Effects of the interactions of carbon dioxide and nutrients on tomato seedlings

Tomato(Hezuo 906) was hydroponically cultured at different carbon dioxide and nutrient concentrations and periodically sampled to study the dynamic weights of tomato roots and the effects of the interactions of carbon dioxide and nutrients with different concentrations on carbon and nitrogen contents and carbon to nitrogen ratios in tomato roots.The results indicated that the dry weight of tomato roots accumulate slowly at the seedling stage and rapidly at the middle and late growth stage,carbon dioxide affected the dry weight of tomato roots in the late nurserying period more heavily than in the early nurserying period,and the response of the dry root weight of tomato roots varied with the ion concentrations in the nutrient solution;and these illustrated that the roots of young tomato seedlings could grow and develop best under the carbon dioxide supply in combination with the nutrient solution with high nutrient concentrations.The quantitative analysis of the relationship of the weight of fresh tomato roots with time showed that tomato roots could change their growth depending on their growth conditions;under the circumstances with high carbon dioxide concentration,the fresh root weights of tomato in the nutrient solution containing 1/2 and 1/4 YAMAZAKI's nutrient solution was fitted to follow a power function at the highest correlation coefficient and those in the other treatments were fitted to follow a conic equation at the highest correlation coefficient.Under the circumstance with high carbon dioxide concentrations,the dry weights of tomato roots in the solution containing 1/2 YAMAZAKI's nutrient solution were fitted to follow a power function at the highest correlation coefficient and those in the other treatments were fitted to follow a conic equation at the highest correlation coefficient.Carbon dioxide reduced the nitrogen contents of the roots growing in the solutions containing 1/2 YAMAZAKI's nutrient solution and raised those of the roots growing in the other nutrient solutions,decreased the carbon percentages of the roots growing in the nutrient solutions containing 1/2 and 1/4 YAMAZAKI's nutrient solution,increased the carbon percentages of the roots growing in the nutrient solution containing 1/8 and 1/16 YAMAZAKI's nutrient solution and the total carbon and nitrogen amounts of the roots growing in all the nutrient solutions,reduced the carbon/nitrogen ratios of tomato roots,which increased with increased nutrient solution concentrations at same carbon dioxide concentrations.