Harmful Effects Of Drought Stress Research Articles

Foliar Application of Growth Regulators Mitigates Harmful Effects of Drought Stress and Improves Seed Yield and Oil Quality of Rapeseed (Brassica napus L.)

Foliar Application of Growth Regulators Mitigates Harmful Effects of Drought Stress and Improves Seed Yield and Oil Quality of Rapeseed (Brassica napus L.)

Exogenous α-Tocopherol Regulates the Growth and Metabolism of Eggplant (Solanum melongena L.) under Drought Stress.

The present investigation was designed to improve drought stress tolerance in eggplant (Solanum melongena L.) through the exogenous application of α-tocopherol (TOC). For exogenous application, two modes, i.e., foliar spray (FS) and pre-sowing seed treatment (PS), were used. Water deficiency treatment (50% field capacity (FC)) was applied on 32-day-old seedlings of two eggplant cultivars, i.e., Janak and Black Beauty. Five levels of TOC (0 mg/L, 50 mg/L PS, 100 mg/L PS, 50 mg/L FS, and 100 mg/L FS) were applied as PS and FS. Pre-sowing seed treatment was conducted before seed sowing, while FS treatment after 30 days of drought stress treatment. After 15 days of TOC as an FS application, it was observed that drought stress significantly reduced plant growth (5-15%) and chlorophyll contents (4-10%), while it increased proline (4-6%), glycine betaine (GB) (5-10%), malondialdehyde (MDA) (10.8%), hydrogen peroxide (15-16%), relative membrane permeability (RMP) (5-8%), and the activities of peroxidase (7-8%) and superoxide dismutase (12-15%) in both eggplant cultivars. The TOC application (FS and PS) exhibited a positive role in overcoming the adverse effect of water stress on eggplants. Plant growth increased (15-18%) as a result of the application of TOC, which could be linked with improved chlorophyll, ascorbic acid (AsA), GB, proline, total soluble proteins (TSP), and the activities of peroxidase (POD) and superoxide dismutase (SOD) activities. The reactive oxygen species H2O2 was also decreased by TOC application. Overall, TOC as a foliar spray was more effective in improving the accumulation of proline, GB, AsA, and activities of SOD and POD enzymes, while PS treatment was more effective in reducing RMP and improving the TSP of eggplant. Cv. Black Beauty was comparatively better in root dry weight, chlorophyll a and b, and MDA contents, while cv. Janak in RMP, AsA, TSP, and activity of the POD enzyme. It can be inferred that the application of TOC was useful in counteracting the harmful effects of drought stress on both cultivars of eggplants.

Investigating Iron Oxide Nanoparticles and Piriformospora indica Roles in Mitigating the Harmful Effects of Drought Stress in Soybean: Antioxidant Enzymes and Oil Content

Drought stress is one of the most important environmental stresses that affects the quantity and quality of soybean production. This study was conducted to explore the role of iron oxide nanoparticles (NPs) application and Piriformospora indica inoculation in alleviating the adversities of drought stress on fatty acid composition and oil production in soybean. The results showed that seed oil synthesis was considerably reduced by drought stress, whereas the membrane lipid peroxidation was accelerated under drought stress condition. The applied NPs (especially 0.75g L-1 ) and P. indica enhanced the activities of enzymatic antioxidants (SOD, CAT, PPO and APX) with simultaneous decrease in malondialdehyde. Under drought stress, an inverse relationship between protein and seed oil was observed, as by increasing protein content, seed oil decreased linearly. In addition, the main oil constituents, oleic and stearic acids increased, while linoleic, linolenic and palmitic acids reached to the lowest level in severe drought stress (FC 20%). Interestingly, the beneficial effects of NPs and P. indica led to improvement in grain weight, fatty acid composition and oil content under drought stress. During drought stress, oleic, linoleic, linolenic and palmitic acids increased and stearic acid decreased considerably in P. indica and NPs treatments. However, combined NPs and P. indica was generally more effective in alleviation of drought stress deleterious effects than individual treatments.

