Photoperiod sensitivity of stem elongation phase and fertile florets at anthesis in wheat Nils differing in photoperiod genetic constitution

GONZÁLEZ FG, SLAFER GA, MIRALLES DJ

Punta del Este, Uruguay

Congreso; XI Reunión Latinoamericana de Fisiología Vegetal, XXIV Reunión Argentina de Fisiología Vegetal, I Congreso Uruguayo de Fisiología Vegetal; 2002

It has been suggested that lengthening the stem elongation phase (terminal spikelet initiation –TS- anthesis –AT-) through its photoperiod sensitivity would result in an increased wheat potential yield. The aim of the present study was to asses the role of some of the photoperiod sensitive genes on duration of TS-AT and the consequent number of fertile florets at anthesis under field conditions. Three wheat Nils (John Innes Center, Norwich, UK) of Mercia: Ppd-D1b - Ppd-B1b (L1, strong sensitivity), Ppd-D1b – Ppd-B1a (L2, intermediate sensitivity) and Ppd-D1a – Ppd-B1b (L3, weak sensitivity) and two monochromosomic recombinant lines (John Innes Center, Norwich, UK) of Cappelle Desprez: Ppd-D1b – Ppd- B1b (C1, strong sensitivity) and Ppd-D1a – Ppd- B1b (C3, weak sensitivity) were exposed to two photoperiod treatments only during TS-AT phase (NP+0 and NP+6, natural and 6 hours extended photoperiod, respectively). Photoperiod modified duration of TS-AT in lines having the Ppd-D1 allele in recessive state (L1, L2 and C1) but had no effect on the other lines (L3 and C3). However, only the lines with both alleles in recessive state (L1 and C1) were the only ones that responded increasing the spike dry weight and therefore the number of fertile florets as duration of stem elongation increased.