R. Najafipour; H. Ramezani Etedali; B. Nazari
Abstract
Introduction: Greenhouses have a key role in agriculture productions. Given the ability of controlling production factors, there is the possibility of out-of-season cultivation in greenhouses, which is important in terms of food security, economics, and agricultural marketing. Estimation of water requirement ...
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Introduction: Greenhouses have a key role in agriculture productions. Given the ability of controlling production factors, there is the possibility of out-of-season cultivation in greenhouses, which is important in terms of food security, economics, and agricultural marketing. Estimation of water requirement for planning the development of greenhouses and their operation is very important. Awareness of the exact amount of water requirement is important both in terms of production and growth. Many studies have shown the usefulness of greenhouses in improving yield, physical and economical productivity. So far, comprehensive studies have not been carried out on the productivity of greenhouse cucumber cultivation and its effects on water resources in Qazvin province. Therefore, the goal of this study was to determine the greenhouse cucumber water requirement and provide a model for estimating evapotranspiration of cucumber under greenhouse condition. Also, determining greenhouse cucumber productivity in Qazvin province and evaluating the effect of this improvement on water resources were other objectives.
Materials and Methods: This research was carried out in a greenhouse near Qazvin city. The height of the greenhouse from the ground was 4 meters, and its plastic cover was made of polyethylene. Experiments were carried out in greenhouse with greenhouse seedling on 20-3-2015 in two rows of pot. The greenhouse was equipped with the necessary tools to measure temperature, maximum and minimum temperature, relative humidity, and solar radiation. Soil texture in this research was clay loam with 30, 32 and 38 percent of sand, silt and clay, respectively. The water content was, , 31% and 16 percent at field capacity (FC) and permanent wiling point (PWP) respectively. An irrigation interval of two days (a favorable condition) was considered. In this experiment, the seeds of the Royal cucumber were used to coincide with the planting time and harvesting length. The plastic pots with a diameter of 18 cm and a height of 23 cm were utilized. The pots were filled with equal quantities of fine and fine gravel (for drainage) and then with the agricultural soil prepared for cucumber cultivation. In order to provide conditions similar to the actual cucumber planting in the flower bed, the pots were placed close to the greenhouse. The irrigation of the plants was carried out manually for 83 days. The relative humidity, temperature and radiation were measured hourly. Further, the effects of irrigation on different characteristics of the test plants were observed and recorded. The moisture content was measured by weight and soil moisture reduction in full irrigation was compensated for the FC moisture content in each irrigation interval. Until 30 days after planting (Stages 4-6), the pots were irrigated with equal amounts. In order to evaluate the effects of deficit irrigation, four treatments were considered. These treatment were as follows: first treatment (FI): irrigation depth equal to 100% of the plant evapotranspiration with five replications, treatment (DI20): irrigation depth equal to 80% of the plant evapotranspiration with five replicates, treatment 3: (DI40) irrigation depth equal to 60% of the plant evapotranspiration with five replicates and the fourth treatment (DI60): irrigation depth equal to 40% of the plant evapotranspiration with five replications.
Results and Discussion: The maximum and minimum evapotranspiration was 8.7 and 1.06 mm/day in 61 and 13 days after transplanting, respectively. By investigation different mathematical models, the best models for estimation of cucumber evapotranspiration in greenhouse was the power model based temperature, humidity and height of crop with R2 of 0.86. The FAO-Penman-Monteith and Blaney-Criddle models exhibited the best and worst performance with R2 of 0.42 and 0.24, respectively. The cucumber water productivities in greenhouses ranged from 9.23 to 22.44 Kilograms per cubic meter. This wide water productivity range shows the importance of management and operation in water productivity improvement in greenhouses.
Conclusion: Estimation of greenhouses cucumber water requirement and water productivity are very important. The best model for estimating cucumber evapotranspiration in greenhouse was the power model based on temperature, humidity and height of crop with R2 of 0.86. In this study, cucumber water productivity was estimated in Qazvin greenhouses. The results showed that cucumber water productivities ranged from 9.23 to 22.44 Kilograms per cubic meter. Consequently, 117 ha greenhouse is required for producing the present value of cucumber in the province. This option would save 15 millions of cubic meter water in this area. Development of greenhouses with regarding to various economic and social aspects can help decision-makers in solving water shortage problems.
