Document Type : Research Article
Authors
university of zabol
Abstract
Introduction
Due to Iran's geographical location and climatic conditions, the quantity and quality of water resources are considered one of the limiting factors for agriculture in this country. Droughts in the last two decades, on the one hand, and lack of attention to the optimal use and proper exploitation of water, on the other hand, have exacerbated the water crisis in Iran. For this reason, the agricultural sector has witnessed serious developments and new perspectives on the rational exploitation of water resources, irrigation shortages, the use of saline water resources in agriculture, changing irrigation systems, and cultivating water-intensive plants in the last two decades. Quinoa has been introduced as a forage crop for ensuring food security in the world, which can tolerate water and drought stress conditions to some extent. However, the development of its cultivation under water and drought stress conditions in Khuzestan Province should be based on determining the limits of irrigation water amounts and determining its tolerance to salinity.
Material and Methods
The present study was conducted to investigate the effect of different amounts of irrigation water and different levels of salinity on quantitative and qualitative parameters of quinoa plant. To carry out the work, quinoa was cultivated under drip irrigation and in a pulsed manner. The treatments studied included irrigation water quantity (I1: 60, I2: 80 and I3: 100% of field capacity), water quality (F (fresh): 0.5 and S (saline): 6 dS/m) and two irrigation managements: continuous drip (C) and pulsed drip (P). At the end of the growing season, sampling was performed to determine quantitative plant characteristics such as height, stem diameter, leaf area index, root length, root volume, fresh and dry root weight, and fresh and dry forage yield. Also, to investigate the effect of treatments on quinoa forage quality, qualitative parameters including leaf chlorophyll a and b content, leaf proline content, total digestible nutrients (TDN), crude protein (CP), cell wall density (hemicellulose and lignin) (NDF), and hemicellulose-free cell wall (ADF) percentage were measured. To investigate the distribution of salinity in the soil profile during and at the end of the growing season compared to its beginning, by digging a profile in the center of all experimental plots, two soil samples were taken from each profile at a depth of 0-30 cm and 30-60 cm. These samples were transferred to the laboratory and saturated extraction was performed on them. Then, the electrical conductivity of these samples was determined using an EC meter. All data collected from the experiment were entered into EXCEL 2019 software. After categorizing the data, SAS 9.1 software was used to analyze them. Data analysis of variance was performed at the 5 and 1 percent levels, and then means were compared using Duncan's test.
Result
The results showed that the treatments of continuous drip irrigation with freshwater and 100% depth, pulsed drip irrigation and 100% depth (first pulse of freshwater, second pulse of freshwater, third pulse of freshwater), continuous drip irrigation with freshwater and 80% depth, and pulsed drip irrigation and 80% depth (first pulse of freshwater, second pulse of freshwater, third pulse of freshwater) had the highest quantitative traits. The highest values of plant height, stem diameter, leaf area index, fresh biomass, and dry biomass were 94 cm, 1.10 mm, 23.152 cm², 25.31420, and 14.8256 tons per hectare, respectively, which were obtained from the continuous drip irrigation treatment at 100% of the plant's water requirement using fresh water. In these treatments, the final soil salinity was close to the initial salinity at the time of the experiment, and the highest amounts of chlorophyll a and b and carotenoids were also observed. The TDN and ADF values were high in two treatments: continuous drip irrigation with freshwater and 100% depth, and pulsed drip irrigation and 100% depth (first pulse freshwater, second pulse freshwater, third pulse freshwater). However, these treatments had low soluble sugar, proline and protein levels. Applying saline water alone or in combination with sweet pulses and water stress in treatments 2, 4, and 12 to 30 increased the quality of the produced forage (due to high soluble sugar, proline, and protein). The highest water use efficiency was obtained from treatment 26, which included pulsed drip irrigation and a depth of 60% (first pulse of fresh water, second pulse of salt water, third pulse of fresh water).
Conclusion
Therefore, considering that both water consumption efficiency and quality are considered in the production of forage products, it is recommended to use this treatment in conditions of saline water and pulsed drip irrigation.
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