The Characteristics Of Rice Genotypes With Tolerance To Low Phosphorus In The Northeast China's Three River Plain

Phosphorus is one of essential nutritive elements in rice. However, the phosphorus content may actually very little be able to meet the needs of rice growth in the soil, the research on tolerance to low phosphorus has become the hot spot of genetics study, which studies really few in the early japonica rice in northeast China. Three rive plain is important commodity grain bases in our country, but rice output enhancement has seriously limited by the effective phosphorus in soil. In this study, the screening appraisal method and the appraisal target research of rice variety characters to bear low phosphorus on forcing was studied, the relation was discussed between with various characters and phosphorus level to bear low phosphorus under the different phosphorus level, and formed appraisal method and target of tolerant character, screened the rice variety to bear low phosphors, which suited Northeast China's Three-River plain. It has vital significance to enhance the rice yield per unit area and realize the agricultural sustainable development and the national grain safety.The results of rice variety characters with tolerance to low phosphorus indicated that the root character of variety had the remarkable difference under different phosphorus level, especially under low phosphorus level. The most sensitive time of the total root length and root radical to phosphorus was at tillering period, the most sensitive time of the root weight was heading period. Before tillering, the root weight increasing mainly was through the number increasing, from tillering to heading period, the increase mainly due to the single root increase. The ratio of root and crown was important factor affecting the absorption efficiency of nutrient, the surface area increase of root was one of effective ways on the enhancing of attracting phosphorus quantity in plant. Under the condition of sand pot culture, the suitable phosphorus level to screen tolerance to low phosphorus genotype was 3mg/kg, under this phosphorus level, the root character and plant dry weight et al were studyied in tillering period, and might initially screening the idioplasm with tolerance to low phosphorus, recombined with field duplicate selection, the result was more accurate.The results of screening and appraisal criterion of rice variety with tolerance to low phosphorus showed that the ratio of root and crown, total root length and root surface area of variety were main characters of rice varieties with tolerance to low phosphorus. Moreover the resistant ability to low phosphorus stress, the relative tillering strength and the ratio of root and crown , the root surface area, the root dry weight, the adult plant dry weight, the total root length showed remarkable or extremely remarkable positive correlation. Therefore, the resistant ability to P stress of a variety could be determined by tillering ability and biological output, which were delimited and evaluated according to the variety with tolerance to low phosphorus ability, the relative tillering ability, and the low phosphorus condition, and formed 9 levels on divisions standards and appraisal criterion, 1～3 levels were type to bear low phosphorus, 4～6 levels were middle type, and 7～9 levels were type for did not bear low phosphorus. Selected 23 varieties with tolerance to low phosphorus, liked longhua 94-667, longjing 2, daobei 54, longhua 84-106, longjiao 89068, longjing 3, andlongjing 7 and so on, those varieties might do for the parents of rice gene with tolerance to P stress, some varieties might directly applied in three river plain which has showed phosphorus deficit.