THE BEE FAMILIES USE AT SUN FLOWER POLLINATION

Valentina Cebotari, I. Buzu

Abstract
    The purpose of the work was to research various systems of bee families placement at the sunflower pollination, to distinguish the advantages of this crop conducted pollination, with the help of the bees and to develop some streamline suggestions to increase the amount of seed production.It was conducted an experiment to test three systems (scheme) of bee families exploitation at the pollination of early hybrid sunflower "El Passo 199" on three agricultural land of 30 hectares each, which were placed at a distance of over 600 - 1000 m from each other. The load of bee families at the pollination was 1 ha per each family. In the first scheme (batch I, witness) – the hives with bee families were placed traditionally in a hearth, at one side (edge) of the field with blooming plants. In the second scheme (batch II) – the bee hives were placed in two hearths at the two opposite sides of the field. In the third scheme (batch III) – the bee hives were placed in four hearths, proportionally at the four sides of the field.The research results have shown that the bee hives placement at the sunflower pollination, proportionally at those 4 symmetrically opposite sides of the field, provides a significant increase of bee visits to the flowers, compared to the witness batch – with 1.4 bees/ 5 min, or 82.5 % (td = 14.2; P < 0.001) and, compared to batch II - with 0.4 bees/ 5 min, or 14.8 % (td = 2.8; P < 0.01). By the total pollen amount collected in the nest daily, on average, bee families from batch II exceeded their fellows of witness batch with 25 g/day, or 16.8 % (td = 4.3; P < 0.001), and those of batch III exceeded their fellows of batch I - with 46 g, or 30.9 % (td = 5.9; P < 0.001). By flight intensity, the bees without pollen balls of batch III exceeded their fellows of witness batch with 46 bees/10 min, or 9.5 % (td = 2.1; P < 0.05), and those with pollen balls - with 35 bees/10 min, or 17.8 % (td = 3.1; P < 0.01). The seeds fertilization degree, in case of isolated pollination was very low, and was 13.1 - 15.8 %. In case of free pollination (entomophilous), contrary, the most sun flower inflorescence seeds were fertile (full), The number of fertile seeds, in this case, exceeded 5.7 - 7.2 times compared to the isolated pollination (P < 0.001). The seeds pollination degree, in case of free pollination, was 88.6 - 92.1 %. The seeds pollination degree from batch III, was higher, compared with witness batch - with 3.5 percentual units, or 4.0 % (td = 2.6; P < 0.01). The total weight of harvested seeds, on average, at one sun flower inflorescence, in case of entomophilous pollination, exceeds compared to the isolated pollination, in all batches and examined sectors 1.8 - 2.2 times more (P<0.001), and by fertile seed weight - 2.3 - 2.6 times (P < 0.001). By the quantity (weight) of fertile (full) seed production, sun flower inflorescences of batch II exceeded their fellows of batch I with 11.9 g, or 18.5 % (td = 5.6; P < 0.001), and the sun flower inflorescences of batch III exceeded their fellows of batch I with 16.1 g, or 23.8 % (td = 6.7; P<0.001). From the obtained information, were deduced the conclusions that the conducted pollination of early sunflower hybrid El Passo-199 with the help of the bees, provides, compared to the isolated pollination, an increase of seeds fertilization degree and of the seed production weight with 2.3 - 2.6 times. The proportional placement of the bee hives at the pollination, as close to the picking source, at the four opposite sides of the sunflower field, contributes to a significant increase of the bees visits frequency to the flowers - with 82.5 %, of the flight intensity of the bees without pollen balls - with 9.5% and of those with pollen balls - with 17.8 %, of the collected pollen amount - with 39.6 %, of the seeds fertilization degree - with 4.0%, and of the seeds production - with 23.8%.

Key words: pollination, conducted, sunflower, bees, systems, placement, hives