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Norollah Jalali; Ali Shahnazari; MZ Ahamadi; Mojtaba Khoshravesh; Mojtaba Rezaie
Abstract
The purpose of this study was to investigate the effects of irrigation management on water requirement and crop coefficient of Hashemi and Kuhsar cultivars in the first crop. This experiment was carried out in Mahmoudabad District of Mazandaran Province in Iran in the form of factorial in a randomized ...
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The purpose of this study was to investigate the effects of irrigation management on water requirement and crop coefficient of Hashemi and Kuhsar cultivars in the first crop. This experiment was carried out in Mahmoudabad District of Mazandaran Province in Iran in the form of factorial in a randomized complete block design, in two growing seasons of 2016-2018. The water requirements for the fields (from transplanting to harvest) and the crop coefficient of these two cultivars were studied in two systems of traditional flooding and system of rice intensification (SRI). The results showed that, in the first crop, the two-year average water requirements of Kohsar and Hashemi in SRI were 534 and 556 mm and for the traditional flooding system 623 and 632 mm, respectively. The water required by the farm in traditional flooding decreased by 13.1% in the SRI. Based on reference evapotranspiration using pan evaporation method for the three stages of vegetative, reproductive, and maturing, crop coefficient values for the flooding system for Kuhsar were, respectively, 1.14, 1.29, and 0.92; and for Hashemi, they were 1.18, 1.32, and 0.92. According to the obtained results, SRI causes significant savings in paddy water consumption, therefore, it is suggested that, due to water shortage in the country, this method be used as one of the adaptation strategies in rice fields.
mostafa yosefian; Ali Shahnazari; mirkhalegh ziyatabar ahmadi; mahmoud raeini; Behroz arabzadeh
Abstract
Due to drought crisis in recent years, the use of alternative cropping methods that save water without any decrease in yield is increasing. Therefore, in order to evaluate the yield, yield components, and water use of rice under different non-submerged water levels and comparing it with permanently submerged ...
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Due to drought crisis in recent years, the use of alternative cropping methods that save water without any decrease in yield is increasing. Therefore, in order to evaluate the yield, yield components, and water use of rice under different non-submerged water levels and comparing it with permanently submerged condition, an experiment was conducted at fields of Rice Research Institute of Mazandaran during 2015 and 2016, using a randomized complete block design with three replications. The treatments consisted of two methods, regulated deficit irrigation (RDI) by irrigating all furrows and partial root drying (PRD) by irrigating alternate furrows, with three levels of drought stress: 10, 30, and 60 KPa (RDI10, PRD10, RDI30, PRD30, RDI60, PRD60) and a control treatment with permanently submerged basin irrigation in puddled soil (traditional method). Rice yield, yield components, and water consumption were measured in each treatment. The results showed that yield, plant height, panicle length, number of grains, 1000-grain weight, and water productivity (kg/m3) and water consumption at different levels of irrigation had a statistically significant difference in different treatments. Although the highest yield of rice was obtained in continuous submergence, yield reduction in alternate furrow irrigation treatments with minor stress (RDI10 and PRD10) was negligible and they were in the same statistical group in the two years of study. Also, partial root drying, significantly reduced water consumption, such that PRD10 treatment resulted in 32% reduction in water consumption compared to the control treatment, and deficit irrigation, especially partial root drying, increased water productivity. The highest water productivity (kg/m3) was calculated in PRD30 treatment at 0.724 kg per cubic meter of water. Based on the results, water consumption in the partial root drying was less than regulated deficit irrigation with the same tension, such that water consumption in PRD10 decreased by 15% compared to RDI10. However, average yield of PRD10v in both years was 1.1% higher. The results related to the yield components were also proportional to yield and partial root drying method compared to regulated deficit irrigation was better.
fatemeh jafari sayadi; Mohammad Ali Gholami Sefidkouhi; mirkahlegh ziyaeetabar ahmadi
Abstract
Water demand is one of the most effective factors in irrigation scheduling. In evapotranspiration formulas, crop coefficient (Kc), as a representative of different plants characteristics, is of great importance. Calculating this coefficient using the existing methods and formulas is costly and time-consuming, ...
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Water demand is one of the most effective factors in irrigation scheduling. In evapotranspiration formulas, crop coefficient (Kc), as a representative of different plants characteristics, is of great importance. Calculating this coefficient using the existing methods and formulas is costly and time-consuming, and results are point-specific. However, nowadays, calculation methods that provide large- scale Kc values are of interest. The methods based on remote sensing have been welcomed by many researchers. The objective of the present study was calculating crop coefficient (Kc) and leaf area index (LAI) of rice in different growing stages, using OLI sensor. In this regard, data LAI of two rice fields (areas of 15 and 65 hectares) located in north part of Sari, Iran, were used in two growing seasons (2014-2015 and 2015-2016). The average Kc at transplantation, tillering, heading, and maturity stages was, respectively, 0.92, 1.24, 1.19, and 1.12, showing that Kc had a good correlation with NDVI at different stages (r>0.97). According to the results, NDVI is a good estimator for rice Kc. In addition, Rice Growth Vegetation Index (RGVI) in all growing stages had a correlation coefficient r>0.93. RGVI is considered as a good estimator of LAI. Approximately at all growing stages, except heading, more than 93% of LAI changes were predicted by RGVI. Generally, it can be concluded that the most suitable indices for estimating Kc and LAI of rice are NDVI and RGVI, respectively.