Intraspecies variation of reproductive phenology in Pinus sibirica ex situ

Abstract

The analysis of the phenology of the development of female cones and male shoots in 25-year-old clones from 4 latitudinal and 4 altitudinal ecotypes of Siberian stone pine (Pinus sibirica) in the clone archive was carried out. The period from the female cone breakout to the formation of the cone with completely closed scales after pollination was 10 days for all ecotypes. The northern and high-altitudinal ecotypes began “flowering” 2 days earlier with the accumulation of the sum of active temperatures of 290 °С than the southern and low-altitudinal ecotypes, which needed an accumulation of 400 °С for this. The greatest contribution to the ecotype differentiation in female reproductive phenology was made by differences in the timing of the receptive cone stages. The transition to the receptivity stage in the northern ecotypes occurred 3 days earlier than in the southern ones, and in the high-altitudinal ones 2 days earlier than in the low-altitudinal ones. In latitudinal ecotypes, cones were receptive for 2-3 days, in high-altitude ecotypes 1.5-2 times longer. The peak of pollen shedding in each ecotype basically corresponded to the timing of the beginning of the female cone scale opening, sometimes it was slightly ahead of it.