Response of durum wheat to different levels of zinc and Fusarium pseudograminearum

Durum wheat (Triticum turgidum ssp. durum) is susceptible to Fusarium pseudograminearum and sensitive to zinc (Zn) deficiency in Australian soils. However, little is known about the interaction between these two potentially yield-limiting factors, especially for Australian durum varieties. The critical Zn concentration (concentration of Zn in the plant when there is a 10% reduction in yield) and degree of susceptibility to F. pseudograminearum was therefore determined for five Australian durum varieties (Yawa, Hyperno, Tjilkuri, WID802, UAD1153303). Critical Zn concentration averaged 24.6mgkg(-1) for all durum varieties but differed for the individual varieties (mgkg(-1): Yawa, 21.7; Hyperno, 22.7; Tjilkuri, 24.1; WID802, 24.8; UAD1153303, 28.7). Zinc efficiency also varied amongst genotypes (39-52%). However, Zn utilisation was similar amongst genotypes under Zn-deficient or Zn-sufficient conditions (0.51-0.59 and 0.017-0.022g DM g(-1) Zn, respectively). All varieties were susceptible to F. pseudograminearum but the development of symptoms and detrimental effect on shoot biomass and grain yield were significantly greater in Tjilkuri. Even though crown rot symptoms may still be present, the supply of adequate Zn in the soil helped to maintain biomass and grain yield in all durum varieties. However, the extent to which durum varieties were protected from plant growth penalties due to crown rot by Zn treatment was genotype-dependent.