Limited Water Stress Research Articles

Methodology for a preliminary assessment of water use sustainability in industries at sub-basin level

The sustainability of industrial production, especially for highly water-demanding processes, is strictly related to water resource availability and to the dynamic interactions between natural and anthropogenic requirements over the spatial and temporal scales. The increase in industrial water demand raises the need to assess the related environmental sustainability, facing the occurrence of global and local water stress issues. The identification of reliable methodologies, based on simple indices and able to consider the impact on local water basins, may play a basilar role in water sustainability diagnosis and decision-making processes for water management and land use planning. The present work focalized on the definition of a methodology based on the calculation of indicators and indices in the view of providing a synthetic, simple, and site-specific assessment tool for industrial water cycle sustainability. The methodology was built starting from geo-referenced data on water availability and sectorial uses derived for Italian sub-basins. According to the data monthly time scale, the proposed indices allowed for an industrial water-related impacts assessment, able to take into account the seasonal variability of local resources. Three industrial factories, located in northern (SB1, SB2) and central (SB3) Italian sub-basins, were selected as case studies (CS1, CS2, CS3) to validate the methodology. The companies were directly involved and asked to provide some input data. The methodology is based on the calculation of three synthetic indexes: the Withdrawal and Consumption water Stress Index (WCSI) allowed for deriving a synthetic water stress level assessment at the sub-basin scale, also considering the spatial and temporal variations; the industrial water use sustainability assessment was achieved by calculating the Overall Factory-to-Basin Impact (OFBI) and the Internal Water Reuse (IWR) indices, which allowed a preliminary evaluation of the factories' impacts on the sub-basin water status, considering the related water uses and the overall pressures on the reference territorial context. The WCSI values highlighted significant differences between the northern sub-basins, characterised by limited water stress (WCSISB1 = 0.221; WCSISB2 = 0.047), and the central ones, more subjected to high stress (WCSISB3 = 0.413). The case studies CS1 and CS3 showed to exert a more significant impact on the local water resource (OFBICS1 = 0.18%; OFBICS2 = 0.192%) with respect to CS2 (OFBI = 0.002%), whereas the IWR index revealed the different company's attitude in implementing water reuse practices (IWRCS1 = 40%; IWRCS1 = 27%; IWRCS1 = 99%). The proposed methodology and the indices may also contribute to assessing the effectiveness of river basin management actions to pursue sustainable development goals.

Nano-Fe nutrition improves soybean physiological characteristics, yield, root features and water productivity in different planting dates under drought stress conditions

Soybean production as an oil and protein crop, especially in water limited conditions, is of global importance. Suitable Nano-iron fertilizer application method can be a useful nutrition technique under water limitation stress. The aim of this study was to investigate the response of yield, physiological and morphological characteristics of soybean to drought stress, planting date and nutrition with iron Nano-oxide in two separate experiments (i.e. 2-year field and a pot) in 2021–2022. Field experiments included planting date (April 09: early planting date, May 05: optimum planting date and June 10: late planting date), nutrition with iron Nano-oxide (control, seed priming 300 ppm, foliar spraying 15 ppm, priming 300 ppm + foliar spraying 15 ppm) and drought stress (100 %, 75 % and 50 % FC). In the pot experiment, all field treatments were applied except planting date. Then, morphological and biochemical characteristics of the root were investigated. The results showed that drought stress, planting date and different methods of iron Nano-oxide nutrition had significant effects on gas exchanges, chlorophyll fluorescence, antioxidant activity and grain yield. The highest gas exchanges, net photosynthesis rate, the maximum photosystem quantum efficiency (FV/Fm) and grain yield were obtained by iron Nano-oxide nutrition as seed priming + spraying in optimum planting date and 100 % FC. However, these traits were decreased with increasing drought intensity (50 % FC), non-use of iron Nano-oxide (control) in early planting date. By increasing the drought severity in the field to 50 % FC, the antioxidant enzyme’s activity increased. The highest activity of catalase and superoxide dismutase were observed in early planting date + non-use of iron Nano-oxide +50 % FC. Based on the results of the pot test, the highest root length, number of nitrogen-fixing nodules, root dry weight, and nitrogenase activity were observed by iron Nano-oxide nutrition (nano priming 300 ppm + 15 ppm spraying) under 100 % FC. The mentioned parameters were reduced by drought, but the number of root branches increased. Combined nutrition (priming + spraying) had more positive effects on the root's morphological and biochemical properties compared with iron spraying only. The water productivity increased due to late plantings, but the negative effect of early planting on this indicator was higher. The maximum water productivity (0.73 kg/m3) obtained from iron Nano-oxide nutrition (seed priming 300 ppm + foliar spraying 15 ppm) in late planting date under 50 % FC conditions and its lowest (0.35 kg/m3) in no iron Nano-oxide nutrition in early planting date under 100 % FC. In general, the optimum planting date (05 May), supply of 100 % FC and combined iron Nano-oxide nutrition (seed priming + foliar application) is suggestible for soybean (Kosar cultivar) production in the climate conditions like the present study.

