The Influence of Nitrogen Nutritional Status on the Physiological Response of Cyphomandra betaceum Seedlings to Flood Conditions

Nitrogen plays an important role in plant nutrition and its positive effect on plant response under flooding conditions has been reported in several crops. One-month-old Cyphomandra betaceum seedlings were transplanted into 1-L plastic pots containing peat as substrate and fertigated with a complete nutrient solution containing two N concentrations (10 and 150 ppm). When differences appeared on shoot length due to the N nutritional status, a group of plants were subjected to flooding stress during three periods (2, 4, and 6 days). Seedlings recovered by 10 days between waterlogging period stress. Another group of plants (control plants) did not receive any flooding stress treatment during the experiment. Results showed that plants grown under high N level (150 ppm) had a higher total plant dry weight (TPDW), shoot length and SPAD readings. When plants were under flooding stress, no differences on TPDW in both N status were observed. However, stomatal conductance (g_s) was conditioned by N level. Plants fertigated with low N showed a lower g_s  compared to plants with high N. These results suggest that good nitrogen nutrition helps C. betacea plants handle temporary flooding conditions.