جستجوی مقالات مرتبط با کلیدواژه « تنش محیطی » در نشریات گروه « زراعت »

Drought stress is one of the environmental factors that affects the growth, yield and yield components of plants. Nitrogen and methanol play a key role in plant structure and metabolism. Black cumin (Nigella sativa L.) is one of the medicinal plants in the family of Ranunculaceae. The seed of Nigella sativa plant has been used since long to protect health and combat different diseases and its frequent application in the pharmaceutical industry. The plant is cultivated in different parts of Europe and Asia including Iran. The purpose of this study was to investigate the responses of growth indices and yield of the black cumin to nitrogen and methanol under water stress conditions.

Healthy seeds of black cumin were provided from Medicinal Plants Research Center, Shahed University. The experiment was a split split-plots study based on randomized complete block design with three factors and three replicates. The experiments were conducted in the farm of Zanjan University, Faculty of Agriculture (36° 41’ N latitude, 48°27’ E longitude, and altitude of 1620 m) during the year farming in 2019-2020. The factors were drought stress with 4 levels (control irrigation, irrigation at 80% soil capacity, irrigation at 60% soil capacity, irrigation at 40% soil capacity) as the main plots, nitrogen with 4 levels (control, 30, 60 and 90 kg per hectare) as the sub-plots and methanol with 3 levels (0, 10 and 30%) as the sub-sub-plots. In fact, for each level of methanol, two g l-1 glycine and one g l-1 tetrahydrofolate as catalysts and one g l-1 tween80 were added to increase the adhesion of methanol solution. In both areas, soil preparation, including plowing, leveling and paving was performed before planting. Black cumin seeds were weighed in the amount of 4 g and the seed was evenly distributed.
At the time of complete ripening, after removing the marginal effects, a random sample was selected from each plot and the plant height, root length crop growth rate (CGR) were measured.
Also, after the final ripening, sampling was done to determine the grain yield after removing the marginal effects and one square meter was taken from each experimental unit and the number of plants per square meter was counted and then the seeds were separated from the plants and weighed and then reported in kg ha-1. To measure yield components (number of capsules per plant, number of seeds per capsule and 1000-seed weight) at the time of harvest, 5 plants were randomly selected from each experimental unit and the number of capsules was counted and then the seeds were taken out of the capsules. To measure the weight of 1000 seeds from the harvested seeds related to grain yield, three thousand samples of seeds were counted and then weighed and their mean as 1000 seeds weight and were used for data analysis.

The results showed that with increasing irrigation stress, plant growth indices and yield decreased, while with increasing nitrogen and methanol concentrations, growth indices and yield increased. In total, application of 10% methanol and 30 kg ha-1 nitrogen increased root length plant height by 9 and 16% compared to the control treatment. The results showed that the triple interaction of control irrigation, application of 30 kg ha-1 nitrogen and 10% methanol increased crop growth rate by 17.44% compared to control treatment. The highest grain yield by interaction of without irrigation stress and application of 90 kg ha-1 nitrogen and application of 10 percent methanol in the amount of 715.40 g were observed. Application of high levels of nitrogen and methanol under severe stress reduced grain yield, while application of lower levels of nitrogen (30 kg ha-1) and methanol (10%) increased grain yield, and the triple interaction of non-stress irrigation, application of 90 kg ha-1 nitrogen and 10% methanol caused a significant increase in grain yield (3.6%).

The results showed that severe drought stress by reducing plant height, root length, crop growth rate, number of seeds per capsule and number of capsules per plant could reduce grain yield in black cumin and methanol application, especially at the level of 30%, with a positive effect on source strength (leaf area index) and reservoir strength (number and size of seeds) as well as root length, was able to increase black seed grain yield under water stress. The maximum crop growth length was obtained by triple interaction of control irrigation, application of 30 kg ha-1 nitrogen and 10% methanol foliar application at 35.31 g m-2 day and according to the importance and economic value of black cumin plant in the pharmaceutical industry The use of this treatment is recommended for producers of this plant.