Limited water stress modulates expression of circadian clock genes in Brachypodium distachyon roots

Organisms have evolved a circadian clock for the precise timing of their biological processes. Studies primarily on model dicots have shown the complexity of the inner timekeeper responsible for maintaining circadian oscillation in plants and have highlighted that circadian regulation is more than relevant to a wide range of biological processes, especially organ development and timing of flowering. Contribution of the circadian clock to overall plant fitness and yield has also long been known. Nevertheless, the organ- and species-specific functions of the circadian clock and its relation to stress adaptation have only recently been identified. Here we report transcriptional changes of core clock genes of the model monocot Brachypodium distachyon under three different light regimes (18:6 light:dark, 24:0 light and 0:24 dark) in response to mild drought stress in roots and green plant parts. Comparative monitoring of core clock gene expression in roots and green plant parts has shown that both phase and amplitude of expression in the roots of Brachypodium plants differ markedly from those in the green plant parts, even under well-watered conditions. Moreover, circadian clock genes responded to water depletion differently in root and shoot. These results suggest an organ-specific form and functions of the circadian clock in Brachypodium roots.

Effect of phosphorus sources on growth and cadmium accumulation in wheat under different soil moisture levels

Both cadmium (Cd) toxicity and water limited stress in crop plants are serious concerns worldwide while little is known about the impact of various phosphorus (P) sources on Cd accumulation in cereals especially under water limited stress. A study was conducted to explore the efficiency of three frequently available P fertilizers on Cd accumulation in wheat under different soil moisture levels. Three different P sources including diammonium phosphate (DAP), single super phosphate (SSP), and nitrophos (NP) were applied in the soil with three levels (0, 50 and 100 mg/kg). The drought stress was applied to half treatments during the latter growth stages of wheat and plants were harvested at maturity. The results demonstrated that water-limited stress decreased the growth and yield of plants than respective treatments without water stress. P supply increased the growth of wheat irrespective of water-limited stress. The effect on growth and yield varied with the sources and levels of P and maximum effects was observed in DAP treatment (100 mg/kg). The P amendments enhanced the leaf photosynthesis and activities of SOD, POD, CAT and decreased the leaf oxidative burst. Water limited stress enhanced the Cd concentrations in shoots, roots, and grains whereas P amendments minimized the Cd concentrations and enhanced the P concentrations in these parts of plants. The results obtained demonstrated that P supply in the form of DAP might be effective in minimization of Cd in grains and can be used for safe cultivation of metal-contaminated soils.

Foliar spray of silicon nanoparticles improved the growth and minimized cadmium (Cd) in wheat under combined Cd and water-limited stress.

