Exploiting durum wheat germplasm to increase nitrogen use efficiency (NUE)

Wheat is, among cereals, one of the most important worldwide in terms of production and utilization as staple food. An increase of 25% in the global production is demanded up to 2050 due to the exponential increases of the world population. The goal of wheat breeding is the development of new wheat varieties with increased production maintaining an high qulaity and high protein content. Low nitrogen content is one of the major constrain of wheat production, thus increased usage of N supply have been mandatory for increasing wheat grain yield and protein content. Several reports have shown that almost 50% of the nitrogen fertilizer applied remains unavailable to crops due to N losses. Many effeorts have been done so far to obtained wheat varieties with an incresed Nitrogen Use Efficiency (NUE). A possible strategy is to exploit the natural diversity available in landraces still cultivated in situ or stored ex sistu in germplasm collections. To create and handy core collection with good representation of the genetic background we developed a durum wheat core collection of 452 genotypes between landraces and local varieties obtained by single seed descent, representative of more than 40 countries and currently characterized for several phenotypic traits. A number of genotypes of the SSD collection have been also selected to be part of the durum wheat reefrence collection (DWRC) recently constituted in frame of the Wheat Initiative. In this work a selection of 14 SSD genotypes plus two control cultivars have been tested in randomized bloks for two years in field in normal and low nitrogen supply (0-100%) and a difference in NUE and its components have been observed between the selected genotypes. Yield, development and photosynthesis related traits have been investigated to dissect the mechanisms underlying the observed differences between genotypes.