Assessment of climatic indices limiting rainfed wheat yield |
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Institution: | 1. Civil Engineering, McGill University, Macdonald Engineering Building, 817 Sherbrooke Street West, Room 492, Montréal, Québec H3A 0C3, Canada;2. Civil Engineering, University of Victoria, PO Box 3055, EOW 206, 3800 Finnerty Road, Victoria, British Columbia V8P 5C2, Canada;3. Bioresource Engineering, McGill University, Macdonald Stewart Building, 21111 Lakeshore Road, Ste. Anne de Bellevue, Québec H9× 3V9, Canada |
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Abstract: | In this study variation of six climatic indices including accumulated precipitation (P), accumulated potential evapotranspiration (PET), accumulated actual evapotranspiration (AET), accumulated crop evapotranspiration (ETC), accumulated water stress (S) and climatic water deficit (D), was investigated. Climatic indices and their variation were calculated during seven growth stages of wheat in five locations in the northeast of Iran from 1983 to 2008. Principal component analysis (PCA) technique was applied to explore major modes of variation in the regional climatic indices during different crop growth stages. The principle component obtained for each region was correlated to the regional winter wheat yield. Finally the regional amount of water and precipitation use efficiency (WUE and PUE) were analyzed in order to assess any possible association with wheat yield. The results showed that the highest precipitation occurred during the tillering stage and spatially decreased from north (Bojnord) to south (Birjand) and from east (Mashhad) to west (Sabzevar). The difference between the highest and the lowest precipitation across all locations was 2.5 of standard value. The variation pattern of AET, compared to other indices, showed more similarity to variation of precipitation at different growth stages and the highest AET (more than 2 of standard value in all locations) occurred during the tillering stage. The PCA indicated that effective components varied in different locations. The most positive and effective components were types of evapotranspiration that are associated with crop (ETC and AET) and precipitation. However none of these effective PCs showed a significant correlation with final yield. The PUE and WUE analysis indicated that PUE provides more information to interpret the relationship between total amounts of precipitation and the final yield. |
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Keywords: | Evapotranspiration PCA Phenological stages Precipitation Wheat yield |
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