The study was aimed to investigate the effect of potato (Solanum tuberosum L.) in vitro plantlets planting density under greenhouse conditions on obtained minitubers number per unit area, multiplication rate and their weight distribution. Three cultivars of different maturity (‘Monta’ – early maturity, ‘Prelma’ – medium early and ‘Mandaga’ – medium late maturity) were used for the study. In vitro plantlets were planted in a greenhouse of State Priekuli Plant Breeding Institute, Latvia in 2014 at four planting densities (PDs) 63 plants per square m, 95 plants per square m, 142 plants per m2 and 184 plants per square m respectively. Fertilized peat was used as a substratum. Significant effect of planting density (p is less than 0.001) and cultivar (p is less than 0.01) was found on analyzed yield parameters. Increased planting densities resulted in increased minitubers number per square m (from 272 minutubers mE-2 at PD 63 plants mE-2 to 414 minutubers mE-2 at PD 184 plants mE-2), decreased multiplication rate (4.3 to 2.7 minitubers per planted plant) and mean fresh weight of minitubers (from 20.26. g to 12.11 g). The highest increase of minitubers number per m2 was observed within size (weight) range 3 to 5 g. Minitubers number per m2 increase within bigger size ranges (5 to 10 g, 10 to 20 g) was less pronounced. Slight insignificant (p=0.330) decrease of minitubers number is greater than 20 g was observed in relation of planting density increase (112 minitubers mE-2 at PD 95 plants mE-2 to 84 minitubers mE-2 at PD 184 plants mE-2).

Morphological parameters and their changes common for artificially reared one year old sea trout were examined from January to May the year 2013 to determine whether these parameters indicated the smoltification in one year old sea trout and whether these fish achieved smolts stage. Fish were reared in flow-through and recirculation systems in hatcheries based on three different rivers (Brasla, Daugava, Venta basin). Sea trout were examined in the Latvia University of Agriculture, Faculty of Veterinary Medicine, Institute of Food and Environmental Hygiene and in the Institute of Food Safety, Animal Health and Environment BIOR, Laboratory of Aquaculture and Fish Pathology. To appreciate fish growth stage condition index, hepatosomatic index, spleen index was calculated and silvering level was evaluated. The fish condition index decreased in all hatcheries and flow-through and recirculation rearing systems from January to April and increased in May. Spleen index was the most stable parameter and did not change a lot showing that fish did not have migratory stress in April and May. Silvering level increased from January to April but suddenly the increase became slower in May without reaching the top level. These results made us to consider that one year old sea trout parrs released in May 2013 probably did not become smolts before release and they had to stay in river for one additional year until reaching pronounced smolt stage.

Oat (Avena sativa L.) is one of the small grain crops produced in temperate climate zone. Common oat has been studied most often due to its multifunctional characteristics and nutritional profile. The main function of the oat husk is to protect grain from harmful conditions during harvesting and storage time. Oat grain size uniformity is an important parameter to the oat milling industry. The aim of this study was to compare the husk content of common oat cultivars grown in Latvia and to obtain its changes at different grain size fractions during three growing seasons. The field trial was carried out at the State Stende Cereal Breeding Institute from 2012 to 2014. Ten husked oat genotypes were studied. Oat samples were fractioned into size fractions and samples of each fraction dehulled by hand. Results showed that significant (p is less than 0.05) differences in the husk content were observed among genotypes, growing season and different grain size fractions. Significantly lower husk content was for genotype ‘Arta’ in all growing seasons. For majority of used genotypes increasing grain size the husk content decreased.

From legume seeds it is possible to make new products with different physical properties such as size and hardness by using extrusion-cooking. Peas are products that normally need a rather long cooking time, but extrusion-cooking can make them more usable in daily human diet. As protein based food products in markets are less represented than those based on carbohydrates, but for balanced diet protein intake is essential, our aim was to ensure availability of such products, so experiments were carried out in order to establish optimal moisture content for grey pea (Pisum sativum L.) flour extrusion. Three grey pea (Pisum sativum L.) based products were obtained with different water amount added before extrusion, and their size, volume mass and colour was analyzed in order to ascertain what amount of water is best for such products. Results show significant differences for size, volume mass and colour changes, establishing that the best of the products was the one with 9.00±0.01 g∙100gE-1 added water. This product had better characteristics than others, where 11.00±0.01 g∙100 gE-1 and 7.00±0.01 g∙100 gE-1 water was added. The products with 9.00±0.01 g∙100 gE-1 added water were by more than 100 g∙LE-1 lighter than other products, also colour changes compared to non extruded pea flour were fewer than for other samples and their size was the biggest of all obtained products, averagely 11±1mm.