Optimizing Sowing Depth and Seeding Rate of Pelleted Seed for Reducing Lodging and Improving Yield of Tef

Abstract

The low productivity of tef is associated with problems inherent to tef botany and lodging. The small seed size of tef poses a major inheritance  problem during sowing operations. Techniques such as pelleting seed with organic matter are effective to make them uniform in size and shape. A  field study was conducted to determine optimum sowing depth and seed rate of pelleted tef for reducing lodging, and improving productivity of tef  under Vertisol conditions during two consecutive cropping seasons (2019 and 2020). A factorial combination of four sowing depths (0, 1, 2 and 3 cm)  and three pelleted tef seed rates (60, 90 and 120 kg/ha~5, 7.5 and 10 kg/ha of un-pelleted tef) were used as a treatment. The experiments were  laid out in RCBD with three replications. Sowing depth had a significant effect on biomass and grain yield of tef. Tef sowing at the shallowest depth  (0 cm) and 1 cm gave the highest biomass yield (11889 kg/ha and 9639 kg/ha, respectively) and grain yield (2786 kg/ha and 2536 kg/ha,  respectively). In contrast, the deepest sowing (3 cm) reduced biomass and grain yield of tef. Seed rate played an important role in the biomass yield  of tef, the highest biomass yield (10399 kg/ha) was recorded from the 120 kg/ha seed rate of pelleted tef. Regarding lodging, the deepest sowing  and lowest seed rate reduced lodging index and a number of root lodged plant. The average lodging index for the deepest sowing (3 cm) was  30.8%, while the shallowest (0 cm) was 69.3%. The result revealed that pelleted tef seed can successfully emerge from a depth of 1 cm without any  apparent penalty of yield. Tef even emerged from 2 to 3 cm depth, while showing reduced lodging, but these had a yield penalty. Therefore, it can  be concluded that a 1 cm sowing depth and 90 kg/ha pelleted tef are optimal for sowing pelleted tef seed for reducing lodging and improving yield.