EVALUAREA UTILIZĂRII ALBINELOR LA POLENIZAREA RAPIȚEI

Abstract

The determination of the efficiency of rapeseed pollination with the help of bees represents the purpose of the current investigation. The researches were conducted in an apiary located near a rapeseed plantation and the following parameters were evaluated: 1) flight intensity of worker bees for nectar and pollen collection, 2) the number of bees, which visited rapeseed flowers, per 1 m2, 3) the mass of rapeseed seeds from plants pollinated by bees. The flight intensity of worker bees during the rapeseed flowering period (13.04.2024-09.05.2024) was studied for 3 consecutive minutes, recording the number of bees that returned from the field with nectar and pollen balls. Three lots of bee colonies were formed at the apiary, 5 in each. In lot I the strongest bee colonies were selected, in lot II – medium-strong colonies and in lot III – weak colonies. The recordings were carried out in the first half of the day at 1000 hours and at 1500hours. The flight intensity of bees varied according to the time of the light-day and the strength of the bee colony. The number of bees collecting pollen was lower compared to the bees collecting nectar. The maximum number of bees that collected pollen (124) and nectar (180) was recorded at 1500 hours (May 6, 2024). For recording flower visitation per 1 m2, three plots were marked on the cultivated rapeseed area: at a distance of 200 m; 800 m and 1500 m from the apiary. It was established that honey bees visited the flowers more frequently at a distance of 200 m where a total of 186 bees were recorded, at 800 m – 103 bees and at 1500 m – 32 bees. The efficiency of honey bee use for rapeseed pollination was assessed on the basis of the amount of seed yield. To determine the contribution of bees to increased seed yield, 5 plants from each plot were isolated at the beginning of flowering. At the beginning of rapeseed harvest, these plants (without pollination by bees) were removed manually from the respective plots. The seeds were collected and weighed, and their mass was compared with the mass of seeds from the pollinated plants. Due to pollination of rapeseed plants by bees, the mass of seeds per plant increased, on average, by 66% and per square meter by 65%. More efficient pollination of rapeseed can be achieved by placing the apiary with strong families near the nectar-pollen source, but not further than 1500 m.