Effect of Nitrogen Nutritional Statuses and Waterlogging Conditions on Growth Parameters, Nitrogen Use Efficiency and Chlorophyll Fluorescence in Tamarillo Seedlings
Climate change has altered rainfall patterns causing waterlogging periods that often negatively affect the performance of horticultural crops in the Andean region in Colombia. An experiment was carried out under greenhouse conditions using three-month-old tamarillo (Solanum betaceum Cav.) seedlings, which were grown under two levels of nitrogen (N) (10 and 150 mg Nâˆ™L H2O). At 28 days after transplanting (DAT), waterlogging treatments were established when well-nourished plants (150 mg N L-1 H2O) significantly showed a higher shoot length than poor-nourished plants (10 mg N L-1 H2O) (~20 cm vs. ~10 cm, respectively). Three different periods of waterlogging were performed between 35 and 37, 51 and 55, and 64 and 70 DAT by covering the holes in the plastic pots to ensure a constant water depth. Results showed that well-nourished plants without waterlogging treatments through the experimentâ€™s stress showed a greater shoot length (30 cm), total plant dry weight (7.95 g), Fv/Fm ratio (0.62) and leaf chlorophyll content (37.51 SPAD units) than poor-nourished plants without stress condition (15 cm, 5.57 g, 0.5 and 12.69 SPAD units, respectively) at the end of the experiment. Overall, waterlogging reduced leaf area and nitrogen use efficiency (about 75% and 50%, respectively) in both N levels. However, periods of waterlogging enhanced dry matter partitioning to stems (around 30-35%) in both N levels. This study showed that tamarillo plants are susceptible to landscaping situations where periods of waterlogging can be expected regardless of their N nutritional status.
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