Influence of Shade Treatment on Plant Growth Characteristics and Spear Production in Five Asparagus (Asparagus officinalis L.) Cultivars

Abstract

The objective of this study was to investigate the influence of a shade treatment on plant growth characteristics, bud break, and spear number of five asparagus (Asparagus officinalis L.) cultivars (Apollo, Atlas, Grande, UC157, and Walker Deluxe) and determine the most appropriate cultivar for cultivation in a shaded rain-shelter house. For the experiment, two-month-old seedlings were grown in the rain-shelter house with 30% shade using polyethylene film on the roof of the rain-shelter house, whereas the control plants were grown in a rain-shelter house without the additional layer of polyethylene. The shade treatment significantly increased the plant height, shoot number, shoot number per week, and bud number, but did not affect the mean number of days to bud break. The number of spears on asparagus grown in the shade was significantly higher than in the control. Under the shade treatment, Walker Deluxe and UC157 showed significantly higher shoot number and shoot number per week than the other cultivars. Compared to other cultivars, Walker Deluxe produced the highest bud number. In the control condition, Grande produced a higher number of shoots, shoots per week, buds, and roots than in the shade treatment. However, the shade treatment increased the ratio of spear numbers to bud numbers of Grande, resulting in a higher number of spears. Walker Deluxe with shade treatment had higher shoots, shoots per week, buds, roots, and spears than the control. These results suggest that Grande is more suited for growth in a rain-shelter house without shade treatment but that Walker Deluxe is more appropriate for cultivating in a rain-shelter house with 30% shade.문초록