Study On The Response Of Different Genotypic Rice(Oryza Satava L.) To Low Phosphate Stress And Its Molecular Mechanism

Screening P-efficient rice variety may represent a more sustainable solution than sole reliance on fertilizer appliance. It is very important to economize resources and avoid pollution in rice cropping systems.34 different rice genotypes, were planted in pot and field , supplied with low(0.5mg/L P ) and high (10mg/L P ) phosphorus, to screen their phosphate efficiency (PE) at seedling and ripening stage respectively. After screening methodology was determined, IR74 (a high PE genotype) ,IR71331 (a moderate PE types) and IR71379 (a low PE genotypes) were planted at the low P deficiency of 0.5mg/L in hydroponic culture, to study the mechanism of PE discrepancy, which includes plant morphology and microstructure, physiological and biochemical properties, i.e. photosynthesis and resistance to low P characteristics, as well as its molecular mechanism. The results can be summarized as follows:It was showed that there were significant differences of tolerant indices to P deficiency in the tested rice genotypes. When rice cultivars were exposed to low P stress with the relative-higher P concentration (1mg/L P) to be screened, relative tiller dry weight (RTW) , relative shoot dry weight (RSW) and relative total plant dry weight(RPW ) could be used as the better screening criteria, especially RTW was considered a sensitive and reliable screening criterion based on the large coefficient of variation (CV) and variable range of data among the tested varieties. However, when rice genotypes were grown in the stress condition with the relative-lower P concentration (0.5mg/L P) , the screening criteria were different, and it suggested that relative shoot dry weight(RSW) or relative total plant dry weight (RPW) was the best single screening criterion. The differences in outside morphological and internal microstructure characters of rice varieties with different P efficiencies were further discussed. It could be showed that the efficient rice tolerant to low P stress resulted from the good development of lateral roots and tiller primordium, the thickness of palisade tissue, the denseness of stoma, moreover, the diameter stem and vessel increased.The genotypic differences in P efficiency of three rice varieties (IR74, IR71331 and IR71379) were studied under the P-deficiency controlled condition in hydroponic culture, and its adaptability to low phosphorus stress about physio-biochemical mechanisms were further studied. The results showed whether rice genotypes tolerated low P stress resulted...