Growth and productivity of apple cultivars ‘Antei’, ‘Kovalenkovskoe’ and ‘Gita’ on rootstocks B.396 and M.9 in the conditions of Latvia

Belorussian apple cultivars are valued for their ecological plasticity and occupy an significant part (about 10 %) of new apple plantings in Latvia. This creates a necessity to find the most suitable rootstocks and growing techniques for them. In 2009 one-year whips of cultivars ‘Antei’, ‘Kovalenkovskoe’ and a new Latvian cultivar ‘Gita’ were planted on dwarf rootstocks B.396 and M.9 at distances 1 × 4 m, using a split-plot design and arranging the cultivars in a randomized way and rootstocks – in rows. The trees were trained as slender spindle. The cultivar ‘Antei’ showed significantly later start of bearing than the other two cultivars. In the following years ‘Gita’ had the highest yield in kg per tree and significantly stronger tree vigour. ‘Antei’ and ‘Gita’ had significantly higher yield per tree than ‘Kovalenkovskoe’. On the other side, ‘Kovalenkovskoe’ had the highest yield efficiency in kg cm-2 (TCSA), while ‘Antei’ – the lowest. Analysis of cultivar-rootstock combinations showed better production on rootstock B.396, but not in all cases. Fruit mass did not differ between rootstocks. Fruitlet thinning trials showed that ‘Gita’ has a tendency of self-thinning, while for ‘Antei’ thinning cannot be recommended in years of low or medium yield, as the high leaf surface relation to fruit number can result in poor over-colour and increases the risk of bitter pit. ‘Antei’ had high chlorophyll content in leaves of annual shoots.