Polinização em amoreira-preta (Rubus sp.), mirtilo (Vaccinium ashei) e ameixeirajaponesa (Prunus salicina)

Abstract

Temperate fruit species have a great economic and social importance for the South and Southeast region of Brazil. Among the several fruit species which can be produced in these regions, some were recently introduced in the country and others had a limited expansion. Blueberry (Vaccinium ashei Read) is part of the first group whereas japanese plums (Prunus salicina L.) and blackberries (Rubus spp), are examples of the last case. Pollination and fertilization process is, perhaps, the most important in the production system, since yield is directly dependent of it. The objectives of the this work were: verifying the need of cross pollination of a few blackberry and plum genotypes; to observe the main pollinizers for blueberries and blackberries, under the climatic conditions of Rio Grande do Sul State and to observe a possible influence of the pollen on fruit quality. Seven experiments were conducted, during the year of 2007, under field conditions, using plants of the Embrapa Clima Temperado collections of plums, blackberries and blueberries. Another experiment was carried out under greenhouse conditions with potted plants of blueberry cultivars. Four blackberry selections and three selections and one cultivar of plum were tested for degree of self-fertilization, bagging production branches, before flower anthesis. Potential pollinizers were observed for both species as well as possible pollinators of the studied plum genotypes. Observations were made on blueberry pollinizers. Controlled crosses of two blueberry selections and two cultivars were done with the aim of measuring possible effects of pollen on fruit quality. Under the conditions tested, the blackberry selections 6/96, 16/96 and 6/2001 were selfertiles whereas 4/96 needed cross pollination. The most frequent insects observed on the blackberry flowers and potential pollinizers were honeybees, Apis mellifera. The cv Gulf Ruby does not produce when isolated from others and cv. Gulf Blaze is a good pollinator for it. Plum selections 1, 17 and 21 had a reasonable degree of fruit set, by self pollination. However, it is believed that it can be improved by the use of a pollinator.Laboratory tests showed that Selection 21 can pollinate Pluma 7 and cv Rosa Mineira can be a pollinator for Selection 17. The cv. America is not a good pollinator for Selection 19. Honeybees are good for pollen transportation in plum orchard. In both species, blueberry and plums, the pollen source influenced in size and soluble solids. Bumble bees (Bombus sp) are the most effective pollinizers for blueberries and the complement the honeybees activities. Trigona spinipes cause damage to blueberry flowers and also to the set.