Physiological and photosynthetic response of quinoa to drought stress

Water shortage is a critical problem touching plant growth and yield in semi-arid areas, for instance the Mediterranean región. For this reason was studied the physiological basis of drought tolerance of a new, drought tolerant crop quinoa (Chenopodium quinoa Willd.) tested in Morocco in two successive seasons, subject to four irrigation treatments (100, 50, and 33%ETc, and rainfed). The chlorophyll a fluorescence transients were analyzed by the JIP-test to transíate stress-induced damage in these transients to changes in biophysical parameter's allowing quantification of the energy flow through the photosynthetic apparatus. Drought stress induced a significant decrease in the maximum quantum yield of primary photochemistry (Φpo = Fv/Fm), and the quantum yield of electron transport (Φeo). The amount of active Photosystem II (PSII) reaction centers (RC) per excited cross section (RC/CS) also decreased when exposed to the highest drought stress. The effective antenna size of active RCs (ABS/RC) increased and the effective dissipation per active reaction centers (DIo/RC) increased by increasing drought stress during the growth season in comparison to the control. However the performance index (PI), was a very sensitive indicator of the physiological status of plants. Leaf area index, leaf water potential and stomatal conductance decreased as the drought increased. These results indicate that, in quinoa leaf, JIP-test can be used as a sensitive method for measuring drought stress effects

Improving water resources management using different irrigation strategies and water qualities: Field and modelling study

The aim of this study was to investigate the effects of two different irrigation strategies, regulated deficit irrigation, RDI and partial root drying, PRD using surface freshwater (SW) and brackish treated wastewater (TWW) for maize and potato crops. The SALTMED model has been applied using the field measurements of two cropping seasons 2013 and 2014 at the Canale Emiliano Romagnolo, CER’s experimental farm located in Mezzolara di Budrio (Bologna, Italy). In 2013, PRD irrigated potato received 17% less irrigation water than RDI but produced nearly the same yield as under RDI. The water productivity, o naverage, was 11% higher for PRD compared with RDI. For maize 2014 season, the PRD strategy received almost 15% less irrigation water, but produced a yield only 6% lower than that of RDI and gave equal water productivity to RDI. Given that the two strategies received the same amount of rainfall the results favour the PRD over RDI. Had the site not received above average rainfall (258 mm in 2013 and 259 mm during the 2014 growing seasons), PRD might have produced higher yield and water productivity than RDI. In terms of model simulations, overall, the model showed a strong relationship between the observed and the simulated soil moisture and salinity profiles, total dry mater and final yields. This illustrates SALTMED model’s ability to simulate the dry matter and yield of C3 and C4 crops as well as to simulated different water qualities and different water application strategies. Therefore, the model can run with “what if” scenarios depicting several water qualities, crops and irrigation systems and strategies without the need to try them all in the field. This will reduce costs of labour and investment

Integrated management tool for water, crop, soil and N-fertilizers: the Saltmed model

Good management will be required to double food production by 2050. Testing management strategies is commonly carried out in the field. Such trials are costly and require quite a long time to produce consistent and reliable results. An alternative option to field trials would be the use of tested models. Models can run with ‘what-if’ scenarios depicting different types of field management. They are a less costly and faster alternative to field trials. In contrast to some existing models, the SALTMED 2013 model is designed for general applications that include various irrigation systems and water application strategies, water of different qualities, variety of crops and trees, different nitrogen based fertilizers and different soil types. The model can simulate up to 20 fields with different treatments, different crops, different irrigation systems and management as well as different N-fertilizer applications. The SALTMED model has been tested using field experiment data from Portugal, Italy, Denmark, Morocco, Egypt, Syria, Brazil and Iran. It successfully simulated soil moisture, salinity, nitrogen content, grain yield and total dry matter. The model provides academics, professionals and extension services with a management tool for crops, soil, water and nitrogen fertilizers. This paper describes the processes, the equations of the model and summarizes the different applications and results obtained

Is the partial root drying irrigation method suitable for sandy soils? Field experiment and modelling using the Saltmed model

