Effect of plastic mulches on microclimate conditions, growth and yields of strawberry plants grown under high tunnels in Northern Canadian climate.

High tunnels are gaining in popularity in Canadian Northern climates to prolong the growing season, increase yields and improve the quality of fruits and vegetables. An experiment was conducted to determine the effects of various plastic mulches on microclimate conditions, growth and yields of day-neutral strawberry grown under high tunnels. High tunnels (8.4 m wide, 4.8 m high and 145 m long) developed by Industries Harnois (www.harnois.com) were installed at Les Fraises de l'Ile d'Orleans inc., near Quebec city, Canada (latitude 47, altitude 137 m). Each experimental unit, consisting of 26 strawberry plants cv. 'Seascape', was replicated four times. Six plastic mulches (white on black, black, green, grey on grey, grey on black and grey on brown) obtained from Ginegar Plastics Products Ltd. (www.ginegar.com) under the high tunnels were compared to an installed outdoor black mulch. Soil at a depth of 10 cm and air temperatures at a height of 20 cm were measured with Hobo temperature sensors obtained from MicroDaq Ltd. (www.microdaq.com). Plant growth was measured periodically, while yields were measured three times per week. Black mulch caused excessive soil and air temperatures in tunnels, but was found adequate outdoors. The best growth was obtained with green and white on black mulches under high tunnels. The highest yields were observed for green and white on black mulches under high tunnels. All mulches in the high tunnels produced higher yields than the outdoor black mulch.