Sweet corn is a major warm-season vegetable crop in Australia, with an annual value of production around $480million. Sweet corn is sown by direct seeding and is unusual among vegetables in that it is a monocotyledon plant (grass) rather than dicotyledon (broadleaf). It also uses a different form of photosynthesis to most vegetables – C4 rather than C3 – which is well adapted to warm conditions.
Sweet corn grows best between 24 – 30C. Prolonged temperatures above 32C can reduce pollen germination to zero, resulting in failure of kernels to develop on the cob. A few days at 32C can reduce yield by 30%. Below 12C sweet corn seeds can fail to germinate, emergence is reduced, and phosphorous uptake is limited.
Sweet corn is not usually planted until soil temperatures reach 15C. The challenge for plant breeders is to develop strains that will still germinate in cold (12C) wet soil earlier in spring.
Breeding for heat tolerance would also be useful. However, there are no known breeding programs currently addressing this issue.