Developing a tall durum wheat plant type for semi-arid, Mediterranean cereal-live stock farming systems

Durum wheat cropping in semi-arid areas of West Asia and North Africa is frequently integrated into a cereal-livestock farming system. The wheat straw, mostly used for feeding animals, represents an important commodity, its average sale price per unit weight being not less than 40% of that of grain in three recently surveyed areas. There is uncertainty whether the widespread, short-statured wheat plant type could be economically preferable in these environments relative to a tall type, especially when considering straw yield. Within the Mediterranean durum wheat gene pool, mediterraneum typicum germplasm possesses a markedly tall stature, implying high straw yield. In a first phase of evaluation under prevailing conditions of northern Syria, 13 entries characterized by early heading and good agronomic performance were identified from a collection of about 2000 Tunisian and Algerian accessions. In a second phase reported here, these entries were evaluated in relation to two widely grown adapted cultivars, i.e., the semi-dwarf variety 'Cham 1' and the local landrace 'Haurani', across four environments of northern Syria diversified for rainfall and soil characteristics. In an economic assessment, the straw value was expressed in terms of grain-equivalent, defining an economic yield as: grain yield + (0.40 x straw yield). Compared with the control cultivars, the mediterraneum typicum entries were taller but tended to later heading with a similar grain filling duration. However, a few entries as early as the controls were also found. Almost all exotic entries outperformed 'Haurani' for economic yield. Two entries showed significantly higher (P < 0.05) economic yield (> 12%) and aerial biomass across environments than 'Cham 1', owing to higher straw yield and similar grain. yield. They compensated for the relatively lower spike fertility by heavier kernels. Genotype x environment interactions were generally limited for yield-related traits. Straw yield was closely associated with plant height (r = 0.76, P < 0.001) but not with number of fertile tillers. No trade-off between grain and straw yields was apparent. The results support the interest of a tall durum wheat plant type derived from the mediterraneum typicum gene pool for enhancing the profitability as well as the sustainability of semi-arid Mediterranean farming systems. (C) 2002 Elsevier Science B.V. All rights reserved.