Comparation Of Phosphorus Efficiency And Study On Physiological Mechanism In Maize Inbred Lines

This research on the difference in phosphorus efficiency by using 2 phosphorus levels for four maize inbred lines( KH12, XIN9005, 58, H21)was carried out at difference stages (jointing, grain filling and maturity) under field experiment, at the same time, the physiological mechanisms were fully investigated with two typical varieties (KH12 and XIN9005 ) in the pot experiment. The main results were summarized as follows: 1. In the field, 58 and KH12 are always high-efficient genotypes at three growth seasons under low and high soil P application.,XIN9005 is always low-efficiency genotype, H21 is high-efficiency in LP and low-efficiency in LP. The difference in phosphorus efficiency between KH12 and XIN9005 and 58 and XIN9005 are more significant, they are typical materials to study mechanisms of high phosphorus efficiency. 2. In pot experiment, the difference in phosphorus efficiency between KH12 and XIN9005 at jointing is the same as in the field, so their difference could be studied through pot experiment. 3. At HP, KH12 has higher phosphorus efficiency than XIN9005. The reason lies in follows: (1) The total root length of KH12 is longer than XIN9005, which mainly results from it's longer lateral root length. (2) The product of photosynthesis of KH12 is more than XIN9005 and it is mainly caused by the larger leaf area. (3) The accumulation and utilization ability to N and K and activity of nitrate reductase of KH12 are stronger than XIN9005. (4) The ability of KH12 acidifying its rhizosphere and its ALPA activity is stronger than XIN9005. 4. At HP, there are no significant difference between KH12 and XIN9005 in the root axis length, root/shoot ratio, photosynthetic rate and cell membrane relative permeability . 5. At LP, the root length of KH12 is longer than XIN9005, which is mainly caused by it's longer lateral root length. The product of photosynthesis of KH12 is more than XIN9005 and the result mainly comes of it's larger leaf area. N utilization efficiency, nitrate reductase activity and K utilization efficiency of KH12 is stronger than XIN9005. KH12 could make its rhizosphere acider than XIN9005 so as to uptake more phosphorus. 6. At LP, the difference in phosphorus in phosphorus efficiency of the two genotypes has little relationship with the length of root axis, root/shoot ratio, the ability of accumulating nitrogen and potassium, ALPA activity in rhizosphere, cell membrane permeability. The photosynthesis rate of XIN9005 is higher than KH12.