessions were selected from different regions in the present study, combining hydroponics and soil culture method, studying the effect of different bermudagrass accessions growth, changes of physiological metabolism, and other nutrients under aluminum stress. On this basis to explore their aluminum tolerance mechanisms,the purpose was to select excellent accessions.The information from this study will be beneficial for the breeding of bermudagrass.The main results are as follows:(1) Hydroponics aluminum concentration of bermudagrass accessions screening, found that low concentrations of aluminum stress (250～1250μmol/L) could promote the growth of bermudagrass accessions, and high concentrations of aluminum stress inhibited bermudagrass growth obviously.With the more increasing concentrations of aluminum stress and time, the more serious inhibition degree was.Through the regression equation obtained critical survival aluminum concentration was3420μmol/L.(2) The65bermudagrass accessions resources from different regions were evaluated in different aluminum stress.By aluminum cluster analysis and membership function values,the65bermudagrass material is divided into four categories,the first category include7accessions of the test material, accounting for10.77%, resistant aluminum membership function is0.4904～0.7606, the second category includes27accessions of the test materials, accounting for41.53%, resistant aluminum membership function is0.3009-0.4853,these accessions are less affected by the stress of aluminum, aluminum tolerance in the upper level of the test material.The last category includes27accessions of the test materials,accounting for41.53%,resistant aluminum membership function is27,influenced by the stress of aluminum, aluminum tolerance in the material under test level.(3)The5parts of Al-resistant germplasm (A75, A84, A551, A43, A556) and5parts of Al-sensitive germplasm (A538, A137, A172, A256, A326) were selected from65bermudagrass materials to plant on acidic soils,validated measured obtaining various growth indicators are significant difference, bermudagrass germplasm resistant aluminum growth inhibition relative to aluminum sensitive germplasm lesser extent, can maintain a high growth rate, on acidic soils Identification results are consistent with the previous results of hydroponics.(4)Aluminum inhibited different bermudagrass accessions absorption of N, P, K, Ca, the difference were significant in the content of N,K,Ca,between Al-resistant and Al-sensitive germplasm shoots and roots.There were significant differences in the content of P between Al-resistant and Al-sensitive germplasm shoots. Al-resistant accessions absorbed more N, K, Ca to transport from roots to shoots.(5)The bermudagrass accessions have physiological metabolic disorders after aluminum stress. Cell membrane permeability increased, chlorophyll content decreased, leaf color fades, total soluble sugar content decreased resistance, there was a lesser extent affected to Al-resistant accessions; simultaneously two types of bermudagrass accessions produced more reactive oxygen species, MDA content was increased, Al-sensitive bermudagrass accessions produced more than Al-resistant bermudagrass accessions; both types of bermudagrass accessions produced more SOD, POD, Pro, a larger increase of A-resistant bermudagrass accessions. The results showed that bermudagrass may increasing the activity of antioxidant enzymes to reduce the stress suffered by aluminum.(6)Bermudagrass under stress, aluminium in root system quantity was big, the accumulation of root tip is the initial site by aluminum plant stress, by far the most by hematoxylin staining root dyeing, with the increase of stress concentration, dyeing range shift to the upper roots, and the degree of dyeing.(7)Aluminum induced root the secretion of organic acids was one of bermudagrass aluminum resistant mechanism, bermudagrass under aluminum stress, the root secretion of organic acids and rhizosphere chelation aluminum, aluminum into the cells, reduce the harm that aluminum toxicity to plants, and bermudagrass secretion of organic acids lag exists.