Drought is one of the critical agro-meteorological hazards in the world including Bangladesh. Rice is the major food grain in Bangladesh, and drought has threatened the food grain and the country's food security. However, drought hazard (DH) in the Boro rice growing period and their associations are less investigated in Bangladesh. Hence, we intend to appraise the DH in the vegetative, reproductive, and ripening phases and the whole growing season based on the daily temperature, precipitation data, and yearly rice phenology dataset from 8 meteorological stations in western Bangladesh from 1980 to 2013. The Mann-Kendall (M-K) test was employed to identify the trend in phenology dates and drought hazard. The standardized precipitation evapotranspiration index (SPEI) was adopted to compute the DH. The results show that moderate to severe drought events occurred in western Bangladesh during Boro rice growing period. The transplanting dates were delayed in the southwestern part by a rate of 1.31 day/year along with a trend towards a shorter and more humid ripening phase (p < 0.05). By contrast, transplanting dates were started earlier in the northwestern part with a rate of - 0.48 day/year along with the enhanced length of the reproductive and the ripening phases (p < 0.10). We appraised the DH during each Boro rice growing season, where the ripening phase faced a more severe DH than other phases that were most susceptible to water stress conditions. There was a strong association between DH and crop yield loss during the whole growth period in the study area.
Keywords: Drought Hazard; Mann-Kendall; Rice phenology; SPEI; Yield loss rate.