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In order to compare the effect of three nutrient solution replacement methods in an NFT system and pruning on hot pepper, a factorial experiment was conducted. Factors included nutrient solution replacement method (complete nutrient replacement, partial nutrient replacement according to EC, and partial nutrient replacement according to plant requirements) and pruning (pruning and non-pruning). Results showed that the highest vegetative growth was recorded in plants fed by complete replacement of nutrient solution, while plant fed based on EC showed the lowest vegetative growth and nutrients concentration. Leaf Chlorophyll a (Chl a) and Total Chlorophyll (TChl) decreased in plants fed according to EC control and plant requirements compared to complete replacement of nutrient solution. All these traits were higher in non-pruned plants than in pruned plants. Fruit yield decreased in plants fed based on nutrient solution EC and plant requirements, and pruning treatment decreased these traits, but the highest single fruit weight belonged to pruned plants fed based on plant requirements. The highest fruit carotenoid content, Total Soluble Solids (TSS), and vitamin C were recorded in plants fed according to nutrient solution EC, and these traits were higher in the pruned plants compared to non-pruned ones. The results also showed that pruning caused a reduction in plant growth and fruit number, therefore, it is not recommended for hot pepper cv. Sentela. [ABSTRACT FROM AUTHOR]

A greenhouse study was carried out to determine the effect of nitrogen forms and different O2 levels on growth and mineral nutrient concentrations of eggplant. The experimental design was a completely randomized factorial experiment with two factors, namely: (i) Two nitrogen forms (Ca(NO3)2 and (NH4)2SO4) and (ii) Three O2 levels of the nutrient solutions (1'0.3, 2'0.3, 3'0.3, and 4'0.3 mg L-1 O2). The results showed that ammonium application reduced all measured parameters of vegetative growth, whereas high oxygen levels increased the vegetative growth. Comparing with nitrate-N, ammonium application increased the concentrations of NPK and Zn in leaves and Zn and Cu in roots, while it decreased the concentration of Mg, Ca, Cu, Mn, and Na in leaves and Ca, Mg, Mn, and Na in roots. High levels of O2 increased N, Mg, Ca, Cu, and Mn content of leaves, as well as Mn and Na content in roots, while it decreased the concentration of K in leaves and P and Zn in roots. According to the results, the increase in O2 amount of the nutrient solutions partly alleviated ammonium toxicity in eggplant. Therefore, in floating hydroponic cultures, O2 level and its distribution should be controlled and must not be lower than 4 mg L-1. [ABSTRACT FROM AUTHOR]

In order to determine the best growing media for Gerbera jamesonii under alkaline conditions, a factorial experiment was conducted with two factors, namely: (i) Growing medium, and (ii) Concentrations of bicarbonate (NaHCO3) in nutrient solution. Results showed that increasing the concentration of NaHCO3 from 0 to 40 mM in nutrient solution significantly decreased plant growth, maximal quantum yield of PSII photochemistry (Fv/Fm), photosynthesis Performance Index (PI), Glutamine Synthetase (GS) activity, Leaf Relative Water Content (LRWC), Chlorophylls (Chl a, b and tota Chl) and carotenoids. Under alkalinity stress, reduction in vegetative growth, Fv/Fm, PI, LRWC, GS activity and photosynthesis pigments content was the lowest in Coconut Fiber (CF) substrate compared to the other substrates. Furthermore, plants grown in CF substrate had higher soluble sugars and proline content than those in other substrates. On the other hand, plants grown on Perlite (P) substrate had the highest reduction in growth and physiological characteristic in alkaline conditions. The alleviation of alkalinityinduced growth inhibition of plants by CF substrate may be related to improvement of photosynthesis, enhancement of GS enzyme activity and osmotic regulation. It is concluded that the use of CF substrate could provide a useful tool to improve alkalinity tolerance of gerbera plants under NaHCO3 stress. [ABSTRACT FROM AUTHOR]