The effects of foliar supply of silicon nanoparticles (Si-NPs) on growth, physiology, and cadmium (Cd) uptake by wheat (Triticum aestivum L.) were examined in different soil moisture levels. Seeds were sown in soil containing excess Cd (7.67mgkg-1) and Si-NPs were applied through foliar dressing with various levels (0, 25, 50, 100mg L-1) at different time intervals during growth period. Initially, all pots were irrigated with normal moisture level (70% water-holding capacity) and two moisture levels (35%, 70% WHC) were initiated after 6weeks of plant growth for remaining growth duration and harvesting was done after 124days of sowing. The results demonstrated the lowest plant growth, yield, and chlorophyll concentrations while the highest oxidative stress and Cd concentrations in plant tissues in water-stressed control (35% WHC) followed by normal control (75% WHC). Si-NPs enhanced the growth, photosynthesis, leaf defense system, and Si concentrations in tissues while minimized the Cd in wheat parts particularly in grains either soil normal or water-stressed conditions. Of the foliar spray, 100mg L-1 of Si-NPs showed the best results with respect to growth, Cd and Si uptake by plants, and soil post-harvest bioavailable Cd irrespective of soil water levels. In grain, Cd concentration was below threshold limit (0.2mgkg-1) for cereals in 100-mg kg-1 Si-NPs treatment irrespective of soil water levels. Si-NPs foliar dressing under Cd and water-limited stress might be an effective strategy in increasing growth, yield, and decreasing Cd concentration in wheat grains under experimental conditions. Thus, foliar dressing of Si-NPs minimized the Cd risk in food crops and NPs entry to surroundings, which might be possible after harvesting of crops in soil-applied NPs.

Physiological and Qualitative Response of Cucurbita pepo L. to Salicylic Acid under Controlled Water Stress Conditions

Limited water stress is one of the most important environmental stresses that affect the growth, quantity and quality of agronomic crops. This study was undertaken to investigate the effect of foliar applied salicylic acid (SA) on physiological responses, antioxidant enzymes and qualitative traits of Cucurbita pepo L. Plants exposed to water-stressed conditions in two years of field studies. Irrigation regimes at three soil matric potential levels (−0.3, −1.2 and −1.8 MPa) and SA at four levels (0.0, 0.5, 1.0 and 1.5 mg/L) were considered as main plot and sub-plots, respectively. The soil matric potential values (MPa) was measured just before irrigation. Results showed that under water stressed conditions alone, the amounts of malondialdehyde (MDA), hydrogen peroxide (H2O2) and ion leakage were higher compared with control treatment. However, spraying of SA under both water stress and non-stress conditions reduced the values of the above parameters. Water stress increased CAT, APX and GR enzymes activity. However foliar application of SA led to the decrease of CAT, APX and GR under all soil matric potential levels. The amount of carbohydrates and fatty acids increased with the intensity of water stress and SA modulated this response. By increasing SA concentration both in optimum and stress conditions, saturated fatty acids content decreased. According to our data, the SA application is an effective approach to improve pumpkin growth under water stress conditions.

Changes in physiological, phytochemical traits and gene expression of two Perovskia species in response to water deficit

Perovskia species are considered as valuable ornamental plants. In the present study, the enzymatic and non-enzymatic antioxidants were evaluated in P. atriplicifolia, and P. abrotanoides in response to water deficit stress. The root harvesting was performed after 0, 3, 5, 7, and 9 days exposure to stress. In both species, total phenolics content, total flavonoids, enzymatic antioxidant activities, total tanshinones, tanshinone IIA, cryptotanshinone, hydroxy-cryptotanshinone, and proline substantially increased with the severity of stress. In the current study, the variations in tanshinone profile and the expression of genes (DXS1, HMGR, KSL) related to tanshinones biosynthesis were also investigated. The results revealed the negative trend between the concentration of malondialdehyde, and hydrogen peroxide as well as the harmonized augmentation in activities of enzymatic antioxidants including guaiacol peroxidase, and ascorbate peroxidase, exclusively on 7th day of stress. The expression ratios of all studied genes were markedly induced by the drought stress. The content of major oxidative stress-related indicators suggested that P. atriplicifolia should be better pre-adapted to water deficit physiological tolerance than P. abrotanoides. Finally, the experimental results can provide further insight into differential responses to imposed water-limited stress along with choice of the optimal eustress treatment to obtain the desired composition of pharmacologically useful diterpenoids.

