Physiological Traits Associated with Yield Improvement under Rainfed Condition in New Wheat Varieties.

Durum wheat is mostly grown under rainfed condition in the Mediterranean region and developing high-yielding wheat cultivars under drought conditions in arid and semi-arid regions is an important objective of wheat breeding programs in Syria. This study aimed at identifing some physiological characters associated with yield improvement in durum wheat grown under a rainfed condition. Thirteen drought tolerant and susceptible, representing old and modem durum wheat varieties were selected and used in this study. The increased yield and yield component was observed in new wheat varieties as compared with old one and were associated with genetic improvement in different physiological traits at vegetative and anthesis stage particularly relative water content, chlorophyll content and chlorophyll fluorescence. Our obtained results showed the importance of physiological traits for development of high yielding wheat varieties and indicated that selection for physiological trait in breeding programs could be effective and contribute to yield improvements.