Information concerning the blooming time of stone fruit varieties is, first of all, an important condition of finding suitable pollinisers securing adequate fruit set. For that purpose, varieties are assigned to blooming-time-groups. Depending on the number (3 or 5) of the groups, i.e. the length of intervals separating the groups established,...pollenisers are to be chosen for self-incompatible and partially self-fertile varieties belonging to the same blooming-time-group. The mutually most overlapping blooming periods of the respective varieties should be found by raising data of their blooming phenology, i.e. dynamics, which is compared by drawing their phenograms and calculating blooming (V) indices. Variety combinations have to be checked, however, concerning mutual fertility relations of the respective pairs of varieties. That is most important in the case of Japanese plums because of the abundant incompatible combinations. Synchronous blooming has been determined by assigning the varieties to blooming-time-groups, or comparing overlaps of blooming phenograms, or by blooming (V) indices. Synchronous blooming phenology has been studied in European plum varieties (111 varietiy combinations) Japanese plums (156 variety combinations) and apricots (153 variety combinations) under Hungarian conditions, over several seasons. In determining overlaps, the less favourable season has been considered as decisive. Polliniser combinations have been chosen with at least 70% synchronous blooming. Blooming time of varieties is an important part of the variety descriptions. Blooming dates may serve also for the estimations of frost risk or security of yield.
Apricot yields are highly variable according to the season. The variation is caused mainly by the adversities during the critical processes of floral biology, i.e. blooming and fertilisation. On the basis of information concerning blooming time and mutual compatibility relations of apricot varieties a system of securing regular and adequate yie...lds has been developed.
Winter frosts of the continental type are well tolerated by most of the apricots, however, after the end of rest period, flower buds are loosing frost tolerance, 'rapidly.
Being one of the fruit species blooming earliest during the early spring, apricot start to bloom in Hungary around the end of March or early April as a mean of many years, but it also happened, exceptionally that apricot started to bloom at February 20 (at Letenye South Hungary). The early season, exposes the floral organs to frost injuries. As a consequence, apricot orchards on the Great Plain produce low yields in 3 years, intermediate yields in other 3 years out of a ten-year-period.
Moreover, weather conditions during the blooming period are often unfavourable for pollination. Cool, windy and rainy weather prevents the flight of insects and on the other hand, warm spells shorten the blooming process, nectarines and stigmata get dry and the female gametes loose viability before effective pollination occurres.
The fertility of individual cultivars are meeting different obstacles. Apricot cultivars differ greatly in the rate of flowers bearing underdeveloped pistils, which may attain even 60% (e.g. Orangered). New commercial cultivars are often self-incompatible. Local varieties of that type in Hungary are the „óriás" varieties (e.g. Ceglédi óriás, Szegedi mammut), and the new hybrid Ceglédi Piroska. Many of the cultivars are variable in their self-fertility (partially self-fertile): Budapest, Harmat, Korai piros, Mandulakajszi.
Inter-incompatibility is also known in apricots. The „óriás " varieties do not fertilise each other. During the growth of fruits, cool spells (2-4 °C) caused severe fruit shed in Ceglédi óriás.
Apricot flowers produce pollen and nectar at average rates related to other fruit species, thus bees are attracted sufficiently. Bee visits are very variable according to growing site and season. Most of the bees are pollen gatherers but sometimes nectar suckers are in majority. Bee pollination is necessary not only for the self-incompatible varieties but also to enhance the yield of self-fertile varieties.
Taking the blooming and fertility relations of the cultivars into account, plantations should not exceed two rows to a particular self-incompatible varieties, and possibly two different polliniser varieties are suggested to be planted as flanking the block in question.
In commercial plantations 2 to 4 bee colonies per hectare are proposed to move for the whole blooming period.
In the small demonstration orchard of the College Faculty of Horticulture at Kecskemét the blooming time, the flower density and the honeybee activity was observed at a number of cultivars of 20 flower species during four consecutive years.
