RESPIRATION OF ACORNS AS RELATED TO TEMPERATURE AND AFTER-RIPENING

Abstract

It is well known that while acorns of the white oak group will germinate as soon as they fall from the tree, acorns of the red oak group will not germinate until they have undergone a period of after-ripening. Although the red oak acorns are morphologically mature they must undergo certain physiological changes before they will germinate even under the most favorable conditions. The nature of the physiological changes occurring during the after-ripening of acorns is not fully understood. Korstian (6) found that after-ripening is affected by temperature. Storage at an average night temperature of 50? F. (10.0? C.) and day temperature of 65? F. (18.3? C.) resulted in the most satisfactory after-ripening as judged by promptness of germination and the percentage finally germinating. It appears that certain chemical and physiological changes occur in red oak acorns during over-wintering and the accompanying after-ripening which do not occur in acorns of the white oak group. It was believed that concurrent measurements of the 02 consumption and C02 production of acorns of the white and red oak groups might supply some information concerning differences in the physiology of the two groups. It also seemed possible that periodic measurements of the rate of respiration and the respiratory quotient of red oak acorns stored at various temperatures would indicate the effects of storage temperature on the rate of after-ripening and the accompanying physiological changes. Acorns of northern red oak [Quercus borealis var. maxima (Marsh.) Ashe] and white oak (Quercus alba L.) were chosen for these studies because they are widely distributed and representative species of the two principal groups of oaks. Methods