Effects of Light Intensity and Girdling Treatments on the Production of Female Cones in Japanese Larch (Larix kaempferi (Lamb.) Carr.): Implications for the Management of Seed Orchards

Michinari Matsushita,Makoto Takahashi,Hiroki Nishikawa,Akira Tamura

doi:10.3390/f11101110

Michinari Matsushita, Makoto Takahashi + Show 2 more

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https://doi.org/10.3390/f11101110

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Abstract

To ensure sustainable forestry, it is important to establish an efficient management procedure for improving the seed production capacity of seed orchards. In this study, we evaluated the effects of girdling and increasing light intensity on female cone production in an old L. kaempferi (Lamb.) Carr. seed orchard. We also evaluated whether there is a genotype-specific reproductive response to these factors among clones. The results showed that female cone production was augmented by girdling and increasing light intensity. There was a difference in the effectiveness of girdling treatment levels, and the probability of producing female cones increased markedly at higher girdling levels. At light intensities where the relative photosynthetic photon flux density was higher than 50%, more than half of the trees tended to produce female cones, even in intact (ungirdled) trees, and the genotype-specific response to light intensity was more apparent in less-reproductive clones. These findings suggested that girdling less-reproductive trees combined with increasing light intensity was an effective management strategy for improving cone production in old seed orchards.

Highlights

Japanese larch (Larix kaempferi) is a major plantation species in central and northern Japan [1].The species has been introduced widely in China, Europe and North America, because of its rapid growth and sparse branching characteristics
We quantitatively evaluated the effects of girdling manipulation and increasing light intensity on female cone production in an old L. kaempferi seed orchard
This study quantitatively evaluated the effects of girdling and increasing light intensity on female cone production in an L. kaempferi seed orchard

Summary

Introduction

Japanese larch (Larix kaempferi) is a major plantation species in central and northern Japan [1]. The species has been introduced widely in China, Europe and North America, because of its rapid growth and sparse branching characteristics. Larix kaempferi often shows superior growth compared to other larch species Koch) and has been widely used in breeding programs involving hybrid breeding [2,3]. As a result of these efforts, hybrids between L. kaempferi and other larches have been used commercially in North America [4], Europe [3] and Japan [5,6]. In Japan, a breeding program for L. kaempferi was initiated in the 1950s. As part of the program, more than 500 first-generation plus trees were selected and used to establish clonal seed orchards [1]

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