Articles
MODEL OF THE INFLUENCE OF TEMPERATURE ON THE ELONGATION RATE OF ASPARAGUS SPEARS
A mechanistic model was developed that describes these responses and predicts that length increases exponentially in thermal time, which agrees with observed behavior.
The model was calibrated for the cultivar Jersey Giant Syn 4 using data from a field experiment in New Zealand, and its robustness was tested by analyzing data from experiments with different cultivars in the USA and Japan.
The model has three parameters, and accurately described spear elongation rate response to air temperature.
The base temperature below which spear elongation ceases was 7.1°C and the rate response to temperature above the base was 0.02232 (°C day)-1. The ‘effective crown depth’, which accounts for any difference between below-ground elongation before spear emergence and subsequent above-ground elongation, was 12.6 cm, slightly less than the actual depth of 15 cm.
Corresponding values from the USA experiment were 6.7°C, 0.02058 (°C day)-1 and 7.0 cm, and from the one in Japan they were 4.8°C, 0.01481(°C day)-1 and 11.1 cm.
The differences suggest that the cultivars had different responses to temperature and that the difference between above- and below-ground spear elongation was greater in the USA experiment.
The stability of the parameters was high, indicating that the model accurately described the data in all cases.