Soil Temperature Effects on Greenhouse Roses in Relation to Air Temperature and Nutrition1

Abstract

Abstract Plant growth and cut flower yield of ‘Sonora’ roses ( Rosa hybrida L.) were increased by soil heating to 25°C at 16° (day)/11° (night), a suboptimal air temperature, in a pot experiment in which differential temperature treatments were imposed immediately after planting. Soil heating at 20° (day)/16° (night) a near optimum air temperature, initially increased the growth rate and shortened the time to flower but growth and flower quality declined when a fertility level for winter production was used. Weak growth and chlorotic foliage on roses growing in heated soil were corrected by use of a higher level of nutrition. Higher air temperature caused earlier bud break after a major peak in flower production but subsequent shoot development was not greatly affected by air temperature. Soil heating increased the number of bottom breaks.