Prediction of Sweet Corn Phenology in Subtropical Environments

Limited information on phenology of sweet corn ( Zea mays L.) grown in subtropical regions is available to processors wishing to manage harvest scheduling. This study was conducted to investigate developmental characteristics of both standard sugary ( su ) and mutant endosperm sugary enhancer ( se ), and shrunken‐2 ( sh 2 ) sweet corn in subtropical Australia. Field experiments were conducted at three locations with numerous times of planting so that a broad range of environments were encountered. Models of daily rate of development for the period sowing to kernel maturity (720 g kg −1 moisture) were derived by an iterative optimization procedure. Development rate was related to mean daily temperature and photoperoid. Temperature was the most important factor affecting rate of development. The temperature response was best described by a broken linear function. Various photoperiod functions fitted as multipliers to the temperature response did not improve goodness‐of‐fit. Cultivars were classified into three maturity groups based on analysis of covariance. Developmental characteristics appeared independent of genetic background as the response of the three sh 2 cultivars was not significantly different from a tropical su type, and the se cultivar ‘Sweet Champion’ did not differ significantly from the majority of su types. Only su cultivar ‘Terrific’ differed significantly from both of these groups. Base temperatures (range from 5.4–6.4°C) were lower than the value traditionally quoted for sweet corn (10°C). Optimum rates of development occurred at temperatures ranging from 30.8 to 33.8° C. The models accurately predict the duration of sowing to maturity and were shown to be a practical tool for harvest date prediction of both standard and mutant endosperm sweet corn in subtropical environments.