Studies On Screening Of Phosphorus Efficient Arabidopsis Ecotypes And Its Nutritional Mechanism

Genotype differences of phosphorus efficiency among 90 Arabidopsis ecotypes were investigated under nutrient solution culture. Two treatments, P-deficiency (CK) and P-sufficiency (+P), were made. The phosphorus efficiency of different ecotypes was estimated with, the coefficient of (-P/+P). The nutritional mechanism was primarily studied. The main results were found out as follows:First, different planting methods were compared. We found that natural soil of low P-content was not compatible for the growth of Arabidopsis and sand was not either. But the method of nutrient solution culture was very befitting. So, the method of nutritional solution culture was adopted to do the experiment of screening of different Arabidopsis ecotypes.Second, different P concentration was conducted to plant Arabidopsis. Plants appeared P-deficient symptom and the difference between different ecotypes was marked when the concentration of P was between 0.15-1.5 mg/L. Based on the results of the first screening experiment, 1.0mg/L was confirmed as the concentration of the treatment of P-deficiency. When the concentration of P was 15 mg/L, plants grew very well, 15 mg/L was confirmed as the concentration of the treatment of P-sufficiency.Third, five experiments were conducted between October, 2001 and February, 2003. The P-efficiency coefficients were analyzed by SAS software. Three phosphorus efficient ecotypes of 01, 03, 05 and four phosphorus inefficient ecotypes of 02, 04, 06 and 07 were found. Their P-efficiency coefficient were 0.702, 0.546, 0.504,0.267, 0.335, 0.387, 0.377.Forth, three phosphorus efficient ecotypes and four phosphorus inefficient ecotypes were planted under nutritional solution culture and the nutritional mechanism was primarily studied. Results indicated that plants appeared P-deficiency symptom after the plants were grown under the P deficient condition. But the P-deficiency symptom of phosphorus inefficient ecotypes was more evident than phosphorus efficient ecotypes. Compared with the treatment of P-sufficiency, dry weight of shoots and roots was all reduced, but efficient ecotypes were influenced less great than inefficient ecotypes. As far as the ratio of root/shoot was concerned, these seven ecotypes were increased under the treatment of P-deficiency, 01,03,05 increased 7.9 %,7.8%,8.1%, 02,04,06,07 increased 0.8%, 1.9%,0.7%,2.5% which indicated the increase of efficient ecotypes was higher than inefficient ecotypes and their difference was marked. Under P deficient condition, the root-length of phosphorus efficient ecotypes increased, but phosphorus inefficient ecotypes decreased. As for P content and accumulation, 01, 02, 03, 04, 05, 06, 07 decreased 48.3%, 65.3%, 59.8%, 66.7%, 56.8%, 65.2%, 65.6% under P deficient condition. Phosphorus efficient ecotypes decreased less than 60% and phosphorus inefficient ecotypes decreased more than 65%. The result of correlation analysis indicated that the weight of dry matter was positively correlated with P accumulation (r=0.881***), but which was negative correlated with P content(r=-0.693** ). Efficient ecotypes were realized high efficient because they could absorb P by stronger root and continuous reuse. In terms of this, the inefficient was weaker. Under nutrient solution culture, Acid Phosphatase (Apase) was researched. The Apase activity of efficient ecotypes increased more than phosphorus inefficient ecotypes. The result of correlation analysis appeared that Apase activity was positive correlated with P-efficiency coefficient (r=0.930***), and which was negative correlated with P accumulation(r= -0.138).