Influence Of Different Nitrogen Forms And Various NPK Combinations On Nutrient Accumulation And Yield Formation Of Spring And Autumn Potatoes

Potato is one of the most important grain crops. Although China has the No.1 planting area and total yield all over the world, the yield per unit is at a low level because of the poor planting technology. A scientific fertilization is an useful way of improving potato yield. Our study used virus-free potato protospecies, chuan yu 117, as the plant material. In order to study the influence of different nitrogen forms and various NPK combinations on the main agronomic traits, dry matter content, yield and effection matters, accumulation and absorption of NPK, we had the fertilization trials in spring and autumn. The results showed that:1. Compared with potato planted in Autumn, the height of potato planted in Spring was lower, and the number of a stem was more. Fertilization could help plants grow, make the stem stronger and increase the leaf area, especially in potato planted in autumn. Different nitrogen forms had no significant effect on agronomic traits in both potato planted in spring and autumn. But fertilization with nitrate nitrogen only could significantly reduce the leaf area in potato planted in spring, and make the stem fatter, the leaf area larger and branch number of per plant more in potato planted in autumn. As to various NPK combinations, the increasing of phosphate fertilizer could help increase yield,but the increasing of potash and nitrogen fertilizers had little use, sometimes even made the leaf area smaller in potato planted in spring; in autumn, too much nitrogen, phosphate and potash fertilizers had little effect on agronomic traits.2. The total number of dry matter content in per plant of potato planted in spring was 21.31g?47.7%? more, and the number of dry matter content in tuber was 25.21g?82.1%? more than that of potato planted in autumn. The number of dry matter content in every part of the plant was the highest, and that of the stem and leaf was the second and third high, and the least was that of the root. From flowering period to mature period, the accounts of aboveground dry matter reduced; the accounts of tuber increased, that is to say, the number which is 67.0% increased to 84.7% in potato planted in spring, and the number raised from 33.4% to 68.7% in potato planted in autumn. And ability of dry matter moving from aboveground to tuber was stronger in spring. Therefore, fertilization had better influence on the development of dry matter accumulation in potato planted in autumn than that in spring.As for different nitrogen forms, dry matter accumulation in dual nitrogen treatment was significant better than that of nitrate and ammonium nitrogen in spring. However, in autumn, it had a little effect on the development of dry matter accumulation in experiment of Nitrate nitrogen, but the difference was significant in different nitrogen forms of dry matter per mature plant. For various NPK combinations, compared with the experiment of dual nitrogen treatment, high phosphorus and potassium reduced the total accumulation of dry matter of per plant significantly in spring, which is due to the little decrease of accumulation in tuber. But high phosphorus was good to the accumulation in stem, which was not significant in experiment in potassium. However, it had no significant effect on that of autumn, in which high nitrogen could highly increased the accumulation of dry matter in flowering period.3. The yield of potato in spring was average 87.2% higher than that of autumn. It was mainly due to the more number of tuber, which was 3.91?98.0%? per plant. Rational fertilization could help increase in production, which was 15.2%-23.9% higher in spring and 17.4%-44.4% higher in autumn. And the increases in autumn of all treatments, except high nitrogen, were higher than that in spring. As for different nitrogen forms, the yield in spring of ammonium nitrogen was the highest, and then dual nitrogen treatment, and the lease was that of nitrate nitrogen, but the difference was not significant. However, in autumn, the yield of experiment of nitrate nitrogen was the first high, and the second was that of ammonium nitrogen. And the treatment of nitrate nitrogen was significantly higher than that of dual nitrogen treatment, which was 7.5%?1.19×103kg/hm2?higher. For various NPK combinations, the yield of potato planted in spring had little difference. But the yield of high nitrogen and dual nitrogen treatments was higher than that of high phosphorus and high potassium. However, the yield of potato in autumn in