Developmental plasticity: a phenological mechanism to endure later stage water deficit stresses in tef [Eragrostis tef (Zucc.) Trotter] varieties

Water deficit at later growth stages (terminal drought) is a major abiotic factor limiting productivity of crops in northern Ethiopia. Varietal selection is among sustainable solutions to curb the problem. In line with this, a study was conducted in Tigray region, northern Ethiopia during 2011 and 2012 main cropping seasons to investigate the phenotypic diversity in tef varieties for developmental plasticity under severe water stress. Fifteen tef varieties were tested under late season water stress. Deferred/delay sowing time by two weeks was applied to expose the varieties to water stress. Soil and crop data were collected and analyzed. The varieties have shown significant ( p<0.001 ) interaction with the imposed stresses both for days to maturity and panicle length. Varieties such as DZ-01-974, DZ-01-899, DZ-cr-358 and Berkayi tend to tolerate the effect of terminal drought by shortening their maturity time, which is referred as drought escape. In contrast, varieties like DZ-01-99, DZ-01-358 and AbatNech have significantly reduced in length of their panicle. This is the actively transpiring part during later growth stage, without significant yield loss. This phenotyping for developmental plasticity has indicate that the tef employ escaping and reduction of evaporative surfaces to overcome the severe effects of terminal drought. To tailor varieties that better suit for drought prone farming systems. Such drought-adaptive traits should be targeted in breeding programs. Keywords: Tef; Delayed planting; Maturity; Panicle; Drought escape and avoidance; Ethiopia.