Substâncias húmicas e reguladores de crescimento na micropropagação de mirtileiro ‘Woodard’

Abstract

The blueberry (Vaccinium sp.) is a promising fruit for the southern region of Brazil; however, the difficulty in propagating some cultivars can compromise the expansion of the crop, and studies aimed at improving the seedling production system are necessary. Therefore, the objective of this work was to evaluate the use of humic substances and growth regulators in the blueberry micropropagation 'Woodard'. The work was carried out in four stages. In the first study, the use of 2iP (2- sopentenyladenine) and concentrations of humic substances in in vitro multiplication were evaluated. The experimental design was completely randomized, in a bifactorial scheme (two concentrations (0; 100 mg L-1) of 2iP and four concentrations (0; 1; 2; 3 mg L-1) of humic substances), totaling eight treatments and five repetitions with five explants. At 60 days it was evaluated: survival, number of leaves, multiplication rate, number of shoots, length of the largest shoot, length of the aerial part, mass of fresh matter and dry mass of aerial part. In the second study, the effect of the presence and absence of IBA (indolbutyric acid) was evaluated, as well as concentrations of humic substances in the in vitro rooting of blueberry 'Woodard'. The experimental design was completely randomized, in a bifactorial scheme (two concentrations (0; 1 mg L-1) of IBA and four concentrations (0; 1; 2; 3 mg L-1) of humic substances), totaling eight treatments and five repetitions with five explants per repetition. At 60 days it was evaluated: rooting, number of shoots, length of the largest shoot, length of the aerial part, number of roots, length of the largest root, mass of fresh matter and dry mass of aerial part. In the third study, the use of humic substances and forms of application in the acclimatization of blueberry 'Woodard' were evaluated. The experimental design was completely randomized, in a bifactorial scheme (three concentrations (0; 1; 2 mg L-1 ) of humic substances and three forms of application (immersion for 24 hours, spraying every 7 days and daily spraying)), totaling nine treatments with five repetitions, each repetition consisting of a Sanpack® tray with 10 micropiles. At 60 days, the following were evaluated: survival, number of shoots, length of the largest shoot, length of the aerial part, number of roots, length of the largest root, dry mass of aerial part and root. In the fourth study, the use of humic substances and types of culture medium in the acclimatization of blueberry 'Woodard' were evaluated. The experimental design was completely randomized, in a bifactorial scheme (three concentrations of humic substances (Solohumics®) (0; 1; 2 mg L-1) and types of culture medium (without (0 mg L-1) or with ( 1 mg L-1 ) humic substances), totaling six treatments and four repetitions with a Sanpack® tray with 15 micropiles each 60 days were evaluated: survival, number of shoots, length of the largest shoot, length of the shoot, number of shoots roots, length of the largest root, dry mass of shoot and root. Thus, it was concluded that for the blueberry micropropagation 'Woodard': a) the in vitro multiplication of can be performed with the use of 1 mg L-1 of humic substances, without using 2iP (study 1); b) in vitro rooting can be performed using 3 mg L-1 humic substance and without using IBA (study 2); c) for acclimatization, 2 mg L-1 of humic substances and daily spraying are the most recommended (study 3) and d) explants from culture medium with the presence of humic substances and, subsequently, immersed for 24 hours in the concentration 2 mg L-1 of these substances are the most suitable for acclimatization (study 4).