Plug size and density during greenhouse conditioning do not affect late summer and early fall production of June-planted 'Albion' strawberry (Fragaria X ananassa Duch.) in the plasticulture system

The influences of plug size and plant density during conditioning of 'Albion' strawberry (Fragaria x ananassa Duch.) plants were evaluated for off-season field production in New Jersey, USA. Two plug densities (168 and 336 plants m−2, 75 cm3 cell volume) during conditioning in a greenhouse were evaluated. Conditioning consisted of 5 weeks under LD (natural daylength supplemented with 24 h incandescent radiation) with 100 ppm N the first week and 800 ppm N once each week during last 4 weeks. Controls were kept for 5 weeks under ND (natural daylength) with 100 ppm N once each week. Following conditioning, plants were evaluated in off-season plasticulture. Larger (134 cm3) plugs were conditioned at 168 plants m−2 to compare with the smaller cells (75 cm3) conditioned at the same density. Inflorescence, runner and branch crown production were monitored and fruit harvested from July through September. Conditioning accelerated flowering and fruiting. New inflorescence production in July was significantly enhanced with conditioning but treatment effects on flowering did not persist. Cumulative yield through early August was enhanced by conditioning however total yield was not affected by conditioning. Conditioning had no effect on branch crown production and significantly reduced runner production. Plug production at a higher density reduced flowering but the short day response was alleviated with conditioning. Smaller plugs flowered earlier, produced more inflorescences and produced fewer runners than plants from larger plugs. Plug size and density ultimately did not affect total yield regardless of treatment.