ALBERT

Description: It is generally accepted that seedlings from large seeds are more tolerant to defoliation than those from small seeds due to the additional metabolic reserves present in the large seeds. However, information on the effects of amount of seed reserves (cotyledon removal) from seedlings resulting from large vs. small seeds on seedling growth and long-term survival in the field is limited. Five legume species with different sizes of seeds were sown in the field and none, one, or both cotyledons removed 7 days after seedling emergence. Seedling biomass, relative growth rate (RGR) and survival were determined at different time. Cotyledon removal, species, and their interaction had significant effects on seedling growth and survival. During the period between 33 and 70 days, seedlings from large seeds had a significantly lower RGR than those from small seeds. Biomass, RGR, and survival of seedlings from large seeds were significantly reduced by removal one or both cotyledons, whereas those of seedlings from small seeds were not affected. Seed energy reserves are more important for the early growth of seedlings from large seeds than for those from small seeds. The overall effect of cotyledon removal on growth and survival varies with seed size (i.e., energy reserves) with seedlings from small seeds being less sensitive than those from large seeds under field conditions. This study determined the effect of cotyledon removal on seedling growth at different growth stage and seedling survival of five common legume species. In contrast with the commonly held view, our results indicated that seedlings biomass and RGR of seedlings from large seeds were significantly reduced by removal one or both cotyledons, whereas those of seedlings from small seeds were not affected, suggesting seed energy reserves are more important for the early growth of seedlings from large seeds than for those from small seeds. Moreover, the relationship between seed mass and seedling biomass varied with seedling growth stage and cotyledon removal treatment, suggesting that the relative advantage of large or small seeds in nature involves seedling growth rates more than seed energy reserves, and the initial advantage of seedling from large seeds will be overtaken by those from small seeds due to relative higher growth rate.