Development of methods for the production of certified seed potato in Lebanon

Abstract

Lebanon imports annually between 20,000-30,000tons of certified seed potato. Potato yield depends greatly on seed quality. Several areas in Lebanon were listed by the International Potato Center as suitable for seed potato production. This study aimed at developing methods for producing certified seed potato starting from production of virus free plantlets and ending by field multiplication of certified seeds.Virus free plantlets were obtained following simultaneous treatment with chemotherapy (using Ribavirin+Dioxo Hexahydro-Triazine) and thermotherapy which gave better virus eradication than chemo or thermotherapy used alone.Virus free plantlets were multiplied by tissue culture to produce pre-nuclear material. Virus free plantlets, the nuclear material, were multiplied by tissue culture to be used for production of pre-basic material (minitubers), three experiments were conducted in insect-proof greenhouse between 2009 and 2010to optimize factors for the production of minitubers. Simple acclimatization by covering the boxes with Agryl was as efficient as using a acclimatization chamber. Results showed that substrate mixes containing 30percent and above potting soil planted with at a density of 12 plantlets-box, equivalent to 66plantlet-m2, gave the highest yield.Field experiments conducted between 2009 and 2011 for production of basic seeds starting from minitubers showed that minitubers of sizes 2-5g gave significantly lower yield than minitubers of sizes above 5g. The larger minitubers, above 20g, tended to give a slightly higher yield that was not statistically different from tuber sizes 5-10g. An in-row spacing of 15cm gave the best economical yield as compared to 10, 20 and 25cm. Minimum till by planting on soil surface and covering with a layer of straw, yielded a significantly higher number of minitubers with lower average tuber weight. For production of certified seed potato, reducing in-row spacing to 10cm gave the highest yield but it was not statistically different from the 15cm spacing. The yield of unc