جستجوی مقالات مرتبط با کلیدواژه « تنش غرقابی » در نشریات گروه « کشاورزی »

Introduction Due to inappropriate irrigation methods, poor drainage in the fields and also warming the planet, flood stress has become an important stress in recent years for crops. On the other hand, due to the importance of soybean in supplying oil and animal feed, sufficient information is available on soybean flooding stress tolerant cultivars or lines in Iran Which have a high yield under flooding stress conditions, Does not exist. Therefore, this experiment In order to select soybean genotypes tolerant to flood stress in the country based on seed yield, seed yield components and tolerance and stress resistance indices. Materials and methods This experiment was conducted as factorial in a completely randomized design with 3 replications and two factors: 1- flooding stress (no flooding stress and 15 days flooding stress) and 2- cultivars (31 soybeans cultivar and lines). Time of action flooding stress was 5-leaf stage (V5). In this experiment, seed yield and biological yield of soybeans, components yield of soybean (number of pods per plant, number of seeds per pod, 100 seed weight), and tolerance and stress resistance indices were measured and calculated. Data analysis was done using SAS software and drawings of diagrams and forms with Excel software. Results and discussion The results of this experiment showed that flooding stress significantly reduces the seed yield and biological yield of soybeans, So that the seed yield for 15 days of flooding stress decreased from 40.6 to 61.7% and biological yields decreased by 17% to 44% during 15 days of flooding stress. The highest seed yield after 15 days of flooding in 326 and 827 cultivars, and the lowest seed yield after 15 days of flooding was observed in cultivars 114 and 937. The results of this experiment also showed that GMP, MP and STI indices have a very high correlation with seed yield under stress conditions and these three indicators can be used to select high yield cultivars under stress and non stress conditions. Based on SSI, STI, MP and GMP indices cultivars 859, 827 and 326 are the most resistant cultivars among the cultivars studied in this experiment. Acknowledgements In general, according to the results of this experiment, soybean varieties do not differ much in terms of response to flood stress and among 31 soybean varieties studied three varietie of 859, 827 and 326 have a good tolerance to flooding stress have and in conditions without flooding stress and in flooding stress conditions seed yield is acceptable.

Seed deterioration and waterlogging stress are factors that lead to lower growth. On the other hand, seed deterioration may affect plant growth that plant growth can be used to quantitatively describe the components of growth analysis.
In order to investigate the mechanisms that lead to the reduction of growth and interaction of these two factors, a factorial experiment in a randomized complete block design (3 treatments seed quality for 0, 72 and 144 hours of accelerated aging and 4 treatment involves waterlogging 0, 5, 10 and 15 days of flooding) in 4 replicates. In this research, wheat seeds (Daria), first in the laboratory for seed quality treatments, were worn by accelerated aging.
The results of laboratory studies showed that seed deterioration slowing, germination and seedling growth reduction is achieved. In the greenhouse, the plants during the tillering stage control (to waterlogging stress) and heading stage control (after waterlogging stress) were collected. The tiller control, by increasing the number of plants decreased seed longevity found. The heading control between different levels of seed aging, the number of tillers per plant and seed deterioration were treated with seed deterioration increases, the number of plants was reduced, but increased the number of tillers. Tillering stage control (to waterlogging stress) that cover the whole plant is not land, leaf area and dry weight depends on the density and the deterioration of seed density decreased, but only the leaves of waterlogging stress reduced pot. At tillering control seed decay with increasing relative growth rate significantly decreased but increased in stages to control the seed deterioration relative growth rate significantly increased. One of the reasons for the increase RGR in plants from the seeds of the decline could be due to offset slow canopy closure due to low density of plants in this plant. After waterlogging stress relative growth rate, net assimilation rate, leaf area ratio and leaf weight ratio to treatment were significant seed deterioration, but to waterlogging stress and interactions were non-significant decline of seed and waterlogging stress.
Seed deterioration treatments, Waterlogging stress and their interaction were effective on the growth response mentioned in wheat

Populus euphratica tree is a species naturally growing in riparian zones of rivers in arid and semiarid region where seasonal flooding and soil waterloging provides the conditions for this species. The aim of current study was to assess survival, growth characteristics and biomass allocation of Populus euphratica seedlings exposed to combined flooding- salinity stress at four levels including control (no flooding- salinity stress), flooding (4 cm above soil surface) with salinity concentrations 0, 50, 100, and 150 Mm NaCl in a completely randomized design for 120 days at greenhouse conditions. At the end of experiment period, survival percentage of flooded seedlings with 0, and 50, 100, 150 Mm NaCl was 100, 88.8, 11.1, and 0 percent, respectively. Flooding with different levels of salinity led to decreased survival, growth characteristics, and biomass of Populus euphratica seedlings compared to control treatment. This decrease was higher at flooding levels of 100 and 150 Mm NaCl than other levels. Also, total biomass and number of adventitious roots at levels of 0 and 50 Mm NaCl were higher than 100 and 150 Mm NaCl. Based on the results it could be suggested that this species can survive and grow and or restore coastal and plain areas, riparian zones in arid and semiarid regions where flooded with fresh and saline water of 50 Mm NaCl concentration. Thus, this species can be used to restore these areas.

