Potential Breeding for High Nitrogen Fixation in Pisum sativum L.: Germplasm Phenotypic Characterization and Genetic Investigation

Abstract

Nitrogen (N) is the most yield-limiting crop nutrient worldwide. Industrially produced N has increased in cost over the past years, and is unavailable in many regions around the globe. Biological N fixation by rhizobial bacteria is a great underutilized resource that this project aims to maximize. Grain legumes fix approximately 20 to 100 kg·N·ha −1 ·yr −1. The amount of N supplied by fixation is affected by genes and traits of both the bacterial and plant partners. The objectives of this study are to identify Pisum sativum varieties with high nitrogen fixation efficiency. This is achieved by germplasm screening and phenotypic evaluation of nodule formation, total plant nitrogen, and residual nitrogen in soil. Significant differences in plant total nitrogen among the various cultivated genotypes were found, with heritability of 0.57. These pea varieties left in the soil a residual N that varies between 11.21 to 65.018 kg·N·ha −1. Our findings reveal a unique opportunity for improving N fixation through genetic crossing and selection.