Chilean geophytes: Micropropagation and cut flower production

Date of Completion

January 2006

Keywords

Agriculture, Horticulture

Degree

Ph.D.

Abstract

Chile is an important geographical origin for geophytic species. Extensive studies have been published on Alstroemeria as an ornamental crop but little work has been completed on other geophyte species from Chile. This dissertation reviews micropropagation studies that were done on Conanthera, Leucocoryne, Rhodophiala and Zephyra , and greenhouse studies on Alstroemeria hybrids. ^ Corms and bulbs of Conanthera and Rhodophiala were grown on different media at different concentrations of N 6-benzilaminopurine (BA) and 2-isopentenyl-adenine (2ip). A significant increase in total plant growth and number of bulblets/cormlets was produced with the addition of BA to the growing media in both species. No significant effect of dose was possible to found at the rates tested. ^ Different chilling treatments and light/darkness conditions were tested during in vitro culture of Conanthera, Leucocoryne, Rhodophiala and Zephyra. In vitro chilling conditions produced a positive effect on the growth of Rhodophiala bulbs and on the total number of corms produced of Conanthera. No effect of light on bulb growth was possible to observe. Chilling treatments did not produce a different effect in cultures initiated as bulbs or seedlings. ^ Different concentrations of sucrose were tested to understand its effect on the growth of plants and bulbs of Rhodophiala bagnoldii growing in vitro conditions. Higher concentrations of sucrose produce a positive response on Rhodophiala bagnoldii plants in vitro. Increase in total plant and bulb growth was obtained with the addition of 60 and 90 g·L-1 to the growing media. Concentrations higher than 150 g·L-1 of sucrose produce a decrease on the overall growth of the plants in vitro. No effect on the final number of bulbs was observed. ^ With the objective to increase the number of bulblets/cormlets in vitro, scooping, scoring and sectioning procedures were used in Leucocoryne, Rhodophiala, Conanthera and Zephyra bulbs. Use of these "traditional" techniques for bulb propagation is possible to use in vitro conditions. Results vary depending on species and technique. The increase of number of bulbs produced in vitro not always implies a larger fresh weight. ^ Alstroemeria plants can be propagated early during the season and stored under cold conditions without these procedures affecting final plant performance. It is necessary to take in account that the process will affect the scheduling of the crop and that are genotypic differences. Lighting during cold storage does not have a positive effect over potted Alstroemeria plants. ^ Harvesting technique used in Alstroemeria for cut flowers will produce a different response depending upon the genetic background and the growing season of the plant. Orchid-type cultivars produce a larger amount of flowering stems when they are harvested by cutting during the first season of growth. No difference in number of flowering stems produced was found for any butterfly-type or hybrid-type tested. ^

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