A. DAG, Y. KAMMER, H. EFRAT. Institute of Animal Science, Volcani Center, Agricultural Research Organization, Ministry of Agriculture and Rural Development ...
Apiacta 3, 2001
CHARACTERIZATION OF CITRUS HONEY FLOW IN ISRAEL A. DAG, Y. KAMMER, H. EFRAT Institute of Animal Science, Volcani Center, Agricultural Research Organization, Ministry of Agriculture and Rural Development P.O. Box 6, Bet Dagan 50250, ISRAEL Abstract Citrus is an important nectar source for the production of high quality honey. The present study characterized citrus honey production in Israel by daily weighing of the beehives. During the years 1995-2000, 8-13 beehives were weighed every morning during the citrus honey flow, at the same site. There was a significant correlation between the temperature and the weight increase. The highest average daily weight increase was 4.3 kg and the highest daily weight increase for a single beehive, was 6.5 kg. The average weight increase during the citrus honey flow was 39.4 kg and the highest total weight increase per beehive was 57.9 kg.
Introduction Citrus groves are the most important nectar source in Israel and in many apiaries, most of the honey is a citrus honey (DAG, 1996). Citrus honey is very popular because of its light color and its delicate taste. The blooming period of citrus lasts from the end of March till the end of April, a period when the weather conditions are not stable, ranging from very hot and dry days with an easterly wind from the desert (‘Khamsin’) to rainy and cloudy days that do not enable the bees to forage. There are wide variations among the various citrus cultivars, in the number of flowers per tree and the volume of nectar per flower, therefore there is wide variation among them in their potential for honey production. The number of flowers per mature tree ranges from 17,000 in grapefruit to 260,000 in ‘Washington’ orange (MONSELISE, 1985). Despite the fact that large volumes of nectar are produced - 57 µl in ‘Shamuti’ orange, 53 µl in grapefruit and 73 µl in ‘Valencia’ orange (HOCHBERG, 1994) - not all of it is available for the bees. This is due to the fact that the nectar is enclosed in a nectar chamber within the filament tube, which impedes the access of the bees to the nectar (ISHAM and EISIKOWITCH, 1999). The aim of the present study was to characterize citrus honey production in Israel by daily weighing of the beehives. Materials and methods At the beginning of March in each of the years 1995-2000, beehives in the Central Breeding Station in Zrifin (ARO) were placed on scales. The apiary is located in the central costal plain in Israel and surrounded by large citrus groves of several varieties. There are no significant spring nectar sources in the vicinity of the apiary, apart from the citrus. In 1995, six beehives were weighted, and in 1996, 1997, 1998, 1999 and 2000, the numbers of beehives weighted were 8, 13, 12, 12 and 11, respectively. The weight data were collected early morning before the time of bee activity. Since the population of brood and adult bees is stable in this season, the significant change in the weight of the beehive is mainly due to change in the weight of honey stored in it, therefore, it is indicative of the rate of honey flow. The beehives selected for the study were occupied by colonies typical of this season- mid- March- i.e. about 8 brood frames and 20 populated frames. Meteorological data were obtained from the Israel Meteorological Service’s station, located 5 km from the experimental site. Results and discussion Figure 1 presents the accumulated average weight during each of the six years of the study. It can be seen that the earliest start of flow was on 23rd March (in 1999) and the latest, on 13th April (1997). Year 1998 was unique: during the honey flow there was a series of seven consecutive days with very hot and dry weather, with midday temperature exceeding 34-39oC and relative humidity of 15-30% at mid-day. This warm event caused shortening of the blooming period in that year - only 19 days. In general it seems that an extended honey flow will lead to high accumulated weight of honey. The average sugar content of the citrus nectar is 32% and that of the honey is 81%, therefore to produce 1 l of honey (1.5 kg) 2.56 l of nectar is needed (HOCHBERG, 1994). At the end of the honey flow almost all the honey is sealed and ripe, therefore, the 6-year average total accumulated honey weight of 39.4
Apiacta 3, 2001
kg during the citrus honey flow (Table II) was the product of 101 l of citrus nectar. The highest average daily weight increase was 4.3 kg in 1999 and the highest daily weight increase for a single beehive, was 6.5 kg in 1997 (Table I). The average weight increase during the citrus honey flow was 39.4 kg (Table II). In general about 8 kg was stored in the broods chamber and was not harvested, hence an average of 31.4 kg was available for harvest. The effect of temperature on honey flow rate is presented in Figure 2. In this figure, the average daily weight increase data for all the years 1995-2000 are grouped together. The data from the first and last days of the honey flow in each years were not included, since on those days the main factor limiting the honey flow is the availability of open flowers. There was significant correlation between the temperature and the weight increase (R2 = 0.23, p
