| This research was conducted with “Honggeer” tomato as test materials, and the tomato was cultivated by substrate in bag. According to the nutrient demand differences of tomato,using the nutrition media of Hoagland as contrast(Its ratio of K/N is 1.55:1), and on the basis of it, reducing the ratio of K/N of nutrient solution before the third inflorescence to get three kinds of nutrient solution which the ratio of K/N is 1.37:1, 1.22:1 and 1.09:1. After the third inflorescence, increasing the ratio of K/N nutrient solution, also to get three kinds of nutrient solution which the ratio of K/N is 1.66:1, 1.78:1 and 1.91:1. Completely combining the nutrient solution of different times and to get 9 treatments of nutrient solution of different ratio of K/N, in addition, setting up a control which the tomato was supplied only with water.This study mainly researched the effect of different ratio of potassium and nitrogen at different time on growth, photosynthetic characteristics, dry matter accumulation and distribution, yield, quality, nutrient uptake and utilization of tomato cultivated in bag.Ultimately screening out the best ratio of potassium and nitrogen, and achieving the optimal management of nutrient solution. The main results were as follows:1. The plant height and stem diameter of tomato were nearly linear growth within 100 days after planting, but the growth rate was still differ in each stage, it showed a trend of slow- fast- slow overall. The effect of different ratio of potassium and nitrogen on plant height and stem diameter is small, before the third inflorescence, the effect of stem diameter was greater than plant height, and after the third inflorescence on the contrary.2. Net photosynthetic rate strengthened gradually from flowering fruit-bearing stage to fruit swelling period, and it reached the maximum height in fruit swelling period, then begun to decline, and bottom out in picking period. Stomatal conductance and intercellular CO2 concentration had little change from flowering fruit-bearing stage to fruit swelling period, and they were significantly lower than the former two periods. Transpiration rate had small change in each period. At flowering fruit-bearing stage, net photosynthetic rate was highestwhen the K/N value was 1.37:1, and from fruit-bearing stage to full bearing age, it was highest when the K/N value was 1.78:1. In picking period, all the photosynthetic indicators lowered with the increase of the K/N value of nutrient solution when the nutrient solution treatment was the same in the early stage.3. The results show that the K/N of nutrient solution values in 1.09:1 to 1.37:1 had no significant influence on dry material accumulation before the third inflorescence. After the third inflorescence, with the increase of the K/N of nutrient solution, the total dry matter increased firstly and then decreased, and the treatment which the K/N value was 1.78:1 had the largest amount of dry matter when the K/N of nutrient solution was the same in the early.At flowering fruit-bearing stage, dry matter mainly stored in the leaf, and it accounted for about 65% of the total amount of dry matter. But from the fruit inflating stage, the dry matter allocation proportion of leaf begun to lower, and the dry matter allocation proportion of fruit begun to rise. In the whole growth duration, the order of allocation proportion of each organ is fruit, leaf, stem and root.4. Before the third inflorescence of tomato, with the decline of the ratio of K/N of nutrient solution, the yield of tomato increased firstly and then decreased, and the comprehensive quality is on the decline. After the third inflorescence of tomato, with the increase of the ratio of K/N of nutrient solution, the yield of tomato increased firstly and then decreased, and the comprehensive quality is on the decline. In the whole growth duration, the treatment which the ratio of K/N of nutrient solution is 1.22:1 in earlier stage and 1.78:1 later stage had the best yield(19.23kg/m2). Compared with nutrition media of Hoagland(16.14kg/m2), its yield increased by 19.14%. The best comprehensive quality is from the treatment which the ratio of K/N of nutrient solution is 1.37:1 in earlier stage and 1.66:1 later stage, its attaching functional value of comprehensive quality reached 6.48.5. The amount of N, P and K uptake all had been on a rise since flowering and fruit bearing periods, among the three elements, the total absorption of K was most, followed by N and P. In general, after the third inflorescence, the treatments which the K/N value was 1.78:1had the higher amount of nutrient uptake when the K/N of nutrient solution was the same in the early. In the whole growth period N2N5(the K/N value was 1.22:1 in the early, 1.78:1 in the late) and N3N5(the K/N value was 1.09:1 in the early, 1.78:1 in the late) had the higher amount of nutrient uptake.In the whole growth period, the nutrient uptake of fruit was highest, followed by leaf,steam and root, and the fruit uptake of nitrogen, phosphorus and potassium accounted for53.99%~68.15%, 62.58%~77.63% and 60.49%~71.60% of the whole plant respectively.The element recovery efficiency of N2N5 and N3N5 were higher compared with othertreatments. The highest recovery efficiency of supplementary N, P and K were 78.18%, 72.85 and 81.14%, and they were 2.07, 11.17 and 2.94 times of Hoagland respectively. The element agronomy efficiency of N2N5 was the highest in all treatments, the agronomy efficiency of N, P and K were 178.11kg/kg, 698.09kg/kg and 102.65kg/kg respectively, and they were 2.17, 2.09 and 1.93 times of Hoagland.Synthetically taking yield, quality and nutrient uptake into account, the optimal K/N value of supplementary nutrient solution of tomato cultivated in bag is 1.22:1 before the third inflorescence, and 1.78:1 after the third inflorescence. |
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