Examine the interaction between zinc nutrition and heat stress on the photosynthetic activity and grain yield of wheat plants under both field and growth room conditions.

• We examined the interaction between zinc nutrition and heat stress on the photosynthetic activity and grain yield of wheat plants under both field and growth room conditions.
• The zinc inefficient cultivar Goldmark was found to have an improved chlorophyll fluorescence ratio (Fv/Fm), a measure of injury to photosynthesis, under heat stress when supplied with elevated levels of zinc compared to plants where less zinc was applied.
• However supplementary zinc did not prevent a decline in kernel weight or grain yield under high temperature conditions.
• The results indicate that supplementary zinc nutrition, in a zinc inefficient genotype at least, can provide thermotolerance to the photosynthetic apparatus of wheat.