فصلنامه اکوفیزیولوژی گیاهان زراعی
پیاپی 45 (بهار 1397)

Water shortage in root environment is the main factor limiting crop growth and productivity in dry regions. There are many reports on the role of methanol spraying for increasing drought tolerance in C3 plants. For this reason, a factorial experiment was conducted using completely randomized block design with 3 replications at Khatam Alanbia University of Behbahan. Methanol applied with five levels; (control, 5, 15, 25 and 35% v/v) and water deficit stress with three levels: irrigation at 100% of field capacity, moderate water stress, irrigation at 75% of field capacity and severe water stress, irrigation at 25% of field capacity. Foliar application of methanol was applied 3 times during the growing season (at seedling, flowering and podding stages) with 10-days intervals. Results showed that the interactions of methanol × drought on the root dry weight, root diameter, root length (p<0.05) and root area (p<0.01) were significant. In normal irrigation conditions, methanol spraying 5, 15 and 25% increased significantly root dry weight as compared to control. Also, the interactions of methanol ×drought on protein and proline were significant (p<0.01). Methanol spraying incresed significantly root proline and protein contents. Interactions of methanol and drought on sodium and potasium consentration, (p<0.05) and calcium (p<0.01) was significant. Interactions of methanol ×drought on root activities of superoxide dismutase and peroxidase were significant (p<0.05). Also, the effect of drought stress on catalase enzyme activity was significant (p<0.01). Methanol spraying decreased root activities of superoxide dismutase and peroxidase, significantly.

To evaluate the effect of selenium (from sodium selenate) on increasing efficiency at water deficit condition a research was conducted in Karaj 1 wheat cultivar in 2014-2015 cropping year with split plot based on completely randomize block design with four replications in Karaj. Irrigation treatments with two levels, normal (I1) and interruption of irrigation at mid flowering (110 days after planting) (I2), which were assigned to main plots and selenium foliar application with six concentrations: 0 (S0), 5 (3.12 micro g.) (S1), 10 (6.24 micro g.) (S2), 15 (9.36 micro g.) (S3), 20 (12.5 micro g.) (S4) and 25 (15.62 micro g,) of sodium selenate per plant (S5) g.ha-1 to sub plots. The results showed that water deficit increased the rate of superoxide dismutase, catalase, glutathione peroxidase and malondialdehyde marker. Foliar application of selenium, increased contents of antioxidant (anti oxidation) enzymes under stress condition and was maximum in 20 g. selenium per ha-1. Content of malondialdehyde was decreased and caused significant increase in grain yield. Increasing antioxidants and reduction of malondialdehyde at normal condition was lower. On the other hand, negative effect of malondialdehyde on yield components, cellular membrane stability and antioxidant enzymes at humidity stress condition was higher than normal condition. Significant increase of cytoplasmic membrane stability, grain yield, grain weight and selenium content of seed was obtained when 15 and 20 g. selenium ha-1 were used as compared with those of higher and lower rates of selenium usage under water deficit and normal irrigation. Suppression of free oxygen radicals, and enzyme induction defense mechanisms against oxidative damage has been effective. Therefore, use of exogenous compounds such as selenium may increase the antioxidant capacity of plant against stress.

Chitosan is a glucosamine polysaccharide deacetylated form of chitin species and could be used as biotic elicitor to improve secondary metabolites and as a fertilizer it controls the release of chemical compounds of toxins and stimulates germination and plant growth. Thus, to evaluate the effect of chitosan NPs on barley plants under late season drought stress, a factorial pot experiment was performed based on a randomized complete block design with three replications. The experimental factors were NPs concentrations at 4 levels (0, 30, 60 and 90 ppm), method of usage at 2 levels (foliar and soil application) and irrigation regimes at 2 levels (normal irrigation and with-holding irrigation 15 days after pollination). Experimental procedure consisted of planting seeds, preparing chitosan NPs solution, and using solutions through soil and foliar application at three plant growth stages (tillering, stem elongation and heading). Results indicated that drought stress significantly decreased contents of carotenoid, chlorophyll a, the chlorophyll b, the total chlorophyll, rate of photosynthesis, stomatal conductance, transpiration, grain yield, as well as, biomass. Results also showed that contents of soluble carbohydrate, glucose, sucrose, fructose, intercellular CO2 concentration (Ci) and photosynthetic water use efficiency (WUE) were increased. Also, under both irrigation regimes, application of chitosan NPs significantly increased the chlorophyll a, the chlorophyll b, the soluble chlorophyll and the glucose. Application of 60 and 90 ppm NPs significantly increased grain yield as compared to that of control. Signifficant diffrences for some traits under study between two usage methods of NPs were not observed. In general, application of chitosan NPs reduced negative effects of drought stress for barley plants and improved its growth and seed yield.