Some growth characteristics of Casuarina equisetifolia seedlings affected by salinity-flooding stresses including 0 (freshwater), 50, 100, 150 mili-Molar NaCl and control (without flooding and salinity) treatments were studied in greenhouse as completely randomized design for 120 days. The results showed survival in all treatments was 100%, but in flooding treatment with 150 mM NaCl it decreased to 33.3%. Height growth and diameter growth decreased in various levels of flooding-salinity, and also with increasing salinity. Flooding-salinity stress resulted in decreasing dry biomass of seedlings and creation of adventitious roots in all flooding levels, but the biomass and number of adventitious roots decreased with increasing salinity. Biomass of adventitious roots in flooding levels with freshwater, and flooding with 150 mM NaCl were 6 and 3 times of main roots biomass, respectively. Based on the observations, in all flooding levels, one week after stress, hypertrophy pores were formed in part of the stem located in water. Generally, this research showed that in the studied period in flooding treatment, growth and biomass allocations of organs of C. equisetifolia seedlings decreased with increasing salinity. However, treatments lower than 100 mM NaCl did not display any decrease in survival, but in lower salinity concentrations survival was always 100%. Regarding to creation of abundant adventitious roots and hypertrophy pores showing different resistance aspects to flooding, accomplishment of such a study in next growing seasons can reveal more accurate resistance of C. equisetifoliaseedlings to salinity-flooding stress.

According to the importance of studies of abiotic stress, present study was done in order to identify of molecular markers with significant association to flooding stress tolerance in barley. This study carried out using of AFLP markers and 40 barley genotypes. Generally 22 variables in both normal and flooded, eight characters including shoot dry weight, length, volume, wet weight, dry weight, leaf area, root diameter and density tolerance was assessed with six indicators (SSI, STI, GMP, TOL, YI and YSI). Seven primer combinations of EcoRI and MseI a total of 245 bands were produced, of which, 227 bands were polymorphic and had an average of 92.37 percent polymorphism. Three combinations E90-M160, E100-M160 and E90-M150 had higher values of genetic variation compared to other combinations and were more effective in distinguish of genotypes. Association analysis was performed using structure matrix and statistical models of GLM and MLM by using of TASSEL software for 22 variables. The MLM model in 5 percent probability level identified 87 markers related to evaluated traits. According to the results of association analysis in normal condition the highest of coefficient of determination was for E100M16027 with explanation of 32 percent of root diameter variation and for tolerance indices and stress condition the highest coefficient of determination were for E80M1501 and E100M15022 with 24 percent explanation of variation of GMP index and shoot dry weight respectively.

In order to examine the growth, morphological and physiological changes of one-year old potted seedlings of Quercus castaneifolia, a research was performed based on completely randomized design with 3 treatments and 4 replicates (with 48 seedlings) in regimes of permanent flooding and periodic flooding (two weeks in between until 120 days) and in the Natural Resources of Tarbiat Modares University of Noor on 120 days. Analysis of LSD’s test showed that the permanent flooding decreased 19% in survival as compared with control seedlings. This is while, that all seedlings in periodic flooding were survived with respect to controls. This reason may be contributed to producing of adventitious and soil drainage that caused increasing gas exchange of rhizosphere. Also flooding decreased growth characteristics, biomass accumulation, and physiological activity such as photosynthetic, stomatal conductance, transpiration and leaf water potential. Of course, except root length and the root/shoot ratio, other parameters in permanent flooding were smaller than those of in periodic flooding. In contrast, diameter growth response in periodic flooding was higher than that in permanent flooding and it was a little greater than that in control. The reason of this phenomenon may be attributed to the development of woody xylem cells. Generally, on the base of findings in this research, it can be stated that Q. castaneifolia seedling is relatively tolerant to flooding (particularly to periodic flooding). It is suggested that for restoration of degraded forests exposed on flooding stresses and or where the natural regeneration of this species is being restricted by flooding, such a research with further seedlings, in different growth phases and during longer periods can be used with this species and also other species with similar ecological nature.

In order to investigation of waterlogging stress effects on morphological and physiological traits of rapeseed (Brassica napus L.) in different developmental stages, a pot experiment was conducted at Gorgan University of Agricultural Sciences and Natural Resources, during 2010-2011. The experiment design was completely randomized with factorial arrangement and three replications. Examined factors were developmental stage (seedling, stem elongation, flowering and grain filling) and duration of waterlogging stress (0, 3, 6 and 9 days). Leaf area, leaf dry matter, shoot high and shoot dry matter, root volume and root dry matter, chlorophyll fluorescence, chlorophyll content and grain yield were measured. An exponential decay and linear models were fitted to quantify waterlogging stress on morphological traits and yield. Waterlogging conditions decreased leaf area and leaf dry matter, then leaf senescence occurred and fall down it So, plant less biomass transmit in to the shoot and root, then, shoot high and shoot dry matter, root volume, root dry matter, FV/FM, chlorophyll content and finally grain yield decreased. Maximum slope of grain yield reduction (-1.73 per day) observed in the flowering stage while the lowest was recorded at stem elongation (-0.6 per day). Control plants had the highest yield (5.1 g per plant) while imposing 9 days waterlogging either flowering or grain filling stages (0.18 and 1.4 g per plant, respectively) decreased the seed yield. Generally, results of the present research indicated that in order to damage of vegetative organs and their lack of proper functioning rather then control markedly decreased seed yield of rapeseed throughout four developmental stages.

