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

Improvement of plant tolerance to adverse environmental conditions has been proven by phytohormones in various plants species. However, the crosstalks between salicylic acid and jasmonic acid hormones under drought stress conditions have not been studied. Therefore, in this study, changes in the growth rate of aerial and underground organs as well as the proline content of aerial parts and roots of R. damacena to jasmonic acid and salicylic acid during the cource of drought stress conditions at three different times point were investigated.

Clonally propagated plants sown into plastic pots were exposed to constant water shortage at 25, 50 and 100% of field capacity for 11 days. Plants under different drought stress treatment foliar spraied with jasmonic acid (50 μM) and a combination of jasmonic (50 μM) and salicylic acid (1.5 μM). The first foliar application was performed a few days before the first day of the experiment and twice after the start of the water stress at intervals of seven days. Sampling was performed on days 1, 4 and 11 and morphophysiological responses (stem height, root fresh weight, root dry weight, Ionic leakage) and biochemical (leaf proline and root proline) were measured. The experiment was performed in factorial format and in a completely randomized block.

Regardless of hormonal treatment, the measured traits such as stem height, root fresh weight, root dry weight decreased compared to the control and other traits such as leaf and root proline, ion leakage increased compared to the control in drought stressed plants. Plants grown under 25% of FC showed a 4 fold increase in proline content when exposed to JA in contrast to that of control sprayed with distilled water after 4 days. This increase in proline content in shoots and roots was similar. However, non-drought stressed plants which were exposed to JA, did not show such changes. The results show that the combination of SA and JA reduces the amount of ion leakage of leaves and the proline content of roots and shoots by half to the amount produced in plants sprayed with distilled water at 25% of FC and this amount of proline is very close to non-drought stressed plants. The results showed that the loss of fresh and dry weight of roots, which was evident in JA–received plant under 25% of FC can potentially be reversed by combination of SA and JA. This was also truth for stem height.

The drought stress mitigation of SA by reversing JA effects manifested in mitigating cell ion leakage, and increase in root fresh and dry weight. Reducing the root and shoot proline content and leaf ion leakage in plant exposed to combination of JA and SA compared to JA alone indicated a negative regulatory effect of SA on JA on modulating leaf and shoot proline content as a physiological indicator of drought tolerance.

Drought is one of the most important factors limiting the environment for plant growth and productivity, especially in the flowering and filling stages of barley. A study was conducted to compare some statistical methods and different indicators of stress tolerance with the aim of introducing an ideal method for selecting drought tolerant lines. After wheat, barley is one of the most important crops. Barley is the fourth cereal crop in the world after wheat, corn and rice. One of the factors affecting the production of plants is water defecit, and barley has more efficient mechanisms against water shortage than other grains. Because it has higher relative drought tolerance compared to other grains. In these arid and semi-arid regions like Iran, the presence of drought stress during plant growth is a natural problem.

In this study, 18 diverse barley lines at two water levels (normal conditions and water deficit stress) were examined. This experiment was performed as a randomized complete block design with three replications at the Seed and Plant Improvement Research Institute of Karaj, Iran in 2020. Drought tolerance and susceptibility indices were assessed. These indices included stress sensitivity index, mean productivity, tolerance, stress tolerance index, geometric mean productivity, harmonic mean productivity, performance under stress conditions (Ys) and normal (Yp) conditions. Correlation coefficient between yield in drought and irrigation conditions and other stress indicators was estimated according to statistical techniques. Correlation between indices and grain yield under stress and normal conditions was calculated using Minitab software. Selection based on multiple traits in breeding programs is likely to be effective in improving grain yield under drought stress conditions. The purpose of this study is to identify the most suitable indicators and compare different stress tolerance indicators to select high-yielding and drought-tolerant lines and to identify the superior barley line.

