Genetic Dissection of Grain Yield and Agronomic Traits in Maize under Optimum and Low-Nitrogen Stressed Environments.

Berhanu Tadesse Ertiro,Maryke Labuschagne,Manje Gowda,Michael Olsen,Biswanath Das

doi:10.3390/ijms21020543

Abstract

Understanding the genetic basis of maize grain yield and other traits under low-nitrogen (N) stressed environments could improve selection efficiency. In this study, five doubled haploid (DH) populations were evaluated under optimum and N-stressed conditions, during the main rainy season and off-season in Kenya and Rwanda, from 2014 to 2015. Identifying the genomic regions associated with grain yield (GY), anthesis date (AD), anthesis-silking interval (ASI), plant height (PH), ear height (EH), ear position (EPO), and leaf senescence (SEN) under optimum and N-stressed environments could facilitate the use of marker-assisted selection to develop N-use-efficient maize varieties. DH lines were genotyped with genotyping by sequencing. A total of 13, 43, 13, 25, 30, 21, and 10 QTL were identified for GY, AD ASI, PH, EH, EPO, and SEN, respectively. For GY, PH, EH, and SEN, the highest number of QTL was found under low-N environments. No common QTL between optimum and low-N stressed conditions were identified for GY and ASI. For secondary traits, there were some common QTL for optimum and low-N conditions. Most QTL conferring tolerance to N stress was on a different chromosome position under optimum conditions.

Highlights

In Sub-Saharan Africa, most maize is produced under N-deficient conditions, owing to limited availability of resources, low purchasing power of farmers, and low incentive from governments [1,2]
Increase in the intensity of N stress decreased trial mean for grain yield (GY), plant height (PH), ear height (EH), and ear position (EPO), and increased trial mean for anthesis-silking interval (ASI) and SEN (Figure 1)
Average genetic variance in all populations was higher under optimum conditions for GY, PH, EH, and EPO, but it was high under low-N conditions for anthesis date (AD), SEN, and ASI

Summary

Introduction

In Sub-Saharan Africa, most maize is produced under N-deficient conditions, owing to limited availability of resources, low purchasing power of farmers, and low incentive from governments [1,2]. In this scenario, developing cultivars tolerant to low-N stressed environments is crucial for sustainable production and ensuring food security in the region. The availability of reliable large-effect quantitative trait loci (QTL) for GY and other traits under optimum, as well as low-N stressed, conditions would accelerate the development and release of new maize varieties meeting yield demand under optimum and poor soil conditions, for resource-poor farmers. Selection based on phenotypic traits is less accurate and expensive compared to marker-based selection

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