LEAF-SPOTTING DISEASES AS A MATTER OF DAMAGE OF ALFALFA BREEDING POPULATIONS IN AN EVIDENT MULTIFOLIATE PHASE IN DIFFERENT CYCLES OF PHENOTYPIC RECURRENT SELECTION

Abstract

Alfalfa (Medicago varia Mart.) is the most important forage crop for considerable amount of regions of the Russian Federation and throughout the entire world. Assessment of the stability and resistance of alfalfa varieties to a complex of leaf-spotting diseases under various environmental conditions is important for breeding programs as a tool for selecting the best varieties and breeding samples. In the course of a three-year experiment (2016-2018) there were tested the productivity and resistance to a complex of leaf spotting diseases of a commercial variety Krasnoyaruzhskaya 1 and breeding populations with high multifoliate expression (evident multi-leaf phase – mf-multi-leaf mutations) obtained on its basis in several cycles (I-III) of periodic (recurrent) selection. Six alfalfa-breeding populations were tested in two ecotopes on two soil differences: plot 1-ecotope of field crop rotation; plot 2-ecotope of a plowed meadow in the floodplain of the river Oskol in Chernyansky district, Belgorod region (meadow ecotope). The data obtained were analyzed by the method of two-way analysis of variance (ANOVA) according to a 2x4 scheme with the calculation of LSD 0.05. There were evaluated organized factors: factor A — selection feature: A1 (G) – high multifoliate expression (mf-mutation) without the manifestation of anthocyanin color of the stem (green color of the stem); A2 (AN) – high multifoliate expression (mf-mutation) with an evident anthocyanin color of the stem (purple color of the stem); factor B – a recurrence selection cycle: C-0, C-1, C-2, C-3. Pearson’s correlation coefficient was used to identify the close relationships between the studied indicators. It has been established that three cycles of recurrent selection are effective for increasing multifoliate expression in alfalfa breeding populations without increasing inbreeding depression based on seed productivity. Multifoliate forms are resistant to the development of leaf-spotting diseases and their prevalence. The most stable are the forms in which selection for the expression of the mf-mutation was carried out simultaneously with the increase in the index of the anthocyanin color of the stem. For a more effective assessment of the resistance of alfalfa breeding populations to leaf-spotting in Central Russia, comparative testing must be carried out simultaneously under conditions of favorable ecotopes of field crop rotation with fertile black soil rich in humus (chernozem) and in adverse conditions of meadow ecotopes.