Root-zone cooling affects growth and development of paprika transplants grown in rockwool cubes

Abstract

The possibility of improving the efficiency of transplant production during a summer season was studied by applying partial cooling of the root-zone during the cultivation of paprika transplants in a greenhouse. Paprika seedlings produced in a closed transplant production system were transferred to rockwool cubes, and cool-water circulation systems using plastic and stainless pipes were tested in a greenhouse during a summer season. The root-zone temperature of rockwool cubes and growth and development of paprika transplants as affected by root-zone cooling were investigated. When plastic pipes were used, the cooling efficacy by circulation of cool water (17A degrees C) was the greatest and the temperature of rockwool cubes decreased by 3.6A degrees C during the day time on a sunny day. Partial cooling of the root-zone enhanced root growth and increased number of flowers as compared with the transplants grown on uncooled rockwool cubes. The results indicate that partial cooling of the root-zone can alleviate damages to transplants commonly caused under high air temperature conditions, which could efficiently improve the paprika transplant production efficiency in greenhouses during the summer season.