Phenology, canopy development, biomass and grain yield of annual canarygrass (Phalaris canariensis L.)

Abstract

Canaryseed (Phalaris canariensis L.) suffers from low and unstable grain yield. This study investigated whether canaryseed phenological responses to air temperature were associated with grain yield instability. Two glabrous- and one pubescent-hulled canaryseed cultivars were compared with a cultivar each of a spring wheat with minimum vernalization requirement and an oat cultivar sown at different dates (SDs). Young seedlings were then exposed to vernalizing treatments of 5, 10 and 15°C for 0, 2, 7, 14 and 21 days in controlled-environment experiments. Canaryseed cultivars generally increased their main stem final leaf number (FLN) with later SDs and reduced their FLN and their leaf stage at floral initiation (MHLSFI) upon exposure of the seedlings for up to 14 days at 5°C and 10°C but not at 15°C vernalizing treatments. Both wheat and oat had similar or slightly altered FLN and MHLSFI with different SDs and vernalizing treatments. A putative low-temperature vernalization requirement of canaryseed was therefore proposed. In the field, FLN of canaryseed was positively associated with the key phenological stages of floral initiation, terminal spikelet formation and anthesis. The length of the pre-anthesis phases with later SDs was altered differentially among canaryseed cultivars but only slightly in wheat and oat. The start of stem elongation in canaryseed was positively associated with FLN, it was negatively correlated with tillering cessation and its duration was shortened with late SDs. In wheat and oat, the start of stem elongation was relatively less affected by SD and tillering cessation was more related to the % of intercepted radiation by the canopy. In canaryseed, earlier tillering cessation together with the suppression of the first few primary tillers may determine tiller number. In wheat and oat, instead, primary tillers were relatively less suppressed. Canaryseed main stem grain yield was relatively stable but tiller-derived yield was positively associated with total plant yield. In contrast, the yield of wheat and oat plants mostly depended more on main stem-derived yield. The crop biomass, biomass components and grain yield of all five cultivars varied. Canaryseed grain yield variation was best explained by changes in the harvest index. Likely, the canaryseed delayed phenological development negatively affected harvest indices with late seeding. The wheat and oat cultivar, which reached anthesis earlier had lower reductions in harvest index and grain yield. Canaryseed phenological response to low-temperature can explain part of the grain yield instability.