Evaluation of Pear Rootstocks for the Cultivar ‘Suvenirs’ in the Baltic Region

In 2001, investigations were carried out on the Latvian origin cultivar ‘Suvenîrs’ grafted on seven pear rootstocks (MA, MC, BA29, Pyrodwarf, Brokmal, Kirchensaller Mostbirne and Kazrauðu bumbiere) in Polli (Estonia), Pûre (Latvia) and Babtai (Lithuania). The aim of the investigation was to evaluate pear rootstocks in different climatic conditions in the Baltic region. In Polli, all trees were planted in a dense planting, and therefore, trunk cross section area did not differ significantly between trees on different rootstocks. The most vigorous tree habit was observed in Lithuania for trees grafted on the rootstocks Kirchensaller Mostbirne and Brokmal, but in Latvia on Kirchensaller Mostbirne and Kazrauðu bumbiere. The highest dwarfing effect was observed for rootstock MC in both places. The highest cumulative yield from the orchard area was found for trees grafted on rootstocks of the quince group in all three locations of investigation. Nevertheless, the winter hardiness of the quince group rootstocks was not sufficient for Baltic climatic conditions. Good overwintering in Latvia and Lithuania was observed for trees on Pyrodwarf. Survival rate of trees grafted on Pyrodwarf in Estonia was unsatisfactory. The worse overwintering in Lithuania was observed for trees grafted on Brokmal. There was a dwarfing effect on trees and better yield on the vegetative propagated rootstocks included in the investigation, but none one of them can be recommended as perspective for commercial orchards in Baltic agro-climatic conditions. Bumbieru potcelmu izmēģinājums sākts 2001. gadā, kad Latvijas selekcijas šķirne ‘Suvenīrs’ uz septiņiem potcelmiem iestādīts Polli (Igaunija), Pūrē (Latvija) un Babtai (Lietuva). Pētījuma mērķis bija novērtēt potcelmus (QA, QC, BA29, Pyrodwarf, Brokmal (OHxF333), Kirschentaler Mostbime un Kazrausu bumbiere) iespējami plašākā teritorijā. Igaunijā visi potcelmi stādīti blīvā stādījumā, tāpēc koku stumbra šķērsgriezuma laukums starp potcelmiem būtiski neatšķīrās. Lietuvā spēcīgāks veģetatīvais augums konstatēts kokiem uz potcelma Kirschentaler Mostbime un Brokmal, bet Latvijā - uz Kirschentaler Mostbime and Kazraušu bumbieres. Abās vietās koku veģetatīvo augumu visvairāk ierobežoja potcelms QC- Visās izmēģinājuma vietās augstākā kumulatīvā raža no dārza platības bija kokiem uz cidoniju grupas potcelmiem. Tomēr šo potcelmu ziemcietība Baltijas apstākļos nav pietiekoša. Labāks koku izdzīvošanas vērtējums Latvijā bija potcelmiem Pyrodwarf un Brok