Different Levels Of Water Deficit Research Articles

Root-shoot ratio of maize (Zea mays L.) as influenced by different levels of water deficit under two different climatic conditions

Root-shoot ratio of maize (Zea mays L.) as influenced by different levels of water deficit under two different climatic conditions

Water relations of cassava cultivated under water-deficit levels

The tolerance of plants to water deficit involves a series of adaptive mechanisms; however, little is known about the physiological characteristics of cassava (Manihot esculenta Crantz), which is one of the most tolerant crops to adverse environmental conditions. The objective of this work was to evaluate the water relations in cassava plants subjected to different levels of water deficit. The treatments were conducted in three evaluation periods (0, 45 and 90 days after water deficit) and at three soil water tensions (− 10, − 40 and − 70 kPa), with five replicates. The plants were mainly affected at 45 days after the water deficit, with an increase of 42.9% in total chlorophyll content and 35.3% in carotenoid content in plants under a tension of − 70 kPa; however, these plants reduced by 30.8% chlorophyll a content at 90 days of the treatments. The water potential, relative water content and electrolyte leakage in the leaf were not altered by the soil water tension. There was an increase of 35.4% in stomatal density independent of soil water status at 90 days and of 16.0% under tensions of − 40 and − 70 kPa; however, the effective quantum efficiency of photosystem II and rate of electron transport were reduced. Cassava can maintain a leaf water potential close to − 0.3 MPa in the predawn and the integrity of the cell membranes in leaves under a soil water tension of up to − 70 kPa.

Impact of Deficit Irrigation on Yield and Chemical Properties of Soybean Seeds in Temperate Climate

Summary The goal of this research is to determine the effects of different levels of water deficit (I100: full irrigation, I65: 35% deficit, I40: 60% deficit and I0: no irrigation) on yield and chemical composition of soybean [Glycine max (L.) Merr.] grown in Srem region of Serbia. Water deficit significantly affected the yield and chemical composition of soybean seeds. The lowest (1.63 t/ha) and the highest (3.21 t/ha) seed yields were obtained from I0 and I65 treatments, respectively. Furthermore, the highest protein (1092 kg/ha) and oil (563 kg/ha) yields were observed in I65 treatment. Lower and higher irrigation levels from I65 decreased the protein and oil yields. Our data indicated that irrigation generally increased K, P, Mg, Mn, Cu, Zn and B concentrations and decreased Ca and Fe concentrations in soybean seed. It was clearly observed that full-watered treatment (I100) provided no potential benefit in terms of soybean yield and chemical composition. For higher economic yield and good nutritional quality, water-saving treatment I65 could be suitable in soybean management in Srem region of Serbia as in other regions with similar soil and climate conditions.

Detecting tree water deficit by very low altitude remote sensing

In a context of climate change and expected increasing drought frequency, it is important to select tree species adapted to water deficit. Experimentation in tree nurseries makes it possible to control for various factors such as water supply. We analyzed the spectral responses for two genetic varieties of Douglas fir sapling exposed to different levels of water deficit. Our results show that the mean NDVI derived from remote sensing at very low altitudes clearly differentiated stress levels while genetic varieties were partially distinguished.

Alterations in growth, photosynthetic activity and tissue-water relations of tea clones in response to different soil moisture content

Significant effect of water stress conditions were observed on morphological and physiological growth parameters of tea (Camellia sinensis). Water stress tolerant tea clones suitable for hilly areas have been identified in this study. The influence of different levels of water deficit on physiological and morphological parameters in tea [Camellia sinensis (L.) O. Kuntze] clones was investigated. Tea clones (BSS-449, BSS-379, P-312, UPASI-9, T-383, RR-17, AV-2 and T-78) growing under controlled condition (under shade, potted condition) were subjected to three irrigation treatment, a control (70.0% soil moisture content), moderate water deficit (38.3% soil moisture content) and sever water deficit (6.9% soil moisture content). Plants submitted to severe water deficit showed significant reduced leaf numbers, leaf areas, and plant heights while reduction in plant height and leaf area and leaf numbers was not significant in moderate water deficit. A significant change in chlorophyll content was observed during the water stress condition. Photosynthesis decreased in both water deficit treatments and was related to stomatal factors and photochemical efficiency of photosystem II. Water relation parameters, e.g. leaf water potential, osmotic potential, turgor potential, relative water content and cellular elasticity were also measured to evaluate plant adaptation to water stress. The highest leaf water potential values were found in the control condition, for all the clones. Cell wall rigidity, measured as elastic modulus, increased under severe water stress, resulting in a loss of turgor at lower leaf water potential. Results of the study suggest that the degree of drought tolerance depends on the interactions between the tea clones and the levels of water stress. The available data also indicates that UPASI-9 is capable of tolerating water stress, and should be suitable for dry areas.

