مجله تنشهای محیطی در علوم زراعی
سال دوم شماره 2 (نیمه دوم 1388)

To study the genetics of drought tolerance in bread wheat, the bi-plot of diallel data was used. Parents (Alvand, Bezostaya, Navid, Roushan, Gaspard, Sardary and Shahriar) and their crosses (without reciprocal crosses) were studied in 2007 using a Randomized Complete Block (RCB) design with three replications under normal and stress conditions. Analysis of variances indicated significant differences among genotypes for all traits. The GGE bi-plot graphical as well as AMMI methods were used for evaluation of cultivar potential. Investigated traits were 1000 kernel weight, kernel weight per plant, spike weight, spike length, plant height, awn length, peduncle length and kernel number per spike. For 1000 kernel weight, Roushan cultivar was the best general combinator. Moreover, Navid and Shahriar cultivars were the best specific combinatory, so that Navid × Shahriar cross was the best hybrid and for all other traits, the Alvand × Sardary was the best hybrid. These results were confirmed by AMMI method. Alvand cultivar was the best tester for 1000 kernel weight. For kernel weight per plant, Roushan cultivar, for spike weight, spike length, plant height and kernel number per plant Gaspard cultivar and for awn length and peduncle length Sardary and Alvands cultivars had the highest general combining ability.

In order to study the effect of arbuscular mycorrhizal fungi (AMF) under drought stress on some physiological characteristics (leaf temperature, chlorophyll index, compatible solute accumulation) of basil (Osmium basilicum L.), a pot experiment was conducted as a factorial trial based on randomized complete block design with four replications. Treatments included application of two mycorrhizal fungi (Glomus mosseae and Glomus intraradices) plus a control check (non-application) and three irrigation regimes (4, 8 and 12 days intervals). Results showed that drought stress had a significant effect on all evaluated parameters, so that reducing soil water content decreased chlorophyll index while increased accumulation of proline and total soluble sugars in leaves as well as leaf temperature. Moreover mycorrhiza colonization had significant effects on all evaluated parameters except proline. The highest and the lowest amount of leaf chlorophyll index and total soluble sugars in leaves were observed in inoculated plants with G. mosseae and control (non-application of mycorrhizal) treatments, respectively.

To study the effect of salinity on seed yield and yield components, morphological characteristics and leaf chlorophyll content of sesame, a factorial experiment based on completely randomized design with three replications was conducted at research greenhouse of the Faculty of Agriculture, Ferdowsi University of Mashhad. Treatments comprised five salinity levels (2.4, 4.4, 6.4, 8.4 and 10.4 dSm-1) and four sesame genotypes, including Giroft, Dezful, Moghan and Borazjan. Results showed that salinity had a significant effect on morphological characteristics and leaf chlorophyll content. The morphological characteristics also showed significant differences between sesame genotypes. The effect of salinity stress on plant height, total dry weight, root dry weight, root dry weight to shoot dry weight ratio and yield components was significant and decreased with increasing salinity levels. The lowest seed yield per plant was observed at salinity level of 10.4 dSm-1. ¬¬Chlorophyll content was increased with increasing salinity levels up to 6.4 dSm-1 and decreased at the highest salinity level. Nevertheless, the leaf chlorophyll content and its corresponding chlorophyll meter number were reduced by increasing plant age. Results showed that at high salt concentrations, root/shoot dry weight ratio of Moghan was higher than other genotypes. The rate of increase in chlorophyll meter number of Moghan was much higher than in other genotypes at high salinity levels and this genotype showed the lowest variation in seed weight per plant and yield components by increasing salinity. So, It seems that amongst studied genotypes, Moghan can be evaluated as a resistant one in the field experiments.

In a field experiment, the growth responses of 7 winter rapeseed varieties to three levels of salinity induced by 1.9, 7 and 12 dS m-1 were investigated using a split plot experiment based on a randomized complete block design with three replications. Salinity was the main plot and varieties were sub plots. The tolerant cultivar(s) was introduced after data analysis based on seed yield and yield components measurement, studying the nutrient uptake pattern and the selective choosing ability of potassium against sodium (K/Na). The results of data analysis indicated that the effect of salt stress on all studied traits were significant (p<0.01) in all varieties, but the interaction between salinity and variety was just significant in relative yield (p<0.05). Increasing salinity reduced total dry matter, seed yield, K uptake, K/Na ratio and plant height, while it increased Na concentration. The varieties were accordingly ranked into different groups. The varieties SLM046 and Modena were classified as saline tolerant group, and okapi and Reg&cob as saline sensitive group, and Talaye, Licord and opera as moderately tolerant.

Seed position on mother plant can affect seed size, color and its germination in several plant species. In order to study the effect of seed position in spike on salinity resistance of barley, a factorial experiment based on RCBD was conducted with two factors including seed position (top, middle and bottom of the spike) and salinity (0, 10, 20, 40, 80, 160, 320 and 640 mM NaCl). Results showed that the interaction between seed position and salinity effects on germination percentage was significant and seeds of the middle of the spike, which were larger than others, had the highest germination at all salinity levels. The estimations of the three-parameter logistic model also showed that the middle seeds had greater salinity tolerance compared to the seeds from the top and bottom of the spike. Increasing salinity significantly delayed seed germination and reduced root and shoot growth, while seed position did not affect these parameters. Concerning to the higher germination percentage of seeds in the middle of the spike (large seeds) under salinity stress, they can be employed for increasing emergence percentage in saline soils.

