جستجوی مقالات مرتبط با کلیدواژه « محتوی نسبی آب » در نشریات گروه « زراعت »

Water stress affects the crucial processes and yield of crops. This study aimed to investigate the effect of water stress on physiological and biochemical traits of safflower genotypes.

A factorial experiment was carried out as randomized complete block design in Seed and Plant Improvement Research Institute during 2017-19. The treatments included two irrigation levels (40 and 80% depletion of available water) and Parnian, Goldasht and Kazak genotypes. Plants were sown in soil columns with a height of 150 and a diameter of 23 cm, and irrigated by a drip system. Antioxidant enzymes, malondialdehyde, proline, relative water content, chlorophyll, seed yield and fatty acid composition were measured at the end.

Water stress significantly increased the accumulation of hydrogen peroxide and malondialdehyde in safflower genotypes which led to increased catalase and peroxidase enzyme activity by 1 and 2.5 U, respectively. The proline content increased about 16 times under water stress conditions. In contrast, the relative water content showed a significant decrease, which resulted in increased canopy temperature and decreased seed yield by 70%. The Kazak genotype had the lowest increase in canopy temperature under stress conditions and showed higher yield stability. Moreover, the fatty acid composition of seed oil changed and the amount of linoleic acid decreased by 1.8% under water stress conditions.

The results showed that in addition to drought-related physiological traits, no increase in saturated/unsaturated fatty acid ratio is also an important indicator in screening superior genotypes for cultivation in water shortage.

Beans are one of the most important legumes in many developing countries as one of the sources of human protein. Drought stress is also one of the factors limiting the growth and production of plants in arid and semi-arid regions, which has reduced the yield of plants, especially legumes. The use of antitranspirants is an effective tool in regulating transpiration with the aim of preserving water in the plant. The aim of the present study was to compare the effects of antitranspirants in the condition of irrigation cut off on seed yield and some physiological characteristics of Kosha cultivar pinto beans. The study was carried out in the form of split plots based on a randomized complete block design with three replications in the two crop years of 2019 and 2020 in agricultural lands located in Khoi city. Experimental treatments include irrigation at two levels; Normal irrigation (irrigation according to local custom) and irrigation cut off at the stage of filling the seeds in the main plots and spraying antitranspirants on eight levels in the sub plots included: salicylic acid (0.5%), phenyl mercuric acetate (100 μM), gibberellic acid (150 μM), cytovit (2%), chitosan (0.5%), castor oil (6%), gum arabic (0.5%) and distilled water (control). The traits measured in the experiment included plant height, number of pods per plant, number of seeds per pod, hundred seed weight, seed yield, biological yield, seed protein percentage, relative water content and proline content. The results showed that the cut off Irrigation had a significant effect on the number of pods per plant, hundred seed weight, seed yield, biological yield, protein percentage, relative water content and proline content of bean leaves. antitranspirants also had a significant effect on all traits except for the number of seeds in pods. The interaction effect of irrigation withholding and antitranspirants was significant in the number of seeds in the pod and the percentage of seed protein. The triple interaction of year, irrigation cut off and antitranspirants on the number of pods per plant and hundred seed weight was significant. In the condition of irrigation cut off, antitranspirants increased the seed yield and the highest seed yield was obtained in the salicylic acid treatment, which increased by 41.1% compared to the control treatment. It seems that by applying a stage of irrigation restriction and consumption of antitranspirants in the areas that faced with the problem of water deficit at the end of the growing season, by improving some morpho-physiological characteristics such as reducing the amount of proline and increasing the relative moisture content of leaves and biological function, it is possible to effectively the slope decreased the yield of pinto beans under drought stress conditions. Therefore, in areas with water deficit, especially due to the simultaneous limitation of water resources, peak consumption in other agricultural products, which causes psychological pressure on to deal with the problem of water deficit, using antitranspirants as an efficient tool and removing a irrigation phase at the end of the growing season can partially compensated for the the reduction of damage caused by water deficit.

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.

Introduction

Abiotic stresses, in particular, water shortage pose immense challenges to crop production and can decrease crop yields by 50% worldwide (Mahajan Tuteja, 2005). Water deficit has negative impacts on growth, development and production of legumes, which may result in decreased chlorophyll a and b and increased proline content of leaf (Karimi et al., 2016). Aerosols are principal air pollutants that can greatly impact human health and plant development. This natural phenomenon, which mainly occurs in Iraq and Iran`s western regions, has exacerbated in recent years and caused a lot of damage (Marsafari, 2011). The objective of this study was to evaluate the effects of aerosol particles and drought stress on grain sorghum photosynthetic pigments, soluble sugars, proline, relative water content of flag leaf, leaf temperature and grain yield.