This study investigated the impact of regulated deficit irrigation (RDI) and partial root drying (PRD) on soil moisture, dry matter, and yield and water productivity of maize grown in sandy soil in Egypt. The experiment was conducted in 2013 and included eight treatments of RDI and PRD. Four RDI treatments [100% full irrigation requirement, FI (control), 80% FI, 60% FI and 40% FI] and four PRD treatments [100% PRD, 80% PRD, 60% PRD and 40% PRD] were conducted. The experimental and simulated results using the SALTMED model showed that maize yields obtained under RDI were higher than those obtained under PRD; this may be due to the fact that the soil is sandy and the PRD treatment received relatively less irrigation water. The latter perhaps have led to a smaller and narrower wetted soil volume within the root zone, and possibly some of the water was partly lost below the root zone due to the high infiltration rate commonly associated with sandy soils. The correlation between the observed and simulated grain yield showed that the SALTMED model was able to simulate grain yield and water productivity for all treatments with high accuracy, producing an average R2 of 0.98 and 0.95, respectively

Applying partial root drying drip irrigation in the presence of organic mulching. Is that the best irrigation practice for arid regions? Field and modelling study using the saltmed model

This research aimed at investigating the impact of irrigation systems, a deficit irrigation strategy and organic mulching using rice straw on maize water productivity in Egypt's arid conditions. The field experiment included 16 treatments over 2 seasons, 2015 and 2016. Irrigation systems were a drip irrigation system (DIS) and a furrow irrigation system (FIS), while the irrigation strategies were 100% full irrigation (FI), 75% FI, 50% FI and partial root drying (PRD). Organic mulching using rice straw (OMRS) was also investigated. The experimental results indicated that there was a positive impact of applying a PRD strategy by drip irrigation in the presence of organic mulching on the yield (12.6 t ha‐1 for 2015 and 12 t ha‐1 for 2016) and on the water productivity of maize (4.81 kg m‐3 for 2015 and 4.58 kg m‐3 for 2016), but under the control treatment (FIS with 100% full irrigation and without organic mulching) yield was 7.22 t ha‐1 for 2015 and 7.34 t ha‐1 for 2016 and water productivity of maize was 0.64 kg m‐3 for 2015 and 0.62 kg m‐3 for 2016. The SALTMED model simulated reasonably well the soil moisture and salinity distribution as well as maize dry matter, yield and water productivity for all treatments, with R2 of 0.998, 0.997 and 0.996, respectively. The results support the use of a PRD strategy by a drip irrigation system accompanied by an organic mulch of rice straw instead of the commonly used furrow irrigation. The PRD would save more fresh water, achieve higher yields and water productivity. In addition, mulching would reduce evaporation losses, retain soil moisture and increase organic matter content

Influence of salicylic acid on seed germination of Vicia faba L. under salt stress

Seed germination is the critical stage for species survival. Salinity affects germination and seedling growth and yield of several crop species, such as broad bean. That is why this study was carried to evaluate the effects of NaCl on seed germination and influence of salicylic acid on seed in order to improving salt tolerant on broad bean. Vicia faba L. is an important pulse crop in the Mediterranean region. In many cases broad bean is grown on saline soils where growth and yield are limited by salinity. The results showed that Irrigation with saline water significantly reduced all seed germination parameters in comparison with the respective control. Alleviation of growth arrest was observed with exogenous applications of salicylic acid (SA) under salt stress conditions. Overall, the positive effect of SA towards resistance to the salinity of V. faba L. will provide some practical basis for V. faba L cultivation

Effect of exogenous salicylic acid on growth parameters, gas exchange, and photosynthetic yields in salt-stressed Vicia faba l. plants

