Quantificação do desenvolvimento e pré-melhoramento de Aspilia montevidensis (Spreng.)

Abstract

Aspilia montevidensis, considered a weed, presents an ornamental potential because of their exuberant flowers. Thus, in the future, through the characterization of the developmental and breeding programs, we may develop ornamental cultivars. The objectives of this dissertation are two-fold: determine base temperature, the plastocron, the final node number, and the duration of some phases of the developmental cycle from A. montevidensis (Chapter I) and to verify seed production and to evaluate the germination of seeds collected from different locations, to evaluate in vitro establishment from A. montevidensis nodal segments from plants of two populations, and to evaluate in vitro multiplication of the population that had the best performance in the establishment (Chapter II). Two experiments were conducted at the experimental field, in the Production Seeds Analysis Laboratory and in the Biotechnology Laboratory of the Federal University of Santa Maria, RS, Brazil. In the first experiment, five planting dates in the field (20/12/2005, 14/02/2006, 06/03/2006, 04/04/2006, 05/05/2006) and one sowing date in a greenhouse (08/06/2006) were used. The date of developmental stages transplanting (T), visible buds (VB), open capitulum (OC) and senescent capitulum (SC), and the number of visible nodes were measured on the maim stem (MS) and on first and secondary lateral branches located on two positions on the mother stem (lower node and upper node) of each plant per pot. The base temperature (Tb) for node appearance and Tb of the T-VB and VB-SC phases was estimated with three empirical methods. The daily thermal time (TTd, °C day) was calculated from transplanting and the plastochron (ºC day node-1) was estimated for each stem. In the second experiment, Capitulum diameter was measured on 45 samples from three populations and the number of viable seeds, aborted seeds and the average seed weight were determined. Germination of seeds was also tested at 20ºC and 30ºC. For in vitro establishment, a MS media and nodal segments from two populations were used, and the following parameters were evaluated: contamination (C), survival (S), establishment (E), total number of nodes (TN), leaf number (LN), presence of lateral buds (PLB), number lateral buds (NLB) and presence of roots (PR). The in vitro treatments were MS, media MS + 1mg L-1 BAP, and MS + 1mg L-1 BAP + 0,01mg L-1 ANA and the parameters evaluated were TN, LN, PLB, NLB, PR, and presence of calluses (PC).The estimated base temperature for node appearance in A. montevidensis was 0ºC and Tb of the T-VB and VB-SC phases was 13ºC e 7ºC, respectively. Plastochron and final node number (FNN) varied among stems and planting dates, with the lowest plastochron and the greatest FNN on the MS. A duration, in ºC day, of the T-VB phase varied among stems and planting dates whereas the duration of VB-OC and OC-SC, in general did not vary among stems and planting dates. Differences in the number and quality of the seeds from different sampling locations allowed to infer that the difference in environment among locations affected the seed production of A. montevidensis. The best temperature for seeds germination is 20ºC. Nodal segments from plants depressed by endogamy presented a poorer in vitro establishment. The media indicated for multiplication is the MS media plus 1mg L-1 BAP and 0,01mg L-1 ANA.