Increasing Levels Of Water Stress Research Articles

Water productivity, yield response factors, yield and quality of alfalfa cultivars in semi-arid climate conditions

This study was carried out for 2 years (2020 and 2021) to elucidate the effects of water stress on yield and quality of alfalfa cultivars, to determine the water-yield and quality relations and the susceptibility of cultivars to water stress. Three different irrigation treatments (100%, 75% and 50% of full irrigation, I100, I75 and I50) and 12 different alfalfa cultivars (SHN, Osmanağa, Şahin 42, Minerva, Elçi, Riviera Vicentina, Magna 601, Magnum V, Prosementi, Ezzelina, Sunter, Nimet) were used in present experiments conducted in randomized-blocks split-plots design with 3 replications to investigate effects of irrigation levels on water, yield and quality parameters of alfalfa. Present findings revealed that water stress decreased crop water productivity, but increased irrigation water productivity of alfalfa cultivars. Herbage yields of the cultivars varied between 48.20 and 64.98 t/ha, hay yields between 11.42 and 14.67 t/ha and protein yields between 2.22 and 3.07 t/ha. Alfalfa was found to be sensitive to water stress in terms of herbage yield, but more tolerant in terms of hay and protein yields. Morphological characteristics (plant height, number of stems per plant, number of main stem branches and root crown diameter) decreased with increasing water stress levels. In terms of quality traits, while acid detergent fiber (ADF), neutral detergent fiber (NDF), crude fiber and crude ash ratios increased, crude protein ratios decreased with increasing irrigation water levels. It was concluded based on present findings that water stress resulted in different responses of different alfalfa cultivars and although it increased quality traits in general, it decreased herbage, hay and protein yields. Again, based on present findings, Magna 601 cultivar could be recommended for semi-arid regions.

Determination of the effects of PGPR isolates and algae on plant growth in broad bean (Vicia faba L.) grown under water stress conditions

In regions exposed to drought stress, the use of bacteria applications to promote yield and quality has increased. This study was carried out to determine the effects of rhizobacteria and algae treatments on some biochemical and physiological properties of broad bean (Vicia faba L.) grown under water stress conditions. According to the completely randomized experimental design, the study was carried out in 4 replications in factorial order. In the experiment, the Filiz-99 broad bean variety was used as a plant material. In the study, 4 different biological applications (control, blue-green algae, and 2 different bacteria) and 3 different irrigation levels – 100% (NI), 50% (RI1), and 25% (RI2) – have been applied. In the study, properties such as root and stem length, stem and root fresh weight, stem, and root dry weight, nitrogen balance index, antioxidant, flavonoid, and phenolic properties were examined. Root length changed between 21.37–25.62 cm in bacteria and algae applications, and the highest value was obtained from the B1 application with 25.62 g. At increasing water stress levels, the nitrogen balance index varied in the range of 128.01–77.50%. In bacteria and algae applications, the highest value was obtained from the B1 application. While the phenolic content ranged between 127.53 and 134.31 mg GAE (Gallic Acid Equivalents) g–1 with increasing water stress, the highest value among biological applications was B1 application with 138.06 mg GAE g–1. As a result of the interaction of factors, the highest phenolic values were obtained from B1 × RI2 (149.85 mg GAE g–1), B2 × RI2 (137.05 mg GAE g–1), B0 × NI (127.43 mg GAE g–1), and B0 × RI2 (123.69 mg GAE g–1) applications, while the lowest values were obtained from B2 × NI (123.22 mg GAE g–1), Alg × RI2 (126.65 mg GAE g–1), Alg × NI (127.75 mg GAE g–1), and B1 × NI (131.73 mg GAE g–1) applications. In the study, it was determined that bacterial applications were more effective than algae applications.

