A factorial experiment (2 transplanting dates X 3 foliar feeding levels) in split plot design was conducted at Gemmeiza Agric. Res. Station, Gharbeya Governorate, Egypt during 2016 and 2017 growing summer seasons aiming to evaluate effects of transplanting date and foliar feeding with NPK and their interactions on growth, productivity and fruit quality of eggplant (Solanum melongena L,) c.v. Black Beauty. The two tested transplanting dates were summer transplanting on April and late summer on June. While, the three examined foliar feeding levels were spraying with tap water as control, spraying with Potassium-F fertilizer at rate of 3 ml/L or with Raizante fertilizer at rate of 2 ml/L. Foliar spray was done three times throughout growing season.
Summer transplanting (April) significantly increased plant height, branches and leaves numbers/ plant and leaf area. Also, leaf percentages of N, P and K as well as total chlorophyll content were increased in April transplanting. Finally, total fruit yield (Ton/ fed) and its quality, expressed as more contents of total soluble solids (%) and total sugars (g/ 100 g D.W.) and less contents of total phenols (mg/ g D.W.) and acidity (%) in fruit tissues, were significantly increased in April transplanting comparing to late summer transplanting (June).
Foliar spraying with Potassium-F at 3 ml/L or Raizante at 2 ml/L significantly increased all the above mentioned growth traits and leaf chemical constituents and in turn resulted significant increases in total fruit yield/ fed comparing to unfertilized control plants. Also, spraying Potassium–F or Raizante significantly reduced fruit firmness (kg/ cm2) and fruit contents of total phenols and titratable acidity, at the same time significantly increased total soluble solids, total sugars and K (%) in fruit tissues. Raizante spray was more effective than Potassium-F in enhancing plant growth and fruit yield and its quality.
Conclusively: when transplanting date interacted with foliar feeding, different significant responses were found. In general, interaction treatment of summer transplanting (April transplanting date) X foliar feeding with Raizante at 2 ml/L significantly increased plant growth traits and leaf contents of N, P, K and chlorophylls. Such interaction treatment resulted in the highest total fruit yield/ fed with the highest quality (high total soluble solids and total sugars and less total phenols and acidity in fruits) comparing all other interaction treatments.