Transpiration and Water Use of an Irrigated Traditional Olive Grove with Sap-Flow Observations and the FAO56 Dual Crop Coefficient Approach

The SIMDualKc model was applied to evaluate the crop water use and the crop coefficient (Kc) of an irrigated olive grove (Olea europaea L.) located in Sicily, Italy, using experimental data collected from two crop seasons. The model applies the FAO56 dual Kc approach to compute the actual crop evapotranspiration (ETc act) and its components, i.e., the actual tree transpiration (Tc act), obtained through the basal crop coefficient (Kcb), and soil evaporation according to an evaporation coefficient (Ke). Model calibration was performed by minimizing the difference between the predicted Tc act and the observed daily tree transpiration measured with sap flow instrumentation (TSF field) acquired in 2009. The validation was performed using the independent data set of sap flow measurements from 2011. The calibrated Kcb was equal to 0.30 for the initial and non-growing season stages, 0.42 for the mid-season, and 0.37 for the end season. For both seasons, the goodness-of-fit indicators relative to comparing TSF field with the simulated Tc act resulted in root mean square errors (RMSE) lower than 0.27 mm d−1 and a slope of the linear regression close to 1.0 (0.94 ≤ b0 ≤ 1.00). The olive grove water balance simulated with SIMDualKc produced a ratio between soil evaporation (Es) and ETc act that averaged 39%. The ratio between actual (ETc act) and potential crop evapotranspiration (ETc) varied from 84% to about 99% in the mid-season, indicating that the values of ETc act are close to ETc, i.e., the adopted deficit irrigation led to limited water stress. The results confirm the suitability of the SIMDualKc model to apply the FAO56 dual Kc approach to tree crops, thus assessing the water use of olives and supporting the development of appropriate irrigation management tools that are usable by farmers. A different way to estimate Kcb is based on the approach suggested in 2009 by Allen and Pereira (A&P), which involves the measured fraction of ground covered (shaded) by the crop and the height of the trees. Its application to the studied grove produced the mid-season Kcb values ranging from 0.40–0.45 and end-season Kcb values ranging from 0.35–0.40. The comparison between the A&P-computed Tc act A&P and TSF field shows RMSE values ranging from 0.27 to 0.43 mm d−1, which demonstrates the adequacy of the latter approach for parameterizing water balance models and for irrigation scheduling decision making.

Integration of crop growth model and constraint-based metabolic model predicts metabolic changes over rice plant development under water-limited stress

Abstract Rice is a major staple food worldwide and understanding its metabolism is essential for improving crop yield and quality, especially in a changing climate. Constraint-based modelling is an established method for studying metabolism at a systems level, but one of its limitations is the difficulty in directly integrating certain environmental factors, such as water potential, to the model for predicting metabolic changes in response to environmental changes. Here, we developed a framework to integrate a crop growth model and an upgraded diel multi-organ genome-scale metabolic model of rice to predict the metabolism of rice growth under normal and water-limited conditions. Our model was able to predict distinct metabolic adaptations under water-limited stress compared to normal condition across multiple developmental stages. Our modelling results of dynamic changes in metabolism over the whole-plant growth period highlighted key features of rice metabolism under water-limited stress including early leaf senescence, reduction in photosynthesis and significant nitrogen assimilation during grain filling.

Investigating response of yield traits and oil content of sesame variety (Sesamum indicum L.) to nano-magnesium fertilizer and biopolymer chitosan under limited water stress