In order to study the relationship between dry leaf yield and some important characteristics of tobacco under drought stress and optimal conditions, 15 hybrid of tobacco, including 10 Iranian hybrids and 5 introduced hybrids from other countries were evaluated in two separate experiments (drought stress and normal) in a randomized complete block design with three replications, at the Research Center of Rasht, Iran, during 2008-2009. Results showed that under normal condition, there was positive and significant correlation between dry leaf yield and days to start flowering, flowering period, stem diameter and leaf area index, but dry leaf yield had negative and significant correlation with stem height. Under drought conditions, there was positive and significant correlation between green leaf yield and days to start flowering, leaf width and leaf area index, while there was no significant correlation between dry leaf yield and other traits. Path analysis of the correlation between dry leaf yield (as dependent variable) and other traits (as independent variables) showed that under non-stress conditions, days to start flowering, leaf length and stem diameter had direct effects on dry leaf yield, while under drought conditions, number of leaf, leaf width and days to start flowering had direct and positive effects. On drought stress conditions, the correlation between days to start flowering and green leaf yield was resulted from indirect effect of number of leaves per plant. To select for tobacco high quality leaves, we can select the best plants indirectly by using of days to start flowering, stem diameter and leaf length under normal water conditions and the number of leaves and leaf width under drought stress conditions.

To study the long-term effect of chilling and freezing on most important grape cultivars in north of Khorasan, two analytical experiments were carried out during 2008. In the first experiment, as Kolahdari and Kaje-Angoor were the most important and qualitative cultivars in the region for processing, fresh consuming and export, effect of natural frost on one- year, two- year and perennial branches of these cultivars in two climate conditions of Mashhad and Bojnord were evaluated. In the second experiment, one-year, two-year and perennial branches of Keshmeshi cultivar in three climate conditions of Golmakan, Qochan and Mashhad were evaluated. Factorial experiments based on completely randomized design with five replicates were used for both experiments. The traits that measured were: anatomical description of branch, re-growth, electrolyte leakage and proline content. Results from the first experiment showed that the main effect and interaction effects of genotypes and age of branches on electrolyte leakage from plant cells were significant (P≤1%). One-year and two-year branches of Kolahdari cultivar and two-year branches of Kaje-Angoor cultivar had the highest electrolyte leakage with 90.8, 89.4 and 85.6 respectively. Results of the second experiment also showed that, the main and interaction effects of branches age and sampling area on electrolyte leakage were significant. The Perennial branches from Mashhad area with mean of 65.6 had the lowest electrolyte leakage. These results also showed that there are no significant difference at all significant levels between sampling areas and branches age and interaction effects of these factors. However the effect of area and branches age on proline content was significant.

In order to evaluate effects of and methanol application on grain yield, oil and protein contents, rate and length of grain filling process of soybean under drought stress, a factorial experiment was done at Research Field of Faculty of Agriculture and Natural Resources, Islamic Azad University-Karaj Branch, Karaj, Iran, during 2008, based on a randomized complete block design with three replications. The first factor was consisted of different levels of methanol equal to 0 (control), 7, 14, 21, 28 and 35 volumetric percentage (v/v), which were used as foliar applications at three times during growth season of soybean, with 15 days intervals. The second factor was water stress conditions in two levels, based on depletion of 40 and 70% of available soil moisture. Some traits such as grain yield, 1000 grains weight, grain protein and oil contents and time of filling process were measured. Results show that there was a significant difference in grain yield, 1000 grains weight, seed yield and protein and oil content among different irrigation regimes in 5% probabilities level. There was a different effect (p>0.05) of applying methanol solutions on grain yield, 100 grains weight, seed yield, protein content and length of grain filling, with the highest values were obtained with applying 14% and 21% methanol solutions. The grain yield had positive correlations with oil and protein yields and 1000 grains weight, and a negative correlation the rate of grain filling. Interactions of methanol and irrigation regime on traits were not significant.

The aim of this research was to investigate changes in communities and the indicator groups of benthic macroinvertebrates as well as classification of water quality of Sabz-kuh River, Charmahal province, which had been impacted by a few rainbow trout farm effluents in the studied area. The study was carried out from the start of the 2005 cultivation period in July and took one year. Along a 35 kilometers distance 7 sampling site were selected covering the inlet and outlet of the four large existing rainbow trout farms. Macroinvertebrates were monthly collected using a 1600cm2 (40×40 cm) Surber sampler at each station. During the study 34 Benthc macroinvertebrates taxa were identified of which the aquatic insect's larvae constitute more than 70%. Hilsenhoff family level biotic index in the studied stations varied from 3.9 (station 1, most upstream) and 5.5 (in station 4 and 6, receiving either the farms and urban effluents) suggesting "Very Good" and "Fair" water quality, respectively, according to Hilsenhoff water quality classification. Based on macroinvertebrates community structures and Hilsenhoff biotic index, the water quality in the stations downstream the effluents had lower water quality than the upstream ones.