Cardinal Temperatures for Borage Seed Germination.

Determination of the cardinal temperatures for borage (Borage officinalis L.) germination would facilitate identification of seeding dates where soil temperatures would be conducive for optimum germination, and subsequent stand establishment and crop performance. The objective of this study was to determine the optimum, minimum and maximum germination temperatures for borage. Mature borage seeds were germinated on a temperature-gradient bar varying between 7 and 36 C. Cumulative germination was calculated for each temperature treatment. Optimum, minimum, and maximum temperatures were derived from regression analysis that generated a 2nd order polynomial for the germination temperature response. Optimum, minimum, and maximum temperatures for borage germination were 23.2, 9.2, and 37.3 C, respectively. This information will enable producers to time borage seeding when soil temperatures are optimum for germination and stand establishment.