Growth,Lodging and yield of TEF (Eragrostis tef) as influenced by seed size and depth of sowing.

Tef is typically hand-broadcasted on the field and, in most cases,seeds are left uncovered.planting depth is reported to enhance crop emergence as it improves seed-to-soil contact.However, the influence of sowing depth in relation to seed size variation is little known in tef.This research was therefore, aimed at studying the influence of seed size and sowing depth on seedling growth, yield and yield components, and examining if grading tef seeds for planting purpose would improve tef growth and performance.A field study was conducted at Melkassa and Alemtena while pot experiment was employed at Melkassa.In both field and pot experiments, the four seed sizes (Small, medium,large and bulk seeds) and three sowing depths (surface, 2-and 3-cm) were laid in Completely Randomized Block Design factorial arrangement with three replications.Under the pot experiment, the small seeds from the 3-cm depth failed to emerge hence excluded from the analysisi.No substantial difference was noted among medium, large and bulk seeds in days to emergence except between bulk and small seeds (P0.05); no significant difference was observed among the planting depth either.Plant height and shoot biomass per plant-1 from bulk seed at seedling stage significantly (P0.001) surpassed the other three sizes, on average, by 3-cm and 0.98g,respectively. But at heading stage, biomass from large-seeded plants significantly (P0.01) srpassed that of bulk and small-seeded plants by 0.12 and 0.31g, respectively.Basal internode diameter, which is an important agronomic trait associated with lodging, increased with depth.Despite the observed varition, all sed size groups emerged from all depths under field experiments.Averaged over all sowing depths, small seeds took longer days (12 days)to emerge compared to bulk seeds which took about a week. seed size showed no effects on days to maturity at both locations while surface sown plants were significantly (P0.05) earlier than either of the two depths at Melkassa. Compared to surface panting, height of the seedlings was reduced for panting depths of 2-and 3-cm.Except at seedlings stage,biomass production plant-1 was increased with depth at both locations; and substantial (P0.001) variations were observed at heading and grain filling stages at Melkassa.Deep sown seeds also produced significnatly (P0.001) heavier leaves at heading and grain filling stages, contributing for the observed difference in shoot biomass at same stages at Melkassa.However, with respect to biomass at harvest, HI, and 100-seed weight, neither the seed sizes nor the sowing depths showed significant (P0.05) effects.The effects of sowing depth on the basal internode diameter were at par with pot experiment, which could be due to better root development.Lodging indices were significantly (P0.01) reduced for plaanting depths of 2- and 3-cm compared to surface planting; but no substantial (P0.05) differences were observed among seed sizes.No significant (P0.05) differences were also observed between bulk and the other tree seed size groups in main panicle weight and main panicle seed wight.Grain yield was significantly (P0.05) higher from medium seeds, 12% more than from small seeds, but was not significantly different from the other two size classes.Rates of chage in biomass for small seed size and surface sown plants were samll compared to their respective counterparts though they were with similar trend at seedling and tillering stages.In general, seed size did not show as such prononced effects as sowing depth on tef growth and development.Deeper sowing should be avoided especially for small seed classseds.but if depth of sowing is to be considered in tef productio, having lage seed size is equally important for better germination and performance of the crop.With respect to this study, variation in seed size had no significant effect on yield, except that yield was significantly inferior from small seed compared to the other three size classes.However, despite the absence of significnat difference among seed placements, planting at 2-cm depth seem good compared to surface sowing under moisture deficit areas.