Testing of triploid poplar hybrids in Voronezh region

The paper presents new data on 28-30-year-olds testing of triploid poplar hybrids (2n = 3x = 57), obtained using in hybridization artificially obtained unreduced diploid (2n) pollen (induced by high temperature or colchicines treatment) in Voronezh region. The growth dynamics, preservation and timber productivity of 26 triploid and diploid (2n = 2x = 38) clones of Populus alba L., P. balsamifera L., P. nigra L. and intersectional hybrids (Populus deltoides Marsh. × P. balsamifera L.) were studied. It was revealed that a preservation of triploid hybrids of white poplar at 28-year-old age was higher than diploid hybrids. The greatest loss of plants of white poplar was observed during the first three years after planting of cutting seedlings in the nursery. In comparison, major loss of plants of P. balsamifera L., P. nigra L. and intersectional hybrids (P. deltoides Marsh. × P. balsamifera L.) was observed after the 2010 drought. Especially high plant mortality was observed in P. balsamifera clone (preservation of 40 %) and to a lesser extent in poplar «Robusta-236» (preservation of 60 %). There were no statistically significant differences in growth between groups of diploid and triploid white poplar clones. Only part of the artificially produced autotriploid hybrids (40 %) were characterized by fast growth and productivity. It is suggested that the heterosis effect in triploids associated with participation of high heterozygous 2n gametes in hybridization. Such were formed on the basis of a synapsis of chromosomes and loss of the I-st meiotic division. Six best triploid and diploid poplar hybrids have been selected as promising for Voronezh region