English

The aim of this work was to evaluate the uniformity of fruit maturity and the productivity of conilon coffee in function of different periods of water stress in the post-harvest period. The study was conducted in a field from August 2014 to July 2015 in an old coffee crop of conilon coffee, cultivar Vitoria 'Incaper 8142', cultivated at a spacing of 3.0 × 1.2 m, located at the Federal Institute of Espirito Santo Campus Santa Teresa, ES, Brazil. The experimental design was in randomized blocks, with 4 treatments and 10 repetitions. Each useful plot consisted of 12 plants. The treatments consisted of the application of different levels of water deficit, being: control (continuous irrigation with humidity close to the field capacity) (T1); water deficit of 20 (T2); 40 (T3); and 60 (T4) days after harvest. Productivity was determined by harvesting and weighing the grains of each useful plot. The maturation uniformity was evaluated by random harvesting of 100 fruits in each plot. The application of the treatment with 60 days of water deficit presented greater uniformity of fruit maturation and water saving when compared to the other treatments. The treatment with estimated water deficit of 33 days after harvest showed higher average grain yield (79.2 sc ha-1). Key words: Coffea canephora, irrigation management, grain quality, water, productivity.

Effect of drought stress on chlorophyll fluorescence, antioxidant enzyme activities and gene expression patterns in faba bean (Vicia faba L.)

ABSTRACTDrought is a major environmental stress that limits faba bean growth, leading to considerable reduction in their productivity. Two genotypes (Giza 3 and Hara) were evaluated under three water treatments (90%, 60% and 30% field capacity). The results showed that water stress affects negatively chlorophyll fluorescence parameters at different levels of water deficit and the variations of Fv/Fm, ΦPSII and electron transport rate in Giza 3 were largely higher than those in Hara. Drought preferentially enhanced the activities of superoxide dismutase, catalase and guaiacol peroxidase whereas it did not affect ascorbate peroxidase activity. Real-time reverse transcriptase-polymerase chain reaction results demonstrated that the expression of aquaporin (PIP), myeloblastosis (MYB), nine-cis-epoxycarotenoid dioxygenase, late embryogenesis abundant, dehydrins (Dhn), heat shock protein (HSP) and APETALA2/ethylene-responsive factor was modified in response to drought conditions and that all genes were differentially expressed in Hara and Giza 3. The observed expression patterns of these genes might be due to water deficit intensity according to cultivar’s tolerance to drought. Hara with the highest level of antioxidant enzyme activities, the accumulation of proline content and the expression level of Dhn, HSP and MYB gene throughout all conditions tested is reported more drought tolerant than Giza 3. This study should contribute to explaining the physiological, biochemical and molecular mechanism tolerance drought stress and improving breeding program in faba bean.

Identification of reference genes for quantitative RT-PCR analysis of microRNAs and mRNAs in castor bean (Ricinus communis L.) under drought stress