A Comparison of the Effects of Rhizophagus Intraradices, Serendipita Indica, and Pseudomonas Fluorescens on Soil and Zea Maize L. Properties under Drought Stress Condition

Drought is one of the most critical environmental stresses that reduce agricultural production. This study aimed to examine the effects of individual and simultaneous inoculation of Rhizophagus intraradices, Serendipita indica, and Pseudomonas fluorescens on the physical properties of soil and the growth parameters of single cross 704 maize under three levels of drought stress (80%, 50%, and 25% available water). It was found that Rhizophagus intraradices significantly increased soil hydrophobicity at all levels of drought stress, as did Serendipita indica at the second and third levels. Pseudomonas fluorescens, on the other hand, decreased soil hydrophobicity at all drought levels. At the optimum moisture level, individual inoculations of the investigated microorganisms did not significantly affect mean weight diameter, but all studied microorganisms increased mean weight diameter as drought stress increased. Additionally, inoculating plants with Rhizophagus intraradices at all levels of drought stress significantly increased the dry and fresh weight of shoots. Nevertheless, inoculating plants with Rhizophagus intraradices and Pseudomonas fluorescens at all levels of drought stress led to a significant increase in plant shoot height. Plant shoot potassium concentrations were significantly reduced by individual inoculation of Pseudomonas fluorescens and Serendipita indica under drought stress at the first and third levels. However, at all drought stress levels, inoculating plants with Rhizophagus intraradices significantly increased phosphorus concentrations in the shoots. Based on the results of this study, simultaneous insemination of maize with Rhizophagus intraradices and Serendipita indica was the most effective microorganism treatment for reducing the harmful effects of drought stress and improving soil properties.

Plant Growth-Promoting Rhizobacteria Eliminate the Effect of Drought Stress in Plants: A Review.

Plants evolve diverse mechanisms to eliminate the drastic effect of biotic and abiotic stresses. Drought is the most hazardous abiotic stress causing huge losses to crop yield worldwide. Osmotic stress decreases relative water and chlorophyll content and increases the accumulation of osmolytes, epicuticular wax content, antioxidant enzymatic activities, reactive oxygen species, secondary metabolites, membrane lipid peroxidation, and abscisic acid. Plant growth-promoting rhizobacteria (PGPR) eliminate the effect of drought stress by altering root morphology, regulating the stress-responsive genes, producing phytohormones, osmolytes, siderophores, volatile organic compounds, and exopolysaccharides, and improving the 1-aminocyclopropane-1-carboxylate deaminase activities. The use of PGPR is an alternative approach to traditional breeding and biotechnology for enhancing crop productivity. Hence, that can promote drought tolerance in important agricultural crops and could be used to minimize crop losses under limited water conditions. This review deals with recent progress on the use of PGPR to eliminate the harmful effects of drought stress in traditional agriculture crops.

Spermine reduces the harmful effects of drought stress in Tropaeolum majus

Drought stress is one of the main causes of low crop productivity due to disturbances in plant growth, physiology and biochemical processes. Spermine application is an alternative to mitigate the harmful effects of this stress on plants. Nasturtium (Tropaeolum majus L.) is an ornamental, medicinal and edible plant cultivated and consumed in several countries. This plant has medicinal properties (among them the presence of glucosinolates and phenolic compounds), in addition to being appreciated in cooking. Thus, the objective of this work was to evaluate the effects of spermine application on growth, gas exchange and antioxidant metabolism of T. majus grown under drought stress. Growth (stem diameter, number of leaves, number of flowers, number of buds, total dry mass and leaf area), gas exchange (gs, A, E and Ci), relative water content, free amino acids, phenolic compounds, reducing and non-reducing sugars, lipid peroxidation and enzymatic activity (CAT, POD and APX) were evaluated. Spermine reduced the harmful effects of severe drought stress on the relative water content, reducing sugars and non-reducing sugars. Spermine reduced the harmful effects of moderate drought stress on the relative water content, amino acids, reducing sugars and non-reducing sugars. Spermine application decreased lipid peroxidation (MDA) of T. majus under severe and moderate drought stress and in plants without stress. Spermine increased the activity of POD and APX in plants under severe drought stress and of CAT, POD and APX in plants under moderate drought stress. Spermine application increases the drought tolerance of T. majus by increasing morphology, gas exchange, relative water content, amino acids, reducing and non-reducing sugars, CAT, POD and APX enzymes, and decreasing lipid peroxidation. Spermine (1 mM) can be used to mitigate the harmful effects of drought stress in T. majus.