The research was conducted to investigate the effect of drought and aerosol stresses on morpho-physiological traits of grain sorghum (Sorghum bicolar L.) at Lorestan Agricultural and Natural Resources Research and Education Center in 2015. A split plot design based on RCBD was used with four replications. The main plots were allocated to four different irrigation regimes: watering after 60, 90 and 120 mm evaporation from pan class A. The subplots were assigned to three levels of aerosols derived from clay soil source) control treatment, 50 and 100 mg m-3 aerosol particles (. Chlorophyll a, chlorophyll b, soluble sugars, proline content, relative water content and leaf temperature were measured at flowering period and yield components and grain yield were measured at harvest time.

The results of the first year of the experiment showed that chlorophylls a and b were only affected by drought stress where they were linearly significantly decreased from 0.017 and 0.012 mg/g FW, respectively, in control treatment, to 0.0068 and 0.0065 mg/g FW in I120 treatment with increasing drought stress. Water stress triggered the production of active oxygen along with the reduction and decomposition of chlorophyll (Karimi et al., 2016). Soluble sugars and proline leaf concentration were not affected by aerosols, but were significantly affected by drought stress. Sugar content linearly and significantly increased from 4.3 mg/g under normal moisture conditions to 7.9 mg/g fresh leaf weight in I120 treatment. Proline concentrations were linearly and significantly increased from 0.25 mg/g under normal moisture conditions to 0.66 mg / g leaf fresh weight in I120 treatment. The results of two-year compound variance analysis indicated that grain number per panicle decreased but thousand grain weight increased due to drought stress. The change in grain yield was attributed to significant linear relationship and negative correlations with increasing drought stress. The highest average grain yield (8257 kg/ha) was obtained from the normal irrigation, which decreased to 6393 kg/ha under drought stress. The highest average relative content of flag leaf water was obtained from the normal irrigation, which was 2.80% and was reduced to 70.3% under drought stress.

In general, it was found that the amount of chlorophylls a and b and the relative water content of flag leaf and, as a result, grain yield were significantly decreased with increasing drought stress, but osmotic compounds (sugars solution and proline content of leaf) and leaf temperature increased significantly. Increasing drought stress decreased the number of grains per panicle and increased 1000-grain weight, but the increase in 1000-grain weight could not compensate for the decrease in the number of grains per panicle and consequently led to the decreased grain yield. Low concentration of aerosols on the sorghum leaves due to being vertical and waxy caused no serious damage to the plant's photosynthetic system and as a consequence to grain production.

Salinity in soil or water is one of the major stresses especially in arid and semi-arid regions and cause plant weak establishment by disturbing the balance of the elements in the soil and this effect depends on the plant sensitivity. In other hand, salicylic acid as an endogenous growth regulator, is one of effective combinations in plant defense system. Goldenberry (Physalis peruviana L.) belong to Solanaceae family and their geographical dispersal occurs mainly in tropical regions of South America and eastern Asia. Physalis can develop in a huge range of soil and climatic conditions. The aim of this study was to investigate the effect of salicylic acid foliar application on the Morpho-physiological and biochemical characteristics of Goldenberry under salt stress condition.

An experiment was conducted at the research greenhouse of Lorestan University (Khorramabad, Iran) in 2018. The experimental design was a factorial based on a completely randomized design with three replications. The treatments were consisted of four NaCl concentrations (0, 35, 70 and 105 mM) and four salicylic acid concentrations (0, 0.5, 1 and 2 mM). Physalis seedling were grown into the pots containing of soil, sand and manure (2:1:1). Plant height, stem diameter, leaf number, leaf area, root, shoot and total dry and fresh weights, relative water content, chlorophyll and carotenoid content, Malone de aldehyde, Electrolyte Leakage, proline and Anthocyanin were measured.

The result of ANOVA showed that the main effects of salinity stress and salicylic acid and their interaction effects were significant for most traits. Salinity stress, decreased Plant height, stem diameter, leaf number, leaf area, root, shoot and total dry and fresh weights, RWC, chlorophyll a, chlorophyll b, total chlorophyll, carotenoid content, anthocyanin and increased MDA content, electrolyte leakage and proline. Salicylic acid foliar application reduced the salinity negative effects, as the highest mean of the most traits was found in plant control (without salinity) with 2 mM concentration of salicylic acid. The maximum (79.09%) and minimum (59.59%) of RWC content were showed in control plants with 2 mM concentration of salicylic acid and plant treated with 105 mM of salinity (without salicylic acid application), respectively. The MDA content maximum was found in 105 mM concentration of NaCl and 0 mM salicylic acid concentration.

