INVESTIGADORES
ROUSSEAUX Maria Cecilia
artículos
Título:
Basal leaf senescence in a sunflower (Helianthus annuus L.) canopy: Responses to increased R/FR ratio
Autor/es:
ROUSSEAUX, M. C.; HALL, A. J; SANCHEZ, R. A.
Revista:
PHYSIOLOGIA PLANTARUM
Editorial:
WILEY-BLACKWELL PUBLISHING, INC
Referencias:
Año: 2000 vol. 110 p. 477 - 482
ISSN:
0031-9317
Resumen:
Senescence of lower leaves (LS) begins before anthesis in sunflower
crop canopies. Using isolated field-grown sunflower plants, it has previously
been shown that pre-anthesis LS is dependent on photosynthetic photon flux
density (PPFD) and is hastened by increases in far-red light. We tested the
hypothesis that increasing the R/FR perceived by basal leaves within canopies
delays LS. To do this, light impinging on the lower surface of north-oriented
8th leaves (cotyledons =0) of crops with maximum leaf area indexes of 3.3 (Exp.
1) and 2.4 (Exp. 2) was enriched (+ 8.33 mmol m-2 s-1)
with red light using light emitting diode (LED) panels. LED panels constructed
with unlit LED or with green LED (PPFD slightly greater than the red LED
panels, to compensate for lower efficiency) were used as controls. Compared with controls, additional R
significantly (P<0.05) increased R/FR perceived by the lower surface and
significantly (P<0.01) delayed LS. On average, leaf duration, as time
between full expansion and a 70% diminution of chlorophyll content, was 5 days
for leaves receiving extra red light (maximum observed LD= 27 days). We
conclude that an increase in the R/FR ratio can delay LS in crop canopies.