Quantitative real-time PCR (RT-qPCR) is one of the most powerful and sensitive techniques to the study of gene expression. Several factors influence RT-qPCR performance though, including the stability of the reference genes used for data normalization. While the selection of appropriate reference genes is crucial for accurate and reliable gene expression analysis, no suitable reference genes have been previously identified in castor bean under drought stress. In this study, the expression stability of eleven mRNAs, thirteen microRNAs (miRNAs) and one small nuclear RNA were analyzed in roots and leaves across different levels of water deficit. Three different algorithms were employed to analyze the RT-qPCR data, and the resulting outputs were merged using a non-weighted unsupervised rank aggregation method. Our analysis indicated that the Elongation factor 1-beta (EF1B), Protein phosphatase 2A (PP2A) and ADP-ribosylation factor (ADP) ranked as the best candidates across diverse samples submitted to different levels of drought conditions. EF1B and Glyceraldehyde 3-phosphate dehydrogenase (GAPDH), and EF1B and SKP1/ASK-interacting protein 16 (SKIP16) were found as the most suitable reference genes for expression analysis in roots and leaves, respectively. In addition, miRNAs miR168, miR160 and miR397 were selected as optimal reference genes across all tissues and treatments. miR168 and miR156 were recommended as reference for roots, while miR168 and miR160 were recommended for leaves. Together, our results constitute the first attempt to identify and validate the most suitable reference genes for accurate normalization of gene expression in castor bean under drought stress.

Different levels of water deficit induces changes in growth pattern but not in chlorophyll fluorescence and water relations of Hancornia speciosa Gomes seedlings

The tree Hancornia speciosa Gomes is commonly known in Brazil as “mangabeira”, the fruit of which has high nutritional value. The knowledge about its physiology is still scarce, mainly during the initial phase of development. Thus, the aim of the present study was to evaluate the effects of different water deficit levels on growth pattern, chlorophyll fluorescence and water relations in H.speciosa seedlings. A A factorial experimental design (water treatment x evaluation time) was used with four water treatments based on the field capacity (FC) (80%, 60%, 40% and 20%) with five replications. Plant height, number of leaves, stem diameter, dry biomass production and partitioning, quantum efficiency of photosystem II (PSII), water potential (Ψw), relative water content (RWC), carbohydrates, proteins and proline content were analyzed. Severe water stress (20% FC) led to a reduction in growth and altered the biomass partitioning pattern in the seedlings. However, water relations were not significantly affected, as the seedlings maintain high Ψw and RWC without significant increase in organic solutes content when cultivated in 20% FC. Moreover, the quantum efficiency of PSII was unaffected by the different water levels, suggesting a lack of photoinhibition due to water stress. The change in growth pattern, with an increase in root depth and reduction in shoot emission, seems to be the main strategy of the H. speciosa seedlings for the maintenance of tissue hydration throughout periods of water deficit.

Determining cwsi to estimate eggplant evapotranspiration and yield under greenhouse and outdoor conditions

ABSTRACT- The crop water stress index (CWSI) is the most common index to monitor and assess crop water stress, based on canopy temperature. To calculate CWSI, upper and lower baselines adaptable to different environments are needed. In this study, empirical and theoretical limiting baseline equations were developed to determine eggplant CWSI values at different levels of water deficit and salinity stress. The limiting baseline and CWSI values of eggplant were obtained under different watering intervals (daily, weekly and every two weeks) and different irrigation water salinity levels (i.e. 0.8, 2.5, 5 and 7 dsm-1) for greenhouse and outdoor conditions. The impact of various levels of water deficit and salinity on total evapotranspiration, yield and CWSI was also studied. With the increase of water salinity, a decrease in the slope of lower baseline was met (from 0.195 to 0.146 in the greenhouse and from 0.134 to 0.098 in the outdoor conditions) along with a rise in the upper baseline. Increase in the levels of water deficit led to greater fluctuations in CWSI variations during the growing season. According to the Duncan's test results, CWSI values were significantly affected by water deficit and salinity in both environments

Genome-wide transcriptome analysis of soybean primary root under varying water-deficit conditions