IntroductionSesamum, scientifically named Sesamum indicum L., is one of the oldest oilseed families and is adapted to warm and semi-warm regions and is known as the queen of oilseeds. The use of nanotechnology in the production of fertilizers results in optimal release and increased efficiency of absorption of nutrients in fertilizer which leads to significant economic and environmental benefits. Chitosan elicits stimulating defense mechanisms and is beneficial to plants, animals and humans and is environmentally friendly. Due to the fact that water stress and dehydration in Iran is always one of the most important agricultural problems and due to the importance of magnesium in photosynthesis of plants and also the use of different polymers such as chitosan to reduce the damage caused by stress, this study aimed to evaluate the effect of nano chitosan and magnesium application under water stress conditions on some sesame traits for sustainable agriculture development in Varamin region. Materials and methodsIn order to evaluate limited water stress and foliar application of magnesium and chitosan on growth and yielding traits and oil content of two sesame varieties, an experiment was conducted as a split factorial based on completely randomized blocks designed with three replications in a research farm in the southern Varamin Province, Iran, during 2016-17 growing season. Irrigation cut-off based on BBCH scale in three-level included: normal irrigation, 65 BBCH (flowering), and irrigation cut-off in 75 BBCH (capsule maturity) as the main factors. Sub-plot included a combination of three factors: two genotypes Oltan and Dashtestan-2, foliar application of Mg-nano in two levels non-application and foliar application (2 g/L) in 65 BBCH stage and foliar application of chitosan in three levels: non-application, foliar application of 4.8 g/L in 65 BBCH stage and 6.4 g/L in 75 BBCH stage. Results and discussionThe results showed that the irrigation up to 65 BBCH caused a reducing 28.08, 20.8, 53.05, 54.04 and 23.10% in the average traits of number of capsules, 1000-grain weight, grain yield, LAI, and oil percentage content in compared to the normal irrigation treatment (control). The highest grain yield was achieved in the application of Mg-nano-fertilizer under normal irrigation in Dashtestan-2 variety with a mean of 1188.2 kg/ha, which 16.3% increased in compared to the control treatment. The highest oil percentage was observed in the application of Mg-nano under normal irrigation was in Dashtestan-2 variety with an average of 50.38%, which 3.5% increase in compared to the control treatment. The highest grain yield was achieved in the application of Mg-nano-fertilizer under normal irrigation in Dashtestan-2 variety with a mean of 1188.2 kg/ha, which 16.3% increased in compared to the control treatment. The highest oil percentage was observed in the application of Mg-nano under normal irrigation was in Dashtestan-2 variety with an average of 50.38%, which 3.5% increase in compared to the control treatment. ConclusionFinally, foliar application of Mg-nano and chitosan (4.8 g/L) under water stress conditions were able to compensate for damage and to modify the negative effects of stress.

Combined use of zinc nanoparticles and co-composted biochar enhanced wheat growth and decreased Cd concentration in grains under Cd and drought stress: A field study

Toxic metals present in soil and water severally affect the food crops and create serious health concerns. The current field study was focused on the impacts of foliar spray of zinc oxide nanoparticles (ZnO NPs) (100 mg/L) and soil applied co-composted biochar (0.5% w/w) on yield and cadmium (Cd) accumulation by grains of wheat ( Triticum aestivum L.) under simultaneous Cd and water limited stress. After 60 days of seeds sowing, drought stress was initiated in half plots by alternate irrigation compared to normal irrigation. Plants were harvested after 122 days and various physiological parameters were measured. Results showed that drought and Cd stress collectively decreased plant dry weight and chlorophyll contents and caused oxidative stress in leaves. While application of NPs and co-composted biochar improved the plants biomass and chlorophyll contents by overcoming the oxidative stress and alterating the antioxidants enzymatic activities in stressed plants. Combined application of NPs and co-composted biochar restricted the Cd uptake below its threshold level in grains (0.2 mg/kg). The current study concluded that the combination of ZnO NPs and co-composted BC was helpful to improve wheat growth and biomass, chlorophylls contents, antioxidant enzyme activities by scavenging ROS and reducing Cd uptake by plants under simultaneous Cd and drought stress. • Cadmium and drought stress inhibited wheat growth under field conditions. • NPs and co-composted biochar improved wheat growth and chlorophyll contents under stress. • The amendments enhanced activities of antioxidants enzymes in wheat plants. • The amendments reduced the Cd concentration in wheat grains.

