EFFECT OF BEES-POLLINATORS IN BUCKWHEAT (Fagopyrum esculentum Moench) CROPS

The aim of the present study was to investigate the effects of bee pollination of buckwheat crops on the seed productivity and plant development. Six plots each 4 m2 in size were arranged in a buckwheat field. Four plots in the field were isolated by a net. Nucs with bees were placed in two of the plots (one per plot). Plant productivity, height of plants and number of branches per marked plant were measured. The plants attractive to insects were identified by counting all insects present in blossoms in an area of 100 m in length and 1 m in width. The tests conducted at the Lithuanian Institute of Agriculture during 1999-2001 showed that bees and other insect pollinators affect not only seed productivity but also development of plants. The plants visited by pollinators were shorter in height than the plants grown in the isolated plots. The insufficiently pollinated plants had 16.8-19.6% more side branches. The length of flowering period of the plants visited by pollinators was 10.0-16.5% shorter. The nectar production of buckwheat depends on the weather conditions rather than on plant density. The tested plants secreted in average 89.8 kg/ha of nectar (from 10.9-160.2 kg/ha), which is 36.1 kg/ha biological sugar. Bees were the main pollinators, they accounted for 81% of all insect-pollinators. The honeybees in wet periods did not fly but bumblebees visited blossoms even in bad weather. The buckwheat plants intensively visited by pollinators produced 21.7-41.4% higher seed yield compared with the seed yield obtained in isolated areas.