Effect of irrigation and planting geometry on soybean seed nutrition in humid climates

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

Submitted to: International Journal of Agronomy
Publication Type: Peer Reviewed Journal
Publication Acceptance Date: 5/3/2021
Publication Date: 5/18/2021
Publication URL: https://handle.nal.usda.gov/10113/7401542
Citation: Pinnamaneni, S.R., Anapalli, S.S., Bellaloui, N., Reddy, K.N. 2021. Effect of irrigation and planting geometry on soybean seed nutrition in humid climates. Crop, Forage & Turfgrass Management. 2021. Article 6625919. https://doi.org/10.1155/2021/6625919.
DOI: https://doi.org/10.1155/2021/6625919

Interpretive Summary: Certain agricultural management practices can impact the seed quality of soybeans, which also contributes to higher crop profitability. We studied the effects of planting (single row versus twin row) and irrigation on soybean quality in the lower Mississippi Delta, USA. Soybean quality was better in irrigated plots than in rainfed only plots. Although climate played a key role in seed quality, research results indicate a potential for improving soybean seed quality by managing irrigation.

Technical Abstract: Investigation on the effects of irrigation and planting geometry (PG) on soybean [Glycine max (L.) Merr.] seed nutrition in humid climates is limited. Therefore, the objective of this study was to investigate the effects of irrigation (FI, all rows-irrigation; HI, alternate row irrigation; and RF, rainfed) and planting geometry (SR, single-row; and TR, twin-row) on soybean seed protein, oil, fatty acids, sugars, amino acids and isoflavones using a maturity group IV cultivar (31RY45 Dyna-Gro). A field experiment was conducted in 2018 and 2019 in the Mississippi Delta. A seeding rate of 336,000 seeds ha-1 was used in both the planting geometries. Results showed that most of these seed components were significantly affected by crop season due to contrasting precipitation and solar radiation patterns, particularly during July-August, coinciding with early reproductive and seed development stages. Both seed protein and oil levels responded positively to irrigation, while most of the amino acids were non-responsive. The protein content ranged between 36.3 and 37.6% in 2018, while it was between 36.4 and 38.3% in 2019. Total seed oil content varied between 24.2 and 26.1% in 2018 and between 25.3 and 26.5 % in 2019. Among amino acids, glycine, alanine, valine, and methionine levels were significantly higher in both FI and HI treatments. Among sugars, only sucrose was higher in response to the RF treatment, and irrigation did not affect both stachyose and raffinose, although year-wise variation was significant for stachyose content. Oleic acid was higher in RF, while no significant differences were observed for linolenic and linoleic acids. Oleic acid ranged from 25.7 to 28.5% in 2018 and from 24.6 to 26.6% in 2019, while linoleic acid varied between from 55.7 to 58.5% in 2018, and it ranged between 55.6 and 57.5 % in 2019, indicating the seasonal variation. The linolenic acid ranged between 5.7 and 7.2% in 2018 and 5.3 and 6.1% in 2019. Similarly, seasonal variation was significant for stearic acid content, but the 2019 season had relatively higher accumulation (Stearic acid: between 4.1 and 4.5% in 2018 and from 4.6 to 4.9% in 2019). These results indicate that both irrigation and climate during seed development can alter some seed composition constituents and play critical roles in determining seed nutritional qualities.