To evaluate mycorrhizal symbiosis of soybean plants (Glycine max L. cv. Williams) under different irrigation systems, a split plot experiment was conducted based on randomized complete block design (RCBD) with three replications at Urmia University in 2015. Treatments were irrigation systems (drip and sprinkler irrigation) assigned to main plots, and mycorrhizal fungi species (non-inoculated as control,Funneliformis mosseae, Rhizophagus intraradices andSimiglomus hoi) to sub-plots. Results indicated that the highest plant height, pod weight, seed yield, 100 seed weight, number of nods per stem, biological yield, harvest index of oil, oil percent and oil yield were obtained by using drip irrigation. The highest LWR (ratio of leaf/aerial parts weight) and SPAD (chlorophyll index) were observed in sprinkler irrigation system. The significant interaction effects were exhibited variable responses of soybean plants to mycorrhizal species under irrigation systems. The highest photosynthetic pigments (chlorophyll-a, -b and total chlorophyll) and carotenoids were obtained from AMF-inoculated plants under sprinkler system, regardless of fungal species. The highest leaf phosphorus belonged to inoculated plants (F. mosseae) in sprinkler irrigation system. All fungi species increased leaf protein, similarly. While the leaf potassium did not show significant differences with non-AMF inoculated control plants. Despite highest root colonization with R. intraradices under sprinkler irrigation system, colonization by all three species of fungi under both irrigation systems were higher than non-AMF inoculated soybean plants. In both irrigation systems, the ratio of fatty acids (unsaturated fatty acids which were four times higher than of saturated fatty acids) in AMF-inoculated plants were equal to that of non-mycorrhizal control soybean. Regardless of different responses of soybean plants to mycorrhizal species, biological seed and oil yields, under drip irrigation system were about 23, 53 and 84% higher than that of sprinkler irrigation system.

Drought is an important factor affecting germination, early plant growth and its rate and decreasing economic performance of seedlings. Thus, seed priming to induce homogenice germination, emergence and increase the rate of growth and reduce adverse environmental effects results higher in yields. It also facilitates seedling emergence early and establishment of the plant. To study the effect of drought stress and seed priming on some vegetative and reproductive traits of castorbean (Ricinus communis), a split plot experiment based on randomized complete block design with three replications was conducted at the Saetlo Station of Agricultural and Natural Resources Research and Education Center of West Azerbaijan, during growing season of 2013. Main factors were drought stress with four levels (60, 90, 110 and 130 mm pan evaporation) and subfacotre were four seed priming treatments: control, hydro-priming, salicylic acid and hydrogen peroxide. Results of variance analysis showed that the drought stress significantly affected plant height, 1000 seed weight, grain yield, oil yield and grain harvest index. Seed priming also, significantly affected plant height, 1000 seed weight, seed yield, oil yield and harvest index. Interaction between water stress and priming treatments significantly affected grain yield. Considering the comparison of mean values, it was observed that plant height, 1000-seed weight, seed yield, oil yield and harvest index, at 60-mm evaporation from the pan had the highest values. Seed priming affected all of the traits and salicylic acid treatment also was able to affected the highest amount of all traits. The highest grain yield and 1000 grain weight were due to the interaction of 60 mm evaporation from the evaporation pan and seed priming with salicylic acid.

Salinity and drought are known as the most important abiotic stresses to reduce the growth and development of crops. To evaluate drought tolerance of lentil landrace genotypes at flowering stage, a split plot experiment based on randomized complete block design with four replications was conducted at the Agricultural Faculty of Islamic Azad University, Tabriz branch, during 2012-2013. Combined variance analysis of data showed that genotype × drought stress interaction was significant for all traits under study. This indicates different response of, genotypes to drought stress for these traits. Mean comparison of yield for genotype × drought interaction showed significant yield reduction for all genotypes under drought stress as compared to non-stress conditions. However, Shavi Varzeghan genotype under both stress and non-stress conditions, showed better response than other genotypes. To evaluate tolerance of of lentil landrace genotypes to salinity and drought stresses, a factorial experiments based on completely randomized design with three replications was conducted in 2013 at the greenhouse of Tabriz Azad University. Factors in this experiment were: drought stress at two level (control and irrigation for 50% of field capacity); two salinity levels (control and 4 ds/m salinity) and 7 lentil landrace genotypes. Analysis of variance showed that three way interactions of genotype ×drought × salinity was significant only for root length which indicates different response of genotypes for this trait for salinity and drought stresses. The effect of salinity and drought stress levels on all traits was significant which indicates reduction in traits value under salinity and drought stresses.Estimation of simple correlation among traits showed that, shoot length and number of shoot correlated pasitively with shoot dry weight and root dry weight with root length and number of lateral roots. Cluster analysis divided genotypes into two clusters. The second cluster consisted to Kaleybar, Horand and ShaviVarzeghan genotypes. These genotypes were tolerant as compared to the other genotypes during vegetative growth stage.The regression and path analysis for shoot dry weight showed number of lateral roots had the highest direct and indirect effect on shoot dry weight under drought and salinity stress. Cluster analysis of traits, divided genotypes into two clusters. The second cluster were Kaleybar, Horand and Shavi Varzeghan genotypes. These genotypes had higher mean values for the traits under study and could be tolerant genotypes for drought and salinity stresses at vegetative growth stage.

