Abstract

The water management in the tomato crop has a direct effect on the development and yield, however the gas exchange rates of the plant can be influenced by the management and evaluation period. The study aimed to analyze gas exchange in tomato, in full production, in plants cultivated under different water management. The experiment was conducted in a completely randomized design with two water conditions during cultivation (with deficit and without deficit). The management of the water deficit adopted using different depths of water replacement, under water deficit the replacement of 60% of the crop evapotranspiration (ETc) was carried out while in the condition without deficit there was replacement of 100% of the ETc. The determination of gas exchanges, in a period with full production, was performed at 70 and 71 days after transplanting, determining photosynthesis (A), stomatal conductance (Gs), internal CO₂ (Ci) and transpiration (E). From the A/E ratio, the intrinsic water use efficiency (iWUE) was calculated. The data were submitted to analysis of variances and the means compared by the Tukey test with 5% of significance. There is significant variation in gas exchange rates depending on the water management adopted and evaluation period. Water deficit has a cumulative effect on plants. Tomato plants cultivated with water deficit (60% of ETc) have lower rates of gas exchange, with no full recovery of rates even after irrigation. Tomato plants grown without water deficit (100% of ETc) show adaptation and compensation in gas exchange due to soil drying.

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