| dc.description.abstract | Long-term climatic variability influences crop evapotranspiration as well as crop
production. This study was carried out to analyze the evapotranspiration and rainfall for
beneficial planning of aman rice cultivation in Dinajpur, Bangladesh. This study assessed
the impacts of climate change on actual evapotranspiration (ETc) of three popular aman
rice varieties i.e., BR11, BR22 and BRRI dhan49. Daily climatic data like rainfall, daily
maximum and minimum temperature, maximum and minimum relative humidity, wind
speed and sunshine hour for a period of 20 years (1991–2010) were collected from the
Bangladesh Meteorological Department, Dhaka, Bangladesh. Reference crop
evapotranspiration (ETo) was determined by the FAO Penman-Monteith method. Actual
crop evapotranspiration (ETc) of the three rice varieties at different growth stages were
determined. MAKESENS trend model was used for determining rainfall trend and ETc
trend. Weibull’s method was used for probability analysis and the expected rainfall and
Actual evapotranspiration (ETc) at 75% probability level were estimated for different
growth stages of those three rice varieties. It was found quite effective to predict the water
availability for aman rice cultivation and to indicate the requirement of supplemental
irrigation. Variation of crop efficient (Kc) and ETo were found. ETc varied at different
growth stages over the total growing season. After probability analysis, it was clear that
BR11 required supplemental irrigation of 27 mm from ‘25th July to 2nd September’
(development stage), 19 mm from ‘3
rd September to 7th October’ (mid stage) and 9 mm
from ‘8
th October to 22th October’ (late stage) in Dinajpur district, when transplanted
between 15th June to 24th July. Similarly, for BR22, as it was transplanted between 30th
June to 8th August, then supplemental irrigation of 49 mm and 38 mm was needed from
‘18th September to 22
th October’ (mid stage) and from ‘23th October to 6th November’
(late stage) respectively. Finally, for BRRI dhan49, as it was transplanted between 21th
June to 10th July, then supplemental irrigation of 4 mm was needed from ‘25th August to
28th September’ (mid stage). After analyzing trend through MAKESENS trend model, it
was observed that most of the rainfall curves had decreasing trend and ETc curve had
increasing trend. It will enable to optimize utilization of valuable water resources and
help to create a better irrigation schedule for BR11, BR22 and BRRI dhan49 for their
successful cultivation. This results can play an important role in sustainable irrigation
water management under changing climate and helps to establish effective water schedule
for aman rice cultivation. | en_US |