Onion is a medicinal plant which have many uses in traditional medicine. It is a valuable crop since ancient times and it ranks second after tomato among cultivated vegetables in the world. Also, onion has great importance in the diet of Iranian people. In this study effect of different nitrogen levels (56, 112, 168 and 224 mg.L-1) on antimicrobial activity and some physiological characteristics of bulb extracts were studied.The highest and lowest amounts of inhibitory efficacy of methanol extract of onion bulbs at concentration of 0.30 mg.L-1 against Pseudomonas aeruginosa and Bacillus subtilis, were observed. According to the results, different levels of nitrogen had a positive effect on the antimicrobial properties onion bulb extract. With increased nitrogen concentration in nutrient solution, antimicrobial activity onion bulb extracts increased. With the increase in nitrogen concentration in nutrient solution content antioxidant activity, total phenol, total flavonoids, and ascorbic acid were increased. Increasing the concentration of antioxidant compounds was associated with increased antimicrobial activity of onion bulb extract. In recent years, the consumption of onion has increased due to its flavor and health benefits. The beneficial properties of onion are mainly related to its high content of sulfur compounds and flavonoids, and the role of these compounds as antioxidants, anti-microbial and anti-cancer have been proven. Nitrogen was effective on the inhibitory effect of bulb methanol extract, which could be due to the effect of nitrogen on the metabolism of sulfur compounds and flavonoids in bulb.

To study the possibility of reducing the consumption of nitrogen fertilizer using biological fertilizer on yield and yield components of cowpea. A factorial experiment in a randomized complete block design with three replications was conducted at Darreb Shahr in 2012. The first factor, which was at 3 levels of urea nitrogen, containing 0, 50 and 100 kg nitrogen per hectare, and the second factor was the biological fertilizer Nitroxin at 3 levels containing no inoculation, inoculation rate of 1 ml per 60 kg seeds and spraying a rate of 3 liters per ha. The results showed that protein content of seed inoculated with bio-fertilizer nitroxin was 24.96 percent which is one percent more than non-inoculated seeds. The amount of protein obtained in application of nitrogen was also more than non-application treatment and the difference between them was significant. The interaction of urea fertilizer and bio-fertilizer, resulted in highest and the lowest yield in seeds inoculated with 50 kg of urea fertilizer and no fertilizer application biological fertilizer no fertilizer urea in 2046 and 1336 kg per hectare, respectively. All levels of nitrogen in the highest and the lowest yield was in a state of inoculation and non-application. Generally the results showed that the use of biological fertilizers can be used as part of the nutrients needed by cowpea, Also, if Nitroxin was supplemented with lower amounts of urea fertilizer seed yield may be increased seed yield may be improved.

To evaluate the effects of four kinds of organic non-living mulches (wheat straw, sawdust, coco peat and peat moss) and metribuzin (herbicide treatment) on weed control and yield of tomato cv. "CH" an experiment was designed in randomized complete blocks with 7 treatments and 3 replications at the College of Agriculture, Shiraz University in 2012. According to the results all mulch treatments showed lower efficiency in weed control than the metribuzin. Also, all mulch treatments showed higher weed density compared to metribuzin. When straw, among non-living organic mulches, showed lowest weed control (62.3 weed.m-2). According to the results the highest tomato yield per unit area was produced by using peat moss mulch (from 5.7 kg.m-2) and the lowest yield from weedy plots (1.2 kg/m-2). To calculate the percentage of predicted performance of each of the treatments, only Gompertz model was applied and only the beginning of weed interference between the treatments was taken into account.

In this study, a total 15 potato (Solanum tuberosum L.) genotypes (11 potato hybrid clones and four control varieties including Caesar, Luca, Savalan and Agria), were evaluated during two cropping seasons in three different locations of Iran, including Ardabil, Hamadan and Karaj, using a randomized complete block design with three replications. During growth period and after harvesting, some of the characteristics like plant height, main stem number, tuber weight per plant, tuber number per plant, marketable tuber yield and tuber dry matter percent were measured. The combined analysis of variance indicated that the effect of genotype on all of the traits under study was highly significant (p