title: Low red/far-red ratios delay spike and stem growth in wheat.
abstract: The responses to low red light/far-red light (R/FR) ratios simulating dense stands were evaluated in wheat (Triticum aestivum L) cultivars released at different times in the 20th century and consequently resulting from an increasingly prolonged breeding and selection history. While tillering responses to the R/FR ratio were unaffected by the cultivars, low R/FR ratios reduced grain yield per plant (primarily grain number and secondarily grain weight per plant) particularly in modern cultivars. Low R/FR ratios delayed spike growth and development, reduced the expression of spike marker genes, accelerated the development of florets already initiated, and reduced the number of fertile florets at anthesis. It is noteworthy that low R/FR ratios did not promote stem or leaf sheath growth and therefore the observed reduction of yield cannot be accounted for as a consequence of divergence of resources towards increased plant stature. It is proposed that the regulation of yield components by the R/FR ratio could help plants to adjust to the limited availability of resources under crop conditions.
authors.affiliation: IFEVA, Facultad de Agronomía, Universidad de Buenos Aires, and Consejo Nacional de Investigaciones Científicas y Técnicas (CONICET), 1417-Buenos Aires, Argentina.
authors.forename: Cristina Cecilia
authors.initials: CC
authors.lastname: Ugarte
authors.forename: Santiago Ariel
authors.initials: SA
authors.lastname: Trupkin
authors.forename: Hernán
authors.initials: H
authors.lastname: Ghiglione
authors.forename: Gustavo
authors.initials: G
authors.lastname: Slafer
authors.forename: Jorge José
authors.initials: JJ
authors.lastname: Casal
mesh_terms: D018507:Gene Expression Regulation, Developmental / Q000528:radiation effects; D018506:Gene Expression Regulation, Plant / Q000528:radiation effects; D008027:Light; D010940:Plant Proteins / Q000235:genetics / Q000378:metabolism; D018547:Plant Stems / Q000235:genetics / Q000254:growth & development / Q000378:metabolism / Q000528:radiation effects; D014908:Triticum / Q000235:genetics / Q000254:growth & development* / Q000378:metabolism / Q000528:radiation effects*
chemical_list: D010940:Plant Proteins