An Artificial Apple Bud for Frost Temperature Sensing

Abstract

ABSTRACT AN artificial apple bud was developed to replace insertion of thermocouples into real apple buds for temperature monitoring. The energy balance of an apple flower bud in the first pink stage was analyzed to determine which bud properties affect the bud-environment heat exchange. Dry and wet bud energy balances were considered. The parameters involved in the bud energy exchange were shape, emissivity, diameter, volume, density, and specific heat. Polystyrene, a plastic with thermal properties similar to an apple bud was tooled to the size and shape of a natural bud. A 3000 ohm, 1% precision thermistor was prepared and inserted into the polystryene. Ten buds were fabricated and tested. On a sample frost night, under nonsprinkled conditions, there was no difference between artificial and natural bud temperature means at a 95% confidence level two out of seven periods. The difference between the means was equal to or less than 0.8 C at all seven periods. Under sprinkled conditions, there was no difference between temperature means of any period.