PHYSIOLOGICAL ACTIVITY OF SOME BLUEBERRY VARIETIES IN PROTECTED AND OUTSIDE CONDITIONS

Abstract

Nowadays, blueberries are one of the most appreciated and fast increasing consumption worldwide. The industrial sector is ready to answer to the consumers’ expectations including all year round fresh fruits and better quality. In respect to this opportunity, we tried to find solutions to extend the harvest period of the Northern highbush blueberry. Three varieties were selected for the experiment: 'Bluetta’ as a very early cultivar, 'Coville’ for middle season and 'Elliott’ as late ripening cultivar. The containerized plants were placed in the spring of 2016 in a solar covered with three types of plastic films (yellow, diffused and clear) in order to emphasize the best coverage material for our purpose. As control, same number of plants/variety was settled down outdoor in the field conditions. To assess the particularities of growing and fructification of blueberry varieties under these circumstances, we have made several measurements of the main physiological processes as follows: photosynthetic rate, transpiration rate, respiration rate, stomatal conductance and internal carbon dioxide. The content of the chlorophyll and carotenoids was also evaluated according to the experimental model. The photosynthetic capacity of the blueberry plants in all of the phenological period swas decreased by the plastic film coverage. Plant’s respiration was more intense in June compared to July or September. 'Bluetta’ variety was highlighted by very fast growing plantsdue to a higher photosynthetic rate recorded. The yellow plastic film significantly decreased the content of chlorophyll a and carotenoids in the leaves of blueberry varieties. Indoor conditions and protective films anticipated the fruit maturation and delay the last harvest till end of the autumn proving as an efficient way to extend the harvest period of the blueberries.