جستجوی مقالات مرتبط با کلیدواژه « simultaneous stress » در نشریات گروه « آب و خاک »

In order to manage application of saline water in irrigated lands and coping with crisis of water resources scarcity in arid and semi-arid regions, it is logical to obtain the optimum yield-salinity-water production functions for crops. In this way, a greenhouse experiment with three irrigation treatments including 100, 75 and 50 percent of water requirement and four salinity levels of irrigation water including 0.7, 4, 8, and 12 dS m-1, as a factorial in the form of a completely randomized block design with three replications was conducted in Kashmar region. The objective of this study was to determine the optimum yield-water-salinity production function of safflower. The crop production functions used in this study were linear, Cobb-Douglas, quadratic and transcendental functions. For assessing the accuracy and efficiency of these functions in predicting yield and yield components of safflower, the statistics of mean absolute error, normal root mean square error, determination coefficient, efficiency function and agreement index were used. Additionally, the plant salinity resistance threshold was determined by Mass-Hoffman linear model. The results showed among the applied functions, the quadratic function the lowest NRMSE and the highest R2, had the most efficiency in predicting yield and yield components of safflower in simultaneous salinity and drought stress conditions. According to Mass-Hoffman linear model, grain yield relative reduction by 10 percent, in salinity of 3.75 dS m-1 and grain yield relative reduction by 25 and 50 percent were occurred in salinity of 6.75 and 11.75 dS m-1, respectively. According to the findings of this research it can be concluded that the quadratic equation is recommendable as the best yield-water-salinity production function of safflower in pot conditions. Since, crop production functions are dependent to soil type, weather and climate conditions and water management in the field, more comprehensive studies should be done in the field conditions for determining the best yield-water-salinity production function of safflower.

The rise in water demand and reduction of water quality and soil in irrigating areas, especially in dry and semi-arid areas of the world, have turned into one of the most crucial challenges for water and soil engineering in recent years. This issue leads us toward optimal quantitative and qualitative management of these valuable resources aimed at achieving economic performance and water productivity. The periodic evaporation and transpiration of the plant in the conditions of simultaneous water and salinity stress are known as one of the most important factors in the qualitative and quantitative growth of the plant yield. Applying mathematical models that simulate the relationship between field variables and yield can be seen as a useful tool in water and soil management issues in such a situation, which has the potential to ensure optimal use of the water and soil resources of any country by providing the plant's water needs and preventing its further loss.

A factorial experiment was performed in 2019 based on completely randomized blocks design with three replications in plots with an area of 9 square meters at the agricultural and animal husbandry farm of Aliabad Fashafuyeh, located in Qom province to examine the simultaneous effect of different levels of water stress and salinity on the periodic evaporation-transpiration and fresh yield of the single cross 704 forage corn cultivar. The applied treatments included the irrigation water salinity at three electrical conductivity levels of 1.8 (S0), 5.2 (S1), and 8.6 (S2) deci Siemens/meter (dS/m), which were prepared by mixing saline well water of the region with fresh (drinking) water and three water stress levels of 100% (W0), 75% (W1), and 50% (W2) of the plant's water requirement. The depth of soil moisture in the corn plant root zone was measured by the TDR device at five depths of 7.5, 12, 20, 40, and 60 cm during different growth stages of the plant using pairs of 7.5, 12, and 20 cm stainless steel electrodes.

The simultaneous water and salinity stresses, which led to the reduced amount of periodic evaporation-transpiration of the yield compared to ideal conditions (without stress), were simulated by additive and multiplicative models. The results suggested a decrease in the evaporation and transpiration with the increased simultaneous water and salinity stresses so that the amount of total evaporation-transpiration in different treatments was measured to be between 692.7 and 344.9 mm and the fresh yield was estimated between 50.4 and 3.2 tons per hectare. Also, the highest amount of periodic evaporation and transpiration in all treatments was found to occur in the development and intermediate stages, and the relative fresh yield in the W0S0 to W2S2 treatments was calculated between 66% and 100%. The results of modeling the relative yield of the crop based on the amounts of relative evaporation and transpiration of corn in different growth stages and under the different treatments of water stress and salinity, indicated that Singh's additive model and Rao's multiplicative model were appropriate, while the Minhas model was recognized to be inappropriate in this estimation.

The research results suggested the significant impact of water stress and salinity at least at the 95% level on evaporation and transpiration and the corn yield. Moreover, the effect of the sensitivity of different growth stages of the plant on the reduction of evaporation and transpiration of corn varies so that in the three treatment groups W0, W1, and W2, the highest average decrease in slope was related to the final stage (13.6%) followed by the middle stage with an average decrease of 8.4% compared to the control treatment. Therefore, the highest decrease rate in evaporation-transpiration slope has been observed in these two growth stages due to the beginning of flowering, fruit formation, and physiological ripening of seeds. These results come from the lack of sufficient water storage and increased salinity of irrigation water in the soil. Water stresses and salinity will reduce water absorption and evaporation-transpiration, and ultimately, reduce crop production due to the decreased amount and potential of water in the soil. Another finding to be mentioned is the priority of water stress compared to salinity stress in reducing evaporation and transpiration and production yield. Also, by managing water and salinity stresses in the critical stages of plant growth (especially the middle stage), which is the time of flowering and the beginning and completion of the maize production process, a significant reduction in the crop can be somewhat prevented.

The lack of water and soil resources and their salinity are important points in the agricultural sector. Investigating the interactions between salinity and irrigation on plant yields is important in order to improve soil management and water use in arid and semi-arid regions. The purpose of this study was to study and evaluate the production functions of Basilicum L. in Mazandaran mass cultivar under simultaneous stress conditions of water and salinity. For this purpose, an experiment was conducted on a hectare research site in the Dushantepheh research center of Tehran. In this study, we used microplate weight-drainage to determine the rate of evaporation-transpiration of basil plant. Factorial experiment was conducted in a completely randomized design with four irrigation treatments including complete irrigation (FI), irrigation with 40 (DI40%), 60 (DI60%) and 80 (DI80%) water requirements of the plant and three subsoil treatments Irrigation water with a conductivity of 175/1 (S1), 3 (S2) and 5 dS / m (S3) for two consecutive years of 1395 and 1396 was carried out. The results showed that the basal plant yield reduction was 3.1 dS / m for irrigation water salinity and 10% for grazing line slope.