Defoliation affects carbohydrate reserves, crown bud development, and spring re-growth in gentian 'Velvet Glove'

Gentians are herbaceous perennials that utilize preformed crown buds as part of their perennating structure. We used leaf removal at different times in the season to assess the importance of accumulating carbohydrate reserves for plant survival during winter and subsequent re-growth in spring. Defoliation of gentian 'Velvet Glove' during the growth season significantly influenced the development of crown buds, winter survival, re-growth in spring, and carbohydrate reserves in crowns (mainly because of reduction in gentianose and sucrose concentrations). Carbohydrate reserves stored in the storage roots of crowns were likely to influence the development of crown buds, winter survival and re-growth. Given the absence of starch in gentians, the predominant carbohydrate reserve in crowns, gentianose, may play a similar role to that of starch in other plant species. From the time of emergence, at least 2884 GDD (base 0 °C) retention of full leaf canopy on plants of 'Velvet Glove' was required for sufficient accumulation of carbohydrate reserves in crowns to result in similar winter survival and re-growth in spring, as with undefoliated control plants.