| In recent years,excessive application of large amount of chemical fertilizer in greenhouse vegetable production has resulted in serious soil nutrient imbalance.In order to find out the cause of nutrient imbalance of horticultural crops,three groups of experiments were set up to study the migration and transformation characteristics of potassium,calcium and magnesium in soil from horizontal direction to vertical direction,the utilization efficiency of tomato with different ratio of potassium and magnesium fertilizer and foliar application of calcium fertilizer were studied.The horizontal migration experiment was conducted with two factors:the amount of potassium fertilizer(450(K1),800(K2),1350(K3)kg·hm-2)and different air humidity(natural humidity(H1),70%(H2),90%(H3).The results showed that:1)The content of water-soluble potassium(K),calcium(Ca),magnesium(Mg)and exchangeable Ca,mg increased with the distance between plant and fertilizing area.The higher the humidity,the higher the total content of water-soluble K and Ca,the lower the total content of water-soluble Mg,and the lower the exchangeable K.A large amount of water-soluble K remained at 0-9 cm.The higher the fertilizer application,the higher the content of water-soluble K and Ca at 0-6 cm.2)The higher the humidity,the lower the stem biomass,the lower the root,stem,K and Mg content,fruit K content and leaf calcium(Ca)and Mg content The higher the fertilizer application,the higher the content of K in root,leaf,root and stem,the lower the content of K and Mg in fruit,and the lower the content of Ca in each organ.In the vertical leaching experiment,the ratio of potassium to magnesium(450:15(R1)and 1350:45(R2)and different irrigation amount(2830(W1),4250(W2)t·hm-2)were selected as two factors.The results showed that:1)The larger the amount of fertilizer applied,the thicker the stem,the longer the root,the higher the content of K in the root,the higher the absorption of K in the whole plant.The soil water content,water-soluble and exchangeable K and Mg content decreased from 0 to 20 cm,but increased from 20 to 40 cm,and the difference was significant.2)The smaller the irrigation,the larger the total root surface area and the leaf biomass,the lower the leaf K content and the root Mg content;The higher the amount of fertilizer applied,the higher the content of K in root and stem,the higher the absorption of K in whole plant,and the absorption of Mg in whole plant was 1.4 times larger,and there was no significant difference.According to the level and the effect of Tomato on Nutrient Utilization in Leach test,a single-factor field experiment of foliar application of calcium fertilizer(CK,calcium nitrate(T 1),calcium superphosphate(T2),calcium amino acid chelate(T3),calcium fulvic acid(T4))was conducted.Research shows,1)The biomass of tomato leaves and fruits increased significantly under the treatment of chelate calcium(T3)and Fulvic acid calcium(T4)with the increase of growth period and the application of different calcium fertilizers;Calcium chelate(T3)and calcium fulvate(T4)significantly increased the contents of K,Ca and Mg in tomato leaves and fruits;and calcium chelate(T3)and calcium fulvate(T4)significantly increased the absorption of Ca,K and Mg in tomato leaves and fruits There was a significant positive correlation between Ca uptake and K,Mg uptake in tomato leaves at one ear fruit-bearing stage and harvest stage.In summary,air humidity,fertilizer application,and irrigation can all affect the efficiency of nutrient uptake by plants in facility agriculture,therefore,it is necessary to adopt appropriate air humidity,fertilizer and irrigation to solve the problem of calcium deficiency in tomato production.At the same time,when spraying chelate calcium and Fulvic acid calcium on the leaves,the biomass of tomato leaves and fruits,the content of potassium,calcium and magnesium and the absorption efficiency were increased more effectively,therefore,spraying chelate calcium and calcium fulvate on the leaves is also an effective measure to solve the problem of calcium deficiency and improve the quality of tomato fruit. |
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