Effects of prolonged root-zone CO2 treatment on morphological parameter and nutrient uptake of tomato grown in aeroponic system

Effects of elevated root-zone (RZ) CO2 on plant morphological parameter and nutrient uptake grown in a greenhouse were investigated over aperiod of 60 days. The root systems of tomato plants were treated with four different CO2 concentrations (370 µL L-1 air, 2500 µL L-l , 5000 µL L-l , 10000 µL L-1 ) at first flower anthesis period by areoponics culture by supplying air with CO2. The result showed that after 60 days of RZ CO2 treatment, the root mineral uptake and transport and plant growth decreased significantly. During 40 to 60 days of RZ CO2 treatment, the plant height of all the treatments were significantly lower than that of ambient RZ CO2. The stern diameter of ambient RZ CO2 was up to 3.23 cm at the end of 60 days treatment, 1.09-, 1.10-, 1.l4-folds respectively of RZ CO2 2500, 5000, 10000 µL L-l air. From 40 to 60 days, the root length of ambient RZ CO2 was significantly longer than that of three RZ CO2 treatments. The results indicated that ambient RZ CO2 maximized the capability of nutrient uptake compared to RZ CO2 treatments. At the end of experiment, root H+-ATPase was significantly reduced for elevated RZ CO2 treatment. It was predicted that prolonged RZ CO2 enrichment could reduce plant growth and root nutrient uptake and transport. It may be main reason for aeroponic plant growing stronger than soil cultivation