Impact of Temperature on Peanut (Arachis hypogaea) Seed Germination.

Experiments were conducted to evaluate the germination response of 11 peanut cultivars using a temperature gradient.  The effect of temperature on germination response was conducted on a 243 (length) x 91 (width) x 7.6 (depth) cm temperature gradient table.  The table is a solid aluminum block with hot water running through one end and cold through the other.  This results in a continuous temperature gradient ranging from 14 to 38 ºC along the length of the table.  Temperatures were randomly measured and recorded at 30 minute intervals with a data logger by placement of thermocouples into holes uniformly drilled on the underside of the table to within 0.5 cm of the table surface.  Seed were randomly distributed on moistened germination paper, which was placed in a Petri dish.  For each cultivar, 22 Petri dishes were placed at 1.0 ºC increments along the length of the table.  Beginning at 24 hours after seeding, peanut germination was counted when the radicle extended for more than 1 mm, and removed from the dish.  Germination was counted daily, through 7 days after seeding.  Peanut germination averaged across the 11 cultivars, was 76% and less for temperatures below 18.4 ºC, 86% and greater between 19.4 and 34.2 ºC, but dropped off to 83% at 36.1 ºC.  Overall, CRSP98 exhibited the weakest germination responses (0 to 95%) with 3081R having the highest germination across all temperature regimes (50 to 100%).