Study of propagation possibility of almond & peach hybrid rootstocks via micropropagation

Nowadays, clonal rootstocks are used for industrial and modern fruit growing systems and in recent decade, interspecific hybrids, especially the cultivars belonging to the genus Prunus are considered as rootstocks for stone fruit trees. In this research, sterilization, establishment, proliferation and rooting potential of HS٣١٤, HS٣١٢ , HS٣١١ and GF٦٧٧ as new almond × peach (P. amygdalus ×P. persica ) hybrids were evaluated. In vitro culture of genotypes was carried out in both growth and dormant stages. Shoots were surface sterilized in fresh ١,٥ - ٢,٥٪ sodium hypochlorite for ٥, ٧ and ١٠ min and HgCl٢ (٠,٥-١ g/l ) for ٥ min. Sections with ١-٢ buds were excised and cultured on WPM, QL, DKW, Knop and modified MS media supplemented with BAP (٠, ٠,٥, ١, ١,٥ mg/l) + NAA ٠,٠٥ mg/l or IBA ٠,١ mg/l. At rooting stage , shoots of about ٢,٥ cm in length were cultured on modified MS and WPM media supplemented with IBA by two methods ; ١) with four concentrations of IBA( ٠, ٠,٥, ١,٥ , ٢ mg/l) _in the culture medium , ٢) the explants base dipped for ٥-٦ seconds in solutions of IBA (٠, ٥٠٠, ٧٥٠, ١٠٠٠ mg/l). The results showed that the best treatment for sterilization of shoot tips was sodium hypochlorite ١,٥٪ , for ١٠ min; whereas sodium hypochlorite ٢,٥٪ , for ٧ min + HgCl٢ ٠,٨٪ , ٥ min was suitable for herbaceous shoots and finally hypochlorite ٢,٥٪ ,١٠ min + HgCl٢ ١g/l ,٥ min was the best sterilization method for hard wood explants. MS modified and DKW media were suitable for HS٣١٤, HS٣١٢, HS٣١١ and GF٦٧٧ with ١mg/l BAP + ٠,٠١-٠,٠٥mg/l NAA in establishment and proliferation stages. Percentage of rooting for HS٣١٤ and GF٦٧٧ ( ٨٠-٧٥٪), HS٣١٢ and HS٣١١ (٦٠ -٧٠٪) rooted on MS modified with ١,٥ and ٢ mg/l IBA after ٧ days in darkness and ٢٠ days in the light had high number, length and rooting percentage, respectively. However, rooting percentage was higher when explants base dipped in IBA (٧٥٠ mg/l). The mean comparison showed that HS٣١٤ had higher root number and length of roots and rooting percentage than other genotypes. Rooted shoots were transferred to pots containing a mixture of peat and perlite in the ratio ١:١ (v/v) and were kept in a greenhouse. Rooted plantlets were successfully acclimatized with ٧٥ % survival. Key words: In vitro culture, micro propagation, interspecific hybrids, Prunus