Study On Phosphorus Uptake Ability Of Different Sugar Beet Cultivars Under Phosphorus Deficiency

This dissertation make a selection among 15 sugar beet cultivars at first, using liquid culture method with phosphate(KH₂PO₄) and organic phosphorus(lecithin). And we group them according to their resistant ability under P-deficiency. Second, we focus on the phosphorus acquisition and utilization characteristics by sand culture method with different phosphorus resources, calcium phosphate and phosphorite. We also mensurate the content of Ca₂-P, Cag-P, Al-P and Ca₁₀-P in the sand. Finally, we determined concentration profiles of phosphorus at the soil-root interface by mini-basin method. This dissertation provides theoretic data for high phosphorus efficiency sugar beet breeding.Different cultivars have different resistant ability with different phosphorus resources. Under phosphate (KH₂PO₄), cultivar 20 and 18 have high resistant ability, while 6, 8, 9,11,13, 17, 19 are moderate, and 7, 10, 12, 14, 15, 16 have low resistant ability. Under organic phosphorus (lecithin), cultivar 11, 13 have high resistant ability, while 6, 7, 8, 9, 10, 12, 17, 18, 19, 20 are moderate and 14, 15, 16 have low resistant ability.The root biomass and fiber length are associate with the resistant ability, but the extent which root/shoot increased is irrelated. In contrast to phosphate (KH2PO4), the velocity and quantity of phosphorus uptake reduced rapidly under organic phosphorus liquid culture, and all the varieties' phosphorus utilization efficiency increased rapidly, but the diversity isn't clearly between varieties.Under rock phosphate condition, the validity of phosphate in environment is low, there is no difference between varieties in phosphorus quantity per plant. But under calcium phosphate condition, cultivar 14 is the lowest, while cultivar 20 is high. And the difference is visible. The better phosphorus nutrition in environment can accelerate the phosphorus acquisition, but it has a counter effect on the phosphorus utilization efficiency. There is no evident difference under phosphorite condition, but cultivar 20 is lower than 14 and 17 clearly under calcium phosphate condition.The acquisition of different forms of phosphorus is varied under different phosphorus condition. The cultivar 20 uptake more Ca₂-P than others in calcium phosphate, but there is no difference under rock phosphate. The the highest acquisition of Ca₈-P is the cultivar 20, while 14 is the lowest. Despite the absolute content of Al-P is little, the difference of uptake ability can be seen clearly. Cultivar 14 is high under rock phosphate, while cultivar 20 performs better in calcium phosphate. Under both phosphorus condition, cultivar 14 can uptake more Caio-P relatively.Under rock phosphate condition, cultivar 20's dry biomass is the lowest(index of P-stress 14, 17, 20: 53,58,36)。 Comparing the pH of rhizosphere soil, we found that cultivar 20 is lower but not clearly. The fibre length of cultivar 20 is lower than 14 clearly, maybe this is the main reason of the ability of resistant low-P stress.The characteristics of concentration profiles of Ca₂-P, Cag-P, Al-P and Ca₁₀-P in rhizosphere can be described by equation y=yo +ae^-bx, cultivar 14 behave better in exhausting distance, volume of exhausting soil and the quantity of phosphorus uptake in rhizosphere. Ca₁₀-P is a kind of phosphorus can't be utilized easily.cultivar 14 has a strong uptake ability than 20 markedly.