Zhang et al.—Photosynthetic contribution of cotyledons to seedling development

New Zealand Journal of Botany abstracts

Photosynthetic contribution of cotyledons to early seedling development in Cynoglossum divaricatum and Amaranthus retroflexus

Hongxiang Zhang

Daowei Zhou*

Institute of Grassland Science
Northeast Normal University
Key Laboratory of Vegetation Ecology
Ministry of Education
Jilin Province
130024, P.R. China

Cory Matthew

Institute of Natural Resources
Massey University
Private Bag 11222
Palmerston North 4442, New Zealand

Ping Wang

Wei Zheng

Institute of Grassland Science
Northeast Normal University
Key Laboratory of Vegetation Ecology
Ministry of Education
Jilin Province
130024, P.R. China
*Author for correspondence:
choudaowei@yahoo.com.cn

Abstract This study evaluated cotyledon contribution to seedling development in a small-seeded species (Cynoglossum divaricatum, seed weight 8.51?mg) and a very small seeded species (Amaranthus retroflexus, seed weight 0.46?mg), focusing on the balance between the reserve storage role and the photosynthetic role of cotyledons. The data provide insight complementary to that from earlier studies which have not generally included seeds as small as those of A. retroflexus. The data highlight the way in which almost total reliance on the photosynthetic role of cotyledons in small-seeded species can achieve a very high relative growth rate during early seedling development, and raise the possibility that quantitative determination of the ratio between the photosynthetic contribution of cotyledons to seedling development and total (photosynthetic plus reserve) contribution may provide a useful indicator of species competitive strategy and fitness for different habitats.

Keywords contribution; cotyledon; photosynthesis; proportion; spectrum; storage

B07018; Online publication date 25 February 2008; Received 19 June 2007; accepted 5 December 2007

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