Date of Award

8-2019

Document Type

Thesis

Degree Name

Master of Science (MS)

Committee Member

James E Faust, Committee Chair

Committee Member

Haibo Liu

Committee Member

Sruthi Narayanan

Abstract

Reducing the amount of fertilizer applied to the plants in ornamental plant production industry is a growing trend due to rising environmental concerns; however, reduced fertilization can result in the failure to supply the retail customer with a plant that contains enough nutrients to sustain further growth in the consumer environment where fertilizer application is frequently lacking. Therefore, the objective of the first study was to examine alternative fertilizer delivery strategies that can maintain petunia quality during greenhouse production and continue to sustain plant growth and flowering in the post-production consumer environment. The fertilizer treatments applied to the plants were defined by a 4×3×3 factorial consisting of four constant liquid fertilization (CLF) concentrations (0, 50, 100, or 200 mg.L-1 N), three controlled-release fertilization (CRF) concentrations (0, 2.4, or 4.7 kg.m 1), and three pulse fertilization (PF) concentrations (0, 300, or 600 mg.L-1 N). The results showed that both CRF and PF had positive effect on growth and flowering of the finished product quality as well as during the subsequent post-production consumer performance. The only negative effect observed in the increased fertilization treatment was the additional growth that occurred during the greenhouse phase. So, a second study was designed to examine the interaction between CLF and plant growth regulator, paclobutrazol (rac-(2R,3R)-1-(4-chlorophenyl)-4,4-dimethyl-2-(1H-1,2,4-triazol-1-yl)pentan-3-ol). Paclobutrazol application is a common practice in bedding plant production in order to achieve a more compact plant that increases shipping capacity and tolerance to postharvest handling stresses. The fertilizer and paclobutrazol treatments applied to the plants were defined by a factorial combination of four CLF concentrations (50, 100, 150, or 200 mg.L-1 N) and four paclobutrazol concentrations (0, 5, 10, or 20 mg.L 1). The results showed that paclobutrazol successfully reduced the growth of plants in the high CLF treatments, but also continued to reduce plant growth and flowering throughout the post-production phase. From these observations we conclude that when applied at the proper rate, paclobutrazol can improve the finished product quality as well as post-production performance, but excessive paclobutrazol application results in poor growth in the consumer environment.

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