experiment of high phosphorus was the highest. And the second one was in dual nitrogen treatment. The increase of yield in treatments of high phosphorus was 11.7%?1.87×103kg/hm2? more than that of dual nitrogen treatment, which had a significant difference. But compared with dual nitrogen treatment, the yield of experiment of high nitrogen reduced 9.2%.4. The highest average nutrient accumulation per plant was in flowering period, and the lowest was in mature period. The number of nutrient accumulation in tuber was higher than that of stem, which in leaf was higher than that of root. From flowering to mature period, accounts of nutrient accumulation in tuber became more and more, and it was higher in spring than that in autumn. The ability of transferring and reserving nutrient in spring was higher than that in autumn. Fertilization could develop nutrient accumulation effectively, and effected more in potato planted in spring than that in autumn.As for different nitrogen forms, nitrate fertilizer or ammonium nitrogen could make the total number of NPK accumulation; and in autumn, the nitrogen from nitrate fertilizer in flowering period was better for the accumulation, while in mature period the effect was not obvious, and it was appropriate for ammonium nitrogen or dual nitrogen treatment. For various NPK combinations, the effect of high nitrogen and phosphorus treatment was not obvious in spring, but it would decrease the accumulation of nitrogen and potassium in high phosphorus, while in experiment of high potassium, it would significantly reduce nutrient accumulation. And in autumn, the effect of high level of nitrogen, potassium and phosphorus was almost the same. High level of nitrogen, potassium would reduce the accumulation of phosphorus significantly in mature period, while in experiment of high nitrogen and phosphorus, it would reduce the accumulation of potassium significantly.5. Absorption efficiency of potassium was the highest, and then the nitrogen, which of phosphorus was the least. And the average absorption efficiency of three nutrients in spring was all less than that in autumn. As for different nitrogen forms, experiment with both nitrate fertilizer and ammonium nitrogen could develop the absorption efficiency of nutrients in spring, while in autumn, it could help absorb potassium, which had no significant effect on that of nitrogen and phosphorus. For various NPK combinations, the increase of nitrogen in spring would reduce the absorption efficiency of nitrogen significantly, while the increase of phosphorus and potassium would decrease that of nutrients. However, the increase of nitrogen would reduce nutrient absorption, while the increase of potassium and phosphorus would decrease absorption efficiency of themselves.6. The efficiency of nutrients in potato planted in spring was not significant with that in autumn. But the use efficiency was higher in potato in spring than that in autumn. Therefore, the average need of nitrogen, phosphorus and potassium in It output in spring was higher than that in autumn respectively, which was N 2.94kg?P₂O₅0.38kg?K₂O 3.77kg?N:P₂O₅:K₂O= 7.6:1:9.8?in spring and N 5.70kg?P₂O₅1.44kg?K₂O 8.13kg ?N:P₂O₅:K₂O=3.9:1:5.6? in autumn. So the need of P was higher in autumn, and the need of N was lower. As for different nitrogen forms, the efficiency of nutrients absorption of dual nitrogen treatment was higher in dual nitrogen treatment in spring, but the use efficiency was lower. The P₂O₅:N and K₂O:N was higher in nitrate nitrogen and ammonium nitrogen in spring. Nitrogen form had no significant in the use of phosphorus and nitrogen, while the efficiency of potassium in experiment of nitrate fertilizer and ammonium nitrogen was higher than that of dual nitrogen treatment. But the P₂O₅:N of dual nitrogen treatment was higher. For various NPK combinations, the increase of nitrogen had no significant influence on nutrient efficiency in spring, while the increase of phosphorus was good for the absorption of nitrogen and potassium, which was bad for that of itself. And the increase of potassium had obvious effect on nutrient efficiency. However, in autumn, the increase of nitrogen had no significant effect on nutrient absorption; the increase of phosphorus helped the efficiency of nitrogen and potassium obviously, while it did not affect that of phosphorus so much; the increase of potassium made the efficiency of phosphorus higher, while it had no obvious influence on that of nitrogen and potassium. So no matter in potato in spring or autumn, high phosphorus could develop P₂O₅:N, while high potassium could increase K₂O:N.