Salt Stress Effects on Seedling Growth Rate and Sodium, Potassium, and Calcium Ions Content of Wheat (Triticum aestivum L.) Cultivars

Effects of salt stress on growth rate and ion content of 17 bread wheat (Triticum aestivum L.) cultivars grown in a hydroculture media under normal (0 ds/m) and salt stress (8 ds/m) conditions were examined during a period of 14 days in an experiment conducted at the greenhouse of Shahid Bahonar University of Kerman. Cultivars of Shiraz and Gascogen showed the highest and lowest root growth rates under normal while Azar2 and Kavir showed the highest and lowest values under salt stress condition. Cultivars Shiraz and Azar2 showed the highest and Kavir and Hirmand the lowest leaf growth rates under normal condition while under salt stress condition Mahdavi and Saison showed the highest and lowest values, respectively. Generally, growth rates were reduced under salt stress compared to the control condition. In another experiment, leaf samples were taken from 10 selected cultivars grown under the same stress condition and in all RWC and Na, K and Ca content were measured. Seedlings under salt stress condition had 34% more Na, 25% more Ca and 48% more K/Na ratio while they had 29% less RWC compared to the control condition. There were no significant correlations between growth rates and ion content. Meanwhile, cultivars with higher growth rates under control condition showed higher growth rates under stress condition. It was suggested that cultivars with higher growth rates under salt stress condition may be able to escape from the detrimental effects of saline top soils and produce more vigorous seedlings which may help them to have better yield performance under salt stress condition. This needs to be investigated in the future studies

Investigation of Some Physiological Characteristics and Grain Yield of Corn) Zea mays L.) Hybrids under Salinity Stress

A great part of lands under corn cultivation are affected by different levels of salt stress. This study was conducted in order to determine the effect of different levels of salt stress on yield and some physiological characteristics of corn plants. Two experiments were carried out in greenhouse (a factorial based on randomized complete blocks design with 3 replications), and field (a split plot based on randomized complete blocks design with 3 replications) at College of Agriculture, Shahid Bahonar University, Kerman, Iran. Treatments included 4 levels of irrigation water salinity (2, 4, 6 and 8 dS/m) and seven corn hybrids (SC-700, SC-500, SC-404, SC-704, SC-647, SC-301 and Maxima). During the growing period, leaf samples were taken from greenhouse-grown plants and their physiological characteristics such as chlorophyll fluorescence and ion leakage were measured. Grain yield was determined in the field plots. Results revealed that salt stress decreases chlorophyll index and photochemical efficiency of PSII of leaf tissues due to increasing original fluorescence (FO) and decreasing maximum fluorescence (Fm). Meanwhile, increasing the salt stress increased ion leakage. Results also showed that high salinity decreased the grain yield. The highest grain yield was obtained in plots with the lowest salinity level. Correlation coefficients showed that Fo and Fm parameters don't have significant correlation with salinity. While, Fv/Fm index had a positive relationship with salinity tolerance. The highest chlorophyll index, photochemical efficiency of PSII, membrane stability and grain yield was obtained for SC-704 hybrid. Therefore, it was the most tolerant hybrid and was recommended as a resistant cultivar against salinity stress

Water Stress Effect on Anatomical and Physiological Characteristics of Two Wheat (Triticum aestivum L.) Cultivars

The aim of this study was to determine the effects of water stress on the anatomy of xylem and phloem vessels, mesophyll and epidermal cells, relative water content and ion transfer rate of two wheat cultivars including Azar2 as drought tolerant and Shole as drought susceptible cultivars at four leaf stages. Seeds were sown in pots under normal (soil water content at 100% of FC) and the water stress (60% of FC) conditions in a factorial experiment based on CRBD design at the Experimental Farm of Kerman University in 2011. Four samples were taken from different positions of the fully expanded 4th leaf. Results showed that in both cultivars water stress decreased the xylem and phloem vessel diameter and the area of the mesophyll and upper epidermal cells at all positions. However, no significant effect of water stress by cultivar interaction was found on lower surface epidermal cell size and RWC. Water stress effect on the amount of ion leakage up to 30 min after soaking the leaf samples in distilled water was highly significant while it was not significant at 60 min after soaking. The effect of water stress on ion leakage was higher in Shole compared to Azar 2. Anatomical changes of the wheat leaf under water stress condition can be considered as adaptation responses. The effects of such anatomical changes on the final yield need to be investigated in future studies

Effect of Irrigation with Wastewater on Yield and Quality of Okra (Hibiscus esculentus L.)

In order to evaluate the effect of wastewater on yield and quality of okra plant, an experiment was carried out in wastewater filtration station of Kerman University during 2008 using a completely randomized block design with three replications. Treatments included different concentrations of wastewater (0, 25, 50, 75 and 100%) applied with drip method. The results showed that the use of wastewater as irrigation water increased total measured parameters. Furthermore, treatment of 100% wastewater significantly increased the chlorophyll content (32%), plant height (33%), stem diameter (25%), fruit fresh weight (36%) and fruit dry weight (12%), fruit number (31%), root dry weight (16%) and biomass of okra (37%). In contrast, wastewater increased concentration of the elements nitrogen, phosphorus, iron and sodium in okra plants. Different concentrations of wastewater had no significant effect on accumulation of copper and zinc in okra. In summary, it could be concluded that wastewater can be used for irrigation of okra without the problem of excessive accumulation of elements in this plant