Key Points
- Temperature drives the duration of crop growth while solar radiation intercepted determines the rate of growth.
- An increase in temperature may reduce potential crop yields due to a reduction in the duration of growth.
- There has been no significant increase in either temperature (GDDs) or solar radiation over the past 50 years (1 September to 31 May) in the four North Island regions analysed.
- If global warming is having any effect, it appears to be over the winter months. From June-August, average temperature have increased by 1 degree C over the past 50 years.