Response of Sunflower Yield and Water Productivity to Saline Water Irrigation in the Coastal Zones of the Ganges Delta

Abstract

The intensification of cropping systems in the salt-affected coastal zones of the Ganges Delta can boost food security in the region. The scarcity of fresh water, coupled with varying degrees of soil and water salinity are however limiting factors for the expansion of irrigated cropping in that area. In this study, we assessed the potential of growing sunflowers using combinations of low and medium saline water for irrigation. The experiments were conducted at two locations with six irrigation treatments in 2016–2017 and 2017–2018. The treatments were: T1—two irrigations at early vegetative (25–30 days after sowing; DAS) and flowering stages (60–65 DAS) with low salinity water (LSW, electric conductivity, ECw < 2 dS m−1); T2—two irrigations, one at the vegetative stage with LSW and one at the flowering stage with medium salinity water (MSW, 2 < ECw < 5dS m−1); T3—two irrigations, one at the vegetative stage with LSW and one at seed development stage (75–80 DAS) with MSW; T4—three irrigations at the vegetative, flowering and seed development stages with LSW; T5—three irrigations, at vegetative stage with LSW, and flowering and seed development stages with MSW; and T6—three irrigations, two at the vegetative and flowering stages with LSW and one at the seed development stage with MSW. Irrigation with LSW at early growth stages and MSW at later growth stages did not significantly (p < 0.05) affect the yield compared to the LSW irrigation at early and later growth stages. Crop water productivity and irrigation water productivity of sunflowers (p < 0.001) increased substantially with the decreasing amount of irrigation water with an average of 1.18 kg m−3 and 2.22 kg m−3 in 2017 and 0.92 kg m−3 and 1.29 kg m−3 in 2018, respectively. Grain yield was significantly correlated with root zone solute potential. The flowering and seed development stages of sunflowers in February–March were sensitive to both low and medium saline water irrigation for seed yield. Overall, the results show that irrigation with LSW (ECw < 2dS m−1) at early growth stages and MSW (2 < ECw < 5dS m−1) at later growth stages could be an option for dry-season sunflowers in the coastal zones of the Ganges Delta which would allow double cropping in this area.

Mitigating Risk and Scaling-Out Profitable Cropping System Intensification Practices in the Salt-Affected Coastal Zone of the Ganges Delta

“…What barriers to improved water management in polders are presented by farmers' crop and management preferences and other water users, and how can they be overcome? Bell et al (2024) and Saha et al (2024). Goswami et al (2024) provides additional important information.…”

“…• Early establishment of different Rabi season crops using different techniques such as zero tillage, relay cropping, dibbling, mulching, etc. (Kabir et al, 2019;Maniruzzaman et al, 2024b;Paul et al, 2020aPaul et al, , 2020bPaul et al, , 2021aPaul et al, , 2021bSarangi et al, 2018Sarangi et al, , 2021bSarkar et al, 2019Sarkar et al, , 2020b) • Development of technology for, and optimum use of, irrigation (Mahanta et al, 2019;Samui et al, 2020;Sarker et al, 2019Sarker et al, , 2024 • Crop production modelling in a complex saline coastal environment (Sarkar et al, 2022) • Selection of suitable cropping pattern and their socio-economic impacts (Goswami et al, 2021(Goswami et al, , 2024Mandal et al, 2020Mandal et al, , 2022Ray et al, 2019Ray et al, , 2020Ray et al, , 2023Saha et al, 2019).…”

“…These questions are addressed in Sarangi et al (2024b, c). Additional output can be found also in Sarker et al (2024).…”