Durum Wheat Genetic Variability Past and Present

The extremely rich presence of durum landraces, especially in southern Italy, helped early breeders to make some progress. The intensive use of such germplasm from the 1920s to the 1970s, first in selection programmes and later in hybridization and selection, could not solve, however, a few fundamental problems impeding improvements in the productivity of the crop.

Most important of all, the attainment of a satisfactory lodging resistance, which permits the application of higher doses of nitrogen fertilizers, together with the incorporation in the species of some level of tolerance to the most dangerous diseases (Puccinia graminis, P. recondita, Blumeria graminis, Fusarium spp., Septoria spp.), had to wait until germplasm from outside the Mediterranean region was included in the breeding programmes. To be sure, the path most frequently and successfully followed was the hybridization of international germplasm with local types. But the local component, although synergic, was never resolutive.

Genetic erosion against native genetic variability might have taken place. Italy, however, had already started in the 1970s a strong programme of collection and conservation in favour of local durum types, which culminated in the establishment, in Bari, of the Germplasm Institute of the National Research Council. There the institutional goals of conservation, evaluation and characterization of Italian, Mediterranean and other durums have been effectively pursued.

The question remains as to whether or not the introduction and widespread cultivation of new varieties with largely 'exotic' parentage may have dangerously narrowed the genetic basis of the modern Italian cereal culture to the point of posing a threat to the safety of the same. Some evidence tends to point to a reappraisal of such a threat. In fact, the number of varieties grown in Italy over significantly large areas is higher now than it was some decades ago. This is required in part by the fact that the Italian peninsula stretches over more than 1500 km of latitude, with climatic differences not only between north and south but also between east and west regions. Although a few varieties appear to perform equally well anywhere, many others fit only their own area of adaptation ('niche'). This suggests the existence of a multiplicity of varietal genetic backgrounds. The same could be concluded considering the differences among varieties with respect to reaction to diseases and environmental stresses, as well as to grain quality characteristics.

This amplitude of the varietal genetic basis can be traced to the multiplicity and cosmopolitanism of the genetic resources assembled, moulded, and distributed by the major international dispensers of germplasm, e.g. CIMMYT or ICARDA. In addition, intensive germplasm exchanges have taken place among the various European national durum breeding programmes.

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