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

Abstract

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.