Post-flowering photoperiod and radiation interaction in soybean yield determination: Direct and indirect photoperiodic effects

NICO M; MIRALLES D J; KANTOLIC A

FIELD CROPS RESEARCH

ELSEVIER SCIENCE BV

Lugar: Amsterdam; Año: 2015 p. 45 - 55

0378-4290

tSoybean (Glycine max (L.) Merrill) exposure to long days during the post-flowering phase increases totalbiomass, nodes, pods and seeds per plant, and also the post-flowering duration, increasing the radiationoffer. This work aims to identify the main mechanisms responsible for yield increases in response to longdays, separating direct photoperiodic effects on yield determination, from the indirect effect associatedwith changes in cumulative radiation when the crop cycle is modified by photoperiod. Two field experi-ments were conducted with an indeterminate soybean cultivar. A factorial combination of two radiationlevels (unshaded and shaded), and two or three photoperiod regimes (control, extended 1.5 and 3 h) wasimposed from flowering to maturity. Yield tended to be reduced by shade and increased by extendedphotoperiod mainly through their effects on nodes per m2, and thereby affecting pods and seeds perm2. Photoperiod extension increased node number due to both increased cumulative radiation (indirecteffect) and delayed reproductive development (direct effect). As a result, more pods were established perunit of cumulative radiation under extended photoperiod. The results suggest that photoperiod exten-sion enhanced yield radiation use efficiency due to the alleviation of intra-nodal interferences. The directpost-flowering photoperiodic effect on node number and the resultant effects on pod and seed number,provide evidence of direct photoperiodic effects on soybean yield determination.