Seed size variability and its influence on germination and seedling growth of five multipurpose tree species

Seed size variation and the effect of seed size on germination and initial seedling growth were studied in Acacia catechu Willd., Acacia nilotica Willd., Albizzia lebbek Benth., Dalbergia sissoo Roxb. and Tectona grandis L.f. All the species showed a wide range of seed size. In A. nilotica, A. lebbek and D. sissoo, the proportion of seeds in bulk sample was highest in medium seed size class. A. catechu indicated maximum proportion of seeds in small seed size class, while T. grandis in largest fruit size class. Of the five species, seed size in A. catechu and A. nilotica showed a positive relation with the germination and related parameters in laboratory as well as in nursery conditions. In A. lebbek, however, medium and large seeds performed better than largest and small seeds in both the conditions. In D. sissoo, large seeds in laboratory indicated better germination, while in nursery condition medium seeds performed better. Seed size also affected initial seedling growth and dry weight in all the species except in T. grandis. Seed size in A. nilotica and A. lebbek showed a positive relation with growth and dry weight of seedling. On the other hand, larger seedlings were produced by medium seeds in D. sissoo and A. catechu. In T. grandis seed size did not seem to affect germination and seedling growth. It was also observed that small seeds of A. catechu. A. nilotica, A. lebbek and D. sissoo performed poorly in terms of germination as well as in seedling growth and dry weight, hence the small seeds should be removed from the sample to get better and uniform germination and quality seedlings.