The obtained results of this research, were showed that increasing salt stress, caused RWC, plant fresh and dry weight and other plant Morpho-physiological and biochemical characteristics decreased and salicylic acid using improved all growth parameters compared with salinity treatment only. Physalis does not tolerate salinity over 35 mM and it seems that sensitive to salt stress. But salicylic acid using in 2 mM somewhat can reduce the salt stress effects. The results of present study suggest that, Physalis plant not recommended for region with salt water.

In order to study the effect of slow release hydrogel-urea complex (SRHUC) on yield, yield components and physiological traits of barley under water deficit, an experiment was performed in 2017-2018 and conducted as factorial in Randomized Complete Block Design (RCBD) in three replications in greenhouse of Aburaihan campus of University of Tehran. The combination of factorial levels were as fertilization factor containing nitrogen (N) from urea source in five levels of no use of N, equivalent 125 and 65 kg.ha-1 N (without SRHUC) as CU-N125 and CU-N65 and equivalent 125 and 65 kg.ha-1 N with SRHUC as SRHUC-N125 and SRHUC-N65 and water deficit in three levels of 70, 50 and 30% of FC. Water deficit decreased yield and yield components, RWC and SPAD. The highest grain yield in a pot belonged to SRHUC-N125 (41.9 g) and there was no significant difference between CU-N125 (41.5 g) and SRHUC-N65 (39.1 g). For most of the traits, there was no significant difference between SRHUC-N125 and SRHUC-N65 and CU-N125. Under stress, utilization of SRHUC for both N amount could generate a better biological yield and SPAD index. Using N in the form of SRHUC was preferred to using of N without SRHUC, especially under stressed conditions.

To compare morphological and physiological responses of three salicornia species to NaCl concentrations, a greenhouse experiment was carried out. The factors consisted of five levels of NaCl concentrations (5, 100, 200, 400 and 600 mML-1) and three Salicornia species (Salicornia persica ، Salicornia perspolitana and Salicornia bigelovii). The results showed that, simple effects of salinity and species on proline, glycinebethein, carbohydrates, chlorophyll a, chlorophyll b, relative water content, osmotic potential in shoots, dry and fresh weights were significant. Interaction effects between salinity and species on proline, glycine betaine, carbohydrates, chlorophyll a, chlorophyll b, osmotic potential in shoots, dry and fresh weight were also significant. Carbohydrates concentration increased by 70-80% at 400 mM and then decreased from 5% to 13% at 600 mM concentration. Increasing salt concentration up to 600 mM, increased proline and glycine betaine contents. Osmotic potential was also increased by 3 to 4 times with increasing salinity levels. The chlorophyll a and chlorophyll b contents decreased at 600 mM. At 200 mM NaCl concentration, wet and dry weights were significantly increased 2 to 3 times as compared control in all of three species while at 600 mM, it was decreased by 60% to 65%. It can be concluded that with increasing salt concentration all three species tolerated higher salt concentrations throught proline and glycine-betaine accumulation and reduction of osmotic potential. S.bigelovii had the highest Na+ accumulation at 600 mM of NaCl and least accumulation of K+, Ca2+ and Mg2+. On the other hand, S.perspolitana at 600 mM NaCl concentration, had the highest accumulation of potassium, calcium and magnesium, and was superior to other species in terms of dry weight yield under salinity.

Water shortage is one of the most important limiting factors for crop production, that affected on growth by changing physiological conditions. Millet is an important plant to investigate the mechanisms of stress tolerance in plants which are relatively resistant to drought. The assimilation and dry matter production is high in this plant in dry conditions and its reason is the mechanism of condensed carbon dioxide. Chavez (2003) stated that the first plant response to stress is stomatal closure and the impact of drought on photosynthesis can be evaluated based on stomatal conductance (4,25). Relative water content is as well as an indicator of plant water status in stress conditions (22). Resistant varieties show high relative water content (27). Low electrolyte leakage indicates membrane integrity (22). electrolyte Leak and membrane lipid peroxidation are indexes of drought resistance (3).
This study was carried out in Research greenhouses of Birjand University in 2014. A factorial arrangement of treatments based on randomized complete block design (Due to the lack of uniformity of light) with four replications was used .The studied factors were drought stress with three levels including 100, 75 and 50 percent of plant water requirement (non-stress, moderate and severe stress respectively) and millet cultivar with three levels (including Bastan, promising lines KFM5 and KFM20). Relative water content, stomatal conductance, electrolyte leakage was measured in 30 and 45 day after stress and yield in maturity.
The results showed that relative water content (RWC) and stomatal conductance decreased as intensity and duration of drought stress increased in all three varieties. Membrane lipid peroxidation, permeability of membranes and electrolyte leakage increased and membrane stability decreased as intensity and duration of drought increased in all three cultivars. Drought stress reduced number of grains per panicle, seed weight and seed yield compared to control. The highest and lowest seed yield was observed in control and severe stress respectively in all three cultivars. All three variety or cultivar had similar status in stomatal conductance and leaf relative water content in 30 day after stress. Although among the varieties, Bastan had the highest stomatal conductance and was less affected under moderate and severe stress (50 and 33 percent respectively compared to control) in 45 day after stress but Bastan had an appropriate realative water content (0.43 and 0.41 respectively) and had not significantly different with other lines. The malondialdehyde content (MDA) was low in Bastan compared to other cultivars and the membrane lipid peroxidation was less affected by increasing drought stress indicating that the variety is of more potential to protect membrane integrity. Bastan indicated greater performance than the other lines, this performance was more drastically decrease compared to KFM20 line under stress treatments.
Bastan is better than the other lines and is advisable to drought stress conditions. Realative water content and stamatal conductance are mechanisms of adaptation and resistance to drought stress and Malondialdehyde is an indix of the amount of damage to the cell membrane that used in order to identify the susceptible and resistant variety to drought stress.

