| Several morphological, phenological and physiological traits (Duwayri
and Shelaldeh 1986; Nachit and Jarrah 1986) are related to yield under moisture
stressed conditions. Grain yield was associated with dry matter production
(r=+0.71***), straw yield (r=+0.53**) and also with
1000 kernel weight (r=+0.57**). The ability to grow at low temperature
leads to the improved growth of canopy and ground cover, increased amount
of water available for transpiration and reduced evaporative water loss.
Plant height was also positively associated with grain yield (r=+0.63***)
under moisture stressed conditions. These results indicate that gene pools from landraces can be used to further increase durum wheat yields under rainfed conditions. The results also suggest that stress tolerance increases yield stability. Further studies are needed to quantify the genetic diversity available in durum wheat landraces, to study the genetic variation of various morphophysiological characters under dry conditions, and establish their association with drought tolerance. Acknowledgement This work was supported by the University of Jordan, CIMMYT and ICARDA. The authors are grateful to Dr. A. Zahour and Fr. R. Miller for their valuable suggestions, to Mrs. G. Nachit for help in data analysis, and to Ms. M. Khawam for typing this manuscript. Literature Cited Christiansen MM (1982) World environmental limitations to food and fiber culture. In (Christiansen MM and Lewis CF, eds) "Breeding plants for less favorable environments", Wilded Interscience, New York Eberhardt SA and Russell WA (1966) Stability parameters for comparing varieties, Crop Science 6: 36-40 Fischer RA (1980) Influence of water stress on crop yield in semiarid regions. In (NC Turner and PJ Kramer, eds) "Adaptation of plants to water and high temperature stress", Wilded Interscience, New York 323-329 Frankel OH (1977) Natural variation and its conservation. In "Genetic diversity in plants" (A Muhammed, R Askel and RV Von Borstel eds), Plenum New York 21-44 Nachit MM and Ketata H (1986) Breeding strategy for improving durum wheat in Mediterranean rainfed conditions. International Wheat Conference, May 2-9, Rabat, Morocco Nachit MM and Jarrah M (1986) Association of some morphological characters to grain yield in durum wheat under Mediterranean dryland conditions. Rachis 5: 33-34 Shaladeh M and Duwayri M (1986) Inheritance of morphophysiological characters and grain yield in durum wheat crosses. Rachis 5: 37-42 |
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