MATHEMATICAL FORMULAS FOR CALCULATING THE BASE TEMPERATURE FOR GROWING DEGREE-DAYS

Much research has been done on finding methods to determine the base t emperature, a very important variable in computation of growing degree days (GDD). Four common methods have been reported often in the liter ature: (1) the least standard deviation in growing degree days; (2) th e least standard deviation in days; (3) coefficient of variation; (4) regression coefficient. The procedures to calculate the base temperatu re associated with these methods are tedious and lack a theoretical ba sis in mathematics. The objective of this research was to find simple and mathematically sound formulae to calculate the base temperature fo r GDD. Mathematical formulae are proposed, proved and tested using tem perature data for snap bean, sweet corn, and cowpea. Compared with pre vious procedures, these proposed mathematical formulae can produce the base temperature easily and accurately. These formulae are applicable to calculating the base temperature for GDD of any developmental stag e for any crop.