Manganese Supply Improves Bread Wheat Productivity, Economic Returns and Grain Biofortification under Conventional and No Tillage Systems

Abstract

Manganese is an important essential micronutrient, and its deficiency causes latent health issues in humans. Agronomic biofortification can promisingly improve the plant nutrient concentration without changing the genetic makeup of plants. This study was designed to assess the best method of Mn application to enhance productivity and grain Mn contents under conventional tillage (CT) and no tillage (NT) systems. Manganese was delivered through seed coating (250-mg kg−1 seed), osmopriming (0.1-M Mn solution), soil application (1 kg ha−1), and foliar application (0.25-M Mn solution). A general control with no seed Mn application was included, whereas hydropriming and water spray were used as positive control treatments for Mn seed priming and Mn foliar spray, respectively. No tillage had a higher total soil porosity (9%), soil organic carbon (16%), soil microbial biomass carbon (4%), nitrogen (2%), and soil nutrients in the CT system. Manganese nutrition through various methods significantly enhanced the yield, grain biofortification, and net benefits for CT and NT systems. Averaged across two years, the maximum improvement in grain productivity was recorded with osmopriming (28%) followed by foliar application (26%). The highest grain Mn concentration (29% over no application) was recorded with Mn foliar applications under both tillage systems. Moreover, the highest economic returns and marginal net benefits were recorded with osmopriming. To improve the wheat production, profitability, and grain Mn concentration, Mn application through priming and foliar application may be opted.

Micronutrients in Food Production: What Can We Learn from Natural Ecosystems?

“…Manganese (Mn) is essential for most living organisms and is required by all plants for photosynthesis, chloroplast breakdown and synthesis, and enzyme structure and function [25,118,119]. In humans, Mn is needed for reproduction, carbohydrate and lipid metabolism, and neurological functioning [120].…”

“…In humans, Mn is needed for reproduction, carbohydrate and lipid metabolism, and neurological functioning [120]. Crops grown for food production are the primary source of Mn for humans, providing over 50% of our dietary intake [118,121]. Although Mn deficiency has not yet been observed in the human population [120], it occurs in c. 10% of arable soils worldwide; global fruit, cereal, and certain vegetable crops are all prone to Mn deficiency, which causes interveinal leaf chlorosis and necrotic spotting, reduced tillering, the inhibition of root growth, stunted plant growth and suboptimal nutrient assimilation [9,25,118,121].…”

“…Crops grown for food production are the primary source of Mn for humans, providing over 50% of our dietary intake [118,121]. Although Mn deficiency has not yet been observed in the human population [120], it occurs in c. 10% of arable soils worldwide; global fruit, cereal, and certain vegetable crops are all prone to Mn deficiency, which causes interveinal leaf chlorosis and necrotic spotting, reduced tillering, the inhibition of root growth, stunted plant growth and suboptimal nutrient assimilation [9,25,118,121]. As such, correcting Mn deficiency is vital for maintaining crop yields, food production and human Mn intake [118,121].…”

“…However, Mn availability decreases at soil pH > 7.5 as it adsorbs strongly into various (hydr-)oxides, clay fractions, organic compounds, and calcium carbonate [25]. Consequently, Mn deficiency typically occurs in arable crops grown in calcareous or heavily limed soils [9,25,118,121]. However, even under alkaline conditions, Mn-containing organomineral and anionic complexes can remain relatively soluble and contribute to Mn availability for plants and microbes [25].…”

“…Hence, arable management practices that alter soil pH or aeration (e.g., reduced organic matter application, tillage, and irrigation) can cause substantial losses of Mn by leaching [25]. Finally, the application of herbicides, such as glyphosate, can inhibit crop acquisition of Mn [9,25,118,121]. Hence, arable management can substantially influence Mn availability by altering abiotic and biotic soil factors.…”