Effects of supplemental root-zone pipe heating systems on the growth and development of strawberry plants in a greenhouse during the winter season

Abstract

ABSTRACT The effects of two types of supplemental root-zone pipe heating systems for strawberry (Fragaria × ananassa) cultivation in a conventionally heated greenhouse during the winter were compared. ‘Seolhyang’ strawberry transplants transplanted on coir grow bags were treated for crown-based heating (CBH) and root-based heating (RBH). The medium temperatures in the RBH system resulted in the longest daily retention time for the optimum root-zone temperature in February, March, and April. The RBH system resulted in the thickest crown diameter, heaviest fresh leaf and root weights, and greatest dry weight distribution in roots. The fruit yield had no significant difference according to the heating systems, except for slightly delayed flower development in the second flower clusters in the RBH system. Aspartic and glutamic acid contents in leaves decreased in the CBH and RBH systems, compared to control. The results indicate that the RBH system may promote the vegetative shoot and root growth of strawberry plants with stable root-zone temperatures, without negatively affecting fruit yield, which can support continuous fruit production in the long-term off-season winter cultivation.