The Dynamics of Calcium and Magnesium Nutrient of Tomato Fruit in Different Substrates of Soilless Cultivation

In order to select the substrate treatment which adapts to tomato growth in soilless cultivation, the paper studied the changes of calcium and magnesium nutrient in tomato that was planted in substrates mixed by different ratio, including grass peat, vermiculite, perlite and sand. The infmite-growth-typed tomato cultivar "weiwei" was planted in an automated greenhouse. Seven different compound cultural substrates were used in this test. Atomic absorption spectrophotometry was used to determine the calcium and magnesium content in tomato fruit. The results show that the calcium and magnesium contents of tomato absorbed from the different treatments are obviously discrepancy. From the overall level, the mixed substrates of grass peat: vermiculite: perlite = 1:1:1 is conducive to the calcium and magnesium absorption of tomato, and it is superior to other treatments. Besides, the calcium content of tomato is decreasing with prolonging growth period; the magnesium content of tomato is increasing with prolonging growth period.