Potential for nitrogen fertilization and Hessian fly-resistance to improve Morocco's dryland wheat yields     

J. Ryan  M. Abdel Monem  J. P. Shroyer  M. El Bouhssini  M. M. Nachit 《European Journal of Agronomy》1998,8(3-4):153-159

Hessian fly (Mayetiola destructor, Say) is a perennial scourge of cereal production in the Mediterranean region, particularly in North Africa. In Morocco, it accounts for considerable yield losses of wheat (Triticum spp.), especially in the semi-arid southwestern coastal provinces. Breeding for resistance is the only feasible approach to abate its effects. Nine major Hessian fly-resistance genes have been identified in bread wheat. Two bread wheat varieties have these characteristics; the first variety with complete resistance was ‘Saada’, released to farmers in 1989, whereas a tolerant variety ‘Massira’ was released in 1994. Another widespread limiting factor for all cereals in Morocco is lack of adequate nitrogen (N). With favorable farmer acceptance, Saada became the focus of on-farm N fertilizer trials throughout the low rainfall (250-450 mm year⁻¹) zone, where it consistently out-yielded the susceptible common bread wheat, Nesma, except when no Hessian fly infestation occurred. In most cases, 40 kg N ha⁻¹ was adequate for maximum yield. Substituting resistant cultivars for Hessian fly-susceptible cultivars and increased N use could have an immediate and positive effect on wheat production in Morocco, especially in areas where the insect is endemic. The future impact will be greater when Hessian fly resistance is also transferred to other bread wheat cultivars and to durum (T. durum) wheat, the major staple food in the Mediterranean region.  相似文献   

Direct and indirect selection for drought tolerance in alien tetraploid wheat x durum wheat crosses     

A. Al Hakimi  P. Monneveaux  M.M. Nachit 《Euphytica》1998,100(1-3):287-294

After the evaluation of numerous accessions of primitive wheats for yield components and morphophysiological traits related to drought tolerance (e.g., maintenance of high relative water content, RWC; photochemical quenching of chlorophyll fluorescence, qQ; and chlorophyll loss, chl, under moisture stress conditions), several accessions belonging to three species (Triticum dicoccum, T. polonicum, and T. carthlicum) were crossed with the improved durum wheat varieties Cham 1 and Om Rabi 5. A direct selection (F₂ progeny) for yield and an indirect physiological trait were applied on interspecific T. durum x T. dicoccum, T. durum x T. polonicum, and T. durum x T. carthlicum populations. Divergent selection was applied to validate the possible use of morphophysiological traits (root parameters, RWC, photochemical quenching, proline content, and carbon isotope discrimination) in selection, and to evaluate the resulting effects on yield. Heritability and selection response of these traits has been evaluated, and the impact of divergent selection for morphological and agronomic characters was studied under field conditions. The divergent populations were evaluated under different environmental conditions in France, Syria, and Yemen. Selection for morphophysiological traits related to moisture stress, such as root parameters, RWC and carbon isotope discrimination was possible due to high h² values and effective, resulting in high genetic gains. However, the effect of selection for these traits on yield stability needs to be further studied. Furthermore, a modified bulk method (F₂ 'progeny method') was developed. Direct selection for grain yield per plant in F₂ was carried out and yield per line in F₃ was evaluated under contrasting environmental conditions in France, Syria, and Tunisia. Results revealed that some F₃ lines were higher yielding than the improved durum wheat varieties Cham 1 and Om Rabi 5 under both stressed (Aleppo) and favourable (Montpellier) environmental conditions. Lines were evaluated in preliminary yield trials at Montpellier (France), Aleppo (Syria), and Constantine (Algeria). Results indicated that the use of related species combined with the use of the modified bulk breeding method is promising not only for increasing durum wheat yield in drought prone environments, but also for improving durum wheat yield stability across contrasting environments. Results of both breeding strategies are presented, and the potential advantages of using related tetraploid species in durum wheat breeding for drought tolerance are discussed. This revised version was published online in August 2006 with corrections to the Cover Date.  相似文献