Responses to nitrogen conditioning in ‘Albion’ strawberry (Fragaria X ananassa Duch.) for off-season plasticulture production are primarily qualitative rather than quantitative

The nature (qualitative vs. quantitative) of growth responses to nitrogen during photoperiod conditioning of ‘Albion’ strawberry (Fragaria x ananassa Duch.) plants for late summer / early fall off-season field production was evaluated in New Jersey, USA. For two different planting dates (14 June and 6 July), plants were conditioned in the greenhouse under ND (natural daylength), LD (natural daylength supplemented with 24 h incandescent radiation (Phillips Duramax Soft White A19 60 W) or LD7W (natural daylength supplemented with 24 h incandescent radiation (C9, 7 W bulbs) followed by elevated nitrogen (800 ppm) for 0–4 weeks. Plants were then established in field plasticulture. Flowering in July was enhanced by LD conditioning; however, these effects did not persist and have an impact on plant productivity. Qualitative responses to N included crown branching, runner production, fruiting precocity and early season yield. Results confirm the previous observation that conditioning plants prior to off-season plasticulture production in the Northeast US is not necessary if plants are established in the field by early July. The LD7W light treatment was more effective than the LD light treatment in eliciting photoperiod responses especially when nitrogen levels were low. Thus, the lower wattage bulbs may be an effective tool for managing photoperiod responses for off-season production when needed (later planting dates) with this cultivar.