Studies On Root Architecture And Biological Characteristics Of Rhizosphere In Apple Stock

The root architecture of apple stock, and the effect of abiotic stress, soil types, fertilization and organism on root architecture and biological characteristics of rhizosphere with seedling and perennial apple stock taken as materials have been studied in this article, by using the combined methods of water-culture, sand-culture, soil-culture in pot and orchard experiments. The results are as the follows:1. The total length, lateral root length, avgdiamten, surface area and volume, Proline content of the drought-resistant young seedlings of Malus sieversii (Ledeb.)Roem. were higher than the drought-sensitive young seedlings of Malus hupehensis Rehd., but lower MDA content. The proportion of fine root and the value of fractal dimension decreased with the enhancement of PEG concentration.2. The value of FD, proportion of fine root, total length, taproot and lateral root length, avgdiamten, surface area and volume of roots were decreased in all treatments with the enhancement of salt stress intensity.3. The proportion of fine root increased significantly, the root diameter and the fractal dimension decreased significantly, the angle between main root and first lateral root enlarged, and root tends to horizontal distribution under nitrogen-deficient or iron-deficient condition. The root fractal dimension in iron-deficient condition is less than that in nitrogen-deficient.4. 10-20 mg?L-1 cadmium chloride decreased significantly the Fractal dimension (FD) of roots, taproot length, surface area, volume and diameter of roots and the proportion of fine roots. The degree of decrease rose with the increasing of CdCl2 concentration and presented dosage relation. The content of proline and MDA in root and the proportion of thick root all increased significantly with the increasing of CdCl2 concentration.5. The modified orchards, raised the activity of enzyme, with the types and quantities of microorganisms raised. But the types of soil texture affected the composition of microbial communities, Loam were highest to the composition of microbial communities, secand was sand, third was clay.6. Loam+Sheep excrement+earthworms were beneficial to enzyme activities and root development, there were about 10 kinds of dominant microorganisms in rhizosphere, five dominant 16S rDNA DGGE bands a, b, c, d and e were sequenced. Bands a and b had DNA sequence with similarity rate of 100% to that of GenBank accession nos., which belong to one species. Bands c, d and e had DNA sequence with similarity rate of 95%, 92% and 89% to that of GenBank accession nos.. oot activity in soil.7. By analysis of the community dynamic directly obtained from the DGGE profiles, seven dominant 16S rDNA DGGE bands a, b, c, d, e, f and g were isolated and sequenced. a, b, e and f had DNA sequence with similarity rate of 100% to that of GenBank accession nos., band d had DNA sequence with 98% similarity rate to that of GenBank accession no. Band c and g had DNA sequence with similarity rate of 93% and 91% to that of GenBank accession nos.. The change of enzyme had seasonal and contacted with application system, a large number of organic manure, could significantly increase the enzyme activities and the diversity of rhizosphere microorganisms.