Comparison of Growth Responses in Sorghum Genotypes and Corn Grown in Arid Regions Under Different Levels of Water and Nitrogen Supplies

Improving the productivity of cropping systems in terms of irrigation water use and nitrogen (N) fertilizer and exploring the associated effective physiological traits are priorities mostly in water-limited areas. Therefore, this field experiment was conducted on a clay loam soil (thermic family of Typic Haplargids) in central Iran with the three planting dates of 2016 (June 30), early 2017 (June 10), and late 2017 (July 11). Three forage sorghum genotypes including SF002, SF001, and Pegah, three grain sorghum genotypes of MGS5, GS24, GS28, and one common corn hybrid were grown under two irrigation regimes (55% and 85% of the maximum allowable depletion – MAD) as well as two N levels (0 and 112.5 kg N ha−1 in the form of urea, 46% N). The results showed considerable genetic variation among the sorghum genotypes in terms of yield. Due to water-limited conditions, the grain and biomass yields of the corn hybrid were decreased more those of sorghum genotypes. However, higher potential sorghum genotypes recorded total dry biomass (shoot biomass and grain yield) values similar to those of corn under both normal and deficit irrigation regimes. On the other hand, the grain share of the total biomass in the corn hybrid was higher in the two irrigation regimes. Under deficit irrigation, the use efficiency values of irrigation water (IWUEb) and N fertilizer (NUEb) for the biomass yield in Pegah and GS24 were higher than those in the corn hybrid. However, IWUEg and NUEg in corn were significantly higher under both irrigation regimes compared to those recorded for even the high-yield potential genotypes of the grain and forage sorghum. The positive effects of N application on the plants declined under water-limited stress, but the negative effects of water deficit stress were reduced with N application, while dry matter and grain yield increased as a consequence of the increase in the maximum leaf area index, chlorophyll <em>a</em>, chlorophyll <em>b</em>, and carotenoid contents, as well as the enhanced antioxidant activities of catalase, ascorbate peroxidase, and peroxidase enzymes. It can be concluded that the corn-based planting system is superior to sorghum even under low irrigation conditions, and N supply could moderate the negative effects of water shortage stress on plant growth.

Combining ability of soybean (Glycine max L.) yield performance and related traits under water-limited stress conditions

Development of improved genotypes requires acquiring adequate information on genetic background and nature of gene action for planning appropriate breeding and selection strategies. This study was aimed at obtaining estimates of general and specific combining ability, identifying the best combiners in developing drought tolerant genotypes and determining gene action of soybean traits. Six genotypes were crossed using the North Carolina II mating design to form eight families, of which Makwacha and Nasoko were regarded as males and TGX1990-137F, TGX1987-23F, 1988-70F and Tikolore were regarded as females. Two-hundred F2 progeny and six parents were evaluated in the field under non-water-limited stress (non-WLS) and water-limited stress (WLS) conditions across 2 sites during the 2018 dry season in a split-plot layout. Water-regimes were allocated to main plots and genotypes to subplots in a randomized complete block design with 3 replications. Significant genotype and water regime effects were found for seed yield and yield components. Most progeny ranked higher than parents under WLS conditions for all traits. Significant general combining ability (GCA) and specific combining ability (SCA) effects for all traits indicated that both additive and non-additive gene effects were important for trait expression under WLS conditions. Both GCA and SCA effects significantly interacted with water regime effects, demonstrating the need for testing of potential progeny across varied WLS levels to determine stable genotypes. Parents and F2 progeny with significant positive GCA and SCA effects, respectively, under WLS were identified as potential material for inclusion in the breeding program for drought tolerance.

Physio-chemical changes of Cassia occidentalis under drought stress

Drought stress is a prime hindrance for Cassia occidentalis, a medicinal plant of potential importance. This experiment was accomplished to interpret the effect of drought stress on C. occidentalis employing four water supply levels (100ml, 200ml, 300ml and control) with soil relative water content ranging from 12% to 65%. The present study was carried out in pot experiments in complete randomized design with three replicates and the results were analysed on the basis of data recorded on growth, physiological and biochemical parameters. The parameters studied were number of leaf, leaf area index, biomass accumulation, NR activity, chlorophyll content and protein accumulation. The result showed a significant decrease in all parameters with the decrease in water supply, however mild level of stress (300ml; 36% SRWC) enhanced the growth. Our study concluded that the experimental plants were able to tolerate a limited water stress (up to 36% SRWC) but excessive drought (100ml) strikingly diminished the physio-biochemical activity and therefore hindered the plant growth.

