Effect of CO2 Enrichment on the Growth and Nutrient Uptake of Tomato Seedlings

Exposing tomato seedlings to elevated CO2 concentrations may have potentially profound impacts on the tomato yield and quality. A growth chamber experiment was designed to estimate how different nutrient concentrations influenced the effect of elevated CO2 on the growth and nutrient uptake of tomato seedlings. Tomato （Hezuo 906） was grown in pots placed in controlled growth chambers and was subjected to ambient or elevated CO2 （360 or 720 μL L^-1） and four nutrient solutions of different strengths （1/2-, 1/4-, 1/8-, and 1/16-strength Japan Yamazaki nutrient solutions） in a completely randomized design. The results indicated that some agricultural characteristics of the tomato seedlings such as the plant height, stem thickness, total dry and fresh weights of the leaves, stems and roots, the G value （G value = total plant dry weight/seedling age）, and the seedling vigor index （seedling vigor index = stem thickness/（plant height × total plant dry weight） increased with the elevated CO2, and the increases were strongly dependent on the nutrient solution concentrations, being greater with higher nutrient solution concentrations. The elevated CO2 did not alter the ratio of root to shoot. The total N, P, K, and C absorbed from all the solutions except P in the 1/8- and 1/16-strength nutrient solutions increased in the elevated CO2 treatment. These results demonstrate that the nutrient demands of the tomato seedlings increased at elevated CO2 concentrations.