Clonal propagation of avocado rootstocks in Colombia: An <i>in vitro</i> approach

Galvis, Lina María Arbeláez; Cano, Diana María; Botero-Garcés, Jorge Humberto; Urrea-Trujillo, Aura Inés

doi:10.1590/1413-7054202549009525

Genetic variability in rootstocks used in commercial avocado plantations negatively impacts traits such as stress adaptation and productivity, especially when plant material is not suited to local conditions. Clonal propagation of desirable rootstocks, including the widely cultivated “Criollo” avocado genotypes in Colombia, has had limited success due to the lack of efficient in vitro propagation protocols. The aim of this study was to develop an in vitro propagation protocol, including ex vitro acclimation and field planting phases, for five “Criollo” avocado genotypes from Colombia. The response of etiolated buds from six-month-old mother plants to the in vitro introduction, multiplication, rooting, and ex vitro hardening stages was evaluated. For bud establishment, WPM and MS media were tested. For multiplication, the ratio of 6-Benzylaminopurine to Gibberellic Acid and the use of LED lighting were assessed. Indole-3-butyric acid (IBA) and naphthaleneacetic acid (NAA) were applied during the rooting phase. Three substrates with different growth promoters (mycorrhizae, Serratia marcescens, and Trichoderma harzianum) were evaluated during acclimation. The results revealed multiplication rates between 0.7 and 1.9 depending on the genotype. Rooting percentages above 50% were obtained using the combination of 1 mg L^-¹ IBA and 0.5 mg L^-¹ NAA, and ex vitro survival rates reached 74.1% in the control. The use of LED lighting, a strategy not previously explored in this crop, promoted faster shoot and leaf development in the Duke7 genotype. Although genotype-dependent, the protocol enabled propagation of Criollo genotypes, representing a step toward avocado productivity and sustainability, with applications to regional materials.

Index terms:
“Criollo” avocado; shoot proliferation; recalcitrant; In vitro propagation

[TFN1] Note: The mean values followed by different letters in the column indicate that the differences were significant, as determined by Dunn’s post hoc test (p < 0.05).

Genotype	Multiplication rate	Number of buds	bud length (cm)	leaf formation (%)
ArLV01	0.71 b	1.3 ± 1.17 b	1.30 ± 1.2 c	16
ArLR02	1.07 ab	1.18 ± 0.49 b	3.10 ± 1.8 b	29.7
ArLF03	0.78 ab	1.22 ± 0.51 b	1.59 ± 0.7 c	14.8
ArLA04	0.82 ab	1.58 ± 0.75 a	1.74 ± 1.3 c	30.8
AgS05	1.92 a	1.30 ± 1 b	3.60 ± 1.9 a	48.9

Treatments	Genotype	Rooting percentage (%)	Number of roots	Length (cm)
NAA	ArLV01	50 b	0.60 ± 0.7	1.80 ± 1.9
	ArLR02	66.6 b	1.44 ± 1.2	5.28 ± 4.8
	ArLA04	50 b	1.00 ± 1.3	3.60 ± 5.0
	AgS05	70 ab	2.10 ± 2.0	4.45 ± 5.0
NAA+IBA	ArLV01	90 b	1.70 ± 1.3 b	4.31 ± 2.5
	ArLR02	100 ab	2.90 ± 1.1 ab	4.14 ± 2.5
	ArLA04	50 b	1.10 ± 1.5 b	3.15 ± 4.0
	AgS05	100 a	4.10 ± 2.0 a	5.90 ± 3.4

Hormonal combination (mg L^-1)	Necrosis (%)	Buds response (%)	Description
BAP 1 and GA₃ 1	33.3	33.3	Necrosis in main bud, new green bud with little development
BAP 1, GA₃ 0.1 and IBA 0.5	33.3	33.3	Development of pre-existing apical and lateral meristems, 4 leaf development, 0.5 cm approx. length
BAP 1 and IBA 0.5	50	50	Development of lateral bud (0.3 mm) with development of small true leaves
BAP 1 and IBA 0.25	33.3	33.3	Initial stimulation of the existing meristem but no further development
IBA 0,1	50	0	All buds necrotized
BAP 0.56 and IBA 1	33.3	66.6	2 buds with development of new shoots
mT 0.1	0	100	Development of apical meristems with leaf development
mT 1	0	0	No development observed
mT 0.1 and GA₃ 0.1	0	0	No development observed
mT 0.2 and GA₃ 0.2	0	100	Development of apical meristems with leaf development
mT 0.3 and GA₃ 0.3	0	100	Development of apical meristems with leaf development
mT 1 and GA₃ 0.1	0	0	No development observed

Clonal propagation of avocado rootstocks in Colombia: An in vitro approach

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