Barley (Hordeum  vulgare L.) is among the most important cereal crops and  large portions of human  populations in many  parts of the world depend on them  as a source of food and animal feed. Drought is one of the most important environmental stresses which affects yield and yield components of plants significantly which plants respond and adapt to drought stress by means of various morphological, biochemical and physiological changes. Nowadays Biochar has been employed for scientific and commercial usage as a soil amendment for improving the productivity of crops. Results of researchs showes that Biochar makes a great contribution in crop plant's growth. For instance investigations showed that drought stressed chickpea plants exhibited considerable reduction in uptake of nitrogen and phosphorous which was ameliorated by Biochar treatments. Jasmonic acid (JA) and its methyl ester, methyl jasmonate (MeJA) are important cellular regulators involved in many growth, developmental and physiological processes. It was found that exogenous application of MeJA improved tolerance to drought, salinity, chilling (Rehman et al., 2018) and heavy metal  stresses in different plant species.

In order to investigation of the impacts of different levels of mineral biochar and methyl Jasmonate on growth, yield and yield components of spring barley under different levels of drought stress a factorial experiment in  randomized complete block design in pots in 5 replications was done in 2019-2020 at the experimental field of university of Zanjan. Reviewed factors included in three levels of drought stress (100% FC as the none stressed, 60% FC as the mild stress and 30% FC as the severe stress), biochar application before cultivation in three levels (without biochar, 1.5% and 3% of the soil weight) and foliar spraying of methyl Jasmonate in three levels (0, 75 and 150 μmol per liter Studied factors included  electrolyte leakage, proline and photosynthetic pigments concentration, water use efficiency, relative water content and economical yield.

Results showed a significant impact of used treats on most of the characteristics. All studied factors in this experiment including WUE, RWC, proline, EL, photosynthetic pigments and yield were affected by drought stress but 1.5% biochar  and 75 μmole per liter methyl Jasmonate resulted in enhancement of studied factors of stressed plants both in 60% of FC and in 30% of FC in comparison to untreated plants. But increasing in usage of these materials  didn’t have any positive impact on studied plants. The highest economical yield was obtained in normal irrigation circumstance with foliage application of 75 μmole per liter of methyl jasmonate and using 1.5% of biochar per soil weight and the lowest yield was obtained when we used 30% of field capacity in irrigation without using methyl jasmonate.

We can find out from these results that as a whole drought in middle and severe levels can be disastrous for both morphological and physiological characteristics of every plant which results in reduction in economical yield. But it's necessary to mention this point that using stress moderator  materials whether materials which are used in soil like Biochar or plant growth regulators like methyl Jasmonate which are known as the anti stress substances cause moderation in the catastrophic effects of drought stress which through enhancing some indexes like the relative water content and ameliorating of water use efficiency in comparison to untreated plants with these materials can diminish the severe impacts of stress and eventually through boosting economical yield can dwindle damages of drought. Nevertheless it's absolutely comprehensible from the results of the experiment that using too much of these materials not only do not have any positive effect on growth, physiological or biochemical indicators under drought stress but also can reduce these characteristics even to lower than their quantity in untreated plants.

Wheat, like other plants, uses antioxidant enzymes to deal with the high production of free oxygen radicals. Antioxidant enzymes are proteins or polypeptides that are activated in cooperation with cellular substances or mineral elements and are responsible for detoxifying reactive oxygen species in organisms. Superoxide dismutase (SOD) is an important antioxidant enzyme responding to plants' abiotic stresses. This study was performed to identify significant regulatory elements within the promoter regions of superoxide dismutase genes in the wheat genome.

