245 ANNALS OF THE UNIVERSITY OF CRAIOVA Series:  Biology  Horticulture  Food products processing technology  Environmental engineering Vol. XXVI (LXII) – 2021 CHARACTERIZATION AND EVALUATION OF SOME POTATO CLONES REGARDING THE BEHAVIOR TO HYDRIC STRESS IN VITRO CONDITIONS Hermeziu Manuela 1* , Tican Andreea 1 , Hermeziu Radu 1 , Chelmea Carmen 1 1 National Institute of Research and Development for Potato and Sugar Beet Brasov (Romania) *Corresponding author, e-mail: hermezium@gmail.com Keywords: potato, culture medium, in vitro, hydric stress ABSTRACT Potato (Solanum tuberosum L.), the third (after wheat, corn and rice), most important food in the world is currently suffering from climate change. The potato crop is strongly influenced by the amount of precipitation and their distribution. The present study was conducted to determine the cultural behavior, respectively the response to hydric stress of some clones from the National Institute of Research and Development for Potato and Sugar Beet Brasov. Two factors were tested: factor I - potato breeding lines 27; factor II – culture medium (clasic medium Murashige – Skoog and medium Murashige – Skoog with osmotic agent). 1982/3 clone was identified with high values and significant differences in case of medium with PEG in 2% concentration, for the number of leaves/plantlets and for root lenght. Also, 1939/2 clone was identified with high values for the number of leaves/plantlets and 1982/1 clone for the root length. 1958/3 clone presented high values for two of the analyzed parameters: plantlet length and fresh plantlets weight, when was applied PEG 2% in the nutrition medium. INTRODUCTION Potato regularly suffers from water scarcity in most regions where it is grown due to irregular rainfall or inadequate irrigation techniques. Potato crop often needs additional irrigation, which is an unavailable resource in many locations. (Obidiegwu 2015). Changing climatic conditions that lead to higher temperatures, dry periods, will increasingly affect potato production in many parts of the world (Evers et al, 2010). Improving drought tolerance of potatoes through conventional breeding methods or biotechnology should be promoted. The aim is to considerably reduce the time of creation of a new variety, so that at the time of its identification there is already biological material with the desired characteristics, to be used for the propagation process (Cabello 2013). At high temperatures, in drought conditions, the temperature of the leaf rises well above the air temperature. Thus, the stomata close, the perspiration process is stopped, the photosynthesis process ceases and the leaf withers (Monneveux, 2014). High soil temperatures are more harmful to potato production than high air temperatures. Drought impairs mitosis, cell elongation and expansion,resulting in a reduction in plant length, leaf area and crop growth (Hussain et al., 2008, Albiski, 2012). Reduction of leaf size is the first morphological manifestation due to drought (Jefferies and MacKerron, 1987) associated with reduced light interception DOI: 10.52846/bhfe.26.2021.35