Grain-Priming with L-Arginine Improves the Growth Performance of Wheat (Triticum aestivum L.) Plants under Drought Stress

Drought is the main limiting abiotic environmental stress worldwide. Water scarcity restricts the growth, development, and productivity of crops. Wheat (Triticum aestivum L.) is a fundamentally cultivated cereal crop. This study aimed to evaluate the effect of grain-priming with arginine (0.25, 0.5, and 1 mM) on growth performance and some physiological aspects of wheat plants under normal or drought-stressed conditions. Morphological growth parameters, photosynthetic pigments, soluble sugars, free amino acids, proline, total phenols, flavonoids, and proteins profiles were determined. Drought stress lowered plant growth parameters and chlorophyll a and b contents while increasing carotenoids, soluble sugars, free amino acids, proline, total phenols, and flavonoids. Soaking wheat grains with arginine (0.25, 0.5, and 1 mM) improves plant growth and mitigates the harmful effects of drought stress. The most effective treatment to alleviate the effects of drought stress on wheat plants was (1 mM) arginine, that increased root length (48.3%), leaves number (136%), shoot fresh weight (110.5%), root fresh weight (110.8%), root dry weight (107.7%), chlorophyll a (11.4%), chlorophyll b (38.7%), and carotenoids content (41.9%) compared to the corresponding control values. Arginine enhanced the synthesis of soluble sugars, proline, free amino acids, phenols, and flavonoids in wheat plants under normal or stressed conditions. Furthermore, the protein profile varies in response to drought stress and arginine pretreatments. Ultimately, pretreatment with arginine had a powerful potential to face the impacts of drought stress on wheat plants by promoting physiological and metabolic aspects.

Effect of the Application of Foliar Jasmonic Acid and Drought Stress on Grain Yield and Some Physiological and Biochemical Characteristics of Chenopodium quinoa Cultivars

Water shortage is a critical problem touching plant growth and yield in arid and semi-arid areas such as Iran. Plant hormones such as jasmonic acid (JA) play a crucial role in altering plant morphology in response to stress. To investigate the effect of JA and drought stress on grain yield and some physiological and biochemical characteristics of quinoa cultivars, a split-plot factorial experiment based on randomized complete block design with three replications was conducted at Kerman Agricultural and Natural Resources Research and Education Center over two crop years (2018-2019). In this experiment, drought stress as the main factor in two levels including non-stress and stress based on 60% and 90% soil available moisture depletion and JA foliar application (0, 1 and 2 mg L-1) and cultivars (Giza1, Titicaca, Q29) respectively, as factorial were sub factor. The maximum grain yield (3775 kg ha-1) was obtained in Giza1 cultivar under non-stress condition and 1 mg L-1 JA foliar application. The greatest grain protein and total chlorophyll content were obtained in Titicaca cultivar under non-stress and 1 mg L-1 JA foliar application by 18.17% and 1.83 mg g-1 fresh leaf weight, respectively. In the opposite trend, the maximum amount of malondialdehyde was observed under drought stress and non-use of JA. In general, given the results of this study, it can be stated that JA caused an increase in grain yield in quinoa cultivars by reducing the harmful effects of drought stress and improving plant growth.

Spermine Reduces the Harmful Effects of Drought Stress in Tropaeolum Majus

Spermine Reduces the Harmful Effects of Drought Stress in Tropaeolum Majus

Seed germination and physiological responses of quinoa to selenium priming under drought stress

