CARBOHYDRATE LEVELS, PEROXIDASE ACTIVITY AND VASCULAR CONNECTION IN TISSUES OF PEACH TREES (PRUNUS PERSICA L. BATSCH) CV. JUBILEU WITH PEACH TREE SHORT LIFE (PTSL) SYMPTOMS DURING THE DORMANCY PERIOD
The objective of this study was to determine the levels of starch and soluble sugars in bud tissues, peroxidase activity, and vascular connections in twigs of peach trees (Prunus persica (L.) Batsch) cv. Jubileu with or without Peach Tree Short Life (PTSL) symptoms during the dormancy period in 2003. Samples were taken from plants grown in Pelotas-RS on the following dates: (06/11, 07/11, 07/29, and 08/05; month/date). The peroxidase activity (UE min.-1 g-1 MF) was determined according to the procedure described by Campos and Silveira (2003), whereas the starch percentage (%) were measured according to the procedure by McCready et al. (1950), and the total soluble sugars were measured according to an adaptation of the method described by Rakngan (1995). Bud vascular connections were evaluated at two dates (07/11 and 07/21) following an adaptation of the Bartolini and Giorgelli (1994) method. In carbohydrate dynamic study, two experiments were carried out in two orchards, based on a factorial arrangement AxB where factor A was collecting date and factor B was kind of tissues. For the peroxidase activity studies, sample twigs materials were collected from both orchards based on a factorial arrangement AxB where factor A was collecting date and factor B was orchard. The break out of PTSL syndrome increased the plant energetic demand intensifying the starch degradation in order to supply glucose and energy to the buds during resumption of growth and to protect tissue against low temperatures. The high peroxidase activity in the twigs of plants with PTSL symptoms during dormancy may be attributed to cold tolerance due to oxidative stress reduction caused by low temperatures. The continuous and well-defined vascular connection in the twigs of plants without PTSL symptoms made possible an adequate transport of water, nutrients and reserves to supply the normal growth and development of the buds during the final stage of floral bud differentiation. On the contrary, the twigs from plants with PTSL symptoms had an irregular distribution of the dye throughout the vascular bundles and an intense darkening in the wood tissue.
Marafon, A.C., Bacarin, M.A., Herter, F.G. and Rodrigus, A.C. (2008). CARBOHYDRATE LEVELS, PEROXIDASE ACTIVITY AND VASCULAR CONNECTION IN TISSUES OF PEACH TREES (PRUNUS PERSICA L. BATSCH) CV. JUBILEU WITH PEACH TREE SHORT LIFE (PTSL) SYMPTOMS DURING THE DORMANCY PERIOD. Acta Hortic. 774, 397-402
starch, soluble sugars, peroxidase, vascular connection, peach tree short life