Submitted to: HortScience
Publication Type: Peer Reviewed Journal
Publication Acceptance Date: June 26, 2006
Publication Date: September 27, 2006
Citation: Russo, V.M. 2006. Biological amendment, fertilizer rate, and irrigation frequency for bell pepper transplant production. HortScience. 41(6):1402-1407. Interpretive Summary: Transplants are required to be of a size that allows them to be transferred to the field using mechanical methods. Plant size can be manipulated by the methods used in the greenhouse. Biotic amendments, mixes of beneficial bacteria and/or beneficial fungi, were added to a medium, fertilized with 8, 16, 24 or 32 mL/L of an organically certified fertilizer, and irrigated either twice a day for 3 min per application or 3 times a day for 3 min per application. Effects of treatment on plant heights and dry weights were determined. The mix of beneficial fungi also contain a polymer that is not able to be used in an organic system. An additional experiment was designed to compare fungal mixes with and without the polymer. Irrigation regime did not affect plant development. The control plants not treated with amendments were of sufficient size to be transferred to the field when the appropriate fertilizer is used. The biotic amendments only provided small benefits to plant heights or dry weigths, and this may have been due to the polymer. A completely organic method for production of bell pepper transplants was developed.
Technical Abstract: Use of biological amendments in vegetable transplant production systems may affect development of plants. In an initial experiment a mix of Rhizobium sp. bacteria, a mix of vesicular-arbuscular mycorrhizal fungi, or a combination of the bacteria and fungi were added to an organically certified potting mix. Controls consisted of no amendments. Bell pepper seed were sown in the mix. Irrigation was either twice a day for 3 min an application or 3 times a day for 2 min an application. Developing plants were provided 8, 16, 24 or 32 mL/L of an organically certified fertilizer beginning 2 weeks after emergence. Plant heights and dry weights were determined 6 weeks after emergence. Irrigation regime did not, but the type of amendment and fertilizer rate, and the interactions of irrigation regime and fertilizer rate, and type of amendment and fertilizer rate affected results. Tallest and heaviest plants were irrigated twice a day, and in the order: both bacteria and fungi used>fungi only used>bacteria only used>control. The fungal mix contains a polymer wetting agent which can not be used in an organic system. An additional experiment comparing fungal mixes with and without the polymer wetting agent was undertaken. Controls did not receive fungal mixes. Responses to the irrigation regimes were similar to the initial experiment. Plants produced with the fungal mix containing the polymer wetting agent were taller and heavier than those produced with the fungal mix without the polymer wetting agent. Results for the latter plants were similar to, or lower than, controls. Results indicate that to produce acceptable bell pepper transplants: addition of fungal mixes is inconclusive; use of Rhizobium bacteria provide a benefit; fewer irrigations for longer periods is preferable; and application of organic fertilizer is dose dependent.