Abstract

Tef [Eragrostis tef (Zucc.) Trotter], the indigenous Ethiopian cereal, has a very minute seed size, yet it has a strong bearing both on the preferences of farmers for planting material and consumers as quality measure. The objectives of this study were to determine the effects of sieve-graded seeds on the grain weight of tef, and to investigate whether large seed size offers yield and agronomic advantages over using un-graded planting seed materials. Seeds of two tef varieties, DZ-01-974 and DZ-Cr-37 (early type) were sieve-graded in to five seed size treatments, and were field grown at Debre Zeit and Akaki experiment stations, in 2005 and 2006, along with the un-graded seed (Mix) as a control. A split-plot design replicated three times in randomized complete block arrangements was used; varieties were used as main plots while seed sizes were kept as sub-plots. Grain yield, days-to-panicle emergence (DPE), plant height, biomass yield and panicle length were considered. There was clear increase of 100-seed weight when seed size increased. However, seed size effects were statistically significant, but not agronomically meaningful, only for DPE. Generally, there were trends of increased grain yield (up to 7%) due to large seeds, but the advantages for the other traits were nil. Relative growth rates (RGR) were similar for the seed-size groups, and therefore, were unable to explain the lack of significant effects. In conclusion, under optimum production conditions, the added advantages of large seed size do not justify tef-seed grading. On the other hand, farmers may consider the use of smaller size seeds for planting and sell large size seeds for consumption purpose.

Key words: Eragrostis tef, seed size, tef, tef agronomy.