Impact of NaCl-salinity on growth, yield, quality attributes and postharvest storage of hydroponically grown tomatoes in three different nitrate to ammonium levels [Thesis (M.Sc.)]
2015
Pitsikoulaki Georgia E.
The effects of NaCl-salinity in conjunction with three different ammonium to nitrate ratios (Nr) on plant growth, nutritional status, yield, fruit quality and post-harvest storage were examined. The electrical conductivity (E.C.) was increased by adding NaCl into the nutrient solution and three different Nr ratios were applied, Nr=0.05, Nr=0.10 and Nr=0.15, while the other macronutrient and micronutrient concentrations were constant in all treatments. The E.C. of the nutrient solution supplied to the plants was 2.2 mS/cm at the low salinity treatments and 7.5 mS/cm at the high salinity treatments. Increased salinity affected plant growth factors and fruit yield, despite the Nr. An increased Nr reduced the pH value of the nutrient solution, while the fruits of the plants cultivated under high salinity obtained reduced Ca, K, Mg, P and N content. Reduced Ca content can lead to blossom rot end disorder and this was evidenced on tomato cultivation under high salinity. However, in the present study this disorder appeared at the very late stages which did not affect the marketability of the fruits. On the other hand, both salinity and Nr=0.15, increased fruit firmness at harvest or following storage, while citric acid, total soluble solids and vitamin C content were increased by salinity too. Total phenols were increased by salinity at harvest date and lycopene and ß-carotene content were increased by salinity at harvest date and/or following storage at 12oC or 25oC.
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