Yield formation strategies of durum wheat landraces with distinct pattern of dispersal within the Mediterranean basin - II. Biomass production and allocation

The purpose of this study was to determine if the geographical pattern of dispersal of durum wheat within the Mediterranean region was associated with variation in biomass and leaf area accumulation and distribution, as well as the relationships between these traits and grain yield. Fifty-two landraces previously genetically characterized as dispersed by the north or south of the Mediterranean basin were grown in three rainfed sites in northeastern Spain. The origin of landraces influenced biomass production and allocation. Landraces from the north side of the Mediterranean basin produced 19% more tillers than those from the south, resulting in larger biomass and leaf area allocation on tillers at anthesis. Southern landraces showed a better adaptation to drought environments. They had 6% larger plot stand at jointing, produced 9% more biomass at anthesis and distributed it mostly in the main stem. Besides, they were more efficient in the allocation of biomass to reproductive organs because their mean harvest index (HI) exceeded that of northern landraces by 7%. Crop dry weight (CDW) and leaf area index (LAI) at jointing were positively related to yield in both groups of landraces, whereas at anthesis, no relationship was found between those traits and grain yield. Pre-anthesis assimilates contributed to grain yield by 40 and 90% in northern and southern genotypes, respectively. These results highlight the relevance of early crop development and the remobilization of stored assimilates to grain as adaptative traits to dry Mediterranean environments. (c) 2005 Elsevier B.V. All rights reserved.