To investigate the regulation of gene expression and the effective factors in regulating superoxide dismutase enzyme using bioinformatics methods, the promoter region of Mn-SOD, Cu/Zn-SOD and Fe-SOD genes was investigated. The reason for selecting these genes is their ability to scavenge the free radicals of oxygen in plants. Also, their gene expression pattern are crucial under stressful conditions. In order to perform the promotor analysis of these genes, first, the sequence of the genes encoding this enzyme from wheat was downloaded using the NCBI site. After receiving the desired gene sequence, all three sequences of this gene were searched to find different versions of the SOD gene in the wheat genome against the genomic sequence of this plant that has been identified and reported on this site so far. Each received promoter sequence was analyzed and their regulatory elements were identified. Fifteen genes encoding superoxide dismutase were identified and annotated in different chromosomes of A and D genomes of wheat. Then, the promoter regions of these genes, including 1500 bp upstream sequences, were separated to identify the corresponding regulatory elements. The promoter sequences were analyzed to detect the statistically significant over-represented regulatory elements.

The results showed that various regulatory elements involved in different biochemical pathways might influence wheat's transcription of superoxide dismutase genes. G-Box, I-box, MBS, TGA-element, A-box, ABRE, and ARE, are regulatory elements annotated by individual and grouping promoter analysis. In this study, genes encoding superoxide dismutase were mainly identified on different chromosomes of wheat's A and D genomes. This indicates that these genes were probably transferred from the parents of wheat that had these two main genomes to wheat.

Finally, the analysis showed that the important regulatory elements identified in this pathway could include ABRE, ARE, CCAAT-box, G-Box, Skn-1_motif, and circadian, which respectively have a role in the pathway of response to abscisic acid, and response to other reactions such as aerobics reactions, the binding site of elements related to genes encoding MYB transcription factor, response to light conditions, endosperm expression pathway and the pathway of regulation of periodic light responses. Most of the regulatory elements of these genes are involved in light reactions and environmental stresses, which protect the plant against their injury effects.

In order to identify cold tolerant cultivars of rapeseed (Brassica napus L.) using stress tolerance indices under the influence of humic acid application, an experiment was conducted as factorial split plot based on randomized complete block design with three replications in 2017 and 2018 at Seed and Plant Improvement Research Institute, Karaj, Iran. Factorial combination of cold stress as planting date factor in two levels including 20 October and 20 November, and humic acid factor in two levels including non-application (foliar spraying with pure water) and application (foliar spraying with a concentration of 1.5 per mil at 4-6-leaf stage) were assigned to the main plots and the cultivars were allocated to the sup-plots. The results showed that rapeseed cultivars differed significantly. Based on the results of means comparison, the cultivar WRL-95-07 showed higher yield in both stress and non-stress environments as well as the application and non-application of humic acid than the other cultivars. The correlation of drought tolerance indices with grain yield under stress and non-stress conditions was used to determine the most suitable indices. Arithmetic mean productivity (MP), geometric mean productivity (GMP), harmonic mean (HARM) and stress tolerance index (STI) had the highest significant correlation with yield under normal and stress conditions. Principal component analysis differentiated indices introducing tolerant cultivars and indices introducing susceptible cultivars, and on this basis, the 10 rapeseed cultivars were divided into three groups using cluster analysis. Finally, WRL-95-07 cultivar performed well under stress and non-stress conditions with the use of humic acid, followed by WRL-95-12 cultivar which displayed better performance than the other cultivars under stress conditions when treated with humic acid.

Today in many parts of the world and specially in Iran, water and soil salinity is one of the environmental stress and a serious risk to plant growth and crop production. One way to modify the salinity of irrigation water for agriculture, identification and application of different types of algae. The aim of this experiment was to investigate the effect of two types of algae on the growth characteristics of wheat and basil under salinity stress.

This research was carried out as factorial in two phases of laboratory (in the form of a completely randomized design) and greenhouse (in the form of a randomized complete block design) in the Faculty of Agriculture of University of Birjand located in Amirabad campus in 2015. The first factor is salinity with four levels (1250, 2500, 5000 and 10000 μs cm-1 in both laboratory and greenhouse sections and the second factor is the application of algae with 3 levels (green-blue microalgae Spirulina platensis (for saline water)), single-celled algae Chlorella vulgaris (for fresh water) and control no use of algae. Algae were grown separately in water salinity treatments described above in 50 × 50 cm aquariums in the laboratory. The soil was well mixed with a small volume of saline solution as required and water added to maintain soil moisture at 0.18 cm3 cm–3 (35% water-holding capacity), and then soil was incubated for 1 weeks for subsequent use in the pot experiment.