The early stages of quinoa germination are sensitive to drought stress. For this purpose, a study entitled the effect of selenium in different concentrations on germination characteristics and some antioxidant enzymes of quinoa under drought stress conditions with polyethylene glycol (PEG 6000) was investigated. The first experimental factor was seed priming with selenium (from two sources: sodium selenate and selenium nanoparticles: SeNPs ? 33.4 nm) at 0.5, 1.5, 3, 4.5, 6 mg·L?1 concentrations, besides, no priming treatment was used as control. The second factor was drought stress with PEG 6000 in concentrations 0, –0.4, –0.8, and –1.2 MPa. Drought stress with accumulation of reactive oxygen species (ROS) had a negative effect on most of the measured traits. In seeds that were primed with appropriate selenium concentrations, germination parameters and antioxidant enzyme activity as well as proline and protein content increased compared to the control treatment. Under conditions of severe stress (–1.2 MPa), the highest activity of catalase (CAT), superoxide dismutase (SOD), and ascorbate peroxidase (APX) enzymes was observed in prime with selenium nanoparticles at concentrations of 4.5, 6.0 and 4.5 mg·L?1, respectively. Concentrations higher than 3 mg·L?1 of selenium nanoparticles and concentrations of 3 mg·L?1 sodium selenate had the highest accumulation of photosynthetic pigments under control (stress-free) conditions. The present study shows that selenium priming can reduce the harmful effects of drought stress on quinoa by altering germination properties and biochemical properties.

The application of biochar alleviated the adverse effects of drought on the growth, physiology, yield and quality of rapeseed through regulation of soil status and nutrients availability

The depletion of soil fertility and freshwater reservoirs in dry and arid conditions of the world are alarming for food and crop productivity. Although many research studies have explored the effect of biochar on plant growth and soil fertility, however, information on the role of biochar on rapeseed under drought stress is limited. The current study was conducted to investigate the effect of biochar on photosynthesis, antioxidants activities, osmolytes contents, growth and yield of rapeseed under drought stress. Rapeseed plants at the flowering stage were subjected to two moisture conditions, no stress (NS) and drought stress (DS) along with four biochar treatments (B0:0, B15:15, B30:30 and B60:60 t ha−1). Drought stress negatively affected rapeseed growth due to the over-production of hydrogen peroxide (H2O2) by increasing 45 %, malondialdehyde (MDA) 21 % and electrolyte leakage (EL%) 40 % in (BO + DS) treatment as compared to control (BO + NS). However, the addition of biochar at 30 t ha−1 alleviated the hostile effects of drought stress in rapeseed to reduce the contents of MDA, H2O2, EL by increasing the activities of superoxide dismutase (SOD) by 63 %, peroxidase (POD) 48 %, and catalase (CAT) 62 % compared to stress-controlled treatment (BO + DS). The results revealed that biochar could alleviate the harmful effects of drought stress by enhancing the activities of antioxidants, osmoprotectants, soil fertility, and the physiological processes of rapeseed which indicate that the biochar application might be a sustainable strategy to enhance rapeseed growth under drought stress.

The role of ACC deaminase producing bacteria in improving sweet corn (Zea mays L. var saccharata) productivity under limited availability of irrigation water

Accumulation of stress ethylene in plants due to osmotic stress is a major challenge for the achievement of optimum sweet corn crop yield with limited availability of irrigation water. A significant increase in earth’s temperature is also making the conditions more crucial regarding the availability of ample quantity of irrigation water for crops production. Plant growth promoting rhizobacteria (PGPR) can play an imperative role in this regard. Inoculation of rhizobacteria can provide resistance and adaptability to crops against osmotic stress. In addition, these rhizobacteria also have potential to solve future food security issues. That's why the current study was planned to examine the efficacious functioning of Pseudomonas fluorescens strains on yields and physiological characteristics of sweet corn (Zea mays L. var saccharata) under different levels of irrigation. Three irrigation levels i.e., 100% (I100 no stress), 80% (I80), and 60% (I60) were used during sweet corn cultivation. However, there were four rhizobacteria strains i.e., P. fluorescens P1, P. fluorescens P3, P. fluorescens P8, P. fluorescens P14 which were used in the experiment. The results showed that severe water stress (60% of plant water requirement) decreased chlorophyll a, chlorophyll b, and total chlorophyll contents, Fv/Fm ratio and nutrients uptake. A significant increase in F0, Fm, proline, total soluble sugars, catalase (CAT) and peroxidase (POX) activity led to less ear yield and canned seed yield. Combination of four strains significantly increased the yield traits of sweet corn i.e., ear and (44%) and canned seed yield (27%) over control. The highest promoting effect was observed in the combination of four strains treatment and followed by P1 strain in reducing the harmful effects of drought stress and improving sweet corn productivity. However, P14 gave minimum improvement in growth and yield indices under limited availability of water. In conclusion, combination of four strains inoculation is an efficacious approach for the achievement of better yield of sweet corn under osmotic stress.

