Effect of coconut water and growth regulator supplements on in vitro propagation of Corylus avellana L

• Proliferation and shoots elongation are limiting factors to micropropagation of hazelnut.
• The addition of 20% coconut water, 2 mg/L BAP and 0.5 mg/L GA3 to culture medium promoted shoot elongation and proliferation.
• There was a synergistic effect between growth regulators and coconut water.
• The ontogenetic state of the plant material used for in vitro culture establishment affected bud development ability.
• The explant orientation affected the proliferation response, with horizontal orientation enhancing proliferation.

Corylus avellana L. represents an economically important crop in the European Union. Several protocols of hazelnut micropropagation have been tested but have not yet provided effective methods to allow large-scale propagation for commercial purposes, due to poor proliferation and yield. The aim of this work was to study the in vitro effects of coconut water (CW) in combinations with gibberellins and cytokinins on proliferation and growth of hazelnut in vitro and the effect of explants orientation on shoot growth. Single axillary buds from mature trees of ‘Tonda Gentile delle Langhe’ cultivar collected from suckers and crown were cultured on a modified DKW semi-solid basal medium enriched with coconut water, BAP, IAA and GA3 in several combinations. The addition of 20% coconut water increased the number of adventitious shoots per explant and the combination of 2 mg/L BAP, 0.01 mg/L IAA and 0.5 mg/L GA3 promoted multiplication and shoots elongation. Shoot multiplication and growth were also affected by explant orientation. The highest rates occurred with sucker explants in the horizontal position.