To deal with aspects of a large project on diagnosis of the deficiency, yield responses to zinc, residual value of zinc, protein increases and improvement of quality, and genotypic effects in relation to zinc.

• Snapshot of some aspects of a large project on diagnosis of the deficiency, yield responses to zinc, residual value of zinc, protein increases and improvement of quality, and genotypic effects in relation to zinc.
• Zinc (as zinc sulphate hepta hydrate) was applied at rates up to 40 kg/ha. Nitrogen was applied at 30 kg/ha. Wheat cv. Hartog was sown at 30 kg/ha. In some experiments Cu was applied at 5kg/ha.
• Yield and protein in the grain increased with application of zinc.
• Zinc deficiency symptoms seen in crops without Zn applied throughout tillering and leaf samples confirmed the deficiency.
• The reduction in yield was largely due to plant mortality and fewer productive tillers per plant.
• Bread making quality as measured by a mixograph showed that the dough strength of zinc deficient grain was very poor.
• However, the dough itself mixed very quickly.
• Residual value of the initial application of zinc is at least 2 years: yield responses have occurred in successive seasons.
• In yield response experiments, responses to zinc have been recorded up 10 kg/ha; at 40 kg/ha, toxicity has been recorded at early tillering but the crop has recovered totally by maturity.