The Influence of Combined Pruning and the Use of Root Application of Two Biostimulants and Foliar Nutrition on the Growth and Flowering of Panicle Hydrangea Plants

Abstract

The experiment assessed the impact of the interaction of two care treatments on the growth and flowering of two varieties of Panicle Hydrangea bushes. The first treatment considered was plant pruning. The second simultaneous treatment was one of the three mentioned, root application of Trichoderma atroviride and BlackJak biostimulator and foliar application of a multi-component fertilizer. The strongest impact on improving the length of hydrangea shoots compared to the control (18%) had their simultaneous pruning and inoculation of the plants with Trichoderma atroviride mycelium. These two treatments used together also increased the number of flowers (16-47% depending on the variety) and the fresh weight of plants (10-28%) compared to the control. The application of T. atroviride alone improved the number of flowers in both varieties (19-24%) and the diameter of inflorescences in the 'Silver Dollar' one (17%). Foliar nutrition in particular increased the mass of plants, depending on the variety and pruning, from 7 to 57%, as well as the diameter and number of inflorescences, but only in one of the varieties considered. Combined with pruning, it intensified the growth of shoots of both varieties (5-10%). The use of the BlackJak biostimulator gave ambiguous results. When pruning plants, the length of shoots improved (15%) for one of the tested varieties and the fresh weight for the other (18%). Without pruning, it increased the number of flowers (16%) and the diameter of inflorescences (9%) in one of the varieties considered, as well as the fresh weight of plants in both varieties (19-21%). Pruning the plants, regardless of the other treatments used, increased the length of the shoots and the fresh mass of the plants. On the other hand, it reduced the number of flowers and their diameter. In most cases, positive effects of the use of biostimulants and foliar fertilization on improving the growth and flowering of plants were obtained. After their use in combination with plant pruning, an improvement in the growth of hydrangea bushes was observed, while the number and diameter of flowers were reduced. The most beneficial care treatments for the growth and flowering of panicle hydrangea were the simultaneous application of T. atroviride and pruning of plants during container cultivation in a nursery.