The combined effect of nitrogen fertilizer and sowing season on response to water-limited stress in barley (Hordeum vulgareL.)

AbstractA field experiment was carried out for over two seasons (autumn and spring) as a split–split plot scheme based on a randomized complete block design with three replications. The main plots included two irrigation levels of the maximum available water depletion (maximum allowable depletion (MAD)) of 55 and 85% as non-stress and drought-stress environments, respectively, and the subplot accommodated two levels of nitrogen (0 and 62.5 kg N/ha, urea fertilizer); also, 20 barley genotypes were assigned to the sub-subplots. The biplot analysis of both sowing seasons showed that grain yield (GY) had a high positive correlation with total biomass (TB), whereas it had a high negative correlation with proline and total soluble carbohydrate as drought-tolerance-determinant characteristics. The genotypes which had the lowest and highest GY ranked significantly (P≤ 0.01) different with changing the sowing season under each irrigation level, indicating a larger plant interaction and non-stability in response to the season change (about two-fold), as compared to the change in the irrigation conditions. It could also be concluded that barley genotypes might experience a higher decrease in GY and sensitivity to water deficit in the autumn sowing season, as compared to the spring planting season, which was also intensified by nitrogen application. However, the response to nitrogen application depends on the plant genotype.

Foliar application of chitosan and nano-magnesium fertilizers influence on seed yield, oil content, photosynthetic pigments, antioxidant enzyme activities of sesame (Sesamum indicum L.) under water-limited conditions

Applying elicitors and nano-fertilizer has been recommended to enhance the growth and yield of secondary metabolites in herbs and medicinal plants under water-limited stress. However, less information is available on the effects of chitosan and nano-magnesium fertilizers on sesame seed yield, oil content, and physiological traits in the presence of nano-magnesium chelate (nano-Mg) under water-limited supply. In this regard, field experiments as a split-factorial experiment was performed based on randomized blocks in three replicates in Varamin city, south of Tehran, Iran, during 2015-2016 to evaluate the impact of chitosan and nano-Mg on physiological, seed, and oil traits of sesame. Irrigation cut-off based on BBCH scale was considered as the main factor including normal irrigation (I1), irrigation cut-off in 75 (I2), and 65 BBCH (I3) stages. Secondary factors as the subplot included ‘Oltan’ (C1) and ‘Dashtestan-2’ (C2) sesame cultivars, and foliar application of nano-Mg (application and non-application) and chitosan (control (CH1), foliar application of 4.8 g L-1 in 65 BBCH (CH2), and 6.4 g L-1 in 75 BBCH stages (CH3)). Further, free proline content, total sugars, the activity of antioxidant enzymes including catalase (CAT, EC 1.11.1.6), peroxidase (POD, EC 1.11.1), and ascorbate peroxidase (APX, EC 1.11.1.11), photosynthetic pigments content, seed yield, and oil content were evaluated in the next stage. Based on the results, irrigation cut-off in 65 BBCH stage (flowering) significantly increased free proline content, total sugars, and the activity of antioxidant enzymes, CAT, POD, and APX. However, chlorophyll a, b, and total contents, seed yield, oil percentage, and yield decreased under water stress. ‘Dashtestan-2’ cultivar had the highest seed yield and oil content, and more tolerant cultivar under water-limited stress. Interestingly, the production of proline content and total sugars increased while the activity of antioxidant enzymes, CAT, POD, and APX decreased under application of nano-Mg and CH2, which influenced both sesame response and seed attributes. As a result, the production of some physiological traits in sesame cultivars may be regulated by adjusting the irrigating practices. Finally, the co-application of nano-Mg and CH2 increased the seed yield and oil content of sesame under limited water supply in the arid and semi-arid region.