The highest GMP and MP were related to 4 and 13 lines. Based on tolerance index (TOL), genotype 1 had the lowest and line 7 showed the highest level of tolerance, respectively. Based on MP and GMP indices, 4, 7 and 13 lines had high drought tolerance. A high positive and significant correlation was observed between MP, GMP, Ys, Yp, which indicates that these indices are suitable for identifying drought tolerant lines. Based on the results of the principal component analysis and the bi-plot diagram, it was observed that the lines tolerant to drought stress are almost consistent with the clustering pattern of tolerant lines and the lines sensitive to drought stress are also consistent with the clustering of sensitive lines. MP and GMP indices are suitable for evaluating drought tolerance because they showed a high correlation with grain yield under normal conditions and under water stress. The closeness of 4 and 13 lines to GMP, MP, HARM, Ys indicates the tolerance of these lines to drought stress and therefore they can be suggested as drought tolerant lines.

Selection of drought tolerant lines based on a combination of tolerance indices can provide useful criteria for drought tolerance. A high positive and significant correlation was observed between MP, GMP, Ys, Yp, which indicates that these indices are suitable for identifying drought tolerant lines. These results help the modifier to select lines in different environments. Principal component analysis showed that it is important to introduce genotypes with desirable traits such as genotypes with high yield and resistance to drought stress. It is possible to speed up the improvement of new barley cultivars by using stress tolerance indicators by breeders. In general, 4, 7, and 13 lines were drought tolerant and can be used for barley improvement programs. Based on principal component analysis, drought sensitive and tolerant lines were consistent with cluster analysis. Exploiting the results of the present study can help breeders to select and identify genotypes that have relative tolerance to drought stress.

In order to study the effect of nitrogen fertilizer treatments on yield traits, essence percentage, and the amount of nitrogen in cumin stem and leaves under different irrigation regimens, an experiment has been conducted as split plot based on randomized complete block design with three replications in the 2016-2017 crop season at the Research Field of Agriculture Faculty, Shahed University, Tehran, Iran. In this experiment, the main plot is consisted of different irrigation regimes at three levels (no stress, mild stress or irrigation based on draining 40% of available water, and severe stress or irrigation based on draining 80% of available water) and the subplot includes four levels of nitrogen fertilizer treatments (100% and 50% fertilizer recommendation of nitrogen (urea), seed stained biofertilizer application (Nitroxin), and combination treatment of biofertilizer and 50% fertilizer recommendation nitrogen). The results show that increasing deficit irrigation at a mild level and, above that, at a severe level, while increasing the percentage of essence, has had a significant negative effect on yield and yield components, total chlorophyll, shoot nitrogen concentration, and essence yield. Application of combination nitrogen fertilizer (urea + Nitroxin) while increasing the yield and yield components of Cumin, increase the percentage and yield of essence, and shoot nitrogen concentration, generally causing the most desirable quantitative and qualitative yield of Cumin.

In many parts of the world where agriculture is important, crops usually encounter a large variation in water supply during their growing seasons. Thus, water deficit is a major constraint to crop production, even in humid environments (Soltani and Sinclair, 2012). In the context of improving water use efficiency (WUE), there is growing interest in deficit irrigation which involves applying stress levels to plants that have minimal effects on yields in order to optimize yields per unit of water used as well as crop returns increment (Rodrigues and Pereira 2009). One of the planting date goals is to detect the time after which crops could be able to keep immune even versus adverse climatic conditions Berzsenyi & Lap (2005). Arid and Semi-arid climate in the most parts of Iran with limited water resources highlights applying adaptive methods as well as new approaches to support crop producers in selecting proper varieties, accurate planting date and using water in an optimum way to maximize productivity and returns.

In order to probe those of agronomic traits contributing to final yield and detecting susceptible growth stages of corn to water stress a field study took place in research farm of College of Agriculture and Natural Resources, University of Tehran. Considering irrigation management and planting date as adaptive techniques and due to the rating of relative maturity (RM) of maize hybrids, (S.C. 704) selected as late-maturing hybrid in this experiment. The experiment implemented in split-plot template based on randomized complete block design with three replicates in 2015 and 2016 cropping seasons. The experimental treatments consist of three planting dates, (PD1: 21st April, PD2: 11th May and PD3: 31st May) assigned to main plots and four irrigation treatments, (100%ETc, 80%ETc, 60%ETc and 40%ETc) of the estimated evapotranspiration (ET) placed in sub plots.