M. Esmaeili; Bahman Farhadi Bansouleh; M. Ghobadi
Abstract
Introduction: Expansion of the area of oilseed crops such as soybean is one of the policies of Iranian agricultural policy makers as Iran is one of the major oilseed importers in the world. However, the area of this crop in Kermanshah province is negligible, but it could be cultivated in most parts ...
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Introduction: Expansion of the area of oilseed crops such as soybean is one of the policies of Iranian agricultural policy makers as Iran is one of the major oilseed importers in the world. However, the area of this crop in Kermanshah province is negligible, but it could be cultivated in most parts of this province. The quantity and quality of the produced grain could be affected by environmental factors such as weather parameters and water availability. The aim of the current study was to investigate the effects of levels of deficit irrigation on the quantity and quality of soybean crop yield in Kermanshah, Iran.
Materials and Methods: For this purpose, a field study was conducted as randomized complete block design with four replications and four irrigation treatments at the research farm of Razi University, Kermanshah in 2012. The size of each plot was 4 * 4 m. Irrigation treatments consisted of four irrigation levels: 20% over irrigation (T4), full irrigation (T3 as control), 20% less irrigation (T2) and 40% less irrigation (T1). The reason to choose T4 treatment was the lack of confidence in estimated crop evapotranspiration as there was no local calibration of crop coefficient (Kc) for this crop. The required water for T3 treatment was calculated based on daily weather data using FAO-Penman-Montith equation. Daily weather data was recorded in a weather station which was located in the research farm and is available in the www.fieldclimate.com. As there was no rainfall during the crop season, all of the required water was supplied through irrigation. The required water for treatments of T1, T2 and T4 was considered as 60%, 80% and 120% of T3 treatment. The required water was applied using a hose connected to a volumetric flow meter with a liter precision. Total amount of applied water during the crop season was 4399, 5865, 7331 and 8797 m3.ha-1 in the treatments. Fertilizers were applied based on the recommendations of soil fertility experts. Weeds were controlled manually. Finally, the area of two square meters in the middle of each plot was harvested in order to determine crop yield in terms of grain, biomass, stem, pod, seed protein content and fat percentage and also water productivity index. Dry weights of the samples were measured after drying samples in the oven for48hours at 70° C. The percentage of fat and protein in the grains are also measured in the laboratory. Water productivity index was calculated for each treatment by dividing crop yield (in terms of grain, biomass, protein and fat) over seasonal water use. Statistical analysis of the results is also done using MSTATC software.
Results and Discussion: The highest and lowest crop yields were measured respectively in the treatments T4 and T1.The mean value of grain yield was 1084, 1367, 1716 and 1940 kg.ha-1,respectively in the treatments T1, T2, T3 and T4. These results showed a 36% decrease in the grain yield by decreasing 40% in the amount of supplied water. However, biological yield was decreasedby the level of irrigation, but the rate of reduction was lower than that of grain yield. By reducing irrigation application, thepercentage of grain protein content increased while the percentage of fat in the grain decreased. Considering simultaneous reduction in grain yield and fat content in the grain, severe reductions in fat yield (oil content) were observed under water stress conditions. Crop yield in terms of fat was reduced by 26.2 and 50.1 %, respectively in treatments T2 and T1 in comparison with T3 (control treatment). The maximum and minimum percentages of protein in the treatments were 31% and 27%, respectively in the treatments T1 and T4. Maximum water productivity in terms of grain, biomass and protein was achieved in T1 treatment respectively with the amounts of 0.24, 0.81 and 0.077 kg.m-3. Maximum and minimum fat percentage was 0.052 and 0.040 kg.m-3, respectively in the T4 and T1 treatments. In addition,the results indicated that water productivity index in terms of grain, biomass and protein increased while they decreased in terms of fat yield.The results of statistical analysis indicated that water productivity index in all terms except protein had significant differences (at 5%) with T3 treatment.
Conclusion: Crop yield and water productivity (except in terms of fat) was increased by increasing applied water. Considering all indices of treatment T2 (20% deficit irrigation), itwas suggested as the best treatment.