Fruit crop species were in flower during 3-4 months altogether. The blooming period of them was...classified into five groups as early (almond, apricot, gooseberry), middle early (sweet cherry, red currant, currant-gooseberry, black currant, white currant, peach, plum, sour cherry), middle late (pear, strawberry, apple), late (black elder, quince, medlar, raspberry, blackberry-raspberry) and very late blooming period (blackberry). The blooming period of the members of the groups of early and medium early blooming often coincided partly and the same happened between the medium and the medium late as well as between fruits of late and very late flowering.
The flower density of some fruit species is extremely variable (currant-gooseberry, medlar), while at others it is fairly stable and evenly dense in consecutive years (sour cherry, sweet cherry, strawberry). At other fruit species it is moderately changeable. Some fruit species tended to attract more honeybees than others (plum, apple, quince, medlar) and some of them tended to attract much less (black elder, pear) but most species can be regarded as of medium attractivity.
On the flowers of some fruit species (pear, strawberry, quince) honeybees gathered pollen predominantly. At most fruit species however pollen and nectar gathering behaviour seemed to be gradually changing during the season. Namely most honeybees tended to gather pollen at the flowers of the early blooming fruit species, but on the other hand typical foraging behaviour gradually shifted to nectar gathering at the flowers of fruit species of moderate and late blooming periods.
Literature dealing with flowering and fertilisation of quince is scarce. Most controversial and scanty are informations on observations of self- and cross-pollination. According to our observations, differences in blooming time are few (2-3) days only, thus flowering of most varieties is synchronous. The varieties observed are grouped as early,... intermediate and late flowering ones. Self fertility of the individual varieties, however, was not assessed unequivocally, therefore it is recommended, by safety reasons, to consider quince actually as a whole to be auto-incompatible. Artificial self-pollination (or rather geitonogamy) as well as cross pollination with other varieties increased substantially fruit set if compared with the results of natural self-pollination (autogamy). According to the fruit set of their open pollinated flowers, varieties have been classified according to fertility as low (below 10 %), medium (between 10 and 20 %) and high (more than 20 %). Cross fertility of varieties is highly variable depending on combination and on season. Contradictory data are probably due to the sensitivity of quince to conditions of search. Better fruit set was coincident with higher number of stout seeds per fruit. Well developed seeds are definitely a prerequisite of larger fruit size.
Earlier studies concerning self-, free- and cross- fertilization of apricot varieties grown in Hungary, proved the existence of self-sterile as well as self-fertile varieties within the recommended assortment. The self-sterile and partially self-fertile varieties should be planted in association with polliniser varieties, only. The present pape...r reports about the yields of trees of the widely grown, self-sterile local variety, Ceglédi óriás (Giant of Cegléd), depending on the distance of adequate polliniser trees. In the univarietal, 27 row-wide block of the relevant variety, an efficient polliniser, Magyar kajszi was planted to the 10th and 19th row. In the close vicinity, another block of polliniser, Rózsakajszi C. 320 was located. The number of fruits set per tree has been counted or estimated in two consecutive years. In both seasons, the yield of the Ceglédi óriás trees diminished with the growing distance from the nearest polliniser trees. Those trees in the center of the block, between the two (10th and 19th) rows of Magyar kajszi bore acceptable yield (40 kg/tree in 1987), however, considerable reduction of the number of the fruits set was stated already in the 4-5th row from the polliniser away. Similar gradient of fruit set was apparent in relation to the neighbouring block of Rózsakajszi C 320. The beneficial effect of the vicinity of polliniser varieties was obvious as far as the distance of the 10th row. Taking into consideration the self-sterility, the early blooming time and the poor fertilization of the variety Ceglédi óriás, a planting design of associating it with at least two polliniser varieties (e.g. Gönci magyar kajszi and Ceglédi bíbor) is highly recommended. On the basis also of earlier results, a proposal has been developed for the association of apricot varieties as recommendations for optimising yields. Blooming time, fertilizing potential, schedule of the picking season and market possibilities have to be considered simultaneously.