In the part of laboratory experiment, the results of analysis of variance showed that there was a significant difference between different levels of salinity stress and algae type on dry weight of plumule and rootlet in wheat and basil, but there was no statistically significant difference between their interactions. The application of algae caused a significant increase in the dry weight of plumule and rootlet wheat. The highest dry weight was obtained in the application of Chlorella algae (0.0125 and 0.0008 g pl-1 per plumule and rootlet, respectively). However, both of algae reduced significantly the dry weight of plumule and rootlet of basil. In pot experiment, the results of variance analysis showed that algae type (P <0.05) and different levels of water salinity (P <0.01) had a significant effect on wheat plant height and for basil just were significant different salinity levels (P <0.01) but their interaction had no significant effect on the trait. The use of algae increased significantly the wheat height (algae Chlorella 9.34% and the use of algae spirulina 6.56%). The interaction effect of algae type and salinity levels (P <0.01) were significant in wheat dry weight but for basil dry weight the simple effect was significant. Results indicated that the interaction of algae type and salinity stress had a significant effect on electrolyte leakage of wheat and basil.

Therefore, it can be concluded that the type of algae had a different effect on the two types of plants, so that for wheat plant chlorella algae and for basil plant type of spirulina algae had more effect on traits and moderated the effects of salinity stress.

Faba bean (Vicia faba L.) is one of the most important legumes for its seed high protein content and nutritional value, and is still considered to have great potential as rainfed crop. Faba bean is a very valuable legume crop that contributes to the sustainability of cropping systems through its ability of biological N2 fixation, diversification of cropping systems leading to decreased disease, pest and weed. The decrease in area under cultivation in Iran, mainly because of high yield instability. This can be attributed to biotic and abiotic stresses Faba bean yield is strongly influenced by environments and breeders often determine the stability of high yield genotypes across environments before recommending a stable cultivar for release. The purpose of this study is the distinguishing the superior genotypes in terms of yield and yield stability in 15 selected faba bean lines from preliminary yield test.

15 selected lines obtained from crosses between ICARDA lines and Iranian improved and landrace varieties and resulted from preliminary yield test of 2013-2014 cropping season, along with control cultivar Barekat, Saraziri, Zereshki and Baluchi were evaluated in a Gorgan, Dezful, Borojerd and Iranshar at two cropping seasons (2015-2017) in a randomized complete block design with three replications. Stability analysis were performed with Eberhart-Russell analysis of variance, Shukla's variance (2i), Wrick equivalence (Wi), environmental variance (S2i), coefficient of environment variation (CVi), coefficient of determination (R2), Finlay and Wilkinson regression coefficient (bi), Lin and Binns superiority index (Pi), yield stability index (YSi) and nonparametric methods such as , , Z1, Z2 and TOP and mean and standard deviation of rank.

Combined analysis of variance was performed after Bartlett test and not significant of it and assurance of uniformity of experimental errors. Combined analysis of variance indicated a significant effect of genotype, environment and genotype × environment interaction on seed yield. Based on Wrick equivalence, Shukla variance and RMSE indices, genotypes 5, 13, 14 and 15 were more stable. Genotype 9 had lowest environmental variance and coefficient of environmental variation and was stable than the other genotypes. genotypes 9 and 11 had the highest R2and the lowest deviation from regression. The coefficient of regression in genotypes 6, 9 and 16 were lower than one and their seed yield were higher than total average seed yield and therefore were the stable genotypes. Genotypes were stable genotypes. According to the priority index in all of environments and favourable environments, genotypes 11, 12, 14 and 15 were adapted to the unpredictable high yielding environments(1, 3, 5 and 7), while 6, 9, 14, 16 and 12 were adapted to low yielding environments(2, 4, 6 and 8).Simultaneous analysis based on seed yield and stability (YSi) indicated genotypes 6, 7, 9, 11, 12, 13, 14, 15 and 16 were as stable genotypes. Based on Top statistic, genotypes 12 and 14 and based on and , genotype 11 were stable than the other genotypes. Results of Selection index of ideal genotype (SIIG) method, Based on all non-parametric methods, showed that 14 and 15 genotypes whit 3478 and 3439 kgha-1 grain yield were the most stable genotypes. ConclusionBased on all indices, genotypes 9 and 11 were the most stable genotype in terms of seed yield and could be considered a good breeding material stock in any future breeding program.