PAP90, a novel rice protein plays a critical role in regulation of D1 protein stability of PSII

IntroductionPhotosystem II (PSII) protein complex plays an essential role in the entire photosynthesis process. Various known and unknown protein factors are involved in the dynamics of the PSII complex that need to be characterized in crop plants for enhancing photosynthesis efficiency and productivity. ObjectivesThe experiments were conducted to decipher the regulatory proteins involved in PSII dynamics of rice crop. MethodsA novel rice regulatory protein PAP90 (PSII auxiliary protein ~90 kDa) was characterized by generating a loss-of-function mutant pap90. The mutation was characterized at molecular level followed by various experiments to analyze the morphological, physiological and biochemical processes of mutant under control and abiotic stresses. ResultsThe pap90 mutant showed reduced photosynthesis due to D1 protein instability that subsequently causes inadequate accumulation of thylakoid membrane complexes, especially PSII and decreases PSII functional efficiency. Expression of OsFtsH family genes and proteins were induced in the mutant, which are known to play a key role in D1 protein degradation and turnover. The reduced D1 protein accumulation in the mutant increased the production of reactive oxygen species (ROS). The accumulation of ROS along with the increased activity of antioxidant enzymes and induced expression of stress-associated genes and proteins in pap90 mutant contributed to its water-limited stress tolerance ability. ConclusionWe propose that PAP90 is a key auxiliary protein that interacts with D1 protein and maintains its stability, thereby promoting subsequent assembly of the PSII and associated membrane complexes.

Response of sorghum genotypes to water deficit stress under different CO2 and nitrogen levels

An open-top chamber experiment was conducted in the present study to investigate the growth and biochemical responses of six sorghum genotypes under two irrigation regimes (based on 40% and 75% soil-water depletion) and two N fertilizer levels (0 and 105 kgN ha−1), at two atmospheric CO2 conditions (390 ± 50 and 700 ± 50 μmol mol−1). The results revealed that water limited stress decreased the plant dry weight by reducing the plant leaf area, SPAD value, Fv/Fm, leaf RWC and membrane stability index (MSI), while it increased the specific activity of APX, CAT and POX enzymes, DPPH, LPC, Phe, TSC, H2O2, MDA and EL. The lowest decrease of the plant dry weight due to limited water stress was observed in the GS5 genotype, which was followed by the lowest decrease in the leaf RWC and MSI; also, the highest increase was seen in APX, Phe and TSC, while the lowest one was recorded in EL. Elevated CO2 improved DPPH and Phe under both control and water limited conditions, resulting in the decrease of APX, POX, H2O2 and EL, while a more pronounced effect was observed in the stress conditions. Furthermore, with the application of nitrogen, the reduction in DPPH, H2O2 and MDA values was greater under water limited stress rather than control conditions. It could be, therefore, concluded that the responses of sorghum genotypes to water deficit stress had interaction with atmospheric CO2 concentrations and nitrogen levels; this could be considered in breeding programs as well as planting management of sorghum.

Water limited stress at jointing stage on fresh waxy maize yield and its interactions with plant density under field conditions

Water limited stress at jointing stage on fresh waxy maize yield and its interactions with plant density under field conditions

Design and fabrication of an intelligent control system for determination of watering time for turfgrass plant using computer vision system and artificial neural network

The majority of the volume in a plant cell is water. Therefore, the growth and metabolism of plants are highly dependent on the changes in plant water content. To optimize plant growth in water limited and drought stress conditions, many mechanisms have been considered. The aim of this study was to design and develop an intelligent system, based on an Artificial Neural Network (ANN) and machine vision that would optimize plant growth in limited water situations. To this end, color, morphological and textural features were extracted from a set of turfgrass plant images under drought stress conditions and were analyzed to determine plant water requirement. To maximize classification accuracy, an optimum set of features [h (hsl color space), L (Lab color space), H (HSV color space) and PDF1 (Probability Density Functions)] were selected using a genetic algorithm. Then a data classification operation was conducted using an ANN. The classifier accuracy for three plant situations (fresh, at the edge of wilting and wilted) as well as its total accuracy were 91.3, 77.8, 97.9 and 90.7%, respectively. The automated irrigation system could measure and determine the plant wilting condition by investigation of four extracted features and then determine and apply the correct amount of water required for optimum plant growth in water limited situations.