BackgroundSoybean is a major crop that provides an important source of protein and oil to humans and animals, but its production can be dramatically decreased by the occurrence of drought stress. Soybeans can survive drought stress if there is a robust and deep root system at the early vegetative growth stage. However, little is known about the genome-wide molecular mechanisms contributing to soybean root system architecture. This study was performed to gain knowledge on transcriptome changes and related molecular mechanisms contributing to soybean root development under water limited conditions.ResultsThe soybean Williams 82 genotype was subjected to very mild stress (VMS), mild stress (MS) and severe stress (SS) conditions, as well as recovery from the severe stress after re-watering (SR). In total, 6,609 genes in the roots showed differential expression patterns in response to different water-deficit stress levels. Genes involved in hormone (Auxin/Ethylene), carbohydrate, and cell wall-related metabolism (XTH/lipid/flavonoids/lignin) pathways were differentially regulated in the soybean root system. Several transcription factors (TFs) regulating root growth and responses under varying water-deficit conditions were identified and the expression patterns of six TFs were found to be common across the stress levels. Further analysis on the whole plant level led to the finding of tissue-specific or water-deficit levels specific regulation of transcription factors. Analysis of the over-represented motif of different gene groups revealed several new cis-elements associated with different levels of water deficit. The expression patterns of 18 genes were confirmed byquantitative reverse transcription polymerase chain reaction method and demonstrated the accuracy and effectiveness of RNA-Seq.ConclusionsThe primary root specific transcriptome in soybean can enable a better understanding of the root response to water deficit conditions. The genes detected in root tissues that were associated with key hormones, carbohydrates, and cell wall-related metabolism could play a vital role in achieving drought tolerance and could be promising candidates for future functional characterization. TFs involved in the soybean root and at the whole plant level could be used for future network analysis between TFs and cis-elements. All of these findings will be helpful in elucidating the molecular mechanisms associated with water stress responses in soybean roots.Electronic supplementary materialThe online version of this article (doi:10.1186/s12864-016-2378-y) contains supplementary material, which is available to authorized users.

Flavonoid dynamic responses to different drought conditions: amount, type, and localization of flavonols in roots and shoots of Arabidopsis thaliana L.

Flavonoids accumulate in plants in response to water deficit. Changes in amount, type, and localization of flavonoids under different drought conditions in Arabidopsis thaliana have not been well investigated. Therefore, in this study flavonoid patterns were investigated under water potentials of -0.2, -0.5, and -0.9 MPa at 0, 24, 48, 120, and 192 h after drought induction. Determination of amount and type of flavonoids was performed by HPLC and spectroscopy. In addition, localization of flavonoids was detected by DPBA staining and a fluorescent microscope. Only quercetin and kaempferol were detected in hydrolyzed extracts of roots and shoots. The maximum amounts of the above-mentioned flavonols were detected under severe drought stress. Under all drought conditions, there was more kaempferol than quercetin. Moreover, amounts of both flavonols and total flavonoids were greater in roots than in shoots. Different fluorescence intensities of the flavonoid-DPBA complex were observed in all seedlings from shoots to root tips. The results of this study suggest that flavonoid responses of Arabidopsis to drought stress are dynamic, and intensity and duration of drought stress could play a key role in determination of type, amount, and localization of flavonoids in response to different levels of water deficit.

Drought resistance of sugar-cane crop for different levels of water availability in the soil

Soil water availability is the main cause of reduced productivity, and the early development period most sensitive to water deficit. This study aimed to evaluate the drought resistance of the varieties of sugar-cane RB867515 and SP81-3250 during the early development using different levels of water deficit on four soil depths. The experiment was conducted at the Department of Biosystems at Escola Superior de Agricultura "Luiz de Queiroz" (ESALQ/USP) in a greenhouse in soil classified as Oxisol, sandy loam texture (Series "Sertãozinho"). Once exhausted the level of available water in the soil, the dry strength of the studied strains are relatively low. Water balance with values less than -13 mm cause a significant decrease in the final population of plants, regardless of the variety, and values below -35 mm, leads to the death of all plants.

Effect of drought on safflower natural dyes and their biological activities.

