The impact of weather on the scheduling of sweet corn for processing 1. Quantifying the link between rate of development and the environment

Abstract

The way in which crop processors can influence the timing of a crop's harvest is by the choice of cultivar and planting date. However, the crop duration (time between planting and harvest) is substantially affected by the weather. Processors' records illustrate the magnitude of these effects. The mean crop duration for the sweet corn cultivar NK51036 was 111 days for the 1980/81 to 1984/85 seasons in the Manawatu, but the range was 38 days. The practical problem facing the processor is how to allow for these effects when planning optimal use of factory plant and labour.

To help quantify the effects of the weather, the contributions of temperature and photoperiod to the variability in crop duration of commercial sweet corn crops in New Zealand were assessed. Temperature was the dominant environmental factor influencing crop duration from planting to harvesting, and a linear degree-day model with a 6°C base temperature was able to account for 92% of the variation in duration for 125 crops grown in the Manawatu over five seasons. Extended to a total of 489 crops grown in three regions, 89% of the variation was accounted for by this model. The coefficient of variation of crop duration expressed in terms of thermal time was 4–5 times lower than when calendar days was used. Photoperiod made a negligible contribution to the observed variability in crop duration.

The adequacy of standard meteorological temperature records for use with this model is discussed.

Keywords:

• sweet com
• Zea mays L.
• temperature
• photopenod
• degree-day model
• crop duration
• phenology
• grain filling