Impact of Seeding Time on Apical Development in Annual Canarygrass: A Case of Vernalization Requirement?.

Annual canarygrass (Phalaris canariensis) originating in the Mediterranean region and Middle East, suffers from unstable grain yield when grown under the long days and variable weather conditions, typical of the Canadian prairies. Recent approval of the crop for human consumption will provide it a market opportunity that would benefit from stable grain production.

Delayed heading of late, versus early, seeded and its correlation with decreased annual canarygrass grain yields provide evidence of an unmet vernalization requirement. In contrast, relatively rapid leaf appearance rates and the simultaneous development of consecutive leaves, casually observed with delayed seeding, could also potentially delay crop heading via increased main shoot Final Leaf Number (FLN). This study was conducted to investigate the phenological and morphological response of annual canarygrass to vernalizing temperatures.

Two annual canarygrass cultivars were exposed to different air temperatures under a long photoperiod by means of contrasting seeding dates (early and late based on local seeding time practices) in field experiments in 2013 and 2014.

Both canaryseed cultivars showed increased FLN with delayed seeding and thus potentially delayed heading. Differences in the rate of elongated leaf primordium appearance between seeding dates were either insufficient or non-corresponding to measured FLN differences. On the other hand, the Leaf Stage at the first Floral primordium (LS_FI) and Terminal Spikelet (LS_TS) initiation of seedlings was correlated with FLN.

The effectiveness of three vernalizing temperatures and five durations, in terms of FLN and LS_FI reductions, were investigated under very long photoperiod in controlled-environment experiments.

Both cultivars responded to relatively low-temperature vernalizing treatments by exhibiting reduced FLN and LS_FI with prolonged exposure of the seedlings up to a period of 14 days.

The results suggest that annual canarygrass cultivars have a low-temperature vernalization requirement.