Drought is the main abiotic constraint that affects crop species behaviour regarding bio-chemical responses. The current study was conducted to examine the effect of water deficit on growth, phenolic and carotenoid contents as well as the antioxidant and antimicrobial activities of two Carthamus tinctorius varieties (Jawhara and 104) flowers. Hence, plants were treated with different levels of water deficit: control (100 %), moderate water deficit (50 %) and severe water deficit (25 %). Obtained results showed that plant growth was significantly (p < 0.05) reduced under 50 %. Drought increased flower phenolic acids contents especially gallic acid where they increased significantly (p < 0.05) by 2.73 fold (104) and by 2.87 fold (Jawhara) with respect to controls under 50 %. However, the amounts of this major compound were reduced at 25 % by 9.66 % (104) and 3.83 % (Jawhara). Similar to phenolic compounds, total carotenoid content was at its highest level especially for Jawhara with an increase by 35.19 % at 50 %. On the other hands, C. tinctorius flowers extracts exhibited high antiradical activity as compared to BHT. A gradual increase by 35.29 % (Jawhara) and 33.33 % (104) especially under 25 % was observed. Moreover, under 50 %, the antimicrobial activity increased significantly (p < 0.05) by 30 % and 10.05 % against Aspergillus carbonarus and Pseudomonas aerogenosa, respectively. Taken together, our findings suggest that C. tinctorius could be a raw material for production of natural dyes under moderate salinity conditions.

Effect of Osmotic Stress on the Initial Development of Bean Seedlings

One of the methods to determine the tolerance of plants to water stress is the observation of germination of seeds under stress induced in laboratory conditions. Thus, the aim was to evaluate the response of four common bean cultivars to water deficit simulated under laboratory conditions. Two common landrace genotypes acquired from farmers (FORT 07 and FORT 08) and two commercial cultivars, IAPAR 81 and Serrano were evaluated. The different levels of water deficit were induced with mannitol solution. The experimental design was completely randomized and a factorial scheme 5 × 4 (osmotic potential x genotypes), with four replications. The characteristics: primary root protrusion, seed vigor, normal and abnormal seedling, seedling and root length, fresh and dry weight of seedling and root were evaluated. By reducing the osmotic potential seedling vigor bean was more affected than the primary root protrusion. Regardless of cultivar, there was a significant and progressive reduction in the normal seedlings percentage from potential -0.3 MPa. The IAPAR 81 and FORT 07 cultivars showed higher tolerance to water deficit compared to other cultivars.

Influence of water deficit and season on biomass yield from clonal stands of eucalyptus

This study aimed to analyze the influence of different levels of water deficit (DH) on initial seedling development of six clonal stands of hybrid Eucalyptus grandis x E. urophylla in two seasons of the year. The experiment was conducted in the experimental site of UFES, in the municipality of Jerônimo Monteiro (ES), over two seasons: from February 9, 2009 to June 9, 2009 (season 1) and from July 11, 2009 to November 7, 2009 (season 2). In all experimental treatments, the first 30 days consisted of acclimating seedlings to the soils, which were thus irrigated. DH levels used in the experiment included: D0 - no water deficit; D1 - 90 days of water deficit; D2 - 60 days of water deficit followed by resumed irrigation for 30 days; D3 - 30 days of irrigation and 60 days of water deficit. The experiment was laid out in a completely randomized design, in subdivided plots (2x4), with four (4) levels of water deficit in the plot and two (2) seasons in the subplots, using three replications. Data on total dry matter of leaves, stem and branches, and root were subjected to analysis of variance and, if found significant, means were compared by the Tukey test at the 5% probability level. The environmental conditions of season 1 favored dry matter yield from both clonal stands, while season 2, having milder climate conditions, failed to favor potential growth of seedlings, even with irrigation conditions being satisfactory. Different levels of water deficit gradually reduced dry matter yield, yet without following a pattern of reduction.

Changes in growth rate, root morphology and water use efficiency of potted Callistemon citrinus plants in response to different levels of water deficit

Callistemon is widely used as a flowering shrub in gardening and landscaping in the Mediterranean area. However, prolonged or severe water stress may alter its physiological and morphological behaviour. Callistemon citrinus plants were grown in nursery conditions and subjected to three irrigation treatments: a control (watered to container capacity) and two water deficit treatments of 50 and 25% of the amount of water supplied in the control treatment (moderate and severe deficit irrigation, respectively). After 53 weeks, the moderate deficit irrigation plants showed a lower relative growth rate but increased root/shoot ratio, improved the root system and increased water use efficiency, while flowering and leaf colour were unaffected. However, severe deficit irrigation reduced flowering and affected leaf colour. Both deficit irrigation treatments reduced stomatal conductance, suggesting an efficient and adaptive stomatal control in this species. These reductions were marked after longer periods in plants submitted to severe deficit irrigation, which decreased photosynthesis and could delay plant recovery and cause permanent damage. Differences between stem and leaf water potential values have seen to be a good indicator of instantaneous shoot transpiration. Water consumption was influenced by the active periods of growth and inflorescence formation. It is concluded that moderate deficit irrigation can be used successfully in C. citrinus plant production to reduce water consumption while maintaining good overall quality.

