Fertilization and Paclobutrazol Application for Sustainable Production and Post-production Performance of Petunia

This study examined the interaction between constant liquid fertilization (CLF) concentrations and plant growth regulator (PGR) application concentrations on petunia (Petunia ×hybrida) growth and flowering in the production and post-production environments. Paclobutrazol application is a common practice in bedding plant production to achieve a compact plant that increases greenhouse space-use efficiency, shipping density, and tolerance to physical handling stresses in the post-production environment. The objective of this research was to determine the best strategy for balancing CLF and PGR application concentration in the greenhouse environment so that growth and flowering can be maximized in the post-production environment. A two-factorial combination of four CLF concentrations [50, 100, 150, or 200 ppm nitrogen (N)] and four paclobutrazol drench concentrations (0, 5, 10, or 20 ppm) were provided to plants during the production phase, and plant growth and flowering were recorded in the production and post-production environments. From a sustainability perspective, the ideal PGR concentration was 5 ppm paclobutrazol, since this concentration resulted in the best combination of production and post-production characteristics and performance. At this PGR concentration, all plant growth and flowering measures increased as CLF increased from 50 to 200 ppm N; however, all CLF concentrations also produced commercially acceptable plants. Therefore, the ideal CLF concentration depends on the size of plant desired; that is, CLF concentrations as low as 50 to 100 ppm N can be provided depending on the market size requirements of the plants being grown. Based on our results, a combination of 50 ppm N CLF with 0 ppm paclobutrazol or 100 ppm N CLF with 5 ppm paclobutrazol both demonstrated adequate growth control during both production and post-production phases.