ESRI ArcMap 10.5 Spatial Analyst tools were used for this purpose. The absolute height of the crop was obtained by subtracting the DTM from the DSM. The software created two ortho-mosaicked images, the digital terrain model (DTM) and the digital surface model (DSM). The images taken by the UAV were processed into a 3D map with Pix4Dmapper using structure-from-motion (SfM) algorithms. Flight altitude was 25 m, with a camera angle of 70° (20° above tangent to ground), 80% front and side overlap, and a pixel size of 1.16 cm. The UAV was flown using the Pix4Dcapture preprogrammed flightpath control set to “double grid” flight formation to create a 3D model to assess canopy height ( Figure 4). The UAV was equipped with a built-in RGB camera with a 4000 × 3000 pixel 4 K resolution sensor, a 20 mm (35 mm equivalent) lens with field of view of 94°, and a 3-axis gimbal stabilizer ( ). An unmanned aerial vehicle (UAV), the Phantom 4 quadcopter (DJI, China), was used as the flight platform. Two flight campaigns were conducted in the 2019 growing season on 3 July and 24 July (7 and 10 weeks after emergence, respectively) to determine tef lodging. However, our observations in field and pot trials ( Figure 1) did not show any visual evidence of culm bending in tef. Since root lodging leads to a change in the angle between the culm and the soil, the actual tissue bending may be at the very bottom of the stem. Despite the delicate stem and leaf architecture of the tef plant, it appears to be mainly susceptible to root lodging ( Figure 1), which is defined as “straight intact culms leaning from the crown”. This intricate relationship between the stem and root properties leading to lodging requires an in-depth analysis of both parts to address the causes of lodging in each species. On the other hand, a flexible stem increases swing moment, which could increase the damage caused by minor force. Pinthus claimed that unless stem breakage occurs, a stiffer culm transfers more force operating on the canopy to the plant part interacting with the soil. Lodging can be divided into stem lodging, in which the stem bends or breaks, and root lodging, in which a change in angle between the stem and the soil is caused by crown bending and/or root disanchoring in response to the torque exerted by the force of the wind on the stems. Lodging is induced by the forces exerted by wind, rain, or irrigation, but usually by their combination for example, rain weighing down plants and lubricating the soil combined with wind pushing plants toward the soil. In summary, this study demonstrated for the first time the feasibility of tef production under irrigated Mediterranean conditions and the potential of a reduced sowing rate as a remedy for lodging. Among the morphological traits assessed, crown diameter, crown root number, and crown root diameter were significantly affected by sowing rate and genotype and were correlated with LI values. Aerial-based LI values were significantly correlated with the ground-based ones and exhibited better capacity to identify minor differences in lodging. Aerial RGB images of the field taken by an unmanned aerial vehicle twice during the second season produced a high-resolution crop surface model, which was used to assess lodging. A significant difference in LI values among the tested genotypes suggested potential for crop improvement. The visually assessed lodging index (LI) increased as the season progressed, with the lowest values recorded under low sowing density. Grain yield and biomass did not differ significantly among sowing rates. Four tef genotypes were grown under irrigation across two years at three sowing rates: low (3 kg/ha), medium (6 kg/ha), and high (common, 9 kg/ha). In this work, we reported on the effects of sowing rate on lodging, lodging-related traits, and productivity of tef under irrigated conditions. Studies in other cereal crops suggested that lowering plant density would lead to sturdier plants less prone to lodging. ![]() Lodging is a major factor limiting tef quality and yield, with losses estimated at 30%–35% and presumably higher under mechanical harvest. Tef yields highly nutritious gluten-free grain as well as high-quality forage, therefore, interest is rising regarding tef cultivation for grain and forage outside Ethiopia. Tef ( Eragrostis tef (Zucc.) Trotter) is a panicle-bearing cereal crop plant, originating from and grown mainly in Ethiopia.
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