Development of an Irrigation Method with a Cycle of Wilting–Partial Recovery Using an Image-Based Irrigation System for High-Quality Tomato Production

The demand for high-quality tomatoes is increasing; however, their production requires skillful techniques. To develop an automated irrigation method for producing high-quality tomatoes in a greenhouse, we used an image-based irrigation system to study how a diurnal periodic cycle of wilting–partial recovery irrigation affects growth, yield, and fruit quality. Three irrigation treatments were performed: a control with sufficient irrigation and two water stress treatments (moderate and severe wilting–partial recovery treatments; MPR and SPR, respectively). The mean daily maximum wilting ratios for MPR and SPR were 8.1% and 13.2% at wilting-level setpoints of 7% and 14%, respectively. The total irrigation amounts in MPR and SPR were 75% and 59% of that in the control, respectively. The corresponding yields in MPR and SPR were 76% and 56% of that in the control, respectively. The Brix and acidity of fruits in MPR and SPR were 15% and 10% and 34% and 24% higher, respectively, than those in the control at the end of the experiment. Plant growth decreased with increasing water stress levels. Plant length, leaf area, and the number of leaves were more sensitive to water stress than other growth parameters. SPR could be an effective irrigation method to improve fruit quality, even at high-air-temperature periods in summer.

Effect of Liquid Organic Fertilizers and Soil Moisture Status on Some Biological and Physical Properties of Soil

<p>This study was conducted to evaluate the effects of liquid organic fertilizers (LOFs) and soil moisture status on some biological and physical properties of postharvest soil of maize cultivation. For this purpose, a factorial greenhouse experiment was performed based on the completely randomized design with three replications. Treatments consisted of five levels of LOFs (control, vermicompost tea, vermiwash, plant growth-promoting rhizobacteria [PGPR] enriched vermicompost tea and PGPR enriched vermiwash) and three levels of soil moisture status (field capacity [FC], 0.8 FC and 0.6 FC). The results showed LOFs caused an increase of soil biological properties (soil microbial respiration, soil microbial biomass, dehydrogenase activity and the number of aerobic heterotrophic bacteria) and the improvement of soil physical condition. LOFs increased aggregate stability, hydrophobicity and total porosity, while decreased bulk density and soil penetration resistance. Increasing water stress levels reduced soil biological activity and made soil physical properties more unfavorable. In general, LOFs improved soil conditions by enhancing soil physical and biological properties and decreased the negative effects of water stress. In addition, results showed that LOFs enriched with PGPR could be more effective than non-enriched ones.</p>

The phytoremediation effect of Medicago scutellata (L.) Mill. on soils under Cd-water stress: a good choice for contaminated dry lands.

Recently, due to increased drought risks, need for crops with higher water stress tolerance has increased strongly. Those crops have a wide range of uses such as supplying food as well as land restoration. Medicago scutellata (L.) Mill. is a Fabaceae widely cultivated for its capacity to produce high-quality forage. This study was designed as a factorial experiment based on a completely randomized design with three replications. Different cadmium levels were the first factor and included 0, 5, 25, 50, 100, and 125 mg kg-1. Second factor was the drought stress, which had three levels (100, 75, and 50% feed consumption). According to the results, Cd uptake in different organs increased with increasing Cd levels up to 100 mg kg-1 while the water stress had a negative effect on Cd uptake by M. scutellata. Average concentration of Cd in the leaves, stems, and roots were 63.16, 30.12, and 20.45 mg kg-1, respectively. The high value of translocation factor (TF) confirms the high ability of M. scutellata in translocation Cd from root to shoot. Fe, Zn, and K concentration of different organs significantly decreased with increasing Cd level. Fe and Zn concentration increased by increasing water stress levels in all organs and K concentration of roots decreased while in leaves and shoots increased by increasing water stress level. These results indicate that M. scutellata has a good ability for eliminating Cd from contaminated soil attribute to its powerful absorption and accumulation for Cd. It also showed a good performance under the co exposure of water stress and Cd indicated by accumulating proline and K in leaves.

Physiological and Metabolic Responses of Rice to Reduced Soil Moisture: Relationship of Water Stress Tolerance and Grain Production.

