نشریه خشک بوم
سال پنجم شماره 1 (تابستان و پاییز 1394)

Terminal drought stress reduces wheat grain yield in many parts of Iran. Selection of tolerant genotypes can eliminate the damage of this stress. Genotypes WS-82-9, Sirvan, WS-86-14, Pishtaz, Parsi, Back cross roshan, Arg, Roshan, Pishgam, Alvand and Mahdavi were evaluated under normal irrigation and terminal drought at Isfahan during 2011-2013. Traits grain yield, biological yield, harvest index and thousand grain weight were studied. Terminal drought stress significantly reduced all traits and stress intensity for the traits was 0.501, 0.259, 0.325 and 0.424 respectively. Genotypes had significant difference for all studied traits. Eleven susceptibility and tolerance indices and also the average rank of each genotype were calculated. Based on the grain yield, varieties of Phishgam, Sirvan, Alvand and WS-86-14 were four tolerant genotypes respectively, and Roshan was the most susceptible genotype. There were significant positive correlations between MP, GMP, STI, HM and MSTI(k1) with grain yield in both stress and non-stress conditions. There was significant positive correlations between grain yield with harvest index, showing the importance of harvest index. Based on harvest index, WS-86-14 and Roshan was the most tolerant and most succeptible genotype, respectively. Varieties of Pishgam and Sirvan can be recommended for cultivation in areas with probability of terminal drought strees.

Regarding the importance of greenhouse cucumber and tomato in agricultural economic conditions in Yazd province, this study examines marketing problems of greenhouse cucumber and tomato. Required data were obtained through questionnaire and interview with 67 producers, 8 wholesalers and 13 retailers, during the period of 2010-2011. Systematic method is used for data collection. In this study, marketing channel was recognized wholesaling and retail selling margin, computed by Mark-up model, and marketing efficiency was computed by Shefferd & Footrel model. Result showed prices that flactuations in the harvesting season and unclearitiy of market were the most market problems for producers. Greenhouse cucumber and tomato have simple channel. Net profit from marketing operations of greenhouse cucumber and tomato producer's was 450 and 850 Rials. Wholesaler margin, retailer margin and total marketing margin for greenhouse cucumber is 2000, 4000, 6000 Rials and for greenhouse tomato is 2500, 4500, 7000 Rials, respectively. Evaluation of marketing margin indicates that the marketing margin was high especially in retailer selling margin and marketing margin of tomato. Share of producer, wholesaler and retailer from consumer price for greenhouse cucumber was 55.5, 14.85 and 29.65% respectively, and for greenhouse tomato was 61.1, 13.9 and 25% respectively. Maximum of marketing efficiency was in channel greenhouser, wholesaler, fruit and vegetable center in other provinces, retailer and consumer. In this channel, thechnical efficiency for cucumber and tomato was 90.7% and 91%, respectively. Price efficiency for cucumber and tomato were 69.5% and 79% respectively, and marketing efficiency for cucumber and tomato were 60% and 70% respectively.

Spatial vegetation pattern refers to establishment and type of plants arrangement in the nature, at any scale, is defined as spatial pattern. Vegetation pattern formation is a manner that vegetation resistantant mechanism against water shortages. Vegetation pattern formation is a mechanism by vegetation which the resistant against water shortages. One of the interesting varieties of vegetation patterns formed in Yazd - ardakan pattern is polygonal vegetation pattern. This study is the first study to investigate the hydrogeomorphological causes of the development of this rare vegetation patterns in fissures in Yazd - ardakan plain. This paper presents a conceptual model for the development of alternative vegetation. The physicochemical parameters of the investigated soil samples (the alternative, and control samples), salt, sand, silt and moisture were significant. The results showed that appropriate arrange for the Haloxylon Spp. only determining factor for the growth of vegetation, not to create a vegetation cover of the etiologic factors pattern (table downfall) is also a may be required.

In order to evaluate of new sugar beet hybrids for salt tolerance, 20 single cross hybrids produced by crosses between 5 diploid pollinators as male and 4 cytoplasmic male sterile as females ( caused by factorial design) along with parents were investigated in Rudasht salinity research station in 2012 and 2013. In each year, genotypes were studied in two experiments under saline (EC for water and soil about 12 and 8 dS/m respectively) and non-saline field conditions (EC for water and soil about 4 dS/m) using a randomized complete block design with two and three replications in first and second year, respectively. Four salt tolerance indices including salt tolerance index (STI), field emergency potential (FEP), beet tolerance index (BTI) and drought tolerance index (DTI) were calculated based on sugar yield in stress and non-stress condition. Regression analysis of sugar yield in two conditions with these indices showed that STI and BTI had significantly positive relationship coefficient with sugar yield under both stress and non-stress conditions suggesting that these indices are more efficient for determining salt tolerant genotypes. In based on the results of cluster analysis, hybrids 2×3, 3×1, 5×3 and 5×4 were recognized as salt tolerant hybrids with high yield and hybrids 1×1, 2×4, 4×3, 3×2 and 5×2 were introduced as susceptible hybrids with low yield for salinity condition.

