Page 113 - PC2019 Program & Proceedings

PLANT CANADA 2019

S11. Evaluation of optical sensors in predicting yield and nitrogen application in sugarbeet (Beta
vulgaris)
MacFarlane, J.; L. Van Eerd
University of Guelph Ridgetown Campus

As farmers dependency on fertilizers to support sugarbeet (Beta vulgaris) nitrogen requirement grows,
determining that requirement becomes important for maximizing the sugarbeet yield potential.
Refinement companies such as Michigan Sugar pay growers based on root yield quantity and yield
sucrose quality. Monitoring plant N levels in sugarbeet during the growing season is important for
maximizing yield, as N fertility positively correlates with root yield but negatively with sucrose. Final
yield sucrose is also impacted by harvest date as later dates have higher sucrose concentrations. Both
having shown promise in monitoring nitrogen, the SPAD meter and GreenSeeker were compared in their
ability to measure sugarbeet N content and predict yield quality mid growing season (2016/2017), and at
two harvest dates (2015/2017). The design was a split-block with three replications, using eight cultivars
¯
of sugarbeet and five N rates (0, 44.84, 89.68, 156.94, 224.2 kg ha ). Optical sensor observations taken in
June and at harvest were compared with N rate, yield, and recoverable white sucrose per ton (RWST) at
harvest. Throughout 2015/2016/2017, root yield (tonnes ha¯) did not have a significant relationship with
optical sensors across cultivar. The optical sensors related better to N rate and RWST in
September/October across majority of cultivar, when fertilizer adjustments would no longer be possible,
making harvest date adjustments more viable to maximize profitable yield, based on sensor yield
predictions.

John MacFarlane (jmacfa04@uoguelph.ca)

S12. Simulating natural environmental cues redefines winter hardiness of Brachypodium distachyon
by connecting cold acclimation, vernalization, and development
1
1
2
Charron, J-B. ; B.F. Mayer ; A. Bertrand
1 McGill University
2 Agriculture and Agri-Food Canada
With the dawning of climate change, it has become relevant to understand how plants respond to
changing environmental conditions. Yet, temperate plants regularly face seasonal change and to persist in
these conditions, have adapted by adjusting their stress tolerance, phenology and development.
Understanding how temperate plants follow seasonal cues during their development can help elucidate
adaptation mechanisms in plants. Cold acclimation (CA) and vernalization (VRN) are processes that
ensure persistence in temperate climates by regulating freezing tolerance and flowering time. However,
how these two processes are integrated into a coordinated developmental response remains poorly
understood. The model grass Brachypodium distachyon has emerged as a model to study CA and VRN in
temperate cereals. By identifying key seasonal cues that occur within the native range of the species, we
designed a diurnal freezing treatment (DF) that combines prevailing summer-to-winter transition signals.
Under DF, B. distachyon manifests coordinated cold acclimation, vernalization and developmental
responses. Altogether, our results demonstrate a direct link between CA and VRN, and that typically used
constant-temperature cold treatments induce an “over-vernalized” molecular state at the expense of
freezing tolerance. This work also stresses the importance of reproducing natural signals in laboratory
conditions.

Jean-Benoit Charron (jean-benoit.charron@mcgill.ca)

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