Photosynthetic activity in leaves on laterals and top leaves on main shoots of Sila cultivar before grape harvest

Abstract

Photosynthesis takes place in all green parts of the grapevine plant, but it is most intensive in the leaves of main shoots and laterals. Importance of various strata and categories of leaves is still not quite clear, even to experts. With this in mind, an investigation was undertaken of photosynthetic activity in leaves of main shoots and laterals of a newly developed Serbian grape variety Sila, which was grown under the ecological conditions of Fruska Gora Mountain. An LCpro+ instrument was used to measure the rates of photosynthesis and transpiration in the top leaf of the main shoot, and in the third leaf from the base of the lateral, that developed in the axilla of that leaf. Measurements were made just before grape harvest, on intact control vines and the vines from which shoots that emerged from secondary and tertiary latent buds were removed in the spring and, later on, grape bunches were removed from laterals. The leaves on the laterals had a higher rate of photosynthesis than the leaves on the top of the main shoots (7.9 and 6.9 µmol CO2 × m-2 × s-1, respectively). The leaves on the laterals also had a higher transpiration rate than the leaves on the top of the main shoots (2.5 and 2.4 mmol H2Om -2 s-1, respectively). Key words: Grapevine, photosynthesis, lateral, main shoot.