,fatmeh hashami; Ali Shahnazari; mahmood raeini; ali ghadami firouzabadi; Ebrahim Amiri
Abstract
The research as reported in related to simulation by WOFOST, predominately focused on traditional methods of deficit irrigation such as terms of percentage in full irrigation conditions or as evaluation of growth and development in certain days after irrigation. Also it should be noted that not only ...
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The research as reported in related to simulation by WOFOST, predominately focused on traditional methods of deficit irrigation such as terms of percentage in full irrigation conditions or as evaluation of growth and development in certain days after irrigation. Also it should be noted that not only these researches was based on a year plants, but also there isn’t any research of sunflower. So, in this research the ability of the last version of WOFOST in simulating of sunflower in DI and PRD in %75 and %55 levels is carried out in contrast to FI in two continued year so that crop coefficient of sunflower could be calculated and by this, the productivity of yield in Sari agricultural and natural resources research field could be achieved. The results of calibrations showed that crop coefficient which depends on weather, coordinates of region and physiologic and phonologic of plant is fixed among the simulation and irrigation coefficient are depend on irrigation treatment and their response in development of growth stages. Also the results showed that by decreasing the volume of water which given to plant, AMAXTB and KDIFTB decreased and adversely EFFTB is increase. Simulated seed yield and total biomass had normalized root mean square error (nRMSE) index less than 10%, coefficient of residual mass (CRM) index near zero, modeling efficiency (EF) about 0.98, correlation coefficient (R) about 0.96 and totally comparing the simulation and observation parameters showed that in the most statistical test done in the present study, the result in acceptable range which represented that WOFOST could be able to simulate the responses od sunflower in DI and PRD treatments by calibrated coefficient.
P. Daneshpazhoh; A. R. Ghasemi; Mohamad reza Nori Emamzadeie; R. Barzegar
Abstract
Introduction: Optimal water utilization is one of the most important challenges of the present century. Due to limited water resources and the existence of alternate droughts in the country, optimal use of it is necessary. The deficit irrigation technique is one of the most effective and practical ways ...
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Introduction: Optimal water utilization is one of the most important challenges of the present century. Due to limited water resources and the existence of alternate droughts in the country, optimal use of it is necessary. The deficit irrigation technique is one of the most effective and practical ways in which it can determine and justify the minimum water consumption with acceptable economic performance. Its use in reducing water consumption for biomass production and for irrigation of annual and perennial crops. To effectively apply water deficit management, an understanding of the effects of irrigation at different stages of vine growth is required. Partial Root-zone Drying (PRD) is also one of the new irrigation techniques over the past years. The results of many studies indicate that water use efficiency has increased and there is no significant reduction in the yield in this irrigation method. In this technique, only half of the roots are irrigated at each turn and the remaining half remains dry. On the other hand, in recent years, the use of natural minerals has improved in order to improve the physical and chemical composition of the soil, which leads to an increase in water holding capacity in the soil. One of the methods for increasing the water use efficiency is the application of water absorbent materials in soil. Super absorbent polymer increases the water saving in soil and decreases the amount of water used for irrigation. Zeolite is one of these minerals that increases the soil water holding capacity. So far, many studies have been carried out on the use of PRD, as well as the use of zeolite, but none has examined the effect of these two simultaneously. Therefore, in the present study, the efficiency of both above method and deficit irrigation on yield and water use efficiency of sweet pepper were investigated.
Materials and Methods: This research was carried out in a completely randomized design with 9 treatments and 4 replications in a greenhouse in Shahrekord University. This study was carried out at three levels of irrigation of 100%, 75% and 50% of the water requirement of the plant by Partial Root-zone Drying and zeolite in two levels of 2 and 4% by weight in the soil, in one and two sides of the pots with a height of 30 and diameter 28 cm. After preparing the culture medium, the F1 type Lummus seedlings were transferred to the pots. During the transfer of transplants into the pot, careful attention was paid to the fact that the roots were developed on both sides. Physiological parameters such as leaf area, total fresh and dry weight of the whole organ, total fresh weight of fruit, diameter and number of fruits and chemical indices including vitamin C, pH, total soluble solids and chlorophyll a, b and total chlorophyll with water use efficiency were measured and evaluated. In order to analyze the results, SAS software (version 1/9) was used. Mean comparison was also performed by LSD test.
Results and Discussion: The results of this study showed that there was a significant difference in the 1% level for fresh and dry weight, fresh weight of fruit and chemical indices of vitamin C, pH and soluble solids, and a significant difference at 5% for diameter fruit and chlorophyll. The results of comparing the meanings showed that fresh weight and fruit diameter were significantly decreased in all treatments than control. The number of fruits in severe irrigation (50%) and in both levels of zeolite showed a significant decrease compared to control. Vitamin C value as an important indicator of fruit quality in all treatments was significantly higher than control, in other words water stress causes an increase in the amount of vitamin C in the fruit, and the amount of pH in the most treatments has decreased significantly compared to the control treatment.
Conclusion: Given that all important processes such as photosynthesis, nutrition, opening and closing of stomatal and plant growth and development are under the influence of water, most of the studied traits in this research (except chlorophyll) in zeolite-containing treatments, showed a significant advantage over non-consumption of zeolite. The results also showed that application of PRD method with zeolite in deficit irrigation resulted in significant increase in water use efficiency in all treatments.