Rice plant requires abundant water during its growth cycle and usually faced with water deficit. Drought stress alters the allocation assimilate, root and shoot growth during the vegetative period and also lower tillering, death tillers, lower plant height and flowering delay. the aim of this study was to screen different Iranian genotypes and some lines from IRRI with identify the morphology and physiology traits such as drought tolerance mechanisms in order to select drought tolerant genotypes. Treatments (56 rice genotypes) were arranged in completely randomized block design in two growth conditions including full irrigation and drought stress at seedling stage in Rice Research Institute of Iran, Deputy of Mazandaran (Amol) in 2013. Some morphological and physiological traits including leaf relative water content (RWC), SPAD value, leaf color (LC), plant height, leaf area and number per plant, root and shoot dry weights, root length, Membrane electrolyte leakage (MEL) and pH were measured. Results showed that all traits in both well watered and stress conditions as well as genotype× environment (G*E) interaction were significantly different. In comparison with the other characters, RWC (17.3%), root dry weight (28.2%) and shoot dry weight (21.9%) were reduced while MEL (86%) was increased in stress conditions. Correlation results showed that root and shoot dry weights were significantly correlated with plant total dry weight in stress conditions. Genotypes with better performance in stress conditions were selected as drought tolerant genotypes. These genotypes are including Tarom-Mahalli, Tarom-Deylamani, Neda, Fajr, Shafagh, Tabesh, Koohsar, Gohar, Hamr, Anboori-Ghermez, Doroudzan, Zayanderoud and Firuzan from Iranian local and improved varieties as well as seven improved lines from IRRI.

In order to the study the effect of drought stress on some physiological characteristics in six Iranian pomegranate cultivars a factorial experiment was conducted based on a complete randomized design with three replications. Two factors including pomegranate cultivars (Rabab nyriz, Nadery badroud, Shyshah cap ferdous, Ardestany mahvelat, Malase yazd and Shirin shavar yazd) and irrigation levels (60% and 40% field capacity "the moderate and severe stresses, respectively" and 80% field capacity as "the control" was used and the plants were kept for six weeks. Some physiological characteristics including photosynthesis rate, evaporation rate, stomatal conductance, Intercellular CO2 concentration, leaf temperature, relative water content and leaf ion leakage in fully developed leaves were then measured. All examined cultivars had similar responses to drought stress treatments, but the intensity of these responses was different in various cultivars. According to the ultimate results, Rabab nyriz and Malase Yazd cultivars were more tolerant to drought compared to the others tolerant cultivars.Furthermore, among the cultivars studied, 'Nadery badroud was so they have been suggested as sensitive cultivar to drought stress.

Pinto bean is a susceptible plant to drought stress. However, there is genotype variation for this trait in this plant. In order to investigate the effects of drought stress on physiological traits and grain yield of pinto bean genotypes cultivated in Zanjan province, an experiment was conducted as spilt plot based on a completely randomized block design with four replications at Zanjan university research farm. Irrigation levels (control and drought stress) and genotypes (Talash, G14088, Khomein and COS16) were set in the main and subplot, respectively. Results indicated that COS16 showed maximum photosynthesis rate, cell membrane stability and relative water content under drought stress. Also, COS16 genotype exhibited the least reduction for photosynthesis rate and relative water content reduction under drought stress in comparison to control. In addition, this cultivar had maximum seed yield and minimum seed yield reduction under drought stress in comparison to control. Thus, it seems that under drought stress, cultivars with stable cell membrane will produce higher seed yield because of higher photosynthesis rate.