This two-year study assessed nitrogen use efficiency (NUE) and its effect on potato tuber protein concentration, focusing on crude protein concentration (CPC), crude protein yield (CPY), and patatin relative abundance (PRA) across 19 potato genotypes and four nitrogen management treatments (organic with no added fertilizers and three integrated treatments with N rates of 60, 120, and 180 kg ha⁻¹). Nitrogen availability significantly affected CPC, with the highest average CPC across genotypes being 10.7% at 180 kg ha⁻¹ and the lowest of 8.15% at 60 kg ha⁻¹. Certain genotypes consistently outperformed others in terms of CPC and/or CPY under varying nitrogen treatments. A significant negative correlation was found between CPC and NUE, and genotypes with higher NUE typically had lower CPC. A positive correlation between CPY and NUE was observed, with the highest CPY of 1.36 t ha⁻¹ at 120 kg N ha⁻¹ in 2020. This suggests that higher NUE genotypes are more efficient in protein production per unit area. PRA varied significantly among genotypes, ranging from 8.7% to 35.51%. Although the relationship between NUE and PRA was weak, the significant and negative correlation indicates that cultivars with high NUE could have low PRA and vice versa. The findings underscore the importance of genotype variability in the relationship between NUE and protein content in potato tubers.

In organic production of potatoes for processing into starch, it is essential to obtain high and stable starch yields, as determined by the yield of tubers and the content of starch in the tubers. The stability of these traits in potato varieties is especially important in variable environments affected by soil properties and climatic conditions. Pre-sprouting of the seed tubers before planting can accelerate plant development and promote acceptable starch yields in a shorter growing period. This study evaluated traits of seven potato varieties important for organic starch production, assessed trait stability in different environments and determined the effect of seed tuber pre-sprouting on plant development and stability parameters. Significant effects of genotype, growing environment, and their interactions on tuber yield, starch yield and starch content of the tubers were observed. No significant effects were found of seed tuber pre-sprouting on the performance of the tested traits. Four trait stability evaluation methods were applied to tuber yield, starch yield and starch content, including a modified Kang’s yield-stability approach, and these showed inconsistent results. The modified Kang’s stability rating could be further used for determination of the best performing varieties, with high values for the essential traits and relatively high stability for each individual trait.

Potato proteins contains essential amino acids in considerably high concentration, therefore potatoes are considered to be one of the most valuable plant origin food for human consumption. Patatin forms one of the largest group of potato proteins with high potential to be used in food industry as a novel food. This study has been performed to approbate patatin determination method for evaluation of protein quality of potato genotypes, as well as evaluate patatin relative abundance (PRA) for breeding programmes to create in the future potato cultivars with higher value and potential to develop new products. The evaluation of patatin was performed in following steps– extraction proteins from potato, determination of patatin concentration and calculation of its relative abundance in proteins. Separation of patatin from potato tubers was made using extraction by SDS extraction buffer and determination of patatin in organically and conventionally (with differnt N suply) grown samples of 20 potato genotypes. The results of one-year study showed that patatin relative abundance of different cultivars varied from 1.65% to 50.2% and it was significantly different among genotypes. The nitrogen content of soil and maturity type of potato did not affect PRA significantly. Results provide impetus for further research.

Dimante I. (2021). Evaluation of possibilities to increase efficiency of potato minituber production. Research paper to obtain for the Ph.D. in Agriculture, Forestry and Fisheries. Latvia University of Life Sciences and Technologies. Jelgava, 149 p. Laboratory, greenhouse and field experiments were carried out at the Institute of Agricultural Resources and Economics, Priekuli Research Center from 2013 to 2017. Hypothesis of the thesis The agronomic efficiency of potato minituber production can be increased without significant financial and technological investment, but the most agronomically efficient growing technology is not always the most cost-effective. The aim of the thesis To evaluate the possibilities of improving the efficiency of potato minituber production by changing the planting density of microplants in the greenhouse to ensure a high yield of high-quality seed potato of the first category under field conditions. Research tasks 1. To assess the effect of increasing the microplant planting density on the number of minitubers of different varieties in the greenhouse. 2. To assess the effect of minituber size on the development of plants and seed yield of different potato varieties under field conditions. 3. To determine the field value of the greenhouse unit area and of one microplant depending on the microplant planting density. 4. To evaluate the economic efficiency of changes in microplant densities (minituber growing technology) in a greenhouse. 5. To examine the effects of the propagation method of microplants on the morphology of microplants and the subsequent effects on the number and yield of minitubers in a greenhouse. The structure of the research paper Chapter 1 - The literature review includes 6 subchapters. A brief overview of potato growth, development and yield formation is provided in the chapter. Insights into the history of the formation of seed potato production systems are given, and potato micropropagation methods and minituber cultivation technologies are examined. Plant growth and development specifically from minitubers under field conditions are described. The approaches used to evaluate the efficiency of tuber cultivation are briefly described. Chapter 2 - Materials and Methods includes 6 subchapters. The chapter describes the methodology of the experiments, the studied material, the observations and analyses performed, the meteorological conditions and the data analysis. Chapter 3 - The results and discussion include 5 subsections. This chapter analyses the agronomic efficiency of minituber production depending on the microplant planting density in the greenhouse. The field performance of minitubers depending on their size and data on the field value of the greenhouse unit area and of one microplant were assessed. The evaluation of the economic efficiency of changes in minituber growing technology has been performed. The effects of the propagation method of microplants on the morphology of potato microplants and the subsequent effects on the number and yield of minitubers in the greenhouse were examined. The conclusions include answers to the research tasks. The paper contains 22 tables, 38 figures, 33 annexes and 342 references.

Different potato genotypes vary in nitrogen uptake and biomass production at different available nitrogen levels. In vitro experiments offer a controlled environment to further explore these variations. The study aimed to evaluate the morphological traits of various potato genotypes in a two-factorial experiment, analysing microplant responses depending on nitrogen availability in the growth medium in vitro. The study, conducted in 2022 in Priekuli, Latvia, tested 19 potato genotypes under varying nitrogen levels in an in vitro medium. The experiment was carried out in three time-shifted series each with four replications. The Murashige and Skoog basal medium used for the experiments included N concentrations of 60 mmol L⁻¹ (N60), 20 mmol L⁻¹ (N20), and 7.5 mmol L⁻¹ (N7.5). The morphological traits analyzed in the potato microplants included plant height, fresh weight (FW) and dry weight (DW) of the total plant, as well as FW and DW of the shoots and roots. Additionally, calculated traits included the root % share, root-to-shoot ratio and the nitrogen stress tolerance coefficient (NstC) of the genotypes. Results showed significant differences in biomass production between different N levels (p<0.05) as well as significant differences between genotypes grown under the same N level were identified. NstC differed between genotypes.