Mitigating the Harmful Effects of Water Deficiency Stress on White Lupine (Lupinus albus L.) Plants by Using Algae Extract and Hydrogen Peroxide. تخفیف الآثار الضارة الناتجة عن اجهاد نقص المیاه على نباتات الترمس الأبیض باستخدام مستخلص الطحالب وفوق اکسید الهیدروجین.

Water deficit is a major growth limitation factor affecting plant growth and productivity. To counteract the harmful effects of drought stress, lupine plants were sprayed with two concentrations of algae extract (1 g L-1 and 2 g L-1) and hydrogen peroxide solution (0.5% and 1%) under low irrigation level. Morphological, physiological and anatomical studies were performed. It was found that all treatments enhanced plant height, root length, number of leaves, average leaf area, shoot and root fresh and dry weights. A significant increment in chlorophyll a and b, carotenoids and total pigments contents, as well as a significant decrease in electrolyte leakage was noted in treated plants compared with untreated under water deficit. Increment in levels of osmoprotectants such as proline, total free amino acids, glycine betaine and total soluble sugars contents was highly significant in case of 2 g L-1 algae extract treatment compared with untreated plants group. Anatomical studies of root, stem and leaf of treated and untreated plants revealed that 2 g L-1 algae extract treatment followed with 0.5% H2O2 induced significant increments in the thickness of the studied plant organs compared with the untreated plants under water deficit conditions. In general, the concentrations of 2 g L-1 algae extract and 0.5% H2O2 were the most effective doses regarding all the studied characteristics.

Yeast Extract and Lithovit Mineral Fertilizer Ameliorate the Harmful Effects of Drought Stress in Wheat

THE effects of two levels of drought stress (25% and 50% of FC) and the control (75% FC) on the growth, some physiological processes and some metabolites in wheat (Triticum aestivum, cv. Masr 2) at seedling (30 days), vegetative (65 days) and yield (160 days) stages were studied. The ameliorative effects of the foliar spray for the harmful effects of drought by the bio-stimulant yeast extract (10%) or the mineral fertilizer lithovit (3.8%) were also studied. The results showed that both levels of drought stress decreased all of the measured growth criteria and chl a and chl b at both growth stages. The foliar spray with yeast extract or lithovit resulted in the alleviation of these inhibitory effects. Carotenoids increased with drought stress but decreased using both foliar spray treatments. Carbohydrates and total soluble proteins decreased under both drought levels, but using yeast extract or lithovit treatment alleviated these effects. Higher activities of catalase, peroxidase and ascorbic oxidase were recorded under the two stress levels, while yeast extract and lithovit treatments inhibited them. At yield stage, both drought levels resulted in severe reduction in all yield parameters, carbohydrates and total soluble proteins contents in the produced grains. Foliar spray with yeast extract or lithovit improved all the measured parameters of yield and increased the contents of the metabolites in the grains. Although lithovit was slightly more effective than yeast extract, the latter treatment seems preferable as it is a natural product with no apparent residual effects on plants and soil.

Growth and Physiological Responses of Vegetable Crops to Water Deficit Stress

Future climate change scenarios have become a major threat and limitation for global food production. The rise in greenhouse gases and temperature throughout the globe has caused perturbance in the natural seasonal cycles. This causes a threat to nutritional and calorific food security for the ever-increasing population in the South Asian Countries. Reduction in the amounts of rainfall in the tropics and subtropics has increased the occurrence of drought leading to more frequent water stress affecting the production of crops, including vegetables, which are predominantly grown in the tropical and sub-tropical regions. India is the second-largest producer of vegetables in the world and heavy consumer of vegetables. The mini-review focused on drought stress effects on the vegetable production and photosynthesis, transpiration, water uptake and other metabolic and developmental processes. Grafting, breeding, cultural and biotechnological strategies are used to combat drought stress and will be used in the future to ease the harmful effects of drought stress.