Access to adequate irrigation resources is critical for sustained agricultural production, and rice, a staple cereal grain for half of the world population, is one of the biggest users of irrigation. To reduce water use, several water saving irrigation systems have been developed for rice production, but a reliable system to evaluate cultivars for water stress tolerance is still lacking. Here, seven rice cultivars that have diverse yield potential under water stress were evaluated in a field study using four continuous irrigation regimes varying from saturation to wilting point. To understand the relationship between water stress and yield potential, the physiological and leaf metabolic responses were investigated at the critical transition between vegetative and reproductive growth stages. Twenty-nine metabolite markers including carbohydrates, amino acids and organic acids were found to significantly differ among the seven cultivars in response to increasing water stress levels with amino acids increasing but organic acids and carbohydrates showing mixed responses. Overall, our data suggest that, in response to increasing water stress, rice cultivars that do not show a significant yield loss accumulate carbohydrates (fructose, glucose, and myo-inositol), and this is associated with a moderate reduction in stomatal conductance (gs), particularly under milder stress conditions. In contrast, cultivars that had significant yield loss due to water stress had the greatest reduction in gs, relatively lower accumulation of carbohydrates, and relatively high increases in relative chlorophyll content (SPAD) and leaf temperature (Tm). These data demonstrate the existence of genetic variation in yield under different water stress levels which results from a suite of physiological and biochemical responses to water stress. Our study, therefore, suggests that in rice there are different physiological and metabolic strategies that result in tolerance to water stress that should be considered in developing new cultivars for deficit irrigation production systems that use less water.

Effect of water stress on roots biomass and secondary metabolites in the medicinal plant Stellaria dichotoma L. var. lanceolata Bge

The experiment was carried out with plants grown in pots with soil to determine the effects of different levels of water stress on roots biomass, secondary metabolites in roots and endogenous hormones (IAA, GA3 and ABA), relative water content (RWC), tissue density (TD) in leaves of Stellaria dichotoma L.var. lanceolata Bge. The results showed that roots biomass, total saponins content firstly increased and then decreased with increasing water stress levels. RWC significantly decreased with increasing water stress levels while the change of TD was inverse. The concentration of IAA and GA3 firstly increased and then decreased with increasing water stress levels and reached maximum value under 60–70% of field capacity (FC). However, ABA concentration sharply increased under≤40–50% FC. With correlation analysis and principal component analysis (PCA), total flavonoids content had significant positive with ABA and TD, but had a negative correlation with RWC. Roots biomass had a significant negative correlation with ABA, while ABA had a very significant negative correlation with RWC and a significant positive correlation with TD. The PCA partitioned the total variance into 2 PCs contributing maximum (90.793%) to the total diversity among the water stress due to the study of various traits. The higher eigenvector of PC I is RWC and ABA, whereas the higher and positive eigenvector of PC II is GA3, total saponins content and IAA. Our study indicated that roots biomass and secondary metabolites of S. dichotoma were first increases and then decreases with increasing water stress levels. Thus, moderate water stress (60–70% or 80–90% FC) was suitable for roots biomass formation and active ingredient accumulation, which was affected by endogenous hormones and water status.

Response of different species of Brassica to water deficit

Development of drought-tolerant cultivars is hampered by a lack of effective selectioncriteria. In this research, response of 36 genotypes of rapeseed from seven species of Brassicaincluding B. napus, B. rapa, B. juncea, B. carinata, B. oleracea, B. nigra and B. fruticulosa wasassessed under three moisture levels (no stress, mild stress and intense stress) in the field during2011-2012. Five drought-tolerance indices were calculated: stress tolerance (TOL), stresssusceptibility index (SSI), mean productivity (MP), geometric mean productivity (GMP) andstress tolerance index (STI). Increasing water stress levels caused significantly more reductionsin the seed yield of all species. Species B. napus had the highest yields in normal and intensestress conditions while B. carinata showed better performance in mild stress condition.Correlation coefficients revealed that among drought tolerance indices, GMP, STI and MP aresuperior criteria for selecting high-yield genotypes under stress and non-stress conditions.B. napus and B. carinata were the most drought tolerant while B. rapa and B. oleracea were themost susceptible species of Brassica based on yield potential. Application of principlecomponent analysis (PCA) for distinguishing drought and susceptible species are discussed.

