Tree vigour, occurrence of mildew and scab, yields, yield efficiency, fruit weight, flesh firmness and soluble solids content of apple trees on M 9 rootstock were monitored between 1998-2005 in 42 commercial orchards situated in all the major growing regions of the Czech Republic. Altogether 50 cultivars were included into the evaluation. The characteristics of newly bred or newly introduced cultivars were compared to the cultivars of standard assortment such as Gloster, Golden Delicious, Idared, Jonagold, Melrose, Rubín and Šampion. The group of late ripening cultivars imported from France (Baujade, Early Smith, Granny Smith and Red Winter) proved to be unsuitable for climatic conditions of the Czech Republic. Cultivars of the Rubín group (Bohemia, Gold Bohemia) showed a better quality of fruits than the cultivars of the Jonagold group, but were significantly inferior regarding yields and yield efficiency. The cultivars Rucla, Pinova and Rubinstep seemed to be potential competitors of Jonagold or Rubín; their fruit quality is similar to Rubín, and their yield efficiency is comparable to that of Jonagold. Topaz, which is resistant to scab and has recently spread in the Czech Republic, is specific for its early yield and a very good productivity observed in a majority of the orchards. In addition, characteristics of other evaluated cultivars and their potential prospects for growing in the Czech Republic are briefly discussed.

Changes in fruit weight, firmness and soluble solids content during the ripening period of Karešova cv. including relationships between these characteristics were studied in 1998-2001. These years differed from each other in the amount and distribution of rainfall and in the course of temperatures. The length of ripening period fluctuated from 14 to 21 days. An increase in average fruit weight during the ripening period was 0.1 g per day. The actual increase in fruit weight was in a close correlation with the amount of rainfall in a few previous days. After heavy rainfalls, above 40 mm, fruit weight increased by nearly 1 g within in a few days. In the course of the ripening period fruit firmness decreased from about 2.5 N at the beginning of the period to about 1.5 N at its end. This decrease seems to be mainly the function of time during ripening. However, a low correlation between the amount of rainfall in the previous days and the decrease in firmness was also found. This correlation could be connected with negative regression of fruit firmness on the weight of the fruit. In the more rainy years 1998 and 1999 these decreases in firmness were more significant than in the other two years. Soluble solids content (SSC) increased from about 12% Brix at the beginning of the period to about 16% at its end. There were also found positive correlations between the weight of fruits and SSC. Taking into account contributions of all studied factors and their changes a conclusion was drawn that Karešova cv. should be harvested within one week from the beginning of its ripening period.

Several series of dwarfing rootstocks were bred in research institutes and universities all over the world in the 1960s and 1970s. These series were reviewed by Bujdosó and Hrotkó (2005). Since 1994 international cherry rootstock trials in Europe were co-ordinated by the Danish Institute of Plant and Soil Science at Aarslev, Denmark. The Research and Breeding Institute of Pomology Holovousy Ltd. has jointed these trials as one of their partners and established an experimental orchard with a range of selected cherry rootstocks in the spring of 1999 using nursery stock material that had been propagated in Aarslev. Preliminary results from the orchard study based upon the first five years of observations have been previously published (Blažková, Hlušičková 2004). This paper deals with more comprehensive results that include a stage of the full cropping of the orchard. Material aND MethoDsFor this study, ten sweet cherry rootstocks (G 154/7, G 195/20, G 497/8, Gisela 3, Gisela 4, Gisela 7, P-HL-A, Tabel Edabriz, Weiroot 158 and Weiroot 53) were used. P-HL-A was considered as a standard (control) for all the others. As a scion cultivar Lapins (of Canadian origin) was used for all these rootstocks. For five of them, the cultivar Regina from Germany was grafted as another tester. Nursery stock of the material was grown from bench-grafted rootstocks at the Danish Institute of Plant and Soil Science at Aarslev, Denmark. It mostly consisted of two-yearold trees without ramification.The experimental orchard was established in the spring of 1999 at Holovousy. Trees were planted in three randomised blocks with three trees per each Lapins cv. -rootstock replication using a spacing of 5 × 1.5 m. In the case of Regina, only one tree per replication was planted on each tested rootstock. Climatic conditions at Holovousy are characterised by the average annual temperature of 8.1°C and the average annual rainfall of 650 mm. The soil was medium loam sandy with a rather deep cultivated layer on gravel substrate. The orchard was located at the altitude of 280 m a.s.l. and it was situated on a very gentle slope facing north. Ten clonal dwarf or semi-dwarf rootstocks were evaluated in a trial that was established in the spring of 1999 at Holovousy. Lapins cv. was used as a scion tester for all these rootstocks; five of them were tested also by Regina cv. Among the new rootstocks G 195/5 was evaluated as the most promising for Lapins cv. The highest rate of mortality and symptoms of poor scion compatibility with Lapins cv. were observed on Weiroot 53 and Weiroot 158. The most vigorous of the tested rootstock was G 497/8 followed by Gisela 7 and Gisela 4. Intermediate vigour was recorded on trees on G 154/7, P-HL-A, Gisela 3 and Tabel Edabriz. The least vigorous were G 195/20, Weiroot 158 and Weiroot 53. The highest accumulated yield per hectare of the Lapins cv. (21.2 tons) was harvested from Gisela 7 rootstock. With Lapins cv. higher yield efficiencies were calculated for P-HL-A, G 195/20 and Tabel Edabriz. In the case of the Regina cv...

