Biomechanical Properties and Agro-Morphological Traits for Improved Lodging Resistance in Ethiopian Teff (Eragrostis tef (Zucc.) Trottor) Accessions

Abstract

Susceptibility to lodging is a major constraint on teff production in Ethiopia, but efforts to develop lodging-resistant cultivars have not been successful. We studied the mechanical properties of teff culms and associated agro-morphological traits in field experiments with 320 teff accessions at two sites in northwestern Ethiopia during the 2018 and 2019 growing seasons. The results showed significant variability in both mechanical properties and agro-morphological traits among accessions. Traits contributing to lodging resistance, such as internode diameter, pushing resistance, and base failure moment, were significantly positively correlated with each other and with plant height. Similarly, the correlation of those traits with lodging index was significant and positive. In contrast, tiller number showed a significant negative correlation with lodging index. The peduncle–panicle length, which generally accounted for 59% of the plant height, should be a target when breeding for semi-dwarfism. Root system development, which reached a depth of more than 1 m in tall and 57 cm in dwarf teff accessions, signifies the presence of genetic variabilities for future root lodging studies in teff, and it may also explain why teff performs well in drought-prone areas of Ethiopia. Breeding programs for lodging resistance might focus on accessions with good standing ability (high base failure moment) and introgression of stem strength with a semi-dwarf phenotype. Alternatively, selection for a large internode diameter, increased pushing resistance and base failure moment, and a reduced tiller number should be considered.

Optimizing Sowing Depth of Tef for Irrigated Mediterranean Conditions: From Laboratory to Field Studies

“…Recently, we reported that lower seedling density reduces lodging index [21]. Published studies on tef [20,29] and other cereals [28] have shown an association between lower plant height and reduced lodging. Both seedling density and plant height were reduced by the deeper sowing in the field (Table 5).…”

“…Plant lodging, defined as the permanent displacement of the stem from the vertical, which is caused by environmental conditions as well as morphological plant traits [17], is the most significant yield-reducing problem in tef, accounting for up to 35% of yield losses [18,19]. While certain studies relate tef lodging to stem characteristics (stem lodging) [20], others [18], including our recently published paper [21], point to shoot-root junction traits (root lodging) as major contributors to tef lodging. In wheat, deeper sowing has been shown to induce a longer, deeper root crown, thus improving plant anchorage and reducing root lodging [17] (and references therein).…”

CRISPR/Cas9‐mediated tetra‐allelic mutation of the ‘Green Revolution’ SEMIDWARF‐1 (SD‐1) gene confers lodging resistance in tef (Eragrostis tef)

“…Resistance to stem bending lodging is the type conferred by SD‐1 mutation in rice (Hirano et al ., 2017b). Under field conditions, lodging in tef is typically measured following the method of Caldicott and Nuttall (1979), but various methods have been described both for field and greenhouse‐grown plants (Bayable et al ., 2020; Ben‐Zeev et al ., 2020; Blösch et al ., 2020; Van Delden et al ., 2010). Since our study was based on potted plants in the greenhouse, we used lodging indices that measured the degree of leaning on a 1–9 rating based on USDA‐GRINS descriptors used for tef and also through time course image analysis using PlantCV functions (Gehan et al ., 2017) that considered changes in plant shape based on height to width ratio over time.…”

“…Tef’s morphological characteristics including plant height, lengths of the panicle, the peduncle, the internodes (culm length), thickness of the basal internodes, angle of the panicle, tiller number, root characteristics and the relationship of these plant parts with each other are known to influence the degree of lodging in tef (Bayable et al ., 2020; Blösch et al ., 2020; Girma, 2019; Ketema, 1983; Van Delden et al ., 2010), besides environmental conditions and agronomic practices (Ben‐Zeev et al ., 2020; Merchuk‐Ovnat et al ., 2020). The reduction in culm length and increased thickness of the first and second basal internodes are likely factors for the increased lodging resistance observed for the sd‐1 tef lines.…”

“…Available tef germplasm pool manifests considerable genetic diversity in plant height, days to maturity, panicle type, caryopsis color and seed size, and plant characteristics contributing to lodging resistance/susceptibility (Assefa et al ., 1999, 2011, 2015; Bayable et al ., 2020). Decades of conventional breeding approaches to improve lodging resistance in tef have been of limited success (Assefa et al ., 2011; Ketema, 1991; Tefera et al ., 2003; Zhu et al ., 2012).…”