Water and wind erosion are the main processes most often considered in erosion and sediment budget studies. While soil loss due to crop harvesting (SLCH) is another type of land degradation which is usually not considered in these studies. During root crops harvesting, a significant amount of soil adhering to the roots is exported from the fields. Despite these crops are widely harvested in the world, a few studies have been done on SLCH and no attempt has been presented to investigate SLCH in Iran. Therefore, this study aimed to investigate the values of SLCH for potatoes, garlic, sugar beet, radish and beet root in 47 selected fields located in Khuzestan province. Crops together with the adhering soils were collected from three 2*2 plots in each field. Soil tares were separated from the roots and dried at 105OC. Result showed SLCH values for potatoes, garlic, sugar beet, radish and beet root were 6273.74, 2525.32, 2264.88, 4101.94 and 6952.50 Kg ha-1 respectively and there were significant differences in SLCH between crops types. The average of SLCH for all crops was 4.31 Mg ha-1 which results in a denudation rate of 0.3 mm yr-1 and is of the order of magnitude as soil losses caused by water erosion in watershed catchments of Iran. Given the harvested areas, total SLCH was estimated for Khuzestan province and whole country at 26800.10 and 731807.84 ton, respectively. In general, because of the importance of SLCH, farmers should be educated to reduce SLCH and it should be considered when calculating soil denudation rates and sediment budgets.

Jujube (Ziziphus jujube) is cultivated widly in Southern Khorasan province. The tree is adapted to arid and warm regions. In this study, urea at 5 concentrations (0%, 1%, 2%, 3% and 4%), boric acid, iron sulfate and zinc sulfate, each with five concentrations (0, 1500,2500,3500 and 4500 mg/lit) alone and in combination with each other were sprayed at three different times before flowering, before flowering 30 days after petal abscission and 30 days after petal abscission on jujube. This experiment performed as factorial in the form of randomized complete blocks design with three replications. The results showed that the spray before flowering and before flowering 30 days after petal abscission caused significant increase in fruit size (length and diameter), fruit weight, yield and TSS (Total Soluble Solids) than spraying in 30 days after petals abscission. Urea, boric acid and Urea boric acid iron sulfate zinc sulfate significantly increased fruit size (length and diameter), fruit weight, yield and TSS in comparison with Iron sulfate and zinc sulfate. All concentrations compared to control significantly increased fruit size (length and diameter), fruit weight, yield and TSS. Foliar spraying fertilizers had not significant effect on the other chemical properties of fruit (Vitamin C, pH, Acidity and amount of carotenoids).

The aim of the study was to investigation effect of irrigation with two types of CaCl2 and NaCl salinities and Zinc application on Cadmium concentration and growth of kohlrabi plant (Brassica olerace var. gongylodes) in Cadmium-Contaminated Soil. This experiment was completely random design (factorial) with three replicates. Treatments were three levels of Zn (0, 50 and 100 mg.kg-1) using Zinc sulfate salt, and three salinity levels (0, 2.5 and 5 dSm-1) by using two types of sodium chloride and calcium chloride salts in irrigation water. For polluted soil, 15 mg.kg-1 of Cadmium by Cadmium nitrate salt was added to all soils before treating soil with different treatments. Result showed that increasing water salinity led to raising Cadmium concentration in above ground of kohlrabi and decreasing kohlrabi growth. CaCl2 salinity compare to NaCl salinity showed less Zinc concentration at root Kohlrabi plant. Zinc treatment had any effect on plant growth properties.

Nitrate pollution of groundwater resources has been increasingly becoming one of the main concerns in Iran. The main objectives for the present research are as following: to evaluation of groundwater nitrate pollution status and evaluate the effect of land use on groundwater nitrate pollution. To fulfill these goals, data for groundwater nitrate concentration were collected (from 50 point) and overlaid with landuse map. The result showed that nitrate concentration of groundwater exceeded WHO (World Health Organization) threshold. In addition, nitrate-polluted wells spatial position was undertaken so that all of wells were located at irrigated farming land use. Investigation of annual fertilizer application indicated that level of nitrate entered to irrigated lands strongly was correlated into groundwater nitrate concentration. Hence it was found that N-fertilizers abuse was the main factor affecting groundwater nitrate pollutions. In order to control the nitrate pollution of groundwater, comprehensive management of N-fertilizer and irrigation is recommended.

For many years, Haloxylon species is used in order to stabilizing the mobile sand in Iran. This species is resistant to the soil with air and low humidity along with high temperature and high salinity. One of the negative consequences of this species in areas under cultivation is salt-sodium to the soil. Due to the presence of revived sands by yellow species of Haloxylon during the time sequence in the desert area of Taybad the changes of the salt-sodium level of soil surface were studied in this area. For this purpose 5 different sites according to the Haloxylon plantation age (aged11, 19, 28, 41) and a control site (no planting Haloxylon) were selected. The results show the maximum salinity was in site aged 41(0/694 ds/m) and the lowest salinity was in the control site (0/34 ds/m). During the time of planting Haloxylon the sodium absorption ratio has increased from 3/49 milliequivalents per liter in the control site to 12/5 milliequivalentsper liter in the site aged 41. Parallel to this, the exchangeable sodium percentage has increased from 3/92 in the control site to 17/3 in the site aged 41. According to the results of this survey, planting yellow Haloxylon (Haloxylon persicum) species lead to the sodium soil in areas where Haloxylon has been planted.