| Wheat Information Service Number 69: 5 - 8 (1989) Utilization of durum wheat (Triticum turgidum L. var. durum) Iandraces to improve yield and yield stability in dry areas M. Duwayri1 and M.M. Nachit2 1 Faculty of Agriculture, University of Jordan, Amman, Jordan Introduction Cereals landraces are important sources of genetic variation (Frankel 1977; Chang 1985) for varietal improvement in dry areas. In the case of durum wheat, this is particularly evident in low rainfall areas of North Africa and West Asia where 70 to 80% of the areas reserved for this cereal are annually covered by landraces, such as Haurani in Jordan, Syria and Lebanon, or selections from landraces such as Kyperounda in Morocco and Cyprus, Zenati Bouteille in Algeria, and Mahmoudi in Tunisia. The use of durum wheat landraces in hybridization programs shows that progress can be made in improving cultivars for dry areas. Omrabi, a line derived from a cross involving Haurani, and Jori C69, a high yielding cultivar when grown in relatively more favorable environments, has been found to be superior to its parents in both favorable and dry environments (Nachit and Ketata 1986). In Jordan, Haurani, the local durum landrace, is mainly grown by farmers in rainfed areas because of its drought tolerance and stability, while Stork, a high yielding variety introduced from CIMMYT, had limited acceptance and is grown mainly in more favorable rainfed and irrigated areas. The current project was undertaken to combine the stress tolerance of Haurani with the yield potential and earliness of Stork since yield stability is a prerequisite to Jordanian wheat cultivation. Material and Methods Twenty-two advanced lines (F8 and F9) from Haurani/Stork crosses along with their parents were evaluated in two locations in Jordan (Ramtha; 277 mm and Jubeiha; 490 mm) and one location in Syria (Tel Hadya; 330 mm) over three years. Two replications in each location were used. Data were recorded on grain yield, biological yield, and plant height. Stability analysis was performed for all recorded parameters according to the model of Eberhart and Russell (1966). Analysis of variance was used to estimate G x E interactions. Results and Discussion Variety x location, variety x year and variety x location x year interactions were all important sources of variation. The estimate of the variance components are given in Table 1. For grain yield, biological yield and plant height the locations, years, locations x years components were all significant at 0.1% level. The variance components of genotypes, genotypes x locations, genotypes x years and genotypes x locations x years were significant at 0.1% level for grain yield and plant height. The variance components of biological yield for genotypes and genotypes x locations were significant at 5 and 1% level, respectively, however, for genotypes x years and genotypes x locations x years no significance was found. In dryland crop production is frequently affected by environmental stresses such as limited water availability, high or low temperatures and mineral stresses (Christiansen 1982). Occasional periods of stress may occur during the growing season, even when the crop is grown in an "optimum moisture environment", resulting in yield decreases. Genetic resistance to stresses is therefore required to attain acceptable yield levels. The genetic manipulation of plants to produce satisfactory economic yields in the presence of abiotic stresses is the most economical solution. Identification of crop varieties carrying genetic stress resistance and yield stability is the most easily transferable part of a technology package to rainfed areas where environmental stresses are the major limiting Production factors. Crosses of Haurani with Stork show that it is possible to develop cultivars that combine yield potential, yield stability and stress tolerance (Table 2). Cross 4 and 20 were tested in rainfed areas of Jordan and Syria in a range of environments with various amounts of rainfall. These crosses also showed better tolerance to environmental variation. The high stability values of these crosses are reflected in their high mean yields, coefficients of regression similar to one and low residual variances. These results corroborate earlier studies on incorporating landrace moisture stress tolerance to improve varieties yielding ability under dryland conditions (Nachit and Ketata 1986). |
| 2 CIMMYT senior durum wheat breeder and Regional Representative, joint CIMMYT/ICARDA durum wheat breeding program, ICARDA, Aleppo, Syria. |
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