Genetic variability to the effects of heat stress during grain filling on durum wheat quality

During the 1996/97 season twenty durum wheat cultivars were grown in Foggia, a typical area of durum wheat cultivation in Italy, in order to assess the varietal response to the effects of heat stress on characteristics affecting grain and milling quality. In the field trial high temperature stress was imposed during grain filling by covering the plots from ten days after anthesis until ripeness with PVC film tunnels, obtaining maximum temperatures about 10°C higher in the tunnels than in the open. Results evidenced that, in general, the percentage of gluten, total and insoluble proteins increased with high temperature whereas a reduction was observed for kernel and specific weight. Considerable differences among the varieties examined in the response to heat stress were observed pointing out different sensitivity levels to this environmental factor. Therefore, on the basis of the changes of insoluble protein percentage, important qualitative parameter of durum wheat, the varieties were arranged in tolerant and sensitive groups and, in relation to grain qualitative characteristics, the different performance of the two groups was also evidenced.