This research explores the climatic effects on the rice yield for three rice ecotypes spatiotemporally in northwest Bangladesh using 40-years datasets. A significant difference was observed in the three rice ecotypes in the rice-growing season: rainfall, temperature, humidity, and sunshine. The study demonstrates that climatic factors have a significant impact on rice productivity. For example, temperature fluctuations were highly linked with the rice yield, similar to earlier studies (Sarker et al. 2014; Shahid et al., 2016; Islam et al., 2020a; Jerin et al. 2021; Kamruzzaman et al. 2021). Besides, the results also reveal different climatic influences on rice yield to show the strong regional variations of rice yields in northwest Bangladesh.
Rice yields for several rice varieties showed a distinct regional pattern, with the Aus yield being more favorable in Dinajpur and Rajshahi regions than other regions. However, most of the northern portion of the study area had a low Aus yield. By contrast, Aman was typically grown in the western parts except for the Dinajpur region but low yield in the southern part. Boro had more yield in the central part of the study region and less in scattered areas. Several factors are contributed to rice yield variations across the study area. Natural factors (e.g., topography, soil, drought/flood, and climatic conditions), management factors (e.g., irrigation, use of fertilizer/pesticides), and agricultural technologies (e.g., plowing approaches and the use of high yielding varieties and hybrid seed) (Zinat et al., 2020). Rice yields have increased threefold between 1976 and 2015, and Boro yield has grown significantly more than Aus and Aman yields. Boro yield may have expanded due to a shift in Boro production from rain-fed to irrigation during the dry season. Sarker et al. (2019) and Ghose et al. (221a) are also reported a similar finding.
In this study, the coefficients resulting from the MLR for each rice type were used to evaluate the expected significance of climatic factors on rice yield. The results demonstrate that sunshine showed strongest significance of trend for all major crops. The MLR model suggests that temperature was the most significant for Aus and Aman rice and insignificant for Boro rice. Here, Rainfall exhibited the highest significance of trend in the Boro, and lowest in the Aus and Aman respectively.
A negative temperature impact on the Aus yield was reported by Ruane et al. (2013); however, this study contradicts the previous research. A significant negative relationship between rainfall and Aman yield was observed, suggesting that Aman yield is the most exposed to climate change among the three rice types due to outrageous climatic occasions like drought and flood in NW Bangladesh (Islam et al. 2017). These results have all around concurred with the outcomes of Amin et al. (2015), where rice yield variability would be high for Aman yield. Temperature demonstrated a statistically substantial positive effect on Boro yield. The prior studies reported the positive impact of minimum temperature on the Boro yield (Sarker et al. 2014) and an adverse effect for maximum temperatures (Rimi et al. 2009; Jhajharia and Singh 2011).
The regional variation of climatic parameters describes the impacts of climates on rice yield (Jhajharia et al. 2014). Rice yield varies in different seasons with the climatic variability (Islam et al. 2021). The significant trends are portrayed by high geographic fluctuation, in both nature and greatness of the trend. High spatial variability was seen in the rainfall trends in the study region. Although the yield rate for all the seasons increased day by day due to overusing chemicals and fertilizers, climatic factors need to be considered for sustainable yield. Ruane et al., (2013) showed that Aman rice yield might reduce in different areas in Bangladesh.
Regarding the contrasting results with Ruane et al. (2013) on rainfall, perhaps this is due to the regional focus of the current paper since the degree of flooding in NW Bangladesh is small compared to other parts of the country. Basak et al. (2010) showed that temperature rises boost Boro yield. Our analysis demonstrates that climate affects regional rice yields and that these effects are not uniform across regions and stations. Boro yield was commonly influenced by irrigation management and the positive impact of climate rather than by rainfall regimes during the dry season (Ghose et al. 2021b).
Our results indicate that production hampers in Aus and Aman's rice triggered by drought and submergence stresses can be lessened considerably in three ways. First, simulated water control in the irrigated field dramatically enhances the production of the Boro rice crop, which is the main crop in the country. Thus, artificial floodwater management should be implemented to protect Aus and Aman crops, and additional irrigation should be added in the event of a drought. Second, by developing improved crop rice varieties that are more tolerant of abiotic pressures and incorporating them with current agricultural management systems, such as sowing date changes, short-duration rice varieties developed to avoid drought seasons, and the use of appropriate farm machinery for rapid harvesting, losses in these rice production can also be lowered (Mishra et al. 2015). Ultimately, newly introduced drought and flood-tolerant rice varieties can lessen losses in rice production noticeably (Mottaleb et al., 2015).
The limitation of taking the total rainfall over the season as the parameter analyzed. In NW Bangladesh, rainfall distribution across the season can vary widely and have distinct effects on rice yield. A crop that receives 300 mm of rainfall in a season that all falls early will have a lower yield than a crop that receives 300 mm of rain well-distributed across the season. The future study should be focused on the prediction of rice yield with climatic variability in Bangladesh. The findings of this study can benefit regional supervisors and decision-makers in developing region-specific adaptive strategies and address food security in Bangladesh by demonstrating the possible risk associated with climate variations. As a result, our study strongly encourages policymakers and significant sponsors to invest in the research, development, and dissemination of novel rice varieties that are more resilient to drought and other abiotic pressures.