Physiological responses of Brassica napus to fulvic acid under water stress: Chlorophyll a fluorescence and antioxidant enzyme activity

The ameliorative effect of fulvic acid (0, 300, and 600mgL−1) on photosystem II and antioxidant enzyme activity of the rapeseed (Brassica napus L.) plant under water stress (60, 100, and 140mm evaporation from class A pan) was studied using split plots in a randomized complete block design with three replications. Results indicated that application of fulvic acid (FA) improved the maximum quantum efficiency of PSII (Fv/Fm) and performance index (PI) of plants under both well-watered and limited-water conditions. The time span from Fo to Fm and the energy necessary for the closure of all reaction centers was significantly increased, but the size of the plastoquinone pool was reduced with increasing water stress levels. Plants treated with FA had higher peroxidase and catalase activities under all irrigation conditions. Activities of ascorbate peroxidase and superoxide dismutase in plants increased with increasing water stress. Malondialdehyde increased under severe water stress, but application of FA significantly decreased lipid peroxidation. Production of reactive oxygen species (ROS) is a common phenomenon in plants under stress. Under this condition, the balance between the production of ROS and the quenching activity of antioxidants is upset, often resulting in oxidative damage. In this study, application of FA significantly increased fluorescence of chlorophyll a, inhibiting ROS production and enhancing antioxidant enzymes activity that destroyed ROS. Thus, ROS in plant cells was reduced under water stress by application of FA and consequently lipid peroxidation was reduced.

Proline, Protein, Rwc and Msi Contents Affected by Paclobutrazol and Water Deficit Treatments in Strawberry Cv. Paros

Abstract Drought is one of the critical environmental stresses that affect growth and development of plants. Plants are damaged directly and indirectly under drought stress. Increasing water stress tolerance in plants is crucial. The aim of this study was to investigate the effects of different water stress levels (-1, -5, and -10 bars) and paclobutrazol application (0 and 50 mg-1) on strawberry cv. Paros. According to analyses of variance there were significant effects of drought stress and paclobutrazol application on leaf area, leaf dry weight, leaf relative water content (RWC), cell membrane stability index (MSI), proline and protein content of leaves. Leaf area, leaf dry weight, leaf relative water content and cell membrane stability index decreased in drought stress, especially at -10 bars. Proline and protein contents were enhanced by increasing water stress levels. Paclobutrazol application increased leaf relative water content and cell membrane stability index, proline and protein contents of leaves. Leaf relative water content was 68.77% in -10 bars drought stress that increased to 79% in paclobutrazol treatment. Also, cell membrane stability index was 69.65% in severe drought stress and reached to 77% in paclobutrazol treatment. According to the results pacloburazol is a benefit substance to ameliorate drought stress effects in strawberry cv. Paros.

Changes in essential oil content and composition of Agastache foeniculum under water stress at second harvest

To study the effect of different levels of water stress on essential oil content and composition of Agastache foeniculum Kuntze at second harvest, a field experiment in randomized complete block design with three replications was conducted. Water stress treatments were: 100% of field capacity (FC), 85% of FC, 70% of FC, 55% of FC, 100–85% of FC (100% at vegetative and 85% at reproductive phases), 100–70% of FC (100% at vegetative and 70% at reproductive phases), 85–100% of FC (85% at vegetative and 100% at reproductive phases). The highest of essential oil content was observed at 70% of FC (1.69) and 100–85% of FC (1.67). Also the treatment 85% of FC (1.33) caused the lowest of essential oil content. There was not significant different between other treatments. The main essential oil constituent was methyl chavicol which showed a increasing with progress water stress till 70% of FC and then decreased at 55% of FC treatment. Limonene, another main component was decreased with increasing water stress levels from 100 of FC to 70% of FC. The highest amount of methyl chavicol (98.3%) and limonene (2.4%) were found at 70% of FC and 85–100% of FC, respectively.

