The study is aimed at establishing an efficient protocol for ”in vitro” medium term conservation of sweet potato. Three medium variants and three different temperatures were used for this purpose. In this experiment 6 varieties of sweet potato were tested (Juhwangmi, KSC1, Yulmi, KSP1, Hayanmi and VSP1). Uninodal segments of fully developed sweet potato plants already established ”in vitro” were cultured on MS basal medium with and without osmotic regulators (mannitol and sorbitol). The cultures were incubated at three different temperatures: 24±2ºC, 20±2ºC and 16±2ºC. After 140 days of ”in vitro” conservation shoots height, number of leaves, number of roots and survival rate (%) were measured. Culture condition variants V1 (MS, 24±2ºC) and V2 (MS + 10g/l mannitol + 10 g/l sorbitol, 20±2ºC) ensured the best results regarding shoots height, number of leaves and number of roots. The highest survival rate (87.78% and 84.44%, respectively) were observed in the V2 and V3 (MS + 15g/l mannitol + 15 g/l sorbitol, 16±2ºC) culture condition variants. The slow growth technique allowed the successful ”in vitro” medium term conservation of sweet potato genotypes.

This paper is the first to report the soluble carbohydrate content at harvest for eight Transylvanian potato cultivars: Christian, Cumidava, Kronstadt, Riviera, Roclas, Rustic, Tampa and Zamolxis. The aim of this study is to explore the soluble carbohydrate composition of the above-mentioned cultivars, since such quantitative information is important for breeding programs, consumers and processing units. High performance liquid chromatography was used for analysis, separations being achieved using a Prominence Shimadzu system with a refractive index detector, under isocratic conditions with a mobile phase consisting of acetonitrile: water (80:20%) delivered at 1 mL/min; baseline separations of the target analytes were accomplished with an EC 250/4 Nucleodur 100–5 NH₂ RP column in less than 10 min. The carbohydrate concentrations were found to range from 24.03 mg/100 g (Zamolxis) to 76.58 mg/100 g (Riviera) for fructose, while the corresponding range was from 52.78 mg/100 g (Zamolxis) to 232.97 mg/100 g (Riviera) for glucose and from 238.41 mg/100 g (Zamolxis) to 378.45 (Cumidava) for sucrose. Chromatographic data were then subjected to chemometric analysis; the association of these complementary techniques allowed a fast selection of cultivars with low-reducing carbohydrate content for food processing purposes—the cultivars Zamolxis, Kronstadt, Christian and Roclas were outlined exhibiting both the lowest reducing carbohydrate content and the lowest sucrose content.

The potato varieties studied in this paper were created at the National Institute of Research and Development for Potato and Sugar Beet Braşov. They have a high biological production capacity and are attractive and very appreciated by farmers, potato producers, consumers and processors, but manifest recalcitrance to the in vitro culture techniques. Thus we tried to find an optimal culture medium variant for these varieties, in order to obtain healty potato seed material in a short time. The study compared the effects of five different culture media using MS medium containing various concentrations of gibberelic acid (GA3) in combination with α-naphthalene acetic acid (NAA) in micropropagation of two recalcitrant potato varieties, Marvis and Brasovia. The longest shoots, maximum number of nodes and leaves, the longest roots and the best rooting efficiency were recorded on MS medium containing 2 mgL-1 GA3 and 1 mgL-1 NAA, for both varieties. The use of a larger quantity of GA3 negatively influenced the potato shoots and roots growth. The culture media using MS medium containing 4 mgL-1 GA3 and 1 mgL-1 NAA had an inhibitory effect on all the studied plantlet characteristics. The results showed that a certain combination of growth regulators (NAA and GA3) improved the micropropagation capacity of the two recalcitrant potato cultivars studied and resulted in the maximum improvement in the parameters.

With a high capacity for adaptation and colonization in many ecological systems, including crops, aphids are interesting models of study. Aphids can cause damages to potato plants by inducing feeding injuries and transmitting plant viruses. In order to evaluate the fluctuations of aphids in potato crop, an investigation was carried out in area of Ţara Bârsei from Braşov (Romania), using 56 years long time series data. To identify the aphid species and to assess the relevance of their structure and abundance, between the years 1963 and 2018, a study of these pests in potato crop was conducted. Aphid monitoring was carried out using the method of yellow water traps, suitable for studies on aphid population structure, abundance and flight activity. Species were identified using keys for identification of alatae aphids. Great differences were observed on aphid structure, abundance, distribution and flight activity over the studied years. For seed potato crop, the greatest interest was presented by Myzus persicae species, the main viral vector from this crop. The monitoring of aphid populations, the analysis of the abundance of aphid species contribute to the knowledge of the activity and evolution of the aphid fauna specific to potato crops over long periods of time.

Being one of the most consumed vegetables across the world, potato is a highly nutritious crop, constituting an important source of essential compounds for human health. The present study evaluated the total content of phenolic compounds (TPC)in the skin and flesh of several Romanian potato cultivars with different resistance to potato virus S (PVS) grown in Brasov, over two years. Significant differences were observed across the cultivars. Lower levels of TPC were found in the flesh than in the skin of the tubers. Blue genotype “Blue Purple of Galanesti” and Romanian cultivar ‘Foresta’ had the highest values for TPC in skin and flesh. This study contains information regarding the content of valuable micronutrients of several new Romanian potato cultivars with good nutritional quality and different resistance to PVS.