This study aimed to evaluate the potential effect of salicylic acid (SA) on the photosynthetic performance of faba bean (Vicia faba L.) plants under salt stress conditions. For this purpose, two salinity levels (0 and 120 mM) combined with two concentrations of SA (0 and 0.5 mM) were applied. Results showed that salt stress decreases the growth and gas exchange parameters (P-N, C-i, g(s), and T-r). Chlorophyll fluorescence imaging parameters showed a decrease in the effective photochemical quantum yield of PSII (YPII), photochemical quenching (qP), and electron transport rate (ETR), while the regulated (Y(NPQ) and unregulated dissipation energy Y(NO)) were increased under stress conditions. However, exogenous SA application under salt stress decreases the non-regulated dissipation and improves photosynthetic performance (Y(PSII), ETR, qP, and Y(NPQ)), growth, and gas exchange parameters. Consequently, SA application had a beneficial effect on the faba bean tolerance to salt stress and can be recommended for field application with low concentration.info:eu-repo/semantics/publishedVersio

Combined effect of salicylic acid and calcium application on salt-stressed strawberry plants

The salinity of water and agricultural lands is a major environmental factor adversely affecting crop productivity. Strawberry plants have been found to be sensitive to salt stress conditions. Salicylic acid (SA) and Ca2+ are endogenous signal molecules involved in many metabolic processes, which can stimulate the plants defence mechanisms to biotic and abiotic constraints. The main objective of this work was to investigate the impacts of SA (0.25 mM) and calcium nitrate (5 mM) application, singly or in combination, on growth parameters as well as physiological and biochemical markers of strawberry plants (Fragaria ananassa Duch, var. Fortuna) exposed to saline conditions (80 mM NaCl). The results showed that high salinity reduces plant growth and photosynthetic pigment content. Salt stress also induced an accumulation of Na, a decrease in K and Ca concentrations, a reduction in the levels of sugars, total phenol, relative water content, photochemical efficiency (F-v/F-m), and stomatal conductance as well as a decrease in proline, proteins, enzyme activities (catalase, superoxide dismutase and peroxidase) and an accumulation of hydrogen peroxide and malondialdehyde. However, SA and calcium treatments enhanced the plants' tolerance to salt stress by improving the above-mentioned parameters. Additionally, the best results were obtained with combined treatment (Ca + SA) under both salinity conditions. These findings indicated that the combination of calcium supplementation with exogenous application of SA may provide an effective solution to improving the strawberry plant's tolerance to saline conditions.info:eu-repo/semantics/publishedVersio

Impact of exogenous application of salicylic acid on growth, water status and antioxidant enzyme activity of strawberry plants (Fragaria vesca L.) under salt stress conditions

Irrigation with saline water can act as an alternate water resource and thus plays an important role in saving freshwater resources as well as promoting agriculture. Furthermore, salinity stress is considered one of the major abiotic stress factors, which strongly reduces crop productivity. In this context, the present work was conducted to examine the effect of exogenous salicylic acid (SA) application on salt stress tolerance of strawberry plants. For this purpose, strawberry plants (Fragaria vesca L.), three months old, were treated with three SA concentrations (0mM, 0.25mM and 0.5mM), then subjected to 80mM NaCl or not. After five weeks of treatment, growth responses, water status, photochemical efficiency and oxidative stress indicators were measured. The obtained results showed that irrigation with saline water negatively affected the growth parameters, the leaf water potential (LWP), the relative water content (RWC), the stomatal conductance (gs) and photochemical efficiency (Fv/Fm). While, the total protein content, the electrolyte leakage (EL), the malondialdehyde (MDA) and the hydrogen peroxide (H2O2) contents were increased in stressed plants compared to unstressed ones. Salt stress also leads to the activation of the antioxidant enzymes. However, the exogenous application of SA under salt stress conditions reduced the H2O2 accumulation, the electrolyte leakage and the MDA content. It has also improved the growth parameters, the LWP, the RWC, the gs, the Fv/Fm, the protein content and the antioxidant enzyme activities (POD, CAT and SOD) in the treated plants compared to those without SA application. Therefore, the beneficial effect of 0.25mM SA on Fragaria vesca L. salinity tolerance may provide some practical basis for strawberry cultivation under saline conditions.info:eu-repo/semantics/publishedVersio