Blažková J., Drahošová H., Hlušičková I., 2010. Tree vigour, cropping, and phenology of sweet cherries in two systems of tree training on dwarf rootstocks. Hort. Sci. (Prague), 37: 127-138.Five cultivars and four rootstocks (Gisela 5, P-HL-A, P-HL-B, and Tabel Edabriz) were evaluated on trees in fruiting stage trained like spindle and on trellis. Tree vigour was significantly related to cultivar, rootstock and to tree training. Spindles were generally more vigorous than trees on trellis with exception of cv. Kordia. In several cases special combinations of cultivar, rootstock, and method of tree training differed significantly from mean effects of the three factors. Time of flowering was significantly dependent on the cultivar and varied annually within 15 days. Time of fruit harvest was also influenced by the rootstock and in two cases mutually contradictory to the tree training method. Yields per tree were generally dependent on the cultivar. With Burlat and cv. Kordia rootstock and tree training were also important. Higher specific yields were recorded on trellis-trained trees. Remarkable in this respect were Vanda and trees of Summit on P-HL-B and Starking Hardy Giant on Tabel Edabriz. Higher specific yields on spindle had Kordia on P-HL-A and Tabel Edabriz and Burlat on P-HL-A. Mean values of annual yields per hectare in spindle ranged between 10.0 to 17.5 t whereas in trellis between 6.7 to 12.3 t. The absolute highest annual yield (35.7 t) was recorded on spindle trees of Kordia on P-HL-A. In trellis the highest yield of 27.1 t had Kordia on Gisela 5. The advantage of spindle over trellis was greater in Burlat and Kordia but much lower in cv. Vanda. Fruit size mainly depended on the year. Only two rootstocks influenced fruit size differently in some years. Training system had no effect on fruit size.

Fifteen sweet cherry cultivars and three rootstocks were evaluated within three years in two experimental orchards established in the same location in the autumn 2004. In one of them drip irrigation was applied in the periods of insufficient rainfall, i.e. from mid-April to mid-August. This irrigation distinctly increased the vigour of trees that was jointly expressed by trunk-cross-section area, total length of shoots and canopy volume. An increase of tree vigour was the greatest in trees on Mazzard, medium on P-HL-C and the lowest on Gisela 5 rootstocks. The trees on P-HL-C that grew without irrigation similarly as the trees on Gisela 5 grew significantly more vigorously when irrigation was applied. Considerable differences in the response to irrigation were also found among cultivars; it increased the vigour of Halka, Sylvana, Aranka and Burlat more distinctly, whereas the least response to irrigation was recorded in the Horka, Jacinta and Justyna cultivars. The vigour of Regina, Tim and Vanda cultivars grown on P-HL-C rootstock was more extensively increased by irrigation than if they grew on Gisela 5. Flower and fruit sets of irrigated trees were with a few exceptions significantly lower than those of trees without irrigation. Tamara, Sandra and Regina were the most vigorous cultivars in this study, whereas Tim and Skeena had the weakest tree growth. Practical aspects of these findings are briefly discussed.