A hypothesis for the development of a defined tissue culture medium of higher plants and in vitro micropropagation of hybrid hazelnut

We hypothesized that a composition of minerals and organic substances in proportions similar to those in the seed composition could provide an optimum culture medium. Based on composition of hazelnut seeds, we first formulated a new tissue culture medium (NM) for hybrid hazelnuts. Mean shoot lengths of explants cultured on NM were significantly higher than those cultured on WPM (Lloyd and McCown, 1980), Nitsch and Nitsch's (1969), Driver and Kuniyuki's (1984) and Murashige and Skoog's (1962) media. The potential multiplication rates on NM and WPM media were higher than those on the other media.; When the amounts of minor salts and organic components in NM were optimized, the growth of explants was further enhanced. Higher amounts of Cu (up to 200) and myo-inositol (up to 8x) enhanced mean shoot lengths of some genotypes more than two-fold. At the higher levels of Cu and myo-inositol, shoots produced between 1.1 to 2.65 more axillary buds. Although at the control (0.025 mg CuSO4 · 5H₂O + 100 mg myo-inositol L−1) level 52 to 75% of axillary buds of two genotypes were not able to produce shoots, at higher levels these rates were as low as 8%. Furthermore, these higher concentrations of Cu and myo-inositol reduced by more than 50% the undesired callus at the explant base of some genotypes.; Microshoots were successfully rooted and acclimatized. Ninety-nine to 100% of shoots treated with 1000 ppm IBA for 5 or 10 s rooted in 15 days. The ex vitro survival of shoots three months after in vitro-root induction was 73% for shoots treated with IBA for 5 s, and 66% for shoots treated for 10 s. The highest ex vitro survival rate (97%) was observed when shoots were rooted ex vitro. A rooting and acclimatization protocol is presented that allows introduction of from 2.2 to 8.5 million plants to the field in one year when beginning with a single-bud explant of mature hazelnut.