Rooting response of Prunus wild relative semi-hardwood cuttings to indole-3-butyric acid potassium salt (KIBA)

Abstract

Wild Prunus germplasm is an important resource for pest and disease resistance traits for the continued improvement of almond and other Prunus rootstocks. Evaluation of resistance in these wild species requires clonal replicates that are traditionally produced by rooting cuttings. Over two consecutive years, leafy cuttings of 20 genotypes of the following wild Prunus species were collected in mid-late May and treated with a 15 s dip in 0, 500, 1000, 2000 or 4000 mg/L of the potassium salt of indole-3-butyric acid (KIBA): almonds (P. argentea (one genotype), P. bucharica (two genotypes), P. dulcis (two genotypes), P. tangutica (three genotypes)), peaches (P. davidiana (two genotypes), P. kansuensis, P. mira (two genotypes), P. persica (three genotypes including a commercial peach rootstock, ‘Lovell’)), and plums (P. cerasifera (two genotypes), P. salicina (two genotypes)).. The cuttings were planted in a perlite-vermiculite medium under intermittent mist and periodically checked for roots. The plum species rooted at a higher percentage, and produced more roots than the peach species; and the almond species generally failed to root. The plums produced the most roots at 2000−4000 mg/L KIBA, although rooting in both P. cerasifera and P. salicina was genotype dependent. The plum cuttings that rooted generally produced from 2 to 14 roots that averaged 0.74–1.73 cm long when the cuttings were harvested; one accession produced 60 roots/cutting when treated with 4000 mg/L KIBA. The wild peach species produced the most roots at 1000−4000 mg/L KIBA, with cuttings of P. kansuensis and P. mira having significantly higher rooting percentages than P. davidiana and P. persica cuttings. All of the wild almond species tested did not root or rooted a very low percentage.