Drought stress is one of the major risks to wheat production in many parts of the world. Due to its multidimensional effects, drought stress become a known concern for food security. The purpose of this study was to evaluate the effect of drought stress on agronomic traits of wheat using meta-analysis. A large number of studies have been conducted worldwide regarding effect of drought stress on crops as a major risk in cereals production. The multi-dimentional effect of drought on agronomic traits of wheat are too complex to compare using traditional methods. Therefore, meta-analysis was used in the present study to identify general trends among numerous independent drought-related studies and combine the results into one measure known as the effect size. Meta-analysis of field trials data can provides an overall view of variables affecting crop traits and precision of experimental data. The purpose of this study was to evaluate the effect of drought stress on agronomic traits and evaluating reliability of studies using meta-analysis.

Using scientific database of agronomic researches, 120 articles were evaluated to build a database of experimental data. The study synthesized results from 60 papers and published researches on drought effects and the database was built based on keywords such as wheat, drought stress, yield and agronomic traits. All studies that met the following criteria were included in the database: (1) available data of trial and control plots, (2) reported data of drought effect on at least one of five traits(yield, harvest index, biological yield, 1000-grain weight and grain per spike of wheat). The effect size for each datasets was calculated using cohen's index. Cohen's methodology applies differences between trial and control data as a measure of effect size. As a common measure in meta-analysis, Standard Mean Difference(SMD) used to evaluate precision and bias of experimental data of studies. I-squared measure used as estimation of heterogeneity for results of studies. An I-squared of less than 50% is usually viewed as low heterogeneity and over 50% as high heterogeneity.

The results of analysis demonstrated that effect of drought stress on all mentioned agronomical traits is significant and negative. Using Cohen's index, the calculated effect size of drought stress on varies from 1.9248 to 4.4280 among traits. Grain yield had highest effect size and harvest index showed the lowest among all traits. Lower effect size in harvest index shows tolerance of the trait and it's relative sustainability during stress period.
Analysis of experiments showed a medium rate of heterogeneity in studies on grain yield, harvest index and biological yield and a higher heterogeneity in trials on 1000-grain weight and grain per spike.

Using meta-analysis in agronomic researches provides a framework to examine reliability and generalizability of experiments and individual studies. Drought stress affects many agronomic traits of wheat in different way in spite of statistical significance, results of many studies are not reliable and evident degrees of biases. Higher heterogeneity of experimental data shows a higher probability of bias and less trustable results in the examined researches and lower reliability of the sources for field application and generalization of the results.

Maize (Zea mays L.) is an annual crop belonging to poaceae family that compared to other cereals has high yield. After wheat and rice, maize dedicated largest cultivation area in the world. Drought stress is one of the most important abiotic stress that often affects many aspects of plant growth and it’s the main limitation factor for crop production especially in arid and semiarid regions. Low irrigation lead to drought stress, which affects the plant growth and development. Drought stress leads to growth reduction, delayed maturity and crop yield loss. The use of modern irrigation methods to increase water use efficiency could help solve the problem of water resources shortage that needed for agriculture. Partial root zone drying irrigation is one of the innovative techniques that enhance water use efficiency without a significant reduction in throughput product. The part of the plant root watering and the other part remains dry; this part of the roots that remained dry by sending a signal to aboveground respond to dry and causes Stomatal closure and reduction of plant water consumption. This study aimed to evaluate the effect of different traditional irrigation and partial root zone drying focuses on physiological characteristics of maize.

