title: Decoupling of light intensity effects on the growth and development of C3 and C4 weed species through sucrose supplementation.
abstract: Light availability has a profound effect on plant growth and development. One of the ways to study the effects of light intensity on plant growth and development without the confounding problem of photosynthate availability is sucrose injection/supplementation. A greenhouse experiment was conducted to evaluate the effects of light levels (0% and 75% shade) and sucrose injection (distilled water or 150 g sucrose l(-1)) on three weed species: redroot pigweed (Amaranthus retroflexus L., C4), lambsquarters (Chenopodium album L., C3) and velvetleaf (Abutilon theophrasti Medic., C3). The average total sucrose uptake was 7.6 and 5.9 g per plant for 0% and 75% shading, respectively, representing 47% of the average total weed dry weight. Plants injected with sucrose had greater dry weights and shoot-to-root ratios under both light levels. In spite of sucrose supplementation the reduction in dry matter due to shading was greater for roots and reproductive structures than vegetative shoot tissues, indicating light level regulation of morphological changes resulting in changed C allocation that are independent of photosynthate availability. Dry weights of plants injected with sucrose under 75% shading were not different from distilled water-injected unshaded plants. However, both sucrose-injected and control plants, regardless of their photosynthetic pathways, underwent similar changes in allocation of dry matter and morphology due to shading, suggesting that these effects are strictly due to light intensity and not related to photosynthate availability.
authors.affiliation: Plant Science Department, McGill University, Macdonald Campus, 21111 Lakeshore Road, Ste-Anne-de-Bellevue, Quebec, Canada H9X 3V9.
authors.forename: Sultan H
authors.initials: SH
authors.lastname: Begna
authors.forename: Lianne M
authors.initials: LM
authors.lastname: Dwyer
authors.forename: Daniel
authors.initials: D
authors.lastname: Cloutier
authors.forename: Louis
authors.initials: L
authors.lastname: Assemat
authors.forename: Antonio
authors.initials: A
authors.lastname: DiTommaso
authors.forename: Xiaomin
authors.initials: X
authors.lastname: Zhou
authors.forename: B
authors.initials: B
authors.lastname: Prithiviraj
authors.forename: Donald L
authors.initials: DL
authors.lastname: Smith
mesh_terms: D027721:Amaranthus / Q000187:drug effects / Q000254:growth & development / Q000528:radiation effects; D027462:Chenopodium / Q000187:drug effects / Q000254:growth & development / Q000528:radiation effects; D008027:Light; D019660:Malvaceae / Q000187:drug effects / Q000254:growth & development / Q000528:radiation effects; D063245:Plant Development; D018515:Plant Leaves / Q000187:drug effects / Q000254:growth & development / Q000528:radiation effects; D018517:Plant Roots / Q000187:drug effects / Q000254:growth & development / Q000528:radiation effects; D018547:Plant Stems / Q000187:drug effects / Q000254:growth & development / Q000528:radiation effects; D010944:Plants / Q000145:classification; D012639:Seeds / Q000187:drug effects / Q000254:growth & development / Q000528:radiation effects; D013395:Sucrose / Q000494:pharmacology*
chemical_list: D013395:Sucrose