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To investigate the effect of droughtstress on chlorophyll content, enzymatic responses and some growth characteristics of Acacia victoriae seedlings and the effect of super-absorbent polymers (SAP) in reducing drought stress, a split plot experiment based on the completely randomized design was conducted. The treatments included four levels of drought stress (15, 30, 60 and 100% of field capacity) and four levels of SAP (0, 0.2, 0.4 and 0.6% weight percentages). The results of ANOVA showed a significant effect of drought stress on all growth characters, chlorophyll content and catalase and peroxidase enzymes activity, while the SAP didn't show any significant effect on the weight and areas of the leaves. The interaction effect between drought stress and SAP on the weight, number of leaves, proportion of root dry weight to aerial organs, chlorophyll and peroxidase enzyme activity was also significant. The effect of drought stress on reducing the number of the leaves, leaf area, length, volume and surface of roots and also increasing the root dry weight to aerial organs dry weight ratio, amount of chlorophyll and activity of antioxidant enzymes was significant. The different levels of SAP could absorb and hold water and consequently reduce the effect of drought stress and improve the growth characteristics and reduce the activity of catalase and peroxidase enzymes.

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Plants infected by arbuscular mycorrhizal fungi can tolerate and recover more rapidly from different biotic and abiotic stresses such as soil water deficits than uninfected plants. Thereby study of the dominant mycorrhiza species in the fields under drought stresses is very useful for increasing crop productivity in these conditions and promising for biological fertilizer production in the future. The objective of this research was to study the variations in morphological and molecular diversity of arbuscular mycorrhizal fungi (AMF) and identification of dominant AMF in wheat and barley fields of some arid and semi arid regions of Iran. For this purpose, about 66 samples containing root and rhizospher soils of wheat and barley plants were collected from some arid and semi arid regions of Iran (Isfahan, Tehran, Ghazvin, Arak, Tabriz). After trap culture of observed mycorrhiza in the samples, they were identified using morphological and molecular techniques. The ITS-rDNA of AMF in root DNA extracts of wheat and barley amplified with the primer pair LSU-Glom1/SSU-Glom1 as specific primer for AMF and ITS4/ITS5 as general primers in the first and second reactions of PCR (nested PCR), respectively. Aliquots of the positive second PCR products were cloned. Positive colonies were digested with Taq1. The restriction fragment length polymorphism (RFLP) patterns of digested samples were compared and 1-3 representatives of each pattern at each cloning reaction were sequenced. Morphological and molecular diversity of AMF showed that more than 90% AMF observed in the regions belong to genus Glomus which coordinates with morphological studies and followed by G. intraradices. Also these studies confirmed presence of following species in some regions: G. fasciculatum, G. geosporum, G. sinosum, G. constrictum, G. macrocarpum and Glomus sp. and Acaulospora (Acaulospora sp.). It is important to note that the species G. etunicatu and G. dimorphicum were not detected in the morphological studies and Glomus mosseae was the most dominant AMF species in the all studied regions.

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The effects of water deficit on grain yield, yield components and the physiological char-acteristics of barley (Hordeum vulgare L.) varieties were studied in a split plot design dur-ing the 1999-2000 growing season in Karaj, Iran. Five irrigation levels [0, 25, 50, 75, and 100% crop water requirements (CWR)] and six barley varieties Karoon Kavir , Rei-hani(drought tolerant), Torkman , C-74-9 (intermediate) , Kavir Badia and Gorgan-4 (2 rowed type, drought sensitive) were arranged in the main plots and sub plots respectively. Results showed that water deficit induced stress and this decreased the grain yield and yield components. Water deficit increased the canopy temperature and those varieties showed a higher canopy temperature under non-stress conditions, performed better un-der drought conditions. Severe stress reduced the chlorophyll content (SPAD values) con-siderably, but the differences were not significant between the 50, 75 and 100% CWR treatments. In addition, no significant differences were observed in the chlorophyll con-tent of barley varieties under drought conditions. The effect of irrigation on the photo-chemical efficiency of photosystemII (Fv/Fm) and the other fluorescence parameters for all varieties were significant. Although the Fv/Fm values were not significant in barley varie-ties at any level of irrigation, in general Karoon Kavir and Reihani varieties showed a better performance under water deficit conditions. Proline content was significantly dif-ferent in various irrigation treatments, but its accumulation at any level of irrigation did not differ significantly in barley varieties. It was concluded that the higher canopy tem-perature (less negative T) under well irrigated conditions and higher grain yield, 1000-grain weight, Fv/Fm values under water stress conditions could possibly be the proper cri-teria for screening the drought tolerant barley genotypes under field or laboratory condi-tions.