THE RESPONSE OF TABLE GRAPE GROWTH AND RIPENING TO WATER STRESS

Arizona is currently experiencing an explosion in the commercial cultivation and production of table grapes. Decreasing water supplies, increasing water cost, and recent groundwater legislation are forcing Arizona growers to be more water efficient if they are to remain competitive with other markets. Research was conducted to determine the effect of water stress on vine growth and berry ripening. “Flame Seedless” table grapes (4th leaf) were subjected to increasing water stress levels based upon infrared canopy temperatures and the crop water stress index (CWSI). A lower water stress level (CWSI = 0.18 units at irrigation) promoted earlier berry sizing, increased berry weight, and increased cluster weight over drier treatments. Significantly higher growth (P= 0.01), based on pruning weights, also was attained at the lower water stress level. However, highest production (grade 1 and 2 packed boxes) was attained when irrigations were scheduled at 0.30 CWSI units. Total applied water to maintain the wet, medium, and dry treatments was 1136 mm (CWSI = 0.18), 775 mm (CWSI = 0.30), and 669 mm (CWSI = 0.33), respectively.

PECAN TREE GROWTH, PRODUCTION, AND NUT QUALITY RESPONSES TO WATER STRESS

Pecan tree (cv. “Western Schley”) water stress was numerically quantified with the crop water stress index (CWSI). The CWSI was used to schedule irrigation at increasing water stress levels to correlate the effects of water strees on tree growth, production, and nut quality from 1987 to 1989. Highest growth increases, production, and nut size were attained at lower water stress levels (CWSI = 0.08 to 0.14 units). Even moderate increases in water stress (CWSI>0.20 units) decreased pecan tree growth and production, and significantly reduced nut size (P=0.01). A significant difference (P=0.05) in nut quality was measured only in 1988. Depending on yearly climatic variation, the amount of irrigation water required to maintain the CWSI below 0.14 units in the same orchard varied 44% over three years. The CWSI is a viable tool to assess pecan water stress.

Reproductive Stage Water Stress and Sterility. I. Effect of Stress during Meiosis1

Increased spikelets sterility is the primary component of yield reduction in rice (Oryzas ativa L.) and other small grains subjected to water stress during reproductive growth stages. The causes of water stress induced spikelet sterility are not clear although the meiotic stage of pollen mother cells is often reported to exhibit yield‐decreasing sensitivity. We exposed rice plants, in which pollen mother cells were actively undergoing meiosis, to the following series of water stress levels as measured by flag leaf water potential: −1.6, −1.9, −2.2, −2.5, −2.8, and −3.5 MPa for 18 to 24 h. Panicles were fixed in Farmer's solution and later examined microscopically for abnormal chromosomal behavior. The occurrence of chromosomal abnormalities such as univalents, lagging of chromosomes, noncongression in metaphase and micronuclei was evaluated in 3822 pollen mother cells in response to increasing water stress levels. Spikelet fertility of comparable panicles grown to maturity decreased linearly from 80% at −1.1 MPa (control) to 50% at −3.5 MPa flag leaf water potential. Chromosomal abnormalities appeared at relatively moderate stress levels (−1.1 to −1.9 MPa) and in general peaked at the −2.2 MPa stress treatment.In general, water stress increased chromosomal abnormalities, except at severe stress levels (−3.5 MPa) where the meiotic process was partially arrested. Each meiotic stage had particular irregularities associated with water stress. Prophase I and II, univalents; Metaphase I, noncongression of bivalents and lagging chromosomes; Anaphase I and II, lagging chromosomes; Telophase II, micronuclei formation. Blasted or immature, small, colorless spikelets also were observed and their occurrence increased with stress level. Blasted spikelets, not included in the calculation of percent sterility, accounted for 10 to 20% of the total spikelets per panicle at moderate stress levels. The cause of this malady is unknown.