IN VITRO MICROTUBERIZATION OF POTATO: EFFECT OF EXPLANT DENSITY, SOURCE, AND GENOTYPE

This study was conducted to examine explant density and source on production of in vitro potato microtubers, as well as survey of different newly-introduced potato cultivars for their microtuberization capacity at the Plant Tissue Culture Facility of the Department of Horticulture, Suez Canal University between 2014 until 2016. Results indicated that as culture density from single node explants increased, microtuber number and yield/petri dish were also increased. However, at the lowest density (10 explants/petri dish), the % tuberization and the average microtuber weight increased significantly over the higher densities (20, 25 and 30 explants/petri dish). Potato microtuber production from plantlets grown in vitroon microtuberization induction medium (liquid over solid media) was also studied using 5, 10 and 15 plantlets per jar.Results showed that microtuber number and yield/jar increased gradually with increasing plantlet density. However, on per plantlet basis, microtuber number increased at the lowest density. Microtuber yield/jar increased significantly at the highest density (1099 mg/jar) compared to 563.6 mg/jar at the lowest density. Average microtuber weight was also affected by culture density and genotype. At the lowest density, microtubers were significantly heavier than at the high density, and the cv. 'Safrane' recorded the highest weight per microtuber. Regarding the effect of explant source on microtuber production, results indicated that the use of single node explants derived from the top of the plantlet produced more microtubers than those taken from the basal part, or 3 node segments. Explant source also affected microtuber yield/dish. Single nodes from the top produced the highest yield compared to 3-nodes segment from the top (205 vs. 104.8 mg). The highest mean microtuber fresh weight was obtained from the culture of 3-node layered segment from the plantlet base, while single nodes from the top recorded lower microtuber fresh weight. The highest microtuber fresh weight was recorded in cv 'Universa' (114.3 mg) using single nodes from the plantlet base. Differences among the tested potato cultivars in microtuber production were detected.