Mitigation of water deficit stress in Dracocephalum moldavica by symbiotic association with soil microorganisms

Symbiotic association with soil microorganisms (plant growth-promoting rhizobacteria (PGPR) and/or arbuscular mycorrhizal fungus (AM)) can help plants to cope with drought stress. The goal of the present study was to consider the effects of Micrococcus yunnanensis (PGPR) and Claroideoglomus etunicatum (AM) under drought stress on growth, mineral nutrients uptake, and secondary metabolites of D. moldavica, as a sensitive plant to water deficit. Experiments were carried out as factorial completely randomized design consisting of three factors, PGPR, AM, and irrigation levels (100, 85, 70, 55, 40, and 25 % field capacity). The results showed that PGPR and AM stimulated plant growth significantly and increased photosynthetic pigment contents of leaves. Higher uptake of nutrient elements partly improved plant growth and dry matter production upon symbiotic associations. Despite a significant increase in the soluble sugars and proline contents under water deficit stress, symbiosis significantly decreased the amounts of those compounds. Drought stress alone elevated plant antioxidant capacity and total phenolic content, but they were decreased in plants inoculated with PGPR and AM. Also, co-inoculation increased the contents of hesperetin, eugenol, p-coumaric acid, and these effects were more pronounced under moderate drought stress than other conditions for hesperetin and p-coumaric acid accumulation. Significantly, higher content of rosmarinic acid was found under drought stress, but inoculations significantly decreased the concentrations of this compound. Overall, these results showed a successful coexistence of soil microorganisms (PGPR and AM) with D. moldavica alleviates the harmful effects of drought stress through higher mineral nutrient uptake as well as secondary metabolites and photosynthetic pigments contents.

LED light mediates phenolic accumulation and enhances antioxidant activity in Melissa officinalis L. under drought stress condition.

The popularity of lemon balm in conventional medicine is suggested by the existence of two groups of compounds, namely essential oil and phenylpropanoids pathway derivatives. One of the promising approaches to improve tolerance to drought stress inducedoxidative damage in seedlings grownin greenhouses and plant growth chambers is replacing the traditional and high-cost light technologies by recently developed light emitting diodes (LED). In this experiment, we analyzed the role of various LED lights including red (R), blue (B), red (70%) + blue (30%) (RB), and white (W) as well as normalgreenhouse light(as control) to stimulate defense mechanisms against drought stress in two genotypes of Melissa officinalis L. The present study demonstrates that pre-treatment with LEDs with high-intensity output for 4weeks alleviated harmful effects of drought stress in the two genotypes. Under drought stress, RB LED pre-treated plantlets of the two genotypes exhibited the highest relative growth index of shoot and root and total phenolic and anthocyanin content compared to those irradiated with other LEDs and greenhouse lights. The highest amount of malondialdehyde level was detected in R LED exposed plants. In response to drought, LED-exposed plants especially RB light-irradiated plants of the two genotypes maintained significantly higher antioxidant and phenylalanine ammonia-lyase (PAL) enzyme activities and higherexpression level of the PAL1 and 4CL-1 genes compared to those irradiated with greenhouse light. We concluded that RB LED light provides a better growthcondition and resistance to drought stress for the two genotypes of lemon balm by the highest antioxidant activity and the least amount of damage to the cell membranes. Our data suggest that LED light pre-treatments as moderate stress activate antioxidant systems, enhance the scavenging of ROS and induce drought stress tolerance in the two genotypes of lemon balm plants.

Role of Ascorbic acid, Glutathione and Proline Applied as Singly or in Sequence Combination in Improving Chickpea Plant through Physiological Change and Antioxidant Defense under Different Levels of Irrigation Intervals.

