S05 - Session P2 - The influence of algae based biostimulants on growth and flowering of annuals

Authors: Leila Mainla *, Pille Peterson, Mariana Maante-Kuljus, Kadri Karp, Ulvi Moor, Priit Pldma

The production of annuals has considered one of the horticultural industry sectors with high mineral fertilization input. On the other hand, the awareness of the consumer on environmentally friendly and sustainable production is pushing also the ornamental production towards finding more environmentally friendly solutions. One solution in reducing the use of mineral fertilizers has considered being biostimulants. We hypothesized that reducing the mineral fertilization by half and adding algae based biostimulants can improve the growth and flowering of annuals. The aim of the study was to find out the influence of algae based biostimulants on growth and flowering of container grown garden verbena ( Verbena x hybrida Lanai `Scarlet With Eye`) and calibrachoa hybrid ( Calibrachoa x hybrida Cabaret `Lavender`). The experiment contained of three treatments: 1. Regular mineral fertilization as control; 2. Micro-algae containing biostimulant (Allgrow®) + mineral fertilizer reduced by half; 3. Seaweed Ecklonia maxima extract and mineral NK fertilizer biostimulant (Basfoliar® Aktiv, NPK 8-0-18 + microelements) + mineral fertilizer reduced by half. The Allgrow treatment was watered with 2,5% and Basfoliar Aktiv treatment with 0,2% biostimulant solution. The mineral fertilization was through drip irrigation. The rooted cuttings of both cultivars were planted in peat-based substrate into plastic containers and plants were grown in greenhouse and open field conditions in containers. The first watering with biostimulants was two weeks after transplanting. Data was collected during three months in 14-day interval. Compared to control both biostimulants significantly improved plant growth, flowering and leaf SPAD value. Calibrachoas watered with micro-algae containing biostimulant had on average twice as much flowers compared to control. At the end of August, the leaf SPAD value of garden verbenas watered with micro-algae containing biostimulant (58) was significantly higher compared to seaweed + mineral fertilizer biostimulant and control (both 51).