Viability of Nopalea cochenilifera (cv. IPA Sertania) photoautotrophic micropropagation.

摘要

Photoautotrophic micropropagation, that promotes higher levels of in vitro plant photosynthesis, has two main advantages: low contamination risk and costs reduction. In this experiment, the Nopalea cochenillifera cv. IPA Sertania shoots development were analyzed in heterotrophic and in photoautotrophic micropropagation conditions. Shoot tips were micropropagated in medium with vitamins, macro and micronutrients of MS supplemented with sucrose at 3% (w/v), agar 0.8% (w/v), 1.0 mg L-1 BAP (benzylaminopurine) and 0.1 mg L-1 NAA (Naftalene acetic. acid). The regenerated shoots were transferred to test tube with fresh medium. The experimental design used was a factorial 2 x 2 x 2 (first: presence or not of sucrose in the medium, second: flasks with aluminum-paper covers or with cotton covers and third: cultivation in growth room or in greenhouse), entirely random, with 15 replications (one plant per test tube). The results indicated that all explants developed better in green-house. The best micropropagation rate was 4.73 new shoots.explant-1 maintained in green-house with aluminum-paper cover and medium with sucrose. The cotton covers did not showed any advantage for micropropagation improvement. The sucrose was fundamental to explants development. In the growth room the micropropagation rate of explants in sucrose supplemented medium was around 10 times higher than that in medium without sucrose. On the other hand, the difference observed in greenhouse was less intense. The greenhouse micropropagation rate in medium without sucrose was around 1/4 of the micropropagation rate with sucrose added. The results indicated that the probable higher levels of photosynthesis in greenhouse condition could be responsible for the micropropagation improving of N. cochenillifera cv. IPA Sertania.