Introduction study and comparative assessment of Phlox paniculata L. cultivar in the Middle Volga region

A comprehensive study of 11 paniculate phlox cultivars (Phlox paniculata L.) was conducted for the first time for the soil and climatic conditions of the Middle Volga region. The research was performed on plants introduced at the Cheboksary Branch of the Federal State Budgetary Institution for Science Main Botanical Garden named after N. V. Tsitsin Russian Academy of Sciences in 2020–2024. The aim of the study was to select the best specimens for industrial propagation and cultivation. The ornamental value of the phlox cultivars and their economically valuable traits were analyzed. Furthermore, the resistance of the cultivars to a range of adverse climatic factors in the introduction region was evaluated. Detailed phenological descriptions and morphological profiles were compiled for each cultivar, enabling a comparative analysis across multiple parameters. Specifically, key biometric indicators were established, including bush height, inflorescence length and diameter, and flower diameter. The study of decorative traits was based on the following plant qualities: bush – height, density, habit; strength and decorative quality of the peduncle; number of flowers per peduncle; inflorescence – structure, shape, size (length-to-diameter ratio), color; fragrance; originality; plant condition; the stability in the ground. The investigation of agronomic and biological qualities of the phloxes focused on: general condition and stability of plants within a cultivar; development and growth rate; ability for vegetative propagation; degree of disease damage. Observations indicated that the studied cultivars varied significantly: height – from 55 to 125 cm, inflorescence size – from (12x12) to (21x13) cm, the number of flowers per inflorescence – from 13 to 37, flower size – from 3.4 to 4.4 cm, color – from white and pink to purple and red-violet. Moreover, variation was noted in the degree of resistance to fungal diseases. Cecil Hanbury, Novinka, and Tchayka cultivars were distinguished by a high degree of resistance to pathogenic fungi. September Glow and Pougatchov were identified as the most susceptible cultivars to diseases. Elbrus and Ottly Ideal were cultivars with early flowering periods from the first ten days of July until July 15. The remaining cultivars belonged to mid-season types – from the second ten days of July until August 5. Specimens with a flowering period exceeding 35 days were classified as long-flowering – Marija Scharonova, Novinka, and Cecil Handbury. Consequently, the following cultivars were identified as the most promising for introduction into cultivation under soil and climatic conditions of the Middle Volga region: Cecil Handbury, Elbrus, Marija Scharonova, Novinka, Tchayka, and Violetta Gloriosa.