Rémy Rageau

Walnut enzyme activity related with carbohydrate mobilization during dormancy period.

Juglans regia L. sprout depends on the carbohydrate mobilization from the parenchyma cells into the buds located in the upper portion of the twigs. The objective of this work was to contribute to the walnut tree sprout acrotony mechanism, in temperate climate, through the activity of alpha-amylase (EC 3.2.1.1), and Sucrose Phosphate Synthase (SPS - EC 2.4.1.14) mensuration, related to carbohydrate mobilization, during the dormancy period. From September to March, five one-year-old twigs were monthly sampled around. In April, close to budbreak, three samples were accomplished. The twigs were divided in apical, sub-apical, and base, and separated in bark, buds and wood (xylem). The average time of bud break in controlled conditions (25oC), water content, and activity of the above mentioned enzymes were determined. The results showed that the sprout gradient develops itself during ecodormancy period, and it is related with the alpha-amylase activity; the relationship of the SPS activity with this gradient is not evident.

Evolução do estado fisiológico da parte aérea do morangueiro durante a armazenagem em câmara frigorífica

The aim of this work was to know the physiological state of the aerial part of strawberry plants (varieties Gariguette and Elsanta) during storage in cold chamber (-2oC) from January until August. According to the biological test (petiole test), the growth capacity was kept up without significant evolution. The flow of metabolic heating (Q) and the respiratory intensity (RCO2) of the apical zone tissues measured at the exit of the cold chamber did not change significantly. Their values measured after 48 and 72 hours of acclimatization at 20oC were higher than at the exit of the cold chamber. The differences between the values without acclimatization and after acclimatization increased during the first weeks of storage, showing an evolution in the apex of the plant. There was a strict parallelism between the values of Q and RCO2 and of the tissues water contents (UP). The growth capacity of the aerial part of the plants seemed to keep up even after 8 months of storage.