Ali Reza Vaezi; uones mazllom aliabadi; Arman Zabihi
Abstract
Dry farming is an important method of crop production, particularly in semi-arid regions, where crop yield strongly depends on precipitation amount and its temporal variation during the growing season. Supplemental irrigation is a suitable practice for mitigating moisture stress and, consequently, improving ...
Read More
Dry farming is an important method of crop production, particularly in semi-arid regions, where crop yield strongly depends on precipitation amount and its temporal variation during the growing season. Supplemental irrigation is a suitable practice for mitigating moisture stress and, consequently, improving crop yield in rainfed agriculture. This study was conducted to estimate the proper time of supplemental irrigation in rainfed land by measuring soil water content during growth period, in 2016-2017. A field experiment was conducted using two plowing directions (along the slope and on contour lines) in plots with 2 m × 5 m dimensions, in a rainfed farm with 10 % slope. Volumetric soil water content (SWC) was measured in root zone by a TDR set at 10-day interval during growth period, from November 2016 to June 2017. Based on the results, SWC in the plots plowed on contour lines was about 6 % higher than the plots plowed along slope, and this difference was statistically different (P< 0.05). The mean readily available water (RAW) during growth period in the plots plowed on contour lines (6.07 mm) was about 2.5 times higher than the plots plowed along slope (2.25 mm) and showed significant difference with it (P< 0.05). The highest RAW was observed at stem elongation and the lowest value was found at grain germination, at which stage, about 6.7 mm water deficit was observed in rainfed wheat. Thus, application of supplemental irrigation at this stage can efficiently prevent water stress and improve wheat grain yield in this semi-arid region.
Habibeh Jahanbakhsh; ali modares; Hamed Keshavarz; mehdi panahi
Abstract
Physiological study of crops under microclimatic changes is very important to improve their production in the future. This research was done in Tarbiat Modaress University Research Greenhouse as factorial arrangement in randomized complete block design with three replications in one year (2015). The ...
Read More
Physiological study of crops under microclimatic changes is very important to improve their production in the future. This research was done in Tarbiat Modaress University Research Greenhouse as factorial arrangement in randomized complete block design with three replications in one year (2015). The objective was to study the effects of carbon dioxide (500, 900, and 1300 ppm), UV-radiation (UV-A, B, and C with intensity of 18, 25 and 40 µW.cm2, respectively) and two irrigation water treatments (full irrigation and deficit irrigation i.e. 60 percent of field capacity) on yield and yield components of sweet corn. Plant height showed a direct relation with the amount of irrigation water and decreased about 10 percent under water deficit stress. The interaction of carbon dioxide and water deficit as well as the interaction of UV-radiation and carbon dioxide reduced the number of leaves below the corns, although this decrease was not significant. Water deficit reduced Specific Leaf Area and Leaf Area Index by, respectively, 11% and 19% relative to the control. In full irrigation, carbon dioxide concentration and number of seeds in each row had direct relation, but under water deficit condition, they had indirect relation. Ultraviolet radiations wave length reduction reduced yield. Water deficit reduced Specific Leaf Area and number of seed in corn row. UV-A and B wave length did not significantly affect yield, but UV-C radiation decreased it. In brief, increase in UV wave length under drought conditions led to decrease in leaf number, leaf area, and yield.
r m
Abstract
Water deficit is not avoidable under arid and semiarid regions. But, the adverse effects of water deficit can be reduced by recognition of the impact processes and application of suitable chemical fertilizers. Nitrogen requirement varies under different irrigation managements and its proper usage can ...
Read More
Water deficit is not avoidable under arid and semiarid regions. But, the adverse effects of water deficit can be reduced by recognition of the impact processes and application of suitable chemical fertilizers. Nitrogen requirement varies under different irrigation managements and its proper usage can prevent drastic reduction of yield under the abovementioned conditions. This study was conducted for evaluating the combined effects of nitrogen and irrigation on the yield and quality of the local cultivar of garlic (Allium sativum L.). The study was performed as a split-block based on randomized complete blocks design with factors of irrigation at four levels (0-3, 3-6, 6-9 and 9-12 meters distance from the main line source), and nitrogen at four levels (0, 50,100 and 150 kg N per ha) using three replications and line source sprinkler irrigation system. The total irrigation water was measured by catch cans that were fixed in the middle of each plot. The results showed that the application of nitrogen significantly increased yield, tuber and leaf nitrogen concentration of garlic, and decreased mean cloves weight. The water deficit decreased yield, mean cloves weight and leaf nitrogen concentration of garlic and increased number of sheaths on bulbs and water use efficiency. The interaction of nitrogen and irrigation was not significant on the measured attributes. The highest amount of garlic yield was obtained by using 409 mm irrigation and 100 kg N per ha.