A study on growth, propagation and rooting of Iranian native pears for developing in vitro conservation system

Multiplication of pear cultivars using conventional vegetative propagation techniques such as soft or hard wood cuttings is difficult. Therefore, the possibility of micro-propagating 10 Iranian native pear cultivars and the establishment of their in vitro collection were studied. In vitro cultures of these cultivars, established using single node soft cuttings on MS Medium supplemented with BAP (1 mg/l) and NAA (0.1 mg/l), were evaluated for growth characteristics. At this stage, time to shoot induction in cvs Ghosi and Natanzi with the mean of 4.75 days was the shortest and in cv Khooj with 20.75 days was the longest, among all cultivars examined in this study. Cultivars Ghosi and Natanzi also produced the highest number of leaves ( 4.25 and 3.25, respectively) and the highest shoot height (9.25 and 6.5 cm, respectively). Micropropagation of in vitro grown plantlets were then studied by assessing 21 days old Micropropagated plantlets on the modified QL medium containing growth regulator combination of BAP (1mg/l), NAA (0.1 mg/l), Zeatin (1mg/l) and 2ip (1mg/l). Cultivar Ghosi produced plantlets with an average of 3.75 leaves and the average height of 4.27 cm, showing the highest growth rate. On the other hand, plantlets of cvs Beiruti and Shahmiveh with an average shoot height of 1 cm showed the lowest growth among the cultivars examined. Modified QL media supplemented with different concentrations of Auxin, IBA, were used for rooting of four selected pear cultivars. NO roots was observed on any of the four cultivars, cultured on media with IBA concentrations of 0.5 and 2.0 mg/l, while all selected cultivars rooted on the medium containing IBA with concentrations of 1mg/l. The highest mean number of roots (6.33) was produced in cv Ghosi and the lowest in cv Sardroodi (1.66). Root length was the highest in cv Shahmiveh and lowest in cv Sardroodi. The results of this research work showed that Iranian native pear cultivars can easily be micopropagated under in vitro conditions, but their growth and multiplication characteristics is genotypic specific. This research also successfully established the first Iranian in vitro collection of native pear genetic resources.