In vitro Propagation and Callus Induction of Pear (Pyrus communis) Cv. Le-Conte

The traditional propagation technique of pear trees by grafting on quince, seedlings or clonal selection of Pyrus communis is not completely satisfactory. This is because of the lack of compatibility with some cultivars, heterogenesis of the pear seedlings and excess growth and also due to the sensitivity of the grafted plants to pear decline. For this the present study was conducted at the Tissue Culture Laboratory, Horticulture, Research Institute, Agricultural Research Center (ARC), Egypt during the period from December 2013 to March 2016 to investigate the effect of different media type Murashige and Skooge (MS), Gamborge (B5) and Woody plant media (WPM) at four salt concentrations (Full, ¾, ½ and ¼) of culture media on micropropagation of pear (Pyrus comumunis) cv. Le-Conte during the establishment stage. Shootlet proliferations were investigated at different concentrations of benzyl amino purine (BAP) and kinetin (Kin) at 0.25, 0.5 and 1.0 mg/l for each, during two successive subcultures. Finally, rooting capacity was studied by various concentrations of indole butyric acid (IBA) and indole acetic acid (IAA) at1.0, 2.0 and 3.0 mg/l on media containing activated charcoal. The culture explants were successfully disinfected by using Colorex 20% for 15 min with 100% survival and 100% free contamination. MS media at full strength was the best culture media that produced shootlet (1.33 shootlet/explant) and shootlet length 3.67 cm with 9.97 leaf/shootlets. Among the different concentrations, 1.0 mg/l BAP showed the highest shoot proliferation of 5.89 and 5.44 shoots per explant at the first and second subculture, respectively. The longest shoot (2.43 and 2.59 cm) was produced in the two subcultures by the treatment combination of 0.25 mg/l BAP. The highest numbers of roots were produced by 1.0 mg/l IAA were 8.0 roots/shootlet and the tallest length of roots were obtained for explants cultured on MS media containing IAA 3 mg/l and use mixture from NAA and 2,4-D 2:2 mg/l to get the highest value of callus formation 100%. Generally, it can be concluded from the obtained results that using Clorox 20% per 15 min at the disinfecting stage and using MS salt at full strength for the establishment stage, then using BAP at 1.0 mg / l to increase the number of shoots at the proliferation stage and using a mixture of NAA and 2,4-D 2:2 mg / l to obtain the highest value of callus formation. Moreover, using IAA at 1 mg / l to obtain the highest number of roots.