Influence of environment, genetics, and management on field pea grain nitrogen concentration and yield response and subsequent effect of legume-based crop rotations on soil organic carbon

Abstract

Field pea (Pisum sativum L). is a cool-season legume, commonly referred to as a pulse crop, that is rotated with cereal and oilseed crops across the northern Great Plains (NGP). Field pea domestic markets have benefited from the growth of the plant-based protein market. North American plant-based protein markets commonly reward pea farmers with value-added contracts for producing high protein pea grain. Previous field pea research has focused on environment, genetics, or management factors that increase yield, while ignoring protein. Additionally, carbon (C) markets are emerging that reward farmers for utilizing practices such as diverse crop rotations to sequester atmospheric C into soil organic carbon (SOC). Pea farmers in the NGP need guidance on how to manage pea for elevated protein while also understanding how long- term production practices influence SOC sequestration. This dissertation provides an approach to understanding how environmental, genetic, and management factors influence pea protein and yield, and how diverse crop rotations affect SOC accrual. An interdisciplinary team conducted research across the USA and Canada from 2016 - 2024. Across the NGP, environment explained 70.5% of the variation in protein concentration observed across 23 environments, while genetics explained 10.5%. Precipitation accumulation during late vegetative growth followed by heat accumulation during grain fill predicted protein concentration. Intra-plant protein variation revealed that bottom pods frequently have a greater protein concentration across the NGP and that the environment x genetic interaction explained 50.7% of intra-plant protein variation. Analysis of genotypes revealed that stability of protein concentration is not associated with mean protein or yield stability, suggesting trait stability should be considered when evaluating pea genotypes. A management study revealed that application of seed-coat insecticide to mitigate pea leaf weevil infestations increased protein by 7 g kg -1. A six-year study revealed that diverse crop rotations that rotate pea and lentil with spring wheat optimize SOC accrual, at a rate of 0.41 Mg SOC ha -1 yr -1. These findings provide foundational information to inform pea growers and the larger plant-based protein industry how pea protein formation is controlled and the subsequent benefit of including field pea in diverse crop rotations to increase ecosystem services.