الفهرس 
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Abstract
This study was conducted to examine some factors affecting the production of potato microtubers in vitro on MS medium with 8% sucrose, and minitubers ex vitro on soil mix. Results of in vitro experiment indicated significant promotive effects of increasing explant densities from single nodes or whole 6-node plantlets on microtuber number and yield, while microtuber FW was increased with low inoculum density. The culture of single nodes taken from the top part of the plantlet produced higher number and yield, but lower microtuber FW than those taken from the base or the 3- node segment. Leaf removal from nodal explants significantly increased the number, yield and microtuber FW over explants with intact leaves. Cultures incubated at 20°C for 4 weeks, followed by 4 weeks incubation at 25°C showed enhanced microtuber induction compared to incubation at 25°C followed by 20°C. Dark or light of 2 k lux incubation were better than incubation at 1or 3 k lux irradiance. Among the 10 evaluated potato cultivars, the new cv. Safran produced the highest number and yield of microtubers per vessel or per plantlet. Results of ex vitro production of minitubers indicated increase in number and yield, with a decline in minituber size with increasing planting densities of micro shoots or microtubers. Among the tested 19 potato cultivars, the cvs. Universa, Safran and Triomph outperformed the rest of cvs. in minituber production. Seed potato production was also achieved from minitubers.
Keywords: Solanum tuberosum L., tissue culture, explant source, density, incubation environment, seed tuber, genotypes