The effects of different concentrations of NH4NO3 and KNO3 on developmental-cellular variation of microtubers in Solanum tuberosum L. var agria In vitro conditions.

The potato (Solanum tuberosum L.) is one of the most important agricultural plants in the world. Today, potato is the fourth most important food crop in the world after wheat, rice and corn. It is propagated predominantly by asexual method (tubers and minitubers). However, propagation by true seed is primarily used for breeding purposes (enhancement of breeding populations) and genetic studies. The traditional methods for asexual propagation of the plant face important problems including contamination of tubers and plants and decreased crops. Therefore, the seed tubers can be replaced by micrutubers produced by tissue culture. In this study solid and culture media used for produce of sterile plantlets and microtuberization. The aim of this study is search about effect of different concentrations of NH4NO3 and KNO3 in media culture Invitro in histological/ cellular variations of the microtubers. The concentrations of 0, 1/2, 1, 3/2 and 2 times more than standard concentrations of the above mentioned compounds in MS medium were used in separate induction media. The results showed that the alternating light and darkness is more suitable for the variety Agria and the samples kept in absolute darkness demonstrated no microtuberization in this study. Sections for light microscopy were prepared from microtubers in each sample after their dimensions were measured and morphological studies carried out. The aim was to study the histological aspects of samples. The number of cell rows, the dimensions of the cells and the starch content of the parenchymal tissues of microtuber's pulp and the cortex were analyzed. The results again showed significant variations in histological features of the microtubers developed in media containing different concentrations of macronutrients. In this study, KNO3 with concentrations of 1.5 times more than standard concentration in MS medium yielded maximum number of cell rows and maximum starch granules content which were proportional to the average dimensions of microtubers. NH4NO3, with concentrations of 1/2 to 1 time more than standard concentrations in MS medium yielded a better differentiation of parenchymal tissues than other concentrations.