Silicium, light and substrate in the pineapple [Ananas comosus (L.) Merr âGomo de Melâ] micropropagation / SilÃcio, luz e substrato na micropropagaÃÃo de abacaxizeiro [Ananas comosus (L.) Merr âGomo de Melâ]

AUTOR(ES)
DATA DE PUBLICAÇÃO

2009

RESUMO

The present work aimed to evaluate silicate sources, natural light, alternative component to the agar and efficient substrates in the micropropagation of pineapple âGomo de Melâ through developmental and anatomical analyses. The pineapple shoots etiolating was promoted in vitro using the MS medium testing different concentrations of ANA and GA3. It was evaluated the etiolated shoots regeneration in different light environments: 1) growth room and 2) greenhouse and three regions of the etiolated shoot as explants source: 1) apical; 2) medium and 3) basal. Calcium silicate and potassium silicate in the dosage of 1,0 g.L-1 added to the MS medium were tested to the pineapple multiplication in vitro. To the in vitro rooting it was evaluated light environmental: growth room and greenhouse and two physical supports: agar 6 g.L-1 and vermiculite 15 g.L-1 in liquid MS medium. Four different substrates were tested during the acclimatization process: send + fern tree fiber + humus; PlantmaxÂ; vermiculite and Plantmax + vermiculite. After 60 days, biometrics and anatomical parameters were evaluated in all the experiments excepted for the etiolating induction experiment. Bigger number of etiolated shoots occurs when is added to the medium 6.5ÂM of GA3 combined with 20 ÂM of ANA. Absence of ANA and 13 ÂM of GA3 promotes greater length of aerial part and number of roots. The addition of 20 ÂM ANA + 6,5 ÂM GA3 provides greater number of internodes. For the in vitro regeneration, the greater number of shoots and fresh mass was obtained in artificial light environment independent of the explants type. To the foliar limb tissues thickness the natural light environment promoted the biggest thicknesses. Natural light and the basal region of the etiolated explants promoted greater number of stomatas/mm2 and polar and equatorial diameter. In the in vitro multiplication, evaluating silicon sources, greater number of shoots, fresh and dry mass was observed when potassium silicate was added to the medium. The addition of potassium silicate to the medium MS provides bigger thicknesses of the foliar mesophyll, bigger number of stomata, as well as, greater polar and equatorial diameters. The use of the vermiculite substrate in artificial light presented better results for all variables. Bigger thicknesses of the foliar limb tissues was verified with the use of vermiculite and natural light, being that, to the agar use, it also increased the thicknesses only when the natural light environment was used. Deal with the number of stomatas/mm2 it did not have significant difference between treatments, greater polar and equatorial diameter was observed in stomatas of leaves cultivated in artificial light and vermiculite and natural light and vermiculite respectively. During acclimatization process the use of vermiculite substrate was the recommended to âGomo de Melâ presenting good characteristics of growth and tissues differentiation.

ASSUNTO(S)

aclimatizaÃÃo anatomia vegetal vegetal anatomy silicatos environment of growing silicates aclimatization ambiente de cultivo fitotecnia

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