In order to evaluate the effect of different traditional irrigation and partial root zone drying on physiological characteristics of corn, an experiment in complete randomized block design with 18 treatments and 3 replication was conducted in Birjand University Agricultural Research Station at 59 degree and 13 minutes of eastern longitudes and 32 degree and 56 minutes altitudes. Irrigation treatment concluding from over irrigation (at 125% water requirement), full irrigation (at 100% water requirement) and combined from traditional low irrigation, low irrigation with fixed furrows and variable furrows after one or two irrigation, that started one month after emergence and continued until the end of vegetative or growth period of plant. low irrigation treatments were applied at 50 and 75% of water requirement. For measuring the volume of irrigation water per plot first net irrigation requirement was measured and then To fine-tune the distribution of water between plots and distribution of water the pumps and water counter were used. Finally, plant height, ear length, leaf area index, Stomatal conductance and relative water content were measured.

The results showed that the effect of irrigation treatment on all treats was significant. The highest averages were observed in irrigation at 125% of water requirement and applying various methods of irrigation lead to reduced plant height, ear length, leaf area index, stomatal conductance and relative water content in all of low irrigation treatments were observed in maize plants, although this different was not statistically significant in some treatments. Although water stress was reduced in maize plants traits, but the difference caused by the stress at the partial root zone drying was less than traditional low irrigation compared to full irrigation. Partial root zone drying also increased the physiological characteristics compared to traditional low irrigation treatments. It has been reported that the use of partial root zone drying in cotton resulted in significant savings in water consumption, earliness and increase the quality of the product, this technique reduces water consumption by 50% and increase water use efficiency by 21 percent compared to conventional irrigation to full irrigation was 43 percent.

According to the results of this study can be recommended partial root zone irrigation at 75 percentages of maize plant water requirement by variable irrigated furrows after twice irrigation as the best treatment for water use reduction in maize seed production. This treatment is appropriate for solving the water crisis.

In order to investigate the effects of chilling stress on saffron plant, a completely randomized design as pot cultivation with four replicates on five ecotypes of saffron including: (Torbat Heydariyeh, Ferdows, Gonabad, Ghaen, Kashmar) was performed. Two temperature conditions 25° C (non-stress conditions) and 5° C (stress conditions) were applied to the ecotypes in the growth chamber (germinator) and twelve morphological traits were measured. The results showed that there was a significant difference in the most studied traits at 1% level. The results of factor analysis showed that three components totally explained 84.6% of the studied traits under non-stress conditions and four components totally explained 86.12% of the studied traits under stress conditions. Cluster analysis under non-stress conditions revealed that Ghaen, Gonabad, Kashmar and Ferdows ecotypes were in the first cluster and Torbat Heydariyeh ecotype in the second cluster. Similarly, Cluster analysis under stress conditions revealed that the Torbat Heydariyeh and Ferdows ecotypes were in the first cluster, the Kashmar and Gonabad ecotypes were in the second cluster, and the Ghaen ecotype was in the third cluster. The discriminant analysis showed a function with Eigenvalue (61.51%) explained 100% of ecotypes variation under non-stress condition while two functions explained 100% of ecotypes variation under stress condition, with only the first function had a specific eigenvalue greater than 1. According to the group membership prediction table, the ecotypes in each of the three groups of dendrogram cuts were correctly divided by 100% probability. It can be concluded that the ecotypes of Torbat-e-Heydariyeh and Ferdows which grouped in one cluster and had the highest biologic yield under chilling conditions can be recommended for cultivation in cold regions.