The lower of grain yield (4150.30 and 3589.60 kg ha-1) and less total biomass (14354.60 and 13563.90 kg ha-1) resulted in stress treatment of 40%ETc respectively in 2015 and 2016. The highest values of irrigation water use efficiency based either on grain yield (1.39 and 1.20) or total biomass (4.79 and 4.53) were culminated in 40%ETc treatment for the period of two years respectively. It seems that in the presence of deficit irrigation plant capability in converting per unit of water to biomass will be improved through transpiration. Our results corroborated by those of Chaichi et al. (2015) who issued stepwise reduction for ear yield, total dry matter and grain yield in stress treatment as ETc decreased. Also lower rates of harvest index (28.76 and 26.34%) also recorded at 40%ETc treatment in both years respectively. Similar results revealed by Farré and Faci (2006) who found that HI decreased markedly with increasing water stress. The lower values of grain yield and total biomass obtained at the later-planted corns due to coincidence of pollination phase with the higher levels of temperature and evapotranspiration in mid and late planting dates (PD2 and PD3).

In fact crops planted earlier in the season tend to develop more gradually, under cooler temperatures with enough accessibility to more abundant soil water supplies and nitrogen availability. In this experiment, water stress during pollination time affected corns under common planting date (PD2). However, as the tail-end maturation of later-planted corns (PD3) approach cooler temperatures of early autumn, due to rapid loss of leaves there is less time for them to compensate yield losses and generally results in lower overall productivity. To help farmers for applying water more efficiently, they must pay attention to align planting date and applied hybrid with local agro-ecological endowments to avoid of irrigations that are surplus to requirements.

IntroductionThe dry and semi-arid climate of the country has become inevitable the cultivation and production of crops under the conditions of environmental stresses (drought, salinity and heat).Crops are show different reactions against these stresses. The occurrence of any of the stresses, or a combination of them, leads to a reduction in production. Sugar beet is one of the plants that tolerates these stresses. The aim of this research was to determine the tolerance of sugar beet S1 pollinator lines to drought stress in field conditions in terms of yield and physiological traits so that based on the results, a model could be presented for better and more effective management of water on farms. Materials and methods This experiment was conducted to evaluate the physiological characteristics of 34 sugar beet genotypes (30 S1 pollinator lines with three controls including Shokoofa, Motahar and Paya and Origin population) under normal irrigation and drought stress conditions in a Randomized Complete Block Design with three replications at experimental field of Khorasan Razavi Agricultural and Natural Resources Research and Education Center in 2016. Irrigation was done routinely up to the thinning and weeding stage. Subsequent irrigations were done after 90 mm and 200 mm evaporation from the class A evaporation pan in non-stress and stress conditions, respectively. In this research, traits such as root yield, sugar content, sugar yield, chlorophyll, Normalized Difference Vegetation Index (NDVI), Leaf Area Index (LAI), Index of difference between the temperature of environment and leaf, leaf relative water content, specific leaf weight, succulence index, specific leaf area and electrolyte leakage were measured. Analysis of variance and estimation of correlations were performed with SAS 9.1 software and also factor analysis was done using Statgraphics 18 software. Results and discussionResults showed that in both conditions (non-stress and drought stress conditions) there are significant different (p≤0.01) between all genotypes for all traits. Combined analysis of variance showed that there was a significant difference (p≤0.01) among studied genotypes and different irrigation regimes in the most traits. In normal irrigation and drought stress conditions, Motahar and S1-15 line had the highest sugar yield (9.09 and 10.5 ton/ha), respectively. Correlation coefficients showed that root yield had a positive and significant correlation with sugar yield and NDVI in normal and stress conditions. In both conditions (non-stress and drought stress conditions), factor analysis led to introduce four main factors which explained 69.55 and 74.75 percent of total variation, respectively. ConclusionsIn general, the results showed that there are considerable variations in yield and physiological traits among the different genotypes of sugar beet due to the potential for drought tolerance in them.

