To develop molecular markers for Zn efficiency.

• The +Zn treatment received 7 kg Zn/ha at sowing plus 2 foliar sprays of 0.33 kg Zn/ha.
• Generally, yield responses to Zn are greater in durum and bread wheat than in barley.
• The most inefficient lines of wheat and barley showed distinctive symptoms of Zn deficiency, such as reduced growth, pale leaves with chlorotic and necrotic lesions along the mid-vein.
• In 1999 a dry spring limited the yield response to Zn to about 0.5 t/ha, whereas, in 1998 yield increases up to 1 t/ha were measured.
• The disparity between the vegetative and the yield responses has tended to be greater in barley than in wheat.
• The wheat cultivars Goldmark and Kukri have low Zn efficiency, whereas the widely adapted, high yielding cultivars Trident, Krichauff and Worrakatta are Zn-efficient.
• Within barley, a number of Japanese breeding lines (eg SBWI-1) are very inefficient, but many current cultivars from SA as well as Arapiles (Vic.) and Stirling (WA) show a high level of efficiency.
• Pot assays for Zn efficiency have been developed and generally show similar rankings to the field tests.
• Wheat double haploid populations derived from the cross between Trident (efficient) and Songlen (inefficient) have been produced to develop molecular markers for Zn efficiency.