Nowadays, corn is recognized as a nutrition seed for human, birds and some animals. Corn is considered as an energetic nutrition. It will be graded after wheat and rice among whole the cereal according to the significance and the rate of cultivation. Breeding for environmental stress is one of the most important goals in plant breeding. Among stresses, drought stress has high influencing on limitation of maize production. potash management under water limitation condition is an important factor to obtain high grain yield of maize. . All the plants are in contact with biological fertilizer. One of the most important effects of such a biological fertilizer is the operation enhancement in the lands which are low fertility, confronting with different land disease, and strengthening the plant against drough. In general, Plants are exposed to environmental stresses. Water and Potassium availability are two major factors for crop production under different conditions In this study, correlation and stepwise regression of biochemical traits with grain yield of corn hybrids under drought stress conditions and application of potassium chemical and biological fertilizers are investigated.

This study was performed to evaluate the effects of chemical and biological potash fertilizers and drought stress Biochemical characteristics and Grain yield of Zea mays varieties in 2014 - 2015 in Dehloran, Iran. The experiment was conducted as split split plots in randomized complete blocks design with three replications. The treatments included drought stress (normal irrigation, cutting irrigation at 12 leaf stage and at tassel emergence) as main factor, potassium sulfate application in three levels (100% potassium sulfate, 70% potassium sulfate fertilizer with 30% fertile-2 fertilizer, and 50% potassium sulfate fertilizer with 50% fertile-2 fertilizer) as sub plots and three corn hybrids (AS71, NS640 and CORDONA) as sub sub plots. Finally, the data was analyzed by the MSTAT-C.

The results of data analysis showed that the occurrence of stress had a negative effect on Some biochemical traitsand and corn yield. Creating stress in the emergence stage of coronal grass compared with the stress in the 12 leaf stage, had more impact on the evaluated indicators. Consumption of biological and chemical fertilizers of potash by modifying the effects of drought stress had a positive effect on biochemical traits and grain yield. Application of 50% chemical potash+ 50 % seed incubation by Fertil-2 led to 10% increasing of kernel yield, Between studied genotypes, AS71 and NS640 showed highest (10717 kg/ha) and lowest (5887 kg/ha) means, respectively. According to interaction between treatments, it was founded that highest kernel yield (12130 kg/ha) was obtained by AS71 under optimum irrigation conditions + 50% urea fertilizer with 50% fertile-2 fertilizer treatment. Grain yield with proline content, chlorophyll a and b had a positive and significant correlation. The results of stepwise regression showed that the effects of chlorophyll a, proline content and catalase and superoxide dismutase enzymes activity on grain yield had a significant .

According to the results of this research and due to the extreme sensitivity of the biochemical characteristics in water stress conditions, and the relationship of these traits with grain yield, it is necessary to prevent the occurrence of water stress at critical stages of plant growth.Combined use of biological potash fertilizers with chemical potash fertilizers were more effective than chemical fertilizers and significantly increased grain yield. In general, due to the changes in the traits, supplying 50% of needed fertilizer in form of potash fertilizer combined with Barvar-2 fertilizer and AS71 in optimal irrigation conditions were selected as the best experimental treatments.

IntroductionRange plants have important and crucial roles in medicinal industry andtogether with scarcity and low quality of the water and soil resources, prevent a quick recovery of the soil plant covering. Because of these restrictions, it is important to consider the use of salt and drought tolerant species for plantation and to preserve plant cover. In this sense, the use of native species such as black cumin (Bunium persicum Boiss) may be of interest due to their medicinal characteristics and potential ability to adapt to adverse conditions (dry and saline conditions). Black cumin (B. persicum) as a medicinal plant plays a vital role in Iranian medicine so there is a need to know about the factors affecting their growth and propagation.
Materials and MethodsTo investigate the effects of drought and salt stresses on germination and growth in black cumin two separate experiments were conducted. Drought stress was applied through incubation in four different concentrations of PEG 6000 that provide solutions with water potentials ranging from -0.2 to -0.8 MPa (including control and four levels of dryness). Salinity treatments (including control and four levels of salinity) were prepared by adding molar concentrations of NaCl to provide a range of salinity from 50 to 300 mM. Germination percentage and speed was calculated by computation of germinated seeds every day. Growth parameters (rootlet, shoot and seedling length total), allometric index and seed vigority were obtained accordingly.
Results and DiscussionSeeds under both drought and salt stress showed significant reduction in germination percentage, germination rate, radicle length, plumule length, and alometric and seed vigor indices. This trend was much pronounced under high levels of NaCl and low levels of water potentials, so that germination at Ψs = -0.6 MP was completely stopped.
ConclusionsAssessment of drought and salt stresses on germination and growth in black cumin is very important in the management of its planting. With increasing salinity and drought levels, the germination reduced significantly. Although due to higher germination of seeds in different levels of salinity rather than drought, this species seems to be more sensitive to drought stress.