Water stress effects on Cumin (Cuminum cyminum L.) yield and oil essential components

The effects of water deficit on yield, fatty acids and essential oil yield and composition of Cumin (Cuminum cyminum L.) were investigated. Plants were treated with different levels of water deficit (I100, I50 and I0). Plant growth (height and dry matter weight) was significantly reduced by I0. This last caused also important reductions of the seed yield and yield components. Drought decreased significantly the fatty acid content and the double bond index (DBI) degree. This later was provoked mainly by a strong reduction of oleic, linolenic and petroselinic acid proportions and the disappearance of palmitoleic and arachidinic acid. Besides, moderate water deficit increased the essential oil yield (expressed as g/100g on the basis of dry matter weight). The main essential oil constituents were p-Menta-1,3-diene-7-al, cuminaldehyde, γ-Terpinene, p-Cymene and β-Pinene which showed a decreasing of their contents under I0.

Polyphenol Composition and Antioxidant Activity of Cumin (Cuminum Cyminum L.) Seed Extract Under Drought

This research evaluated the effect of drought on total and individual polyphenol contents as well as the antioxidant activities of cumin (Cuminum cyminum L.) seeds of 2 geographic origins, Tunisia (TCS) and India (ICS). Plants were treated with different levels of water deficit: control. Our results indicated that, in both varieties, moderate water deficit (MWD) improved the number of umbels per plant as well as the number of umbellets per umbel and the seed yield, in comparison to the control, but it decreased under severe water deficit (SWD). Besides, total phenolic contents were higher in the treated seeds and drought increased the level of total and individual polyphenols. This increase was appreciably more important in TCS than in ICS. Moreover, antioxidant activities of the extracts were determined by 4 different test systems, namely 2,2-diphenyl-1-picrylhydrazyl, β-carotene/linoleic acid chelating, and reducing power assays, and showed that treated seeds exhibited the highest activity, for both TCS and ICS.

Superoxide dismutase is a critical enzyme to alleviate oxidative stress in Aloe vera (L.) Burm. plants subjected to water deficit

Background: Aloe vera, a plant with crassulacean acid metabolism naturally adapted to water deficit, was introduced in the semi-arid regions of Chile in 1999. Aims: Our objective was to evaluate how A. vera scavenged the superoxide ion (O2 •‐), formed during oxidative stress, induced by water deficit. Methods : Total and specific activity, enzyme accumulation and expression of genes encoding superoxide dismutase (SOD) were determined in leaf tips and leaf bases collected from plants subjected to different levels of water deficit. Results: Two isoenzymes, Mn-SOD and Cu/Zn-SOD, accumulated significantly under water deficit, with a higher accumulation of Mn-SOD in the leaf bases, and of Cu/Zn-SOD in the leaf tips of plants under different degrees of water deficit (soil water availability ranged from 100% to 25% of field capacity; FC). The expression of sod genes increased only in gradually stressed individuals, where plants were pre-treated at 75% FC or 50% FC prior to being subjected to a severe water deficit of 25% FC. The superoxide ion levels increased more in the tips than in the leaf bases when plants were grown at 50% and 25% FC. Under gradually increasing water stress conditions, the accumulation of superoxide ions decreased to 50% of that of the control plants, associated with an increment in Cu/Zn-SOD accumulation and a higher expression of the mn-sod and cu/zn-sod genes. Conclusions: These results indicate that A. vera plants are stressed under severe water deficit and suggest that SOD is a key enzyme to decrease the reactive oxygen species levels induced by water deficit.