Water use efficiencies of different maturity group soybean cultivars in the humid Mississippi Delta

Authors: PINNAMANENI, SRINIVASA - Oak Ridge Institute For Science And Education (ORISE); Anapalli, Saseendran; Fisher, Daniel; Reddy, Krishna

Submitted to: International Journal of Agronomy
Publication Type: Peer Reviewed Journal
Publication Acceptance Date: 5/25/2021
Publication Date: 5/27/2021
Citation: Pinnamaneni, S., Anapalli, S.S., Fisher, D.K., Reddy, K.N. 2021. Water use efficiencies of different maturity group soybean cultivars in the humid Mississippi Delta. International Journal of Agronomy. 13(11):1496. https://doi.org/10.3390/w13111496.
DOI: https://doi.org/10.3390/w13111496

Interpretive Summary: The irrigation water pumped out of the Mississippi Valley Alluvial Aquifer far exceeds its natural recharge levels, threatening irrigated agriculture's sustainability in the Mississippi Delta region. Introducing alternative cultivars with better water productivities can help lessen pressure on groundwater for crop irrigations. To address this, scientists with the USDA ARS Sustainable Water Management Research Unit and Crop Production Systems Research Unit, Stoneville, MS, experimented with seven recently released and pre-released soybean maturity group III, IV, and V cultivars for water productivity in the MS Delta. The cultivars were ranked as (1) Dyna-gro 4516x under Maturity group IV, and LG03-4561-14 and P37A7 under Maturity group III for water productivity in early soybean production systems in the MS Delta for conserving water resources.

Technical Abstract: Due to high intra-seasonal variability in rainwater availability, farmers in Mississippi (MS) Delta region generally meet their crop water requirement by irrigating crops by pumping water from the shallow Mississippi Valley Alluvial Aquifer (MSVAA) underlying this region. Water withdrawals beyond the aquifer’s natural recharge levels result in significant groundwater declines, threatening sustainable irrigated crop production in the region. Introducing alternative cultivars with enhanced water use efficiencies can help alleviate pressure on groundwater for crop irrigations. A two-year field study was conducted in 2019-2020 to compare the water use efficiencies (WUE) of recently released and pre-released soybean {Glycine max (L.) Merr.} cultivars in maturity group (MG) III (cv. P37A78, LG03-4561-14), IV (cv. Dyna-gro 4516x, DS25-1, DT97-4290), and V (cv.S12-1362, S14-16306) on a Dundee silt loam soil in the MS Delta. The experimental design was a split-plot with cultivar as the main unit and irrigation (IR) and no irrigation (RF, rainfed) as subunit, replicated three times. In the two-year experiments, the window between consecutive phenological stages is wider for MG V cultivars while the window is relatively narrow for MG III and MG IV cultivars. Across the two years, the MG IV cultivar Dyna-gro 4516x recorded the highest grain yield and WUE: grain yields were 4.58 Mg ha-1 and 3.89 Mg ha-1 under IR and RF, respectively in 2019, and 4.74 Mg ha-1 and 4.35 Mg ha-1 in 2020. The WUE were 7.2 and 6.9 kg ha-1 mm-1, respectively, in 2019 under IR and RF, and 13.4 and 16.9 kg ha-1 mm-1 in 2020. The WUE across different MG and cultivars ranged from 4.5 to 7.2 kg ha-1 mm-1 in 2019, while it varied between 8.3 and 16.9 kg ha-1 mm-1 in 2020. In terms of higher grain yields and WUE, the cultivars can be ranked as (1) Dyna-gro 4516x (MG IV), (2) LG03-4561-14 (MG III), and (3) P37A78 (MG III) for adaptation in early soybean production system (ESPS) in MS Delta for sustainable production for conserving water resources.