Endophytic Fungal Root Colonization of Eragrostis tef in Eroded Croplands of the Ethiopian Highlands Is Limited by Low Spore Density and Fertilisation

Gezahagn Getachew,Hans Sandén,Boris Rewald,Douglas L Godbold

doi:10.3390/agronomy9020073

Abstract

Eragrostis tef (teff) is a (sub-)tropical cereal crop and a staple food in Eastern Africa. As soil erosion has become increasingly worse in the Ethiopian highlands, we test the hypotheses that (1) eroded soils possess low arbuscular mycorrhizal fungi (AMF) spore densities, (2) teff growth is limited by low endophytic fungal root colonization rates and (3) colonization rates and spore densities are additionally reduced by fertilization. A pot experiment was set up to study the effect of cropland soil inoculation using pristine fungal communities (from adjacent forests) or fertilization. AMF spore densities in soil with and without teff and root colonization by AMF and dark septate endophytes (DSE) were related to straw and grain yields. AMF and DSE colonization rates were higher after inoculation, which provides evidence that a low spore density limits teff root colonization in eroded soils. However, teff yields were significantly increased after fertilisation but not inoculation. N-P fertilization further lowered root colonization rates and spore density. We conclude that forest soils serve as a refugium for soil biota in the degraded landscape of the Ethiopian highlands. As both increased AMF and DSE increase the stress resistance of plants, their inoculation potential should be considered when developing sustainable management methods for teff.

Highlights

Eragrostis tef is a warm-season, annual cereal crop that is primarily grown in Ethiopia and Eritrea
Arbuscular mycorrhizal fungal (AMF) spore density was highest in the inoculated treatment and Arbuscular mycorrhizal fungal (AMF)
The arbuscular mycorrhizal fungi (AMF) colonization rate was positively and significantly correlated with the spore density colonizationrate ratereached waspositively positively andat significantly correlated with theper spore density

Summary

Introduction

Eragrostis tef (teff) is a warm-season, annual cereal crop that is primarily grown in Ethiopia and Eritrea. Teff accounts for about a quarter of total cereal production in Ethiopia [1,2], but it is increasingly cultivated in Kenya, South Africa, Australia and across the Americas. Teff is a valued forage crop for its high palatability, nutritive value, yield, rapid growth and drought resistance [3]. In the region, it is mainly used for making “Injera”, a traditional flat bread, and accounts for more than half of the daily protein intake by Ethiopian people [4]. Teff grains are increasingly popular around the globe because of their gluten-free nature, low glycaemic index and beneficial nutrient composition—holding high fiber, protein, iron and calcium contents [3,5]. Teff straw is used as an alternative source of forage and is frequently incorporated into traditional construction materials in Ethiopia and the wider eastern African area [6]

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Results

Conclusion