Genetic and silvicultural research promoting common walnut (Juglans regia) for timber production in the United Kingdom

Abstract

A combination of genetic and silvicultural research is required to improve the viability of common walnut for timber production in the UK. A summary of a research programme, initiated in 1996, is provided. Establishment of walnut plantations using tree shelters indicated positive benefits using 0.75 m shelters but larger shelters (1.20 m) caused early flushing and increased dieback. Direct seeding trials indicated that pretreatment of seed with gibberellins was highly effective in reducing the need for lengthy pre-treatments and promoted 87% germination. Artificial application of nitrogen fertiliser on newly established walnut trees indicated that applications up to 500 kg ha^-1 had no effect on survival or early growth. Assessments of a range-wide collection of walnut, including provenances from Kyrgyzstan, point to high variability in flushing and growth between provenances and progenies 4 years after establishment. Genotype by site interaction within the three provenance trials is evident. Adoption of new, to the UK, silvicultural systems incorporating tree and shrub nurses indicated promising benefits from using the nitrogen-fixing nurse species autumn olive and Italian alder.

Parent Publication

• Black walnut in a new century, proceedings of the 6th Walnut Council research symposium; 2004 July 25-28; Lafayette, IN.

Citation

Hemery, Gabriel E. 2004. Genetic and silvicultural research promoting common walnut (Juglans regia) for timber production in the United Kingdom. In: Michler, C.H.; Pijut, P.M.; Van Sambeek, J.W.; Coggeshall, M.V.; Seifert, J.; Woeste, K.; Overton, R.; Ponder, F., Jr., eds. Proceedings of the 6th Walnut Council Research Symposium; Gen. Tech. Rep. NC-243. St. Paul, MN: U.S. Department of Agriculture, Forest Service, North Central Research Station. 138-145