Geographic Variation in Germination Traits in Melia azedarach and Rhaphiolepis umbellata

Tetsuto Abe,Michio Matsunaga

doi:10.4236/ajps.2011.21007

Abstract

Some plant species traits may not be uniform across populations distributed across a wide latitudinal range. This study examined intraspecies variation in the effects of cold stratification on the germination of seeds of two widespread trees, Rhaphiolepis umbellata (Rosaceae) and Melia azedarach (Meliaceae), collected from the subtropical Ogasawara Islands (southern seeds) and the temperate Japan mainland (northern seeds). Under the no-treatment control, the southern seeds germinated faster in R. umbellata and achieved a higher germination percentage in M. azedarach. The regional differences in germination performance were reduced by cold stratification. It was reasonable that these germination traits increase fitness under each climate region. Because the remote Ogasawara populations are sufficiently isolated to have developed some distinct characteristics, even common, widespread species may have important conservation value where they exist within insular biota.

Highlights

Seed germination traits for useful tree species is significant information in silviculture
This study examined intraspecies variation in the effects of cold stratification on the germination of seeds of two widespread trees, Rhaphiolepis umbellata (Rosaceae) and Melia azedarach (Meliaceae), collected from the subtropical Ogasawara Islands and the temperate Japan mainland
In R. umbellata, the southern seeds germinated significantly faster than the northern seeds in the control (RMANOVA, F1,22 = 2.1, P < 0.001, Figure 3), there was no significant difference in the final germination percentages (GLM, G = 0.0, df = 1, P = 0.985)

Summary

Introduction

Seed germination traits for useful tree species is significant information in silviculture. Seed germination traits usually contain intraspecific variation such as geographic variation [1]. The isolation of vegetation populations on remote islands leads to high rates of endemism. The rate of endemism in insular angiosperm flora is usually within the range of 30% to 80% [2]. A relatively high proportion of native insular plants are widely distributed species common to the closest major land masses. These species have usually been classified by morphological characteristics. Genetic variation of insular plants has often led to more cryptic divergence of separate populations, even between neighboring islands [3]

Methods

Results

Conclusion