Optimization of in vitro micropropagation stage of pear varieties regionalized in Belarus

The objects of the study were 9 pear varieties regionalized in the Republic of Belarus including 8 varieties of Belarusian selection (Belorusskaya pozdnyaya, Viliya, Zaveya, Kupala, Prosto Maria, Spakusa, Yasachka ( P. communis × P. × ussuriensis ), Kudesnitsa ( P. communis × P. × pyrifolia )) and 1 introduced variety Talgarskaya krasavitsa ( P. communis × P. × pyrifolia ). Optimal nutrient media for pear propagation were determined: agarized DKW medium for varieties Kupala, Prosto Maria and Yasachka, and DKW and modified MS medium (the NH 4 NO 3 content was reduced to ¼) for varieties Spakusa, Talgarskaya krasavitsa, Belorusskaya pozdnyaya, and Kudesnitsa. The optimal concentration of 6-BA for propagation of pear varieties made 1.0 mg/l. Increasing the concentration of 6-BA to 2.0 mg/l allows increasing the number of shoots per explant, but reduces the height of the shoots (i. e. readiness for rooting) and results in narrow and unexpanded leaves with symptoms of vitrification. Stimulation of growth of axillary buds and increase in propagation coefficient of all studied pear varieties, maintaining the quality of the shoots, can be achieved by removing the apical bud and leaves of microshoots and placing them horizontally (shoot length 1.5–2 cm) on nutrient medium. The use of large-volume culture vessels (250–450 ml) has a positive effect on proliferation rate of pear varieties.