Phosphorus utilization characteristics of forty spring maize hybrids with high-yielding potential in north of China

【Objective】 A pot experiment was conducted to evaluate phosphorus utilization characteristics of different spring maize hybrids with high-yielding potential that are widely grown in north of China, to illustrate differences of phosphorus accumulation and transportation of different maize hybrids, and to provide scientific information for the high efficient breeding of phosphorus in maize. 【Methods】 Forty maize hybrids were cultivated in pots and planted in 60000 plants/hm2 with the same environmental conditions. Three plants were selected in every hybrid at the flowering stage and maturity stage, and divided into four parts, roots, stalks, leaves and grains. Dry matter weight was measured after stoving. The phosphorus contents of different organs were determined with the colorimetric method. Phosphorus grain production efficiency(PGPE) was applied to divide the phosphorus efficiency of different maize hybrids. The related parameters of phosphorus utilization characteristics were calculated, and relationship between PGPE and related parameters of phosphorus utilization characteristics was analyzed. 【Results】 The results indicate that the maize hybrids can be classified into four types according to values of PGPE, including phosphorus efficiency of high(type I), moderate(type II), low(type III) and super-low(type IV). The much more number of cultivars were found in the type III(with a ratio of 45%), followed by the types II(27.5%) and I(22.5%), and the fewer number of cultivars were observed in the type IV, with a ratio of 5%. The contents and distribution ratios of phosphorus at the growth stage after the flowering exhibit significant differences among these four-type maize hybrids, while those before the flowering are not significant. At the flowering stage, the phosphorus accumulation in stalks is the highest in the type IV(P0.05), and the differences of phosphorus accumulation in roots, stalks and leaves are not obvious in the types I, II and III(P0.05). At the maturity stage, the phosphorus contents of different organs are the highest in the type IV(P0.05), and the phosphorus contents in grains of the type III and II are higher than those of the type I(P0.05), but there are no obvious difference between the types III and II(P0.05). The phosphorus accumulation amounts and distribution ratios in roots, stalks and leaves are the highest in the type IV(P0.05), while the phosphorus accumulation amounts and distribution ratios in grains of the types I, II and III are higher than those of the type IV(P0.05). The phosphorus accumulation amounts and distribution ratios in roots, stalks, leaves and grains arent obviously different in the types I, II and III(P0.05). Among the four type hybrids, the values of phosphorus dry matter production efficiency(PDMPE), phosphorus harvest index(PHI), phosphorus partial productivity(PFP), phosphorus transportation amount(PTA), transportation efficiency(PTE) and phosphorus contribution rate(PCR) in the type IV are the lowest(P0.05). The values of PFP, PHI, PTA and PTE in the types I and II are significantly higher than those in the type III(P0.05), but the difference between the types I and II is not obvious(P0.05). The phosphorus uptake efficiencies(PUpE) and phosphorus agronomic efficiencies(PAE)of the four type hybrids are not obviously different(P0.05). Furthermore, the correlation and path analyses show that PDMPE and grain weight are significantly correlated to PGPE. 【Conclusions】 Most spring maize hybrids with high-yielding potential that are widely grown in north of China are low efficiency of phosphorus, and the phosphorus distribution ratios in grains are the highest in the type I after the flowering stage, while the phosphorus distribution ratios of roots, stalks and leaves in IV are the highest. High grain weight and PDMPE could be considered as the key characteristics of maize hybrids with high phosphorus efficiency.