Micropropagação de Adenium obesum

Abstract

Adenium obesum is a plant native to arid and semi-arid areas of Africa and the Arabian Peninsula, cultivated all over the world, presents compact growth habit, succulent roots, showy caudex and lush flowering. The objective was: a) to evaluate the effect of colored LEDs and culture media on germination and initial growth; b) evaluate different photoperiods and concentrations of MRA medium in the initial growth and; c) determine the most effective period of time in seed asepsis. From the 3rd to the 32nd the number of germinated seeds and contaminations were evaluated daily and at 60 days the following were evaluated: a) germination; b) germination speed index; c) average germination time; d) average germination speed; e) number of leaves; f) leaf length; g) total length of the plant; h) fresh mass and, i) dry mass of the whole plant; j) chlorophyll-a; k) chlorophyll-b; l) total chlorophyll (a+b) and, m) carotenoid. The experimental design was completely randomized. The evaluations began on the first day after sowing. There was a significant difference between the treatments used for all variables analyzed. The germination responses of A. obesum seeds varied according to the spectral quality of the LED and the culture medium. The best LED for light supplementation is red for MRA medium and purple LED for MS medium, for increased germination with lower mortality rate. For the initial development of A. obesum seedlings, the best was the red LED for both culture media with positive changes in all morphological variables. The best LED was white for the MS medium and the green LED for the MRA medium, providing a better amount of pigment contents. Each phase of the crop requires a different spectral quality in order to promote germination and initial growth. The in vitro germination of A. obesum occurred in the different times of immersion in the NaClO solution, with emphasis on 30 min, which presented a lower percentage of contamination and imperfect seedlings, with a higher percentage of perfect seedlings when compared to the other times of asepsis. The sodium hypochlorite solution (30%) at 30 min of immersion positively influences the germination of A. obesum seeds, allowing the production of perfect seedlings free of contaminants.