No abstract

Due to specific climatic conditions, perennial ryegrass breeding in Serbia is focused on resistance or tolerance to abiotic stress factors, especially to drought and high temperatures. These traits should be associated with high dry matter yield and quality. Therefore, most frequently used initial material is autochthonous populations and ecotypes adapted to local agro-ecological conditions, but knowledge about their variability of important traits for breeding is missing. Pre-selection evaluation of ten populations of perennial ryegrass originating from Serbia is presented in this paper. Twenty five traits were investigated during the two-year period and processed using analysis of variance and multivariate statistical methods (cluster and principal components analysis). The goal was to determine diversity and genetic distances of investigated populations by phenotyping and to define traits considerably affecting the variability and discrimination of populations. On cluster diagram two groups of population are observed, but geographic origin of populations (lowland, hilly, mountainous habitat) was not influence to clustering of collection. Factor analysis has clarified that first seven principal components (PC) described almost 95%. The traits which show high correlation coefficients with first principal component were plant height in first cut, leaf length and width, DM of generative tillers, spike and spikelet length and 1000 seed weight, and with second principal component time of heading, terminal internode length, DM of vegetative tillers, spikelet number and FSU. It can be concluded that variability between populations was high and that differences of population were mainly affected by most important traits for breeding, such as components of dry matter production and some seed yield components

Products of metabolism that are directly involved in growth, development and reproduction and also secondary products of metabolism were studied in 16 natural populations of three species of the genus Trifolium (T. repens -four populations, T. alpestre -three populations, T. pannonicum -nine populations), collected from the central Balkans region, i.e. territory of Serbia. Statistical analysis showed the presence of variability in all species of the test material. The best quality of dry matter, estimated by the ratio of crude protein and crude fiber, was achieved in the populations of white clover. In this species, average protein content was 216.4 g kg . It can be concluded that the selection of these populations may lead to creation of different varieties of fodder crops that could give safe animal feed and would be suitable for growing under adverse conditions of mountainous climate.

The aim of this study was to examine genetic variability, heritability and correlation of seed yield components and seed yield of progenies of autochthonous populations and cultivars of perennial ryegrass, and that on the basis of these results distinguish genotypes that would be later used in the creation of new local cultivars of perennial ryegrass. Research was carried out on experimental fields and laboratories of the Agricultural Institute of Republic of Srpska in Banja Luka in 2007. and 2008., on 6 natural populations of perennial ryegrass collected in Bosnia and Herzegovina and two cultivars, Maja and Calibra as standard. Following parameters were analyzed: number of generative tillers per plant, time of flowering, spike length, number of spikelets per spike, seed yield per spike and plant and 1000 seed weight. Analysis of the results of the number of generative tillers per plant indicates a statistically significant difference in the studied populations and cultivars of perennial ryegrass. The highest average number of tillers per plant was found in the cultivar Maja (193.8), and the least number was detected in population Dragočaj (78.9), so statistical differences were highly significant. The longest period to beginning of flowering was determined in cultivar Calibra (56.5 days) and the shortest in population Laminci (43 days). The average length of spike of perennial ryegrass in the studied population was 22.78 cm and was significantly lower than cultivar Maja. Statistically significant differences between populations and variety Maja in the number of spikelets per spike were detected. The average seed yield per spike of studied populations was in level with cultivar Maja and 37.5% higher compared with variety Calibra. In the studied populations of perennial ryegrass seed yield ranged from 5.21 g (Dragočaj population) to 15.40 g (Kupres population). Weight of 1000 seeds was highest in the variety Calibra (2.60 g) and lowest in population Maglajani (1.94 g). Proportion of genetic to phenotypic variance for time of flowering, the number of generative tillers, seed yield per spike and plant and 1000 seed weight indicate that the variability of these traits in this collection of genotypes, largely derived from plant genotype. In this investigation, the presence of a highly significant positive genetic correlation was found between time of flowering and spike length (0.98), time of flowering and 1000 seed weight (0.97), number of generative tillers and seed yield per plant (0.91) and spike length and 1000 seed weight (0.98). [Projekat Ministarstva nauke Republike Srbije, br.TR31057

In limited growing conditions, intercropped field peas and oats can represent a significant source of forage rich in protein. If applied correctly, factors such as nitrogen fertilizer, the mowing phase, and sowing norms can significantly increase the productivity of these mixtures. Field trials were conducted to examine their productivity under different nitrogen levels (0, 40, 80 kg ha−1), different sowing norms/mixtures (field peas: oats—100:15%; 100:30%), and two stages of growth (full flowering, full pod formation). Nitrogen fertilizer and different sowing norms had a significant effect on the biomass, hay, and crude protein yields. On average, the highest hay yields were achieved with 80 kg ha−1 N (4.96 t ha−1), followed by 40 kg ha−1 N (4.27 t ha−1). The highest protein yields were achieved with 40 kg ha−1 N (CP—704.1 kg ha−1), followed by 80 kg ha−1 N (CP—637.6 kg ha−1). Sowing norm 100:30% achieved higher hay yields: 100:30%—4.82 t ha−1; 100:15%—4.44 t ha−1, while 100:15% achieved higher crude protein yields: 100:15%—730.4 kg ha−1; 100:30%—692.7 kg ha−1 on average. The costs were not significantly increased with the nitrogen fertilizer, but the net profits were increased by as much as 163%, depending on the nitrogen level and the mixture. Nitrogen fertilizer also achieves higher economic efficiency for the mixture 100:15% compared to the 100:30% mixture. Mixtures of field peas and oats outperform single-grown crops and provide cost-effective feed for a short time. Using optimal seed ratios and nitrogen fertilizer can significantly increase the productivity and profitability of the feed with minimal impact on the overall production costs.