Abstract
Greenhouse-grown strawberries (Fragaria Xananassa Duch.) are a new crop for the United States and Mexico. The present study was conducted to determine the nitrogen (N) requirements for strawberries produced in soilless media in a passively ventilated greenhouse. Two soilless media: 1) pine bark and 2) coconut coir, and four N levels in the nutrient solution: 40, 80, 120, and 160 mg L-1 N, were evaluated in a factorial designed experiment. Plants grown at a density of 21 plants/m2 received a complete nutrient solution at every irrigation event, the only variation being the level of N in each treatment. Increasing N level in the nutrient solution significantly increased the number of runners. Neither early nor total marketable yields were significantly affected by N level or media. Increasing N level in the nutrient solution significantly decreased fruit-soluble solids on two of the three sampling dates. Higher values of soluble solids occurred during the cooler months of the season. The soluble solids content in the fruit was reduced as the temperature increased. Thus, N levels as low as 40 to 80 mg L-1 N in a constant fertigation system can be used to produce strawberries in either coconut coir or pine bark media in a greenhouse environment.
