Understanding the changes in irrigation requirement and possibility of high-temperature stress on major crops are important for food security of Bangladesh. Different water requirement components including potential crop water requirement and potential irrigation requirement were estimated for early, normal and late planting dates of wheat in Bogura using daily observed climate data in CropWat model for 19802013 time period. Significant decreasing trends of reference crop evapotranspiration was found during wheat growing months because of changes in climatic conditions. Potential crop water requirement and irrigation requirement showed significant decreasing trends. Sens rate of decrease of potential irrigation requirement was 1.44, 1.35 and 0.84 mm/year for early, normal and late planting, respectively. On average, the potential irrigation requirement for early planting was only 1.9 mm less compared to normal planting, while for late planting was 32.5 mm higher. High-temperature stress was evident during maturing stage under late planting and during reproductive stage for all planting dates of wheat. Increasing number of high-temperature days for late planting and decreasing number of high-temperature days for early and normal planting were observed during 19802013. Therefore, recent climate change induced high-temperature stress adversely affected wheat cultivation only under late planting conditions. However, climatic water demand did not impose any additional pressure on available water resources during last three decades.
Key words: Irrigation requirement, Heat stress, Planting date
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