The Auxin and Cytokinin Balance Influence the in Vitro Regeneration ofPhalaenopsisShoots (Orchidaceae)

Abstract

AbstractOrchids (Phalaenopsis) are considerably appreciated or their high and durable flowering rate and exotic appearance. The optimization of in vitro cultivation begins with an understanding of hormonal balance and its implications in production. This work aimed to regenerate shoots from seeds germination of thePhalaenopsisGolden Peoker ‘BL’ HCC / AOS’ under exogenous auxin and cytokinin influence. To do so, naphthalene acetic acid (NAA), 6-benzyladenine (BA), and Kinetin (Kin) were added to the culture medium to induce organogenesis, totaling 17 treatments with eight replications per treatment. The variables number of shoots (NS), shoot length (SL), and presence of root primordia (RP) were evaluated. A non-parametric test (the Friedman test), followed by the Bonferroni procedure, was used to compare the different groups. Hence, the MS medium provided 610 complete plants after 90 days of cultivation. The T6 treatment had the highest median NS (1.5 shoots per plant at 15 days) and SL. At 30 days, the highest NS was for the T16, with 6.15 shoots per plant; for SL, the one that stood out was the T9. Regarding RP in shoots, the best treatments were T2, T3, T9, T10, and T17, with the formation of RP at 15 days, remaining these treatments at 30 days. In conclusion, the T9 is the most suitable for an efficient protocol reproduction, as it showed the best plant development.HIGHLIGHTS (MANDATORY)The auxin and cytokinin balance promoted shoot regeneration.The BA and NAA combined promoted the shoot formation ofPhalaenopsisGolden Peoker ‘BL’ HCC/AOS’.The use of KIN isolated showed hyperhydricity and malformation in shoots ofPhalaenopsis.