| Genotype differences of phosphorus efficiency among 145 rice cultivars were investigated under pot culture, nutrition culture and field in the low-p soil. Screen and judge the 40 rice genotype of to P-tolerance in order to establish the chart and writing data-bases, meanwhile research the root characters to the 31 rice genotype of P-tolerance in nutrition culture The generation of Pi(P-sensitivity), P2(P-tolerance), F1 , RF1 , F2 and F2,3 analysis the genetic characteristic. Main research results :1. 145 rice cultivars were planted to screen the low-P tolerant genotype within the seedling and the total bearing periods. We used low-P tolerant index (TPI, which was defined as the ratio between the index under phosphorus stress and usual phosphorus condition) to show the discrepancy between all varieties. The number of tiller of rice genotype was investigated during the tillering period, and calculate the relative tillering rate. We got 40 genotypes of which the relative tiller rate was beyond 80% and 16 genotypes of which the relative tiller was below 40% with screening method, simultaneity 4 genotypes of which the relative tiller rate was between 41% and 79% and the growing force and plant shape was good. These 60 genotypes were identified during total bearing period, and 35 rice genotypes tolerant to low-P stress and 12 rice genotypes sensitive to low-P stress were confirmed with the index of TPI for shoot dry weight, economic yield etc. as well accounting for all round factors such as different response to phosphorus nutrition during seedling, the tiller period, the period of autumn, and growth force, plant shape etc. we doing deeper research within 35 genotypes, and discuss the low-P tolerant mechanisms which were classified between different rice genotypes.2. The difference of root trait of 31 rice genotypes which were screened and identified under low-P stress during early period tolerant to low-p researched, and we adopted flowing solution culture method. Different genotypes tolerant to low-P had different root shapes under low-P stress which could be showed as follows: under low-P stress, relative main root length of six genotypes of 7, 30, 5, 12, 6, 4 increased, relative root dry weight of 17, 29, 4, 10, 30 increased, the relative fresh weight of root of all genotypes did not increased apparently, the ratio of root and shoot of all genotypes increased under low-P stress, the relative ratio of root and shoot of different genotypes increased differently in scope. The ability of root of different rice tolerant genotypes adapting to low-P stress existed dominant genotype difference under low-P stress, and which was found through experiment.3. The heredity of P-tolerance was studied in different P-tolerance of two inbred lines ofrice and their F1, F2.3, generations by the means of field cultivation . The results indicated that: relative the tiller ratio and relative efficiency spike in plant was under control of 2 major gene addition-dominance-epistatic effect, the main gene heredity ofrelative the tiller ratio was 65.38%, relative the efficiency spike 54.70%; On contrast, the relative biomass of shoot and the relative yield in plant accord with the model of 2 major gene addition-dominance-epistatic effect + the multi-gene. The relative biomass of shoot had main gene heritability (60.08%), and the relative yield in plant had main gene heredity (37.70%), respectively the multi-gene heritability reach to 32.15% and 58.9%.4. Rice root genetic analysis with four generations including P1, P2, F1, F2 showed that: Comparing F1 to RF1, we found that controlled main root length , root fresh weight and root dry weight and root R/s in plant existed in nucleus. The main root length accord with the model the 2 major gene addition -dominance- epistatic effect + addition-dominance multi-genes .The heritability of major genes for the main root length are 62.47% and the heritability of multi-gene are 20.49% ;and that the root fresh weight , the root dry weight and the root R/S were control the 1 major g... |
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