EFFECTS OF PLUG SIZE, MYCORRHIZAE INOCULANT AND GROWTH PERIOD ON THE DEVELOPMENT OF WATERMELON TRANSPLANTS

Modern watermelon production is almost exclusively based on the use of transplants. Watermelon transplants are grown mostly in plug trays of various sizes and cell volumes. The aim of this research was to determine the optimal plug size, cultivation period and influence of arbuscular mycorrhizal fungi on the quality of watermelon transplants. The research was conducted in a heated plastic greenhouse during 2003 and 2004. A three factorial trial was set up as a randomized complete-block design with three replications. There were three plug sizes - 100 ml cells (plug tray with 40 cells), 80 ml cells (plug tray with 60 cells) and 60 ml cells (plug tray with 84 cells). The second factor, “mycorrhizae” included the substrate with or without inoculation with the arbuscular mycorrhizal fungus Glomus mosseae. Cultivation time was 30 and 45 days in 2003, and 40 and 55 days in 2004. In both years the best developed watermelon transplants (highest stem, greatest number of leaves, largest stem diameter, highest plant and root mass) were the ones planted in 100 ml cells. Differences between transplants grown in 60 and 80 ml cells were shown not significant. In 2004, inoculated transplants were better in all attributes compared to uninoculated ones. In both years transplants grown for 45 and 55 days were larger and had more leaves per plant, larger stem diameter, and greater plant and root mass compared to those grown for 30 and 45 days.