Mechanisms Of Genotype Differences In Phosphorus Efficiency Of Wheat

Phosphorus is one of the essential nutrients for plant, which plays very important role in agriculture production. However, in natural ecosystems phosphorus tends to disappear during the course of elemental cycle in chemosphere, meanwhile most of phosphorus in soil is unavailable to plants, and phosphorus fertilizer use efficiency was always not higher than 20 percent, as a result there is a profound significance to exploit the huge soil phosphorus bank and improve fertilizer use efficiency via biological ways.Two typical wheat genotypes, Xiaoyan54 and Jing411, had been adopted in present research work for investigating plant growth and phosphorus nutrition characteristics of wheat seedlings under different phosphorus supply in the nutrients solution. Together with some physiological traits related to phosphorus nutrition, the work targeted to discover the mechanisms of genotype differences in phosphorus efficiency of wheat and provide scientific basis for choosing proper wheat genotypes under different soil.Results of the experiments indicated that under phosphorus insufficiency, there were marked differences in self-protection of the two genotypes under phosphorus deficiency. The permeability of cell membrane of Xiaoyan54 was relatively low and the SOD enzyme activity was high which could efficiently prevent loss of internal phosphorus from efflux, which means that the self-protection ability was high, while the case was contrary for Jing411.Different mechanisms worked for the two genotypes in adaptation to phosphorus insufficiency. Xiaoyan54 intended to have high phosphorus level via different methods. Which showed high phosphorus concentration, phosphorus content, high phosphorus uptake efficiency per root length unit and relative large total root absorbing area and active absorbing area. Xiaoyan54 showed advantages of maintaining better growth and larger relative biomass, which contributed to its high phosphorus uptake efficiency.The APA activity of two genotypes in root was higher than in leaf, which means different wheat genotype have high phosphorus use efficiency with the help of APA in root under phosphorus insufficiency. From the result we can see, Jing411 adaptation tophosphorus stress could be found in high phosphorus use efficiency, and which could be explained by the higher activity of internal and root excreting APA than Xiaoyan54.With phosphorus re-supply after absence, internal phosphorus concentration hi Xiaoyan54 quickly reached the normal level with the help of high phosphorus absorbing rate, and it can regulate the absorbing of phosphorus to avoid phosphorus toxicity .But for Jing411 the recovery of phosphorus uptake is relatively slow and the growth recovery could be attributed to high phosphorus use efficiency and function of efficient growth regulation.Plant growth, especially for root to shoot ratio of Xiaoyan54 react tardily to changes in phosphorus supply. In contrast, growth of Jing411 was sensitive to changes in phosphorus supply which could be well demonstrated by the enlarged root to shoot ratio under phosphorus deficiency and high phosphorus use efficiency. In summery, Xiaoyan54 intended to survive under phosphorus deficiency with the help of high phosphorus uptake rate of roots, while the enhanced root growth of Jing411 for enlarging root accessible volume played the leading role in adaptation to phosphorus deficiency. Xiaoyan54 could be chosen as genotype to grow on barren soils while Jing411 should be classified as genotype suitable for high input production systems.