T. Raeisinejad; N. Yazdanpanah
Abstract
Introduction: Water has been known as an important limiting factor for plant growth and agricultural yields in arid and semi-arid regions. It is a significant input to agricultural production and also an essential requirement for domestic, industrial and municipal activities. Increasing population and ...
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Introduction: Water has been known as an important limiting factor for plant growth and agricultural yields in arid and semi-arid regions. It is a significant input to agricultural production and also an essential requirement for domestic, industrial and municipal activities. Increasing population and standards of living are contributing to a steep rise in demand for fresh water. By using proper irrigation management practices in farmlands, it is possible to utilize water, soil and fertilizer to produce high yield and quality products. Drip irrigation is considered as one of the most efficient irrigation methods. One of its major advantages is the ability to apply water to the soil as often as desired and in smaller quantity than the other irrigation methods. Two systems of drip irrigation including surface and subsurface drip irrigation methods have been widely used in arid and semiarid regions to reduce the water deficiency impact. Subsurface drip irrigation has been used for many years because of its effectiveness in reducing soil surface evaporation. It has been widely used in horticultural crops under both greenhouse and outdoor field conditions. However, the surface drip irrigation system can be used easier than the subsurface drip irrigation system. In addition, deficit irrigation is one of the strategies for efficient use of water and increasing water use efficiency in agricultural district. Deficit irrigation is a suitable solution to gain acceptable and economic performance by using minimum amount of water. The aim of this study was to evaluate the yield and yield components of sunflower affected by different levels of soil matric potential in combination with two contrasting drip irrigation method i.e. surface and subsurface. In addition, water use efficiency as an important criterion of yield was used to achieve the best and more suitable irrigation method under water scarcity conditions.
Materials and Methods: In order to investigate the irrigation management of sunflower, a field experiment was carried out during 2016 growing season at an experimental farm in Jiroft city. The treatments were laid out in split strip plots based on randomized complete block design with three replications. The treatments were comprised of three soil matric potentials of 40, 55, and 70 centibar for initiation of irrigation in the main plot and sub plots consisted of two drip irrigation systems (surface and subsurface). In the surface systems, drip lines were placed on the soil surface at a distance of 15 cm from the plant and in the subsurface systems, drip lines were placed at a depth of 30 cm. The irrigation time was determined based on the readings of metal tensiometers. These tensiometers were installed in three depths of 15, 30 and 50 cm of soil and at a distance of 20 cm from the plant. In this regard, in both irrigation systems, the mounted tensiometer at a depth of 15 cm of soil was used in the early growth and development, and mounted Tensiometers at depths of 30 and 50 cm soil were used in the middle and final stages of growth. In order to carry out irrigation at the potential point of view, the tensiometers were fully controlled and when the calibrated tensiometer screen showed the desired potential point, irrigation was carried out and the irrigation process continued until the soil moisture reached the crop capacity level. Yield, yield components such as number of seeds per head, along with water use efficiency were measured. Data were statistically analyzed using SAS Statistical software. Treatment means were compared using LSD test.
Results and Discussion: The results showed that the water usage parsimony of 153.6 mm (21.5 percent) between the 40 and 55 c-bar tensions caused that the yield, number of seeds per head and height of plant decreased by 12.5%, 12.8% and 11%, respectively, but water use efficiency increased 10.3%. Compared with 55 c-bar tention, 70 c-bar also decreased the yield, number of seeds per head and height of plant by 33.4%, 22.9% and 22.5%, respectively but increased water use efficiency by 4.7%. Moreover, the yield in subsurface drip irrigation increased by 499 kg/ha compared with surface irrigation. In addition, parsimony of water usage was 10% and water use efficiency increased by 21.5%. Number of seeds per head and the height of plant increased by 8.2% and 8.7%, respectively in subsurface drip irrigation.
Conclusion: According to the results of this study conducted on sunflower in Jirot area, it was concluded that the application of soil matric potential of 55 centibar in subsurface drip irrigation system is the best approach to increase water use efficiency during periods of drought.
