Exploring the Yield Potential of Spring Canola - Border Effects in a Controlled Environment Study.

Investigating the upper limits of crop yield potential in controlled environment experiments requires accurate simulation of the canopy light environment by accounting for border effects.  We conducted a greenhouse experiment to determine the width of unharvested border required to measure true yield potential in hybrid spring canola.  Plants were grown five per pot, with 64 24-cm pots arranged in an 8 x 8 grid (plant density = 87 m^-2).  The seed yield in the absence of border effects was 6.2 Mg ha^-1, or about twice a typical field yield.  Pots on the outer edge of the grid yielded 40% higher than this; the increase was attributable entirely to increased seed yield on branch racemes, as main racemes were unaffected.  The increased yield on branches was due to the increased branch number and associated increased pod number, not seeds per pod or seed size.  A buffer 0.48 m (two pots) wide was sufficient to fully eliminate border effects.