Effect of Different Temperature Conditions during Early Seedling Stage on Hypocotyl Length and Rooting Ability in Kale

Abstract

In a plug seedling nursery, seedlings are raised densely in a plug seedlings tray. Thus, seedlings may show spindly growth since the cells are dense under high temperature and high humidity conditions. Kale tends to show hypocotyl elongation, it is important to control this elongation for good-quality seedlings, and the result is directly related to the yield. Therefore, in order to clarify the influence of the nursery temperature on the production of good-quality seedlings of Kale, the hypocotyl length and root viability of seedlings were investigated. It was revealed that the hypocotyl length of kale is influenced by temperature, and a high temperature from 4 days after sowing makes it easier to elongate the hypocotyls. Therefore, when treated for 4 days from 4 to 7 days after sowing, the elongation of hypocotyls was suppressed at a low temperature of about 15°C, but rooting 9 days after planting was improved. This temperature condition had a noticeable effect in the photoperiod, and the high temperature in the photoperiod made it easier to extend the hypocotyls. Moreover, since the root weight did not increase even when treated at a low temperature, it was considered that the improved rooting was due to the increase of root activity. Thus, temperature control in the daytime during the 4 days from the 4th day after sowing may promote good-quality seedling production in kale nurseries.