Effects of Shade Treatment on Plant Growth Characteristics, Phenolic Contents, and Antioxidant Activities of All-Male Cultivars of Asparagus (Asparagus officinalis L.)

This study examined the effects of 30% and 70% shading on the growth characteristics, phenolic content, and antioxidant activity of three male cultivars (Atticus, Avalim, and Herkolim) of asparagus grown in a rain-shelter house. The 70% shading treatment significantly increased the shoot elongation rate of all three male cultivars compared with the control and 30% shade treatments. Compared with the control treatment, 30% shading increased the shoot production rate and bud number of the Atticus and Avalim cultivars. Most of the plant growth characteristics of the Herkolim cultivar were not affected by the 30% shade treatment, except root diameter. Polyphenol contents in all three cultivars were significantly decreased under the 30% shade treatment compared with that in the plants under the control and 70% shade treatments. The Atticus cultivar had a higher polyphenol content than that in the Avalim and Herkolim cultivars under shade treatments. The flavonoid contents in Atticus and Avalim plants under the 30% shade treatment were lower than that in plants under the control treatment. Compared with the control treatment, the 30% shade treatment sig- nificantly decreased antioxidant enzyme activities such as superoxide dismutase, catalase, and peroxidase as well as the 2,2'-azino-bis3-ethylbenzothiazoline-6-sulphonic acid (ABTS) free-radical scavenging activity of Atticus and Herkolim. Under the 30% shade treatment, the polyphenol and flavonoid contents in the Atticus cultivar were significantly higher than those in the Avalim cultivar. The results suggest that the 30% shade treatment can be applied in the cultivation of the Atticus cultivar to improve spear production in the following season and minimize decreases in phenolic content. KCI Citation Count: 0