Integrative Biology Journals

JOURNAL OF FORESTRY RESEARCH ›› 2024, Vol. 35 ›› Issue (1): 124-.DOI: 10.1007/s11676-024-01777-9

• Original Paper • Previous Articles     Next Articles

Pollen source affects acorn production in pedunculate oak (Quercus robur L.)

Ryan McClory1, Richard H. Ellis1,b, Martin Lukac1,2, Jo Clark3   

  1. 1 School of Agriculture, Policy and Development, University of Reading, PO Box 237, Agriculture, Earley Gate, Whiteknights Road, RG6 6EU, Reading, UK
    2 Faculty of Forestry and Wood Sciences, Czech University of Life Sciences Prague, CZ 165 000, Prague, Czechia
    3 Future Trees Trust, Harwell Innovation Centre, Building 173, Curie Avenue, OX11 0QG, Harwell, Oxford, UK
  • Received:2024-02-23 Accepted:2024-03-29 Online:2024-10-16 Published:2024-10-16
  • Contact: Richard H. Ellis

Abstract:

Acorn production in oaks (Quercus spp.) shows considerable inter-annual variation, known as masting. The effects of pollen sourced from trees within or outside the stand on acorn production were investigated in pedunculate oak (Quercus robur L.) in an ancient mixed woodland during two moderate masting years. Comparisons were made between natural pollination, hand pollinations with out-of-stand pollen, in-stand pollen or a 1:1 combination of the two pollen sources, and for bagged flowers left unpollinated. After all treatments, > 85% of the flowers or developing acorns were aborted between May and August of both years. When flowers were protected with pollen bags and no pollen added, no acorns were produced. In contrast, hand pollination with out-of-stand pollen produced the most acorns both years and significantly more than within-stand pollen or natural pollination in 2022. Hand pollination with out-of-stand or within-stand pollen provided significantly more acorns than natural pollination in 2023. In 2022, hand pollination with a 1:1 mixture of out-of-stand and within-stand pollen yielded an intermediate number of mature acorns between those for the out-of-stand and within-stand pollination treatments. The study provides clear evidence of maternal choice during acorn development in pedunculate oak and of the benefits of pollen supplementation. It also confirms that pedunculate oak is a fruit-maturation masting species; abortion of pollinated flowers and immature acorns determines a mast year (rather than the number of flowers produced) at this site.

Key words: Quercus robur L., Acorns, Masting, Pedunculate oak, Pollination