EFFECTS OF MEDITERRANEAN CLIMATE ON WHEAT BREAD-MAKING QUALITY

The unpredictability of the Mediterranean climate causes a large fluct uation in wheat yield and quality but offers the opportunity for the p roduction of high quality wheats which are lacking in the European Uni on. This paper describes the effects of nitrogen fertilization rate an d timing on five Triticum aestivum L. cultivars differing in bread-mak ing quality, cultivated in six representative Italian sites (years/loc ations). Nitrogen was applied at each location at two rates, the first corresponding to the amount estimated to maximize grain yield, the se cond 30% higher. Three timings of nitrogen applications were tested in cluding a late application at the boot stage. Breadmaking quality was evaluated with the Chopin alveograph and each sample was assigned to t he following qualitative classes of the Italian market: Class 1, impro ver wheat; Class 2, for direct bread-making; Class 3, ordinary wheat. Cultivars differed significantly in all agronomic and qualitative trai ts. Grain yield was highest in the northern location (7.1 t ha(-1)) an d lowest in the south of the Italian peninsula (2.6 t ha(-1)), while i n Sicily abundant rains in both years enabled a yield of 6.4 t ha(-1) to be obtained. As far as bread-making quality is concerned, the great est proportion of grain samples belonging to Class 1 was obtained from the northern location. The year of cultivation strongly affected qual ity, particularly with regard to gluten tenacity, in all locations, th ough the quality ranking of the cultivars remained substantially stabl e across locations. Nitrogen applications greater than those considere d optimal to maximize yield, combined with a better distribution durin g the life cycle, significantly improved breadmaking quality. It was c oncluded that high quality wheats can be obtained in a wide range of g rowing conditions in the Mediterranean climate. However the likelihood of genotype x environment interactions, statistically significant for both yield and quality, call for a more precise management of nitroge n fertilization in relation to the cultivars chosen and the climatic f eatures of each site. (C) 1997 Elsevier Science B.V.