Precocious Male Cone Production associated with Low Nutrient Status in Clones of Pinus radiata

Abstract

WAREING1 has reported that in Pinus sylvestris male and female cones are frequently borne on separate shoot systems. Female cones develop first, appearing on strong leading shoots on the main stem, and later also on vigorous first-order branches. Male cones are not produced until some years after the first female cones, and then appear on weaker twigs in the basal region of the lower branches. This distinction in the position of male and female cones suggests that the type of cone developing on a branch system is dependent on the internal condition of that system. Moorby and Wareing2 have since suggested that the condition necessary for the onset of male coning is a certain degree of ageing, and they showed that ageing occurs in a branch system when this becomes sufficiently complex to lead to intensified competition for nutrients between the constituent shoots of the system. That is, male cones may tend to occur on twigs where the nutrient supply is limited.