Abstract:

The aim of this study was to determine the appropriate transplanting time of the cucumber seedlings and provide scientific basis for practical use. ‘Jinyu 5’ was used as material to study the root physiological and biochemical characteristics in different growth stages, by the method of plug seedling culture. These characteristics included root morphology, the ratio of root/shoot, root vigor, activities of protective enzymes of root and root structure. The root system was classified into fine roots (<0.05 mm), middle roots (0.05-0.45 mm) and coarse roots (> 0.45 mm) according to root diameter. Compared to the seedlings with one and two leaves, the results showed that the root length and surface area with three leaves were longer and bigger for roots with different diameters. However, the ratio of fine roots with stronger absorbing capacity of seedlings with three leaves was lower than those of seedlings with one and two leaves while the ratio of middle roots was obviously higher than those of seedlings with one and two leaves. Additionally, compared with the other two treatments, for seedlings with three leaves, the fresh weight of seedlings increased, the ratio of root/shoot decreased, root activity reduced, while SOD and POD activities increased. The number of vessel tubes of seedlings with three leaves was increased but a single vessel diameter was decreased. In conclusion, the current study indicated that seedlings with one leaf had no significant difference from seedlings with two leaves, and both could be used for transplanting, while seedlings with three leaves were not suitable for transplanting due to over growth.