Growth, propagation, flowering and its compounds in reserve Costus arabicus L.

Author(s)

Vanessa Rebouças dos Santos

• Document type: Doctoral Thesis
• Press: Campinas, SP.
• Institution: Universidade Estadual de Campinas (UNICAMP). Instituto de Biologia
• Defense date: 2009-02-18

Examining board members

Lilian Beatriz Penteado Zaidan; Glaucia Moraes Dias Tagliacozzo; Catarina Carvalho Nievola; Jorge Vega; Clovis José Fernandes de Oliveira Junior

• Advisor: Lilian Beatriz Penteado Zaidan

Abstract

The world market for floriculture is encouraging the introduction and production of new tropical plants, with their unusual forms, exuberant and colorful, with high ornamental potential. In Brazil, the cultivation for production of tropical flowers are increasing due to, favourable environmental factors, availability of land, water, energy and relatively cheap labour which reflects directly on the quality of the products and offers competitive costs in foreign markets. But there are limitations to the expansion of new products, including the misinformation about the conditions of intensive cultivation of new plant species and their potential conservation in tropical conditions. The species of the genus Costus (Costaceae) are attracting great interest because of their ornamental flowers with high beauty and exoticity. The objective of this work was to study propagation, growth, flowering and the reserve compounds in plants of Costus arabicus L. growing under glasshouse conditions, aiming to offer technical information and physiological knowledge for the cultivation of this species as an ornamental plant. Plants of C. arabicus were transplanted to pots and kept under the conditions of a greenhouse. The plants were subjected to photoperiodic treatments of 8, 12, 16 and 20 h. Vegetative growth (shoots, stems, height and number of leaves) and flowering were evaluated. For vegetative propagation, rhizomes of C. arabicus were divided in their distal, middle and proximal regions and were grown in different seasons: planting held in July (winter), when the plants were in a stage prior to flowering; planting held in November (spring), when the plants were flowering and planting held in March (autumn), when the plant were in vegetative stage. Flowering was assessed by the appearance of floral buds, the developmental stage of the inflorescence, the number of flowers developed and elapsed time from anthesis to senescence of the flower. Analysis of soluble starch and carbohydrates (total and reducing carbohydrates) of rhizome were performed. Fresh mass (FM) and dry matter (DM) of the shoot and the rhizome were recorded to calculate the ratio FM/DM. The experimental design was a completely randomized. The averages were compared according to Tukey at 5% probability. The results indicated that the growth of variables analyzed were influenced by photoperiod and favored by long days. In general, the ability of the rhizome to propagate not depends on the region used, but the proximal region favored vegetative growth development, formation of shoots, the development of rods, plant height and number of leaves, mainly on summer. Plants of C. arabicus have annual cycle of development, with a phase of vegetative growth, followed by latency of winter season and flowering between November and April. Floral buds were observed in all photoperiodic treatments, and therefore floral induction was not a qualitative response to this environmental factor. However, the response of flowering, based on the various aspects assessed was favored in the photoperiod of 16 h in quantitative terms, photoperiod of 8 h was unfavorable for flowering. The best season for flowering was when planting is in July, because the process of flowering occurred after only four months of cultivation of the plants, when compared with the plants obtained from rhizomes, cultivated in November and March, which brought about 12 and 8 months, respectively, to flower. Starch was considered the main carbohydrate reserve of rhizome and noted that it was hydrolyzed during the process of flowering, while the total sugar were used as a primary energy source for the sprouting of the rhizomes. The results of growth, vegetative propagation and flowering allow the plants of C. arabicus can be used as ornamental plants since its morphological characteristics, such as spiral phytolaxy, the green inflorescence, and the white flowers with pink labelo, are interesting aspects to the market for floriculture. (AU)