Morteza Pouzesh Shirazi; Hassan Haghightnia; Rahim Khademi
Abstract
Introduction: Tomato is one of the most important vegetables that are used by human. High price of tomato due to its out of season production in Bushehr province has made a great tendency for farmers of this area to cultivate it in fall and winter in nearly 12000 hectares in the province. Mean annual ...
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Introduction: Tomato is one of the most important vegetables that are used by human. High price of tomato due to its out of season production in Bushehr province has made a great tendency for farmers of this area to cultivate it in fall and winter in nearly 12000 hectares in the province. Mean annual precipitation is about 250 mm per year. Maximum and minimum annual temperatures are 51 and -1 Celsius degrees. Mean annual evaporation is 3000 mm. Recent droughts and going down of water table because of over usage of underground water are main problems of this region that have enforced farmers to decrease irrigation water utilization and try to increase water use efficiency by using new technologies. Therefore, any new technical methods which can increase water use efficiency will help crop production quality and quantity and result in yield stability in the region. Many researchers have proved that mycorrhizal fungi can improve agricultural systems sustainability because of their ability to increase water absorption due to their long and expanded hyphae. Also they are known to increase nutrient uptake from soils even poor in minerals. Therefore, a greenhouse project was designed to determine the effect of Arbuscular mycorrhizal fungi on nutrients uptake and water use efficiency of tomato under drought stress in Bushehr province in southern Iran.
Materials and Methods: The experiment was carried out on completely randomized block design in factorial with three replications during 2016-2017 in the greenhouse of Bushehr agricultural and natural resources research organization located in Southern Iran. Factors were as follows: 1) four Arbuscularmycorrhizal fungi (Glomus mosseae ،Glomus intraradices، Glomus vsersiform and Glomus caledonium) and a control (without inoculation), 2) irrigation at three levels based on soil moisture depletion at I1=25, I2=50 and I3=70 percent of available water to show stress (from non-stress to low and high stress levels). Soil used for this experiment was dried in sunshine for one month to be evacuated from any native fungi. Soils of the region are calcareous ones with low salinity limitation (EC= 3.70 dS/m) and poor nutrition elements and slightly alkali (pH=7.9). Inoculation of roots by fungi was done by pouring one spoon of fungi near tomato roots while cultivating the transported seedlings in the pot. This would help the roots to be exposed to fungi directly while spreading through growing. Irrigation water used were 22.3, 20.1 and 17.7 liter for each pot filled with 10 kg soil during the season. The experiment lasted 100 days and tomato properties were measured such as yield, colonization percent, nutrition elements concentration and also, water use efficiency. Dried leaves were milled and put in furnace at 550 Celsius degrees. Roots were soaked in water for five minutes to be detached from soil and cleaned toughly. Detached roots were maintained in small glass jars filled with alcohol and were kept in refrigerator at 5 Celsius degrees. Roots were then colored by Try pan blue method and root colonization percent was measured by Grid line intersect method.
Results and Discussion: Results showed that interaction effect of mycorrhizal fungi and irrigation levels was significant at 1% level on tomato properties (except for N concentration in leaves). Mean comparison with Duncan`s test proved that increase in drought stress caused decrease in all tomato properties but fungi inoculation could mitigate water shortage in comparison to non-inoculated tomatoes Higher drought stress decreased colonization significantly. Drought stress caused significant deficiency in nutrition elements such as N, P and Fe, however some elements such as K, Zn and Mn were increased in medium drought stress. Inoculation with all mycorrhizal fungi improved nutrition elements concentration in tomato leaves. Water use efficiency was increased 67.9, 49.6 and 52.1 percent from non to medium and high stress respectively in tomatoes treated with Glomus intraradices.
Conclusion: Using of mycorrhizal fungi specially Glomus intraradices and Glomus caledonium increased tomato water use efficiency and improved growth properties due to the increment of water resistance ability in plant. This phenomenon is caused by higher nutrition elements uptake by roots and optimization of water relationship in tomato in the presence of mycorrhizal fungi. According to results, it is suggested tomato roots inoculation with mycorrhizal fungi especially in regions with high water stress potential.
