Assessment of triticale (Triticale spp) root morphology on seed production under water deficit conditions

Plant roots, with respect to their intrinsic characteristics, have important role in both improvement and development of germplasms of drought resistant plants. This experiment was conducted to study direct and indirect effects of root morphological traits on grain yield of four triticale genotypes (three promising lines of ET-82-8, ET-82-15 and ET-79-17 along with the conventional Junillo-92 cultivar) under two available moisture levels in soil (irrigation after 50% moisture depletion in the root zone, as control) and moisture stress (irrigation after 80% moisture depletion in the root zone) as a randomized complete blocks design in factorial arrangement with four replications, in Research Greenhouse of College of Agriculture, Ferdowsi University, Mashhad, Iran, in 2008. The results showed that water stress caused a 9% reduction in root depth development. Also, the difference between deepest root in ET-82-15 and the shallowest root in Junillo-92 was about 8.2 cm. Delay in irrigation caused a 25% reduction in accumulated root length. The 43% difference between highest accumulated root length in ET-82-15 and lowest accumulated root length in ET-79-17 was significant at 1% level. The role of root morphology of these genotypes on seed production was different under various soil moisture conditions. In optimum soil water content, direct effect of accumulated root length with regression coefficient of 0.543 was more than water deficit conditions with regression coefficient of 0.286. On the other hand, direct relation of total root surface with grain yield was negative in normal moisture conditions and negative under water deficit. In general, it seems that accumulated root length and root surface are effective characteristics in seed production of these genotypes; total root surface has more important role in water deficit conditions, and accumulated root length in optimum soil moisture levels.