Effects of Gypsum and Cocopeat on Some Physiological Characteristics and Growth of Spinach in Hydroponics Culture under Saline and Non-saline Conditions

This research was carried out to investigate effects of gypsum, cocopeat, and NaCl salinity on some physiological and growth characteristics of spinach cv. Virofly. The experiment was conducted in a factorial combination based on a CRD with three replications in greenhouse conditions. The experimental factors were: gypsum at four levels (0, 3, 9, and 27%), NaCl salinity at two levels (0 and 110 mM), and cocopeat at two levels (0 and 15%). The effect of gypsum on studied characteristics depended on the level of gypsum, cocopeat, and salinity. The use of 3% gypsum had no significant effect on root and shoot dry matters, plant height, and leaves number. Unexpectedly, use of 9 and 27% gypsum significantly reduced these characteristics under saline and non-saline conditions. The effect of salinity on studied characteristics was different regardless of presence or absence of cocopeat. The effect of cocopeat was significant on all studied characteristics, but its effect depended on the level of salinity and gypsum. The sensitivity of spinach plant root to NaCl salinity stress was greater than shoot. The use of cocopeat in perlite medium is not recommended for hydroponic cultivation of spinach. In treatments with cocopeat, high levels of gypsum decreased root and shoot dry matters, plant height, leaves number, leaf chlorophyll index, and leaf chlorophyll fluorescence. It is suggested to conduct more investigations with lower levels of gypsum, lower concentrations of calcium and sulfate in the nutrient solution, and application of other types of cocopeats under saline and non-saline conditions.