Water stress is the most important abiotic stress in crop production. Silicium (Si) is the second most abundant element in the soil with beneficial effects on plant tolerance to biotic and abiotic stresses. In order to evaluate the effect of this element in increasing tolerance to water deficit in wheat, a factorial experiment was conducted based on a completely randomized design with three replications in the greenhouse of College of Agriculture, Shiraz University, Shiraz, Iran. Treatments included four wheat cultivars, Shiraz, Sirvan, Ofogh, Baharan, foliar silicon application in two-levels, zero (control), and 3 mM, and three levels of water deficit (field capacity, 40% and 60% of field capacity). The results showed that water deficit reduced spike length (31%), dry matter per plant (41%), grain yield (25%), greenness index (11%), flag leaf relative water content (24%), catalase (24%), peroxidase (70%) and superoxide dismutase activity (41%). Baharan and Sirvan cultivars were superior for greenness index and peroxidase activity. However, foliar silicon application at 3 mM concentration ameliorated the negative impacts of water deficit stress. Foliar application of silicon enhanced all the above parameters including antioxidants. For a majority of the measured characteristics, it was evident that Baharan and Sirvan, as water deficit tolerant cultivars, and Ofogh, were superior compared to Shiraz cultivar. The results showed that foliar application of silicon increased the activity of antioxidant enzymes and as a result ameliorated the negative impacts of water stress.

IntroductionRapid population growth in developing countries have resulted to adverse effect such as food shortages and malnutrition. Lack of protein in the diet is accounted for the largest portion. Pulses with high amounts of protein are the second largest source of food after cereals. Among pulses, beans as a supplier of plant proteins in many countries, particularly developing countries has high consumption. Area under cultivation of bean is 240000 hectares with an average yield of 1500 kg per hectare in Iran. In arid and semi-arid area due to excessive exploitation of water resources, the water shortage is constantly evolving and according to the climatic conditions that are considered hot and dry, and sensitivity of bean to drought further research in this field is clear. Humic acid is extracted from different sources, such as humus and, soil and using chelating essential elements improve and increase fertility and productivity of soil, especially in conditions of stress. As we mentioned before, purpose of this study was evaluating effect of water stress and use of humic acid on agronomic, physiological and quality traits.
Materials & MethodsThis experiment was performed at agricultural Research Station in Arak, Iran in 2014. The experiment was performed in split plot arangment based on randomized complete block design with three replications. The main factor was irrigation hold at 3 levels: complete irrigation (control), irrigation hold at flowering stage and irrigation hold at pod stage and sub factor was humic acid foliar application in three levels of non humic acid application (control), 1.5 and 3 liters per hectare humic acid 12% at pre flower satage and pod stges applications. In this study the red bean seed was from D81083 cultivar. In this study, biological yield, grain yield, number of seeds per pod, number of pods per plant, harvest index, seed weight, chlorophyll a, b and a content, RWC, iron, zinc and protein contents in grains and also, leaf electrolyte electrical conductivity were measured. Analysis of data was done with SAS software and comparisons of means were performed with Duncans multiple range test at 0.05 statistically significant level.
Results & DiscussionMean comparison of irrigation treatment indicated that the highest seed yield was in complete irrigation and hold irrigation at pod stage and lowest rate was for hold irrigation at flowering stage. In this experiment, use of humic acid in normal conditions and in conditions of hold irrigation at flowering and pod stage could be increase the yield. The highest harvest index was in complete irrigation and hold irrigation at pod stage. The results showed that the highest 100 seed weight was from control and hold irrigation at pod stage treatment and the least weight was from hold irrigation at flowering stage which shows the sensitive stage for bean is cut-irrigation at flowering stage and maybe the need for water is low in pod stage. Among yield components, seeds per pod had significant correlation with yield. The highest number of pods per plant during irrigation hold was at flowering stage and control treatment and irrigation hold at pod stage had the lowest rate of pods per plant. Most of seed protein obtained from hold irrigation at flowering stage and the lowest amount of it was in hold irrigation at pod stage. The effect of hold irrigation and the effect of humic acid opplication was as well as the interaction bouth. There were significant differences on levels of iron and zinc in seeds. The highest amount of chlorophyll a, b and a were in hold irrigation at flowering stage. The effect of 3.5 liter per hectare foliar application of humic acid could be increase total chlorophyll. Hold Irrigation treatment also had a significant effect on the leaf relative water content in pod stage.
ConclusionThe results showed that the irrigation hold had significant effect on all studied traits. Generally, the highest and lowest yield was related to complete irrigation treatment but in some cases the hold irrigation at flowering stage was the same result. The effect of hold irrigation at pod stage was the same as complete irrigation treatment which this point can be used in saving water. Also, Spraying with different amounts of humic acid showed that the humic acid improved the agronomic characteristics and quality of the beans in range of 1.5 litter per ha. Therefore, Using of humic acid may improve agronomic, qualitative and physiological characteristics of red bean.

