Light and growth regulator effects on propagation of wild almond (Amygdalus scoparia) by in vitro embryo culture

Wild almond (Amygdalus scoparia Spach), is one of valuable almond species in Iran with medicinal and nutritional values as well as soil conservation and other environmental characteristics, which is also utilized as a rootstock in cultivation of domestic almond cultivars. After in vitro culturing of embryos of the species and enough shoot growth on DKW medium, with growth regulators such as IBA, BA and TDZ in 0.01, 0.5 and 0.05 mg.l-1 respectively, effects of light and growth regulators on rooting ability of the embryo driven shoots were investigated, using a factorial statistical model, based on a completely randomized design. Light as the first factor with 2 levels (a: 16 hours light and 8 hours darkness, b: permanent darkness for ten days) and growth regulators of DKW culturing medium as the second factor in 5 levels (1: NAA‐ each for 1 mg.l-1, 2: NAA for 1 mg.l-1 , 3: IBA for 1 mg.l-1 , 4: IBA for 0.5 mg.l-1, 5: NAA for 0.5 1 mg.l-1) were used. Based on the results of analysis of variance, the two factors of light and growth regulator had significant effects on all of the studied characteristics. Light caused better growth of embryo grown shoots, compared to darkness. Various levels of growth regulators had also different effects on shoot and root production. Using a combination of IBA and NAA, produced the highest number of main roots. But 1mg. l-1 IBA caused the longest main root as well as higher number and length of lateral roots. Interaction effects between light and growth regulators significantly affected shoot length, main root length, number and length of lateral roots. So that combination of the two growth regulators produced the most number of lateral roots, whereas, utilizing 1 mg.l-1 NAA in darkness resulted in the most number of lateral roots. Results of analysis of variance indicated significant effects of light and culturing media factors on all of the studied characteristics. So that light caused remarkable increments on all of the studied characteristics. Various levels of applied growth regulators caused different effects on the studied characters. Meanwhile, IBA growth regulator caused significant increment of number and length of main and lateral roots. But NAA growth regulator showed significant effects on shoot length and number of leave. Interaction between light and media factors had significant effects on shoot length, main root length, number and length of lateral roots. Alternate light and darkness as well as IBA growth regulator are necessary for asexual propagation of wild almond through micropropagation.