In recent years, the harmful effects of drought stress have been be mitigated by using bioactive compounds such as antioxidants and osmolytes. In this research, pot experiments were carried out to investigate the effects of ascorbic acid, glutathione and proline on alleviating the harmful effect of drought stress in chickpea plants during season 2017. Chickpea plant seeds were soaked in ascorbic acid (0.75 mM), glutathione (0.75 mM), proline (0.75 mM) singly and/or in sequence combinations for 4 h and then planted in pots. The pots were irrigated with water after seven days (to serve as control), after 14 days (moderate drought stress) and after 28 days (severe drought stress). The sequence combination of antioxidants and proline under drought stress has not been studied yet. The results showed significantly decreased in plant growth, yielding characteristics, photosynthetic pigments and soluble protein content in response to moderate and severe drought stress. Moreover, treatment with antioxidants caused increment the antioxidant enzyme activity, non-enzymatic antioxidant (ascorbic acid and glutathione) contents and endogenous proline in stressed and unstressed plants. In conclusion, The sequence combination of antioxidants and proline caused improvement in plant growth under drought stress by up-regulating the antioxidant defense system and osmolyte synthesis.

Effect of utilization of treated wastewater and seawater with Clinoptilolite-Zeolite on yield and yield components of sorghum

Under conditions of water shortage, utilizing unconventional waters, such as treated urban wastewater and/or seawater, in combination with soil amendments such as zeolite, can reduce the harmful effects of drought stress on crop yield. To investigate the agronomic and physiological effects of a mix of water qualities and soil treatments on sorghum, a randomized split-plot research was conducted at Gharakheil agricultural research station, Ghaemshahr, Northeast Iran. Six combinations of water qualities and three different use of soil amendments were tested over two seasons in 2016 and 2017. The water quality treatments with increasing salinity included well water as the control (W1); 75 % well water and 25 % seawater (W2); 25 % well water and 75 % seawater (W3); 100 % treated urban wastewater alternating with 100 % seawater (W4); 50 % seawater and 50 % treated urban wastewater (W5) and 100 % treated urban wastewater (W6). The soil amendments were no-zeolite as the control (Z1) and calsic (Z2) and potasic (Z3) zeolite. With increasing salinity, the forage yield decreased significantly. Maximum and minimum forage yield were respectively 129.6 ton.ha−1 inW6-Z2 in 2016 and 46.9 ton.ha−1 in W3-Z1 in 2017. Irrigation Water Use Efficiency (IWUE) was the highest with the treated urban wastewater in combination with zeolite. All six combinations (W4-Z2, W4-Z3, W5-Z2, W5-Z3, W6-Z2 and W6-Z3) had significantly higher IWUEs (range 2.0–2.4) compared to the control (IWUE = 1.7) and the other soil and water treatments. The combinations of 75 % seawater and no zeolite had by far the lowest IWUE (range 1.1–1.7). The same trends were observed for the Leaf Area Index (LAI) and leaf and stem protein. The use of saline sea water increased the soil salinity levels significantly, but the levels were still well below the FAO threshold values for yield reduction. Overall, we can recommend use of treated wastewater in combination with calsic zeolite soil amendment as the combination that had the best effect on crop yield, IWUE, LAI and leaf and stem protein for sorghum production under the conditions of north of Iran.

Retraction Note to: Impact of Drought Stress on Some Grain Quality Traits in Rice (Oryza sativa)

The study was conducted to ascertain the harmful effects of drought stress on grain quality traits in rice. For the purpose, grain shape quality traits of twenty rice genotypes were studied in order to understand the effects of drought stress on these quality traits. The result of analysis of variance clearly indicates that genotypes significantly differ in grain quality traits under both normal as well as drought prone environments. Higher heritability estimates for grain length and length to width ratio under normal and all quality traits under stress environment indicate that these characters are controlled by multiple genes and selection of these characters would be effective at early generation. Results showed that grain length was positively correlated with length to width ratio (0.863* and 0.668*) and negatively correlated with grain width (−0.614** and −0.313**) and grain breadth (−0.321**and −0.030ns) under both normal and stress conditions respectively. Grain width was positively correlated with grain breadth (0.711** and 0.486**) and negatively correlated with length to width ratio (−0.926* and −0.910*) under both conditions respectively. Grain width was highly correlated with yield per plant (0.386** and 0.315**) under both, normal and drought stress respectively while grain breadth was positively correlated (0.553**) only under normal condition. It shows that reduction in grain width has direct effect on grain yield. Under normal condition, yield was positively correlated with grain width (0.386**) and grain breadth (0.552*) indicating that grain width and grain breadth should be considered while screening high yielding genotypes under normal condition and grain width alone should be considered for drought stress among the studies characters.