Effects of lifting date and storage time on changes in carbohydrate content and photosynthetic efficiency in three deciduous species

Abstract

SummaryThe effect of lifting date and storage duration on the change in carbohydrate reserves during cold storage and the photosynthetic capacity after storage was examined in red-osier dogwood, common oak and silver birch of two genotypes ‘Asarum’ and ‘Halstenbeck’. Plants were grown at a ®eld site in southern Sweden and were lifted on two dates, 21 September and 30 November 1998. Plants were packed in closed plastic bags and kept in cold storage. Carbohydrate reserves were measured at lifting and after 8, 16 and 24 weeks of storage. Plants were removed from storage after 8, 12, 16, 20 and 24 weeks and were subsequently grown in a climate chamber. After four weeks, plants were assessed for mortality, die-back, growth and photosynthetic capacity, measured as chlorophyll fluorescence. Chlorophyll fluorescence indicated that lifting per se is a strong stress factor, as plants, independently of lifting date and storage duration, were stressed and had low photochemical efficiency in photosystem II. Further, the low efficiency was more pronounced in plants lifted early. Die-back appeared in early lifted plants of all species after 3–4 months of storage, except for silver birch ‘Asarum’. Carbohydrates in roots and shoots declined during storage in early lifted plants, but only in late lifted plants of roots and shoots of red-osier dogwood and shoots of common oak. Shoot growth decreased in early lifted red-osier dogwood plants, with longer storage. This study has shown that lifting date and storage duration are two strong stress factors, which have a detrimental effect on plant vitality, even if plants are stored in closed plastic bags.