To study the effects of mycorrhizal inoculation of fenugreek (Trigonella foenum-graecum L.) plants and on its growth and yield under drought stress conditions a greenhouse experiment was carried out in split plot using a randomized complete block design at Zabol University green house in 2013. Treatments were three drought stresses: control, mild stress and severe stress (70, 50 and 30% FC) assigned to main plots, and three species of mycorrhizal treatments (Glomus intraradices, G. versiform, G. mosseae and non-inoculation as control) to sub-plots. The effects of drought on all traits under study were significant, and reduced number of leaves per plant, plant height, root length, chlorophyll b and total chlorophyll by 15.6, 7.6, 10.7, 2.5 and 8.4 % and increased proline and carbohydrates by 38.6 and 17.7 % as compared with the control. Mycorrhizal treatments did not affect the amount of carbohydrates and proline content significantly. Interaction of mycorrhiza and drought stress was significant on grain yield, chlorophyll a and total chlorophyll. Among the mycorrhizal strains G. mosseae affected the traits significantly under drought conditions. The results suggested that mycorrhizal treatments of plants at different drought stresses could improve grain yield of fenugreek and reduce the negative effects of drought by increasing photosynthetic pigments and other quantitative and qualitative traits.

This study was conducted to determine the effect of Cliniptilolite natural Zeolite on deficit irrigation stress tolerance on maize cultivar KSC704. The experiment was laid out as a factorial design based on randomized complete block with three replications at Seed and Plant Improvement Institute, Karaj in 2012. Four Irrigation levels, including Irrigation after 70, 95, 120 and 145 mm cumulative evaporation from evaporation pan class A and three zeolite levels including control, 6 and 12 ton /ha were considered as the factors. The effect of irrigation was significant (p< 0.01) for days to silking, ASI, ear height, and grain yield and it was also significant (p< 0.05) for days to anthesis, plant height, ear diameter, number of ears and 1000-kernel weight. The using zeolite was significant for 1000 kernels weight and it was significant (p< 0.05) for ASI, ear height and grain yield. The maximum yield obtained from normal irrigation and using zeolite 12 ton /ha (7352 and 6134.1 kg / hectare respectively). From the result of this experiment for the maximum grain yield in available water condition for maize cultivar KSC704 irrigation after 70 mm evaporation from evaporation pan can be recommended and this contrition using natural zeolite is not necessary. But in water deficit condition, irrigation after 95 mm evaporation from evaporation pan and using zeolite 12 ton per hectare can be recommended. More deficit irrigation will decrease grain yield significantly.