Flooding stress problem threats about a million hectares of Iran fields and barley (Hordeum vulgare L.) as the world's fourth most important cereal, despite of relatively desired tolerance to salinity and drought stress but specially in prone provinces of rain the flooding damage can be serious. Therefore an experiment was designed according to split-plot form with using a randomized complete blocks design in order to identify of more tolerant genotypes to flooding stress. Flooding stress was the main factor with three levels (Control, 10 and 20 days of stress) and 77 barley genotypes were the subplot. There were significant differences between genotypes for all traits in terms of root and shoot dryweight. After compare of means for all trait most tolerant barley genotypes were identified using the ranking of genotypes based on the results of the method of Arunachalam and tolerance index of TOL, YI and GMP. In agreement with these analysis, Cluster analysis of genotypes divided genotypes into two main groups too, that considering to second group for studied traits were higher than total mean therefore can introduce this group as more tolerant group. The overall results revealed identified tolerant genotypes if be confirmed at other environments can be introduced for cultivation in prone areas to water logging stress of country.

In this study, hardwood cuttings of Populus caspica Bornm. were collected from three origins of Golestan (sub-humid), Mazandaran (humid) and Guilan (very humid) regions and their transplants were planted in nursery of Koloudeh, Amol, north of Iran. In July 2009, seedlings were subjected to flooding stress for 150 days. Experiment was carried out as Completely Randomized Block Design in four replications. Results showed that among control seedlings, survival rate of origins varied between 93.7 and 100%. Golestan origin showed maximum height and collar diameter increment and Guilan origin indicated highest root biomass, total biomass and leaf area. In flooded conditions, survival did not differ among the origins and it always was higher than 93.7%. Likewise, no significant differences of height and collar diameter increment, root biomass, and total biomass were found among the origins. Generally, although the values in most of attributes of seedlings were smaller under flooding than control, but seedlings of three origins displayed relatively good response to flooding. This study confirms that Populus caspica is a good flood-tolerant species and thus, it can be used for planting in wetlands, riversides and flooded areas of northern Iran.

To evaluate and analysis growth parameters and the effective quantities on them, an experiment was conducted in the Agricultural Research Station, Ahvaz Islamic Azad University, during 2006-2007 and 2007-2008 cropping seasons.Under studied treatments were 3 wheat cultivars (Chamran, Dez and Vee/Nac), waterlogging period (0,7 and 14 days) and waterlogging stress in different Growth stages containing stress at the beginning of tillering stage (ZG21),stress at the beginning of stem elongation stage (ZG31)and stress at the commencement of booting stage (ZG45).Among the using cultivars,the growth stage period of Vee/Nac was about 2 weeks shorter than other cultivars. Experimental design was a factorial randomized complete block design (RCBD) with three replications. Results showed that increasing waterlogging stage,significantly decreases LAI (Leaf area index) and tiller number in m2, especially when stress applying at ZG21 and ZG31. The maximum LAI and tiller number was observed in Chamran cultivar and the minimum in Vee/Nac cultivar. NAR (net assimilation rate) decreased significantly when waterlogging stress was applied at ZG21 and ZG31 stages, but the duration of waterlogging affect was not significant. The maximum NAR was observed in Vee/Nac cultivar. TDM (total dry matter weight) and CGR (crop growth rate) decreased significantly after increasing the duration of waterlogging and applying stress in ZG21 and ZG31 stages. The maximum CGR at primary growth stages and the minimum TDM in the end of growth stage in Vee/Nac cultivar was obcerved.

In order to study the effects of different waterlogging duration in growth stages ZGS11, ZGS13 and ZGS31 on root and shoot growth of three wheat genotypes Chamran, Vee/Nac and Yavaros, a pot experiment was carried out in the Ramin Agricultural and Natural Resources University in 2004. The experiment was a factorial according to a Randomized Complete Block Design with three replications. Study of root dry weight and root elongation trend showed different responses among genotypes, start of waterlogging periods and different waterlogging levels, as short period of waterlogging (10 days), had unrecoverable effects on the growth. Analysis of variance of root dry weight and root length at the anthesis and physiological maturity stages indicated significant different among all of treatments levels. Vee/Nac genotype was found superior with respect of root dry weight and root length to other genotypes. ZGS11 and ZGS31, had the highest and the lowest responses to waterlogging, respectively. Duration of 10, 20 and 30 days waterlogging at anthesis stage decreased 37.75, 44.31 and 54.01% of root dry weight, and 25.85, 47.02 and 58.88% of root length compared to control, respectively. Investigation of the root anatomy of wheat genotypes under waterlogging stress showed formation of cortical root aerenchyma as a waterlogging-resistantce mechanism.