Drought tolerance of Eragrostis tef and development of roots

Drought is a major environmental constraint affecting the growth and production of tef (Eragrostis tef). The selection of tef cultivars has been mainly empirical since little is known about how various cultivars respond to drought stress. Using cultivars that differ in drought tolerance, this study aimed to identify mechanisms of drought tolerance and the extent of variation within cultivars. Five representative cultivars of tef (Kaye Murri, Ada, Balami, Fesho, and Alba) were selected and cultured in 100-cm polyvinyl chloride tubes for 24 d. They were subsequently subjected to drought stress until the soil water potential reached -2.0 MPa. Photosynthetic rate, transpiration rate, leaf water potential, relative water content, osmotic adjustment (OA), total root length, and maximum root length (MRL) were measured during experimental periods. MRLs were 34.6% and 35% longer under drought conditions for Kaye Murri and Ada, respectively, compared with irrigated conditions, while the largest OA value of 1.38 MPa was observed for Fesho. Balami decreased relative growth rate with declining MRL and without OA. This study suggested that the ability to elongate MRL and to undergo OA contributes to better performance in drought tolerance for Kaye Murri, Ada, and Fesho compared with Balami and Alba.