Study Of The Different N-applications On The Uptake And Utilization Efficiency Of The Phosphorus And Potassium In Different Growth Types Rice

A field experiment was carried out to study difference of response to phosphorus and potassium use efficiency of rice genotypes by using 118 rice genotypes as materials under 4 N levels including zero (0N/666.7m2),low (10kgN/666.7m2), medium (15kgN/666.7m2) and high (20kgN/666.7m2). Study the difference on phosphorus and potassium utilization rate of different N-applications and growth type. The results as follows:1. Using the nitrogen fertilizer can promote the rice to absorb and utilize phosphorus and potassium fertilizer, but the excessive application of nitrogen has some hindrance function to absorb phosphorus and potassium fertilizer on the rice. This test indicates: the absorption efficiency to phosphorus and potassium of the rice is highest under the medium nitrogen level.1)The effect of nitrogen fertilizer to P content is greater than the K content. In the earlier and later stage of growth process, the K content variation of different N-applications is not remarkable. The P content of the zero nitrogen level in the jointing stage is the highest. The K content of the heading stage is highest after using the nitrogen fertilizer, and increases with the increase of N-application. But the K content of some late-maturing types remains the jointing stage highest. K content of jointing stage is all the highest, every stage increases with the increase of N-applications, and slightly drops on the high nitrogen level.2) N-applications are all extremely remarkable to the P accumulation and K accumulation. The P accumulation of the plant is the highest with the maturing stage, and increases with the increase of N-application. In later of the growth stages too much application of nitrogen to make the P accumulation of late-maturing rice slightly drop. The K accumulation has slightly difference; the highest value is in the heading stage. In the maturing stage, the leaching loss and loss of old leaves make the K accumulation drop, but all increase with the increase of N-application. The excessive application of nitrogen makes the late-maturing type slightly drop. 3) The P stage accumulation and K stage accumulation of the plant in the jointing to heading stage is the highest, increasing with the amount of nitrogen's application increasing, and dropping when in the high nitrogen level. But some early-maturing type rice still increase in the high nitrogen level. Because of the losses of the potassium, the K stage accumulation is shown as negative in later of the growth stages.4) The absorption intensity of the rice to phosphorus is higher than the potassium, and both intensities are highest in jointing to heading stage. The absorption intensity of f rice to phosphorus is affected by nitrogen fertilizer remarkably at every stage, but the potassium can not be affected by nitrogen fertilizer remarkably in middle and later periods. In the jointing stage, the absorption intensity of rice to phosphorus and potassium all increase with the amount of nitrogen application's increasing, and to the heading and maturing stage the absorption intensity of rice have slightly dropped in high nitrogen level especially late-maturing type rice. The absorption intensity of potassium is shown as lost intensity in maturing stage. It is lowest to the losing intensity in the zero nitrogen level, and the losing intensity to potassium descends with the increasing of the amount of nitrogen application, it is to say the ability of the firm potassium is strengthened.5) The effect of the amount of nitrogen application to P content, P accumulation, K content and K accumulation in the grain have all reached the extremely remarkable level. The grain P content and P accumulation increase with the amount of nitrogen application's increasing, and descend to the high nitrogen; The grain K content and K accumulation increase with the amount of nitrogen application's increase, but only the late-maturing type rice descend when the high nitrogen is dealt withes.6) The proportion of operation to the grain of potassium is higher than the phosphorus. Among different nitrogen fertilizer level, the variation of phosphorus harvest index reaches remarkably only among late-maturing types; the variation of potassium harvest index has all reached the remarkable level. And both increase with the amount of nitrogen application's increasing, slightly descend in the high nitrogen level, the late-maturing type descend remarkably.2. The increasing of the growth process' length can promote the absorption amount of phosphorus and potassium in the rice, but reduce the phosphorus and potassium's proportion in the plant at the same time. The variation of all kinds of rice's phosphorus and potassium absorption is not remarkable in the jointing stage. The phosphorus absorption of the rice continues increasing in the maturing stage, but losses of potassium are greater than absorbing.1) The variation of plant P content of different growth type rice has reached the extremely remarkable level in every stage, but the k content has not reached the remarkable level in the jointing stage. In the jointing stage and heading stage, plant P content and k content of the medium japonica rice and late japonica rice increase with increasing of the growth stage's length, the late-maturing type rice slightly descends; In the jointing stage and heading stage, plant P content and k content of the medium Japonica rice and late Japonica rice increase with increasing of the growth stage's length, the late-maturing type rice slightly descends; In the maturing stage the growth stage's length and P content have direct proportion relations, but the k content is reduced with increasing of the growth stage's length. P content and k content of Indica rice is higher than Japonica rice in all stages.2) Every stage the P and K accumulation of rice increase with the increasing of the growth stage's length, ant the variation are not obvious among different growth type rice in jointing stage. The Indica rice is lower than the late Japonica rice in the absorption of the phosphorus, The Indica rice is lower than the late Japonica rice the absorption of the phosphorus, but it get higher slightly in absorption for potassium, and lie between the early-maturing late Japonica rice and medium-maturing late Japonica rice.3)It have reached extremely remarkable that the variation of p stage accumulation and k stage accumulation of different growth type rice, and increase with the increase of the growth stage's length, the p accumulation has descending in heading to maturing stage on some late-maturing type rice. The loss amount of the potassium increases with the growth stage's increase in the medium Japonica rice and late Japonica rice in heading to maturing stage, among them what the Indica rice lost is the fewest.4) Variation of the phosphorus and potassium absorption intensity (or the losing intensity) in different growth type rice has reached the extremely remarkable level. And they increase with the growth stage's increase in the heading to maturing stage and the seedling to jointing stage, but reduce with the growth stage's increase in jointing to heading stage. The absorption intensity of Indica rice is higher than other types rice in each stage's, especially the seedling to jointing stage.5) Variation of the grain P content and P accumulation of different growth type rice are not remarkable, the grain P content descend gradually with the growth stage's extensions, but the grain P accumulation increases gradually, the late-maturing type slightly descends; Variation of K content and K accumulation of the grain are quite large, and increase with the growth stage's increase in different types of rice grain. The Indica rice grain is relatively low to the absorbability of the potassium.6) Phosphorus and potassium's harvest indexes of different growth type rice do not have remarkable difference, all increase with the increase of N-application. But the harvest indexes of phosphorus descend remarkable, if the time to mature is too long. The Indica rice's harvest indexes of phosphorus are in the medium level, but those of potassium are relatively low.3. Through relativity analyzing, preliminarily confirm the useful index and research direction to breed the high-efficient in using phosphorus and potassium and the high-yield rice genotype. P accumulation in Maturing stage, K accumulation in heading stage, the phosphorus and potassium accumulation in the jointing to heading stage, the absorption intensity of phosphorus and potassium in seedling to jointing stage, the absorption intensity of phosphorus in the heading to maturing stage and the harvest index of the potassium can all be used as the index of the high using efficient of phosphorus or potassium and high yield.