Nitrogen fertigation of greenhouse-grown strawberries

Abstract

Two greenhouse experiments were conducted with strawberries (Fragaria ananassa) grown in plastic pots filled with 12 kg of soil, and irrigated by drip to evaluate the effect of 3 N levels and 3 N sources. The N levels were 3.6, 7.2 or 10.8 mmol Nl−1 and the N sources were urea, ammonium nitrate and potassium nitrate for supplying NH4/NO3 in mmol Nl−1 ratios of 7/0, 3.5/3.5 or 0/7, respectively. Both experiments were uniformly supplied with micronutrients and 1.7 and 5.0 mmoll−1 of P and K, respectively. The fertilizers were supplied through the irrigation stream with every irrigation. The highest yield was obtained with the 7.2 mmol Nl−1 due to increase in both weight and number of fruits per plant. With this N concentration soil ECe and NO3-N concentration were kept at low levels. Total N and NO3-N in laminae and petioles increased with increasing N level. With the N sources the highest yield was obtained with urea due to better fruit setting. The N source had no effect on soil salinity and residual soil NO3-N; residual NH4-N in the soils receiving urea and ammonium nitrate were at low levels.