MORPHOPHYSIOLOGICAL TRAITS TO COMPLEMENT GRAIN-YIELD SELECTION UNDER SEMIARID MEDITERRANEAN CONDITIONS IN EACH OF THE DURUM-WHEAT TYPES MEDITERRANEUM TYPICUM AND SYRIACUM

Some 238 landraces from Algeria and Tunisia representative of the medi terraneum typicum durum wheat type and 265 landraces from Syria and Jo rdan representing the syriacum type were grown in a semi-arid Mediterr anean environment of Northern Syria characterized by moderate drought stress. The germplasm types were compared for mean value, level of var iation and relationships with grain yield of various morpho-physiologi cal traits possibly usable for indirect selection of best yielding mat erials. The syriacum germplasm showed higher yield mainly due to great er earliness of cycle, slightly longer grain filling period, shorter s tature, lower early growth vigour and higher drought tolerance express ed by a visual score recorded in another, more stressful environment i n the region. It also showed lower variation for all morpho-physiologi cal characters except plant glaucousness, for which it was more variab le. The wheat types differed not only for architecture but also for op tima of individual morpho-physiological traits required to maximize th e yield response in the given environment. Higher yield of syriacum ma terials was attained at same heading and three to four days delayed ma turity with respect to average phenology of three well-adapted control cultivars, and it was favoured by increasing number of kernels per sp ike, early vigour and drought tolerance. Higher yield of mediterraneum typicum landraces was related to heading and maturity dates approachi ng those of the control cultivars and to increasing kernel weight, ear ly vigour and drought tolerance. Plant stature hardly affected the yie ld. Both absent and strong glaucousness could confer a yield advantage in syriacum materials.