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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]

The mechanism of osmoprotectant action on photosynthesis process is still not well known, especially under salt stress. The objective of this study was to evaluate and explain the effect of glycine betaine (GB) on photosynthetic efficiency and other physiological parameters of cucumber plants grown under salinity stress. Our results indicated that salinity decreased chlorophyll and carotenoids content, Ca2+ and K+ concentrations, and quantum yield parameters, such as probability that a trapped exciton moves an electron in to the electron transport chain beyond QA, quantum yield of electron transport from QA to QB in PSII, quantum yield of reduction of end electron acceptors in PSI, performance index for the photochemical activity, total performance index for the photochemical activity, trapping per reaction centers, and other parameters related to primary photochemical reactions of PSII. However, the exogenously applied GB increased most of tested parameters including the total soluble carbohydrate, proline and GB content, and Ca2+ and K+ concentrations, under salt stress. We suggest that GB can play an essential role as regulator to improve photosynthetic efficiency and thus yield of cucumber plants under salt stress conditions. At the level of photosynthesis process, the application of exogenous GB indirectly enhanced the performance of the photosynthetic machinery of cucumber plant due to the reduction of the dissipated light energy, as heat, and the increase of primary reactions of photosynthesis efficiency. [ABSTRACT FROM AUTHOR]

The effectiveness of poultry manure application time was studied on pistachios (Pistacia vera L.) trees. The experiment consisted of seven different poultry manure application time, including poultry manure application as one time in 1) last week of October 2) last week of December 3) last week of January 4) mid-March and dividing into two parts and use in fall or in winter, dividing into four parts and use in dormant seasons (fall and winter). Based on the results, there were significant differences among treatments. The highest number of fruit per cluster (27.4) was found in poultry manure applied in last week of October. The highest nut splitting percent (84.3%) and the lowest nut blanking percent (8.6%) were obtained in poultry manure applied by dividing into four parts. Half kernel nuts followed a similar trend with blanking percent. Weight of 1000 nuts increased and responded positively and number of pistachios nut per ounce decreased by manure application when divided into two parts and used in the winter. Application of poultry manure in the mid-March enhanced the nut protein (19.63%). [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]

This study was conducted to determine the effects of arbuscular mycorrhizal fungi (Glomus mosseae and Glomus intraradices) symbiosis on mineral uptake of two pistachio cultivars (Pistacia vera cv. Qazvini and Pistacia vera cv. Badami-Riz -Zarand) grown in the greenhouse under different drought stress levels. Drought stress (DS) reduced the mycorrhizal colonization in both cultivars as well as nutrient uptake. The mycorrhizal plants had higher P, K, Zn and Mn concentrations than non -mycorrhizal plants regardless of soil moisture conditions while Cu and Fe concentrations were unchanged. Distribution of elements was affected by AMF treatments where all except P were accumulated more in leaves than in roots. Contrastingly, under drought conditions, the absorbed elements tended to remain in root tissue. In the case of P and Mn uptake, Qazvini was superior in comparison with Badami. In conclusion, it is suggested that AMF inoculation improves drought tolerance of pistachio cultivars at least in part through the enhanced uptake of slowly diffusing mineral ions such as PO42- and Zn2+. Moreover, arbuscular mycorrhizal (AM) colonization provides better osmotic adjustment which can be correlated with K+ accumulation in top portions of inoculated plants. Results of this study also emphasized that 'Qazvini' cultivar may be more tolerant to drought than 'Badami'. [ABSTRACT FROM AUTHOR]