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Fifteen endemic ecotypes of the fenugreek were evaluated under well-watered and water deficit stressed conditions in the lysimetric system. Results of analysis of variance revealed that there was significant genotypic diversity for all of the traits, except root branch number. Also, ecotype × water treatment interaction was significant for all traits, except days to ripening, canopy temperature, and grain weight. Based on structural equation modeling, predictors in the causal diagram could explain 59%, 29%, 65%, and 51% of the total variation of dependent traits consisting root length, stem diameter, shoot dry weight, and percent assimilate partitioned to grain, respectively. These dependent traits had high broad sense heritability and explained 100% variation of grain weight. Transpiration efficiency had a positive effect on grain weight through stem diameter, root length, shoot dry weight, and percent assimilate partitioned to grain. Results of membership function value of drought tolerance index and heat map clustering revealed that Jahrom ecotype was a highly drought susceptible ecotype, and Yazd and India were drought susceptible ecotypes. Also, Tiranchi and Shiraz were identified as drought tolerant ecotypes. Overall, under water stress conditions, the drought tolerant ecotypes had deeper roots than the other ones. Therefore, these ecotypes might be considered as donor parents in fenugreek breeding programs.
 

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Clovers (Trifolium spp.) are one of the main forage crops in temperate regions. This research was conducted to identify water-stressed tolerance among Iranian wild annual clovers under different climatic regions. Seventeen accessions, belonging to seven species, were planted in a field in two consecutive years, at two locations (Mashhad and Urmia) in Iran, under normal and water-stressed conditions. Combined analysis of variance, Scheffe analysis, and Duncan’s new multiple range test showed significant differences in forage production among clover accessions as well as species. In addition, drought-tolerance/susceptibility indices were calculated for each accession and species. Then, these indices were applied in factor analysis. Extracted Bi-plot based on factor analysis confirmed the results of Duncan and Scheffe analyses. In water-stressed conditions, T. resupinatum (cultivated accession) produced the highest forage in Urmia with 349 mm annual rainfall, whereas in Mashhad, with 149.8 mm annual precipitation, T. purpureum and T. echinatum (both, wild species) had the highest production. The accessions as well as species were ranked based on their forage production for each location and experiment. Ultimately, this work proposed some new Trifolium species, such as T. echinatum, T. diffusum, and T. purpureum, for forage production in agronomic systems.
 

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In order to assess the effect of water-deficit stress on the activity of antioxidant enzymes and agro-physiological attributes of maize, a split-plot field experiment was conducted with three replications based on the randomized complete block design. Three levels of irrigation (well-watered, intermediate and severe water-deficit stress) and four maize families including 10 genotypes were considered as the main and sub factors, respectively. Post treatment, the electrophoretic analysis of three enzymes in maize leaves including SuperOxide Dismutase (SOD), Catalase (CAT) and Peroxidase (POX) was carried out on 8% horizontal acrylamide gel. Moreover, agro-physiological attributes such as MalonDiAldehyde (MDA), H₂O₂, chlorophyll index (SPAD), Relative Water Content (RWC), and grain yield were measured. Concomitantly with increasing intensity of water-deficit stress, the activity of most isozymes and the contents of MDA and H₂O₂ increased while POX2 activity, chlorophyll index, RWC, and grain yield decreased. Under intermediate stress, POX1 isozyme in Lia0688 line (233%) and, under severe stress, POX2 isozyme in AR68 hybrid (201%) showed higher increase compared with the well-watered treatment. Overall, POX1, SOD2, CAT isozymes and MDA, chlorophyll index, and RWC were identified as suitable traits. Based on enzyme activity and agro-physiological attributes, SC706 and TWC647 hybrids were superior to the other genotypes and expressed higher tolerance to water deficit stress. Moreover, among parental lines, MO17, B73 and Lia0688 were promising, although Lia0688 and MO17 were more tolerant lines and showed better performance compared with the line B73 and other lines under well-watered and stress conditions.