The seed pretreatment with salicylic acid has an important role in improving seed germination and increasing plant resistance to environmental stresses. This study was performed to investigate the effect of salicylic acid on seed germination of Milk thistle under salinity and drought stress. A factorial experiment was conducted in a completely randomized design with three replications. Treatments were consisted of 4 levels of salicylic acid (0, 100, 200 and 300 mg/l) and four levels of each drought and salinity stress (0, - 4, - 6, - 8 Bar). The results showed an interaction effect between pretreatment with salicylic acid and drought and salinity stresses was significant at the 1 % level. On high salinity level (-8 Bar), seed germination percentage and rate, root and shoot length, fresh and seedling dry weight reduced significantly. The short length, fresh weight and percent germination reduced in all three levels of drought stress. Pretreatment with salicylic acid (200 and 300 mg/L) significantly reduce the harmful effects of drought and salinity stress (-6 and -8 Bar) on germination and seedling growth parameters of Milk thistle. The results of this experiment showed that seed treatment with salicylic acid can lead to increase resistance of Milk thistle to salinity and drought stress in seed germination.

GGE (genotype + genotype×environment) biplot is one of the new graphical methods to study genotype×environment interaction in which the effects of genotype and G×E interaction are not separated and selection is based on both of these effects. In the present research, GGE biplot was used to study 14 safflower genotypes over six research stations under water stress and non-stress conditions in spring planting. The results of analysis of variance showed that 93.9% of total variation was due to environment and 6.1% due to genotype and G×E interaction. The polygon-view of GGE biplot recognized six superior genotypes and four mega-environments. The best genotypes within each environment were determined. The seven genotypes located in sectors that no environment was placed indicated that these genotypes were poor in most of the environments. Simultaneous evaluation of yield and stability through average environment coordinate biplot showed that Hartman, Gila and Sina with high seed yield had higher yield stability. Hartman was the nearest variety to ideal genotype (assumed genotype with the highest yield and stability) and Gila and Sina varieties were also close to ideal genotype, too. Biplot of correlation among environments revealed that Shirvan and Kohdasht were similar environments, so that water stress and non-stress conditions were not able to make differences between these locations. Zanjan, Ghamlo, Kohdasht and Sararood environments under non-stress conditions had higher discriminating ability.

Salinity is the most important environmental stress that reduces plants growth and yield. It has been shown that salicylic acid, as an endogenous signal, is responsible for inducing stress tolerance in plants. In this experiment, the effect of salicylic acid and sodium chloride on growth of bean (Phaseolus vulgaris) was studied. When bean plants were at two-leaf stage, they were sprayed by three concentrations of salicylic acid (0, 0.5 and 1 mM). Then, plants were treated with two concentrations of sodium chloride (zero and 100 mM) for 14 days. The results showed that salinity caused a significant reduction in fresh and dry weight of root and shoot, relative chlorophyll content, percentage of relative water content (RWC) of leaf, stress index and significant increase in proline and soluble sugars as compared to the control treatment. Plants that were treated with both concentrations of salicylic acid showed higher fresh and dry weights. Also, application of salicylic acid in both concentrations, in saline conditions, improved the percentage of leaf RWC, amount of relative chlorophyll and chlorophyll fluorescence (Fv/Fm) of leaves as compared to control plants. In summary, it was concluded that spraying of salicylic acid on bean plants could improve growth and thus resistance to salinity under saline conditions.