Yield and water productivity variation of Boro rice with irrigation strategies and transplanting dates under climate change – a case study in south-western Bangladesh

Abstract

Climate change has imposed major uncertainties on food and water security in Bangladesh. Understanding the recent changes in potential yield and water productivity of major crops is essential to formulate effective adaptation strategies under climate change conditions. This study assessed the yield and water productivity variation of dry season <em>Boro</em> rice with different irrigation regimes and transplanting dates over long-term (1985-2017) in a south-western District (Khulna) of Bangladesh using AquaCrop model. The evaluation of yield and water productivity was done for five transplanting dates (1<sup>st</sup> & 15<sup>th</sup> of December and January and 1<sup>st</sup> of February) and four irrigation strategies (fixed short- and long-interval irrigations, and measured irrigation with ‘<em>low stress</em>,<em> low dose</em>’ and ‘<em>high stress</em>,<em> high dose</em>’). Transplanting rice seedlings on 1<sup>st</sup> December results in 17% yield increase compared to transplanting on 1<sup>st</sup> January. There are significant (p£0.05) increasing trends of attainable biomass, grain yield and water productivity of <em>Boro</em> rice. The measured irrigation practices are superior to the traditional fixed irrigation practices. The ‘<em>low stress, low dose</em>’ irrigation strategy increases irrigation-water productivity and provides an opportunity to exploit the possible benefits of climate change. Adjustment of the irrigation strategy can reduce water usage without reducing the potential yield of <em>Boro</em> rice with an eventual increase in irrigation-water productivity, while adjustment of the transplanting date can increase potential yield with additional water usage. These findings would help develop suitable agricultural adaptation strategies for irrigated rice cultivation under climate change.

Projection of the irrigation requirement of potatoes under climate change in Northwest Bangladesh

“…The increase in variable effective rainfall is projected to be 10.5-14.4%, 13.3-14.4% and 9.4-11.2% for the 2030s, 2040s, and 2050s and 12.4-14.9%, 13.4-15.0%, and 11.3-12.5% for the 2060s, 2070s, and 2080s, respectively, during potato and other major crop growing seasons in Tajikistan under three different scenarios, RCPs 2.6, 4.5 and 8.5 (Kobuliev et al, 2021a). The ndings of this study is consistent with the study by Acharjee & Mojid (2023). They found that the average irrigation requirement of wheat in Northwest Bangladesh would be 5.7% and 13.9% higher during 2050s and 2080s, respectively, compared to the base period under moderate climate change.…”

“…A very high increase in potential irrigation demands from the 2050s to the 2080s was detected under rapid climate change. The ndings of this study is consistent with the study byAcharjee & Mojid (2023). They found that the average irrigation requirement of wheat in Northwest Bangladesh would be 5.7% and 13.9% higher during 2050s and 2080s, respectively, compared to the base period under moderate climate change.…”

Impact of Boro Rice Establishment Methods on Soil Salinity, Crop Growth and Yield in South-West Salt-Affected Coastal Region of Bangladesh

“…The common practice of Boro rice cultivation is transplanting seedlings into soil in puddled conditions. Boro rice needs (145-155 days growth duration) about 1200-1500 mm (farmer's practice) of water for seedbed preparation, puddling of soil for transplanting and to meet water requirement throughout the growing season (Acharjee et al, 2022;Paul et al, 2013;Yesmin et al, 2019). However, irrigation water at permissible level of salinity is very scarce in the coastal area.…”