Natalia Georgieva

Evaluation of damage caused by Bruchus pisorum L (Coleoptera: Chrysomelidae) on some parameters related to seed quality of pea forage cultivars (Pisum sativum L.).

It was evaluated the damage caused by Bruchus pisorum L (Coleoptera: Chrysomelidae) on the germination ability of pea farage varieties (Pisum sativum L.). Result of damage by Bruchus pisorum in seeds with parasitized larva was significant decrease of the germination by 16.4% percentage points, the length and weight of primary radicle by 16.8 and 24.5%, the length and weight of plumule by 12.3 and 14.1%, the vigor index of primary radicle and plumule by 32.5 and 32.8% as well as the germination index by 17.4%. The inhibitory effect was on average 17.8%. Essential significant changes in regard to the studied parameters were found for damaged seeds with bruchid emergence hole. In these seeds the gewrmination decrease by 58.3% percentage points, the length and weight of primary radicle by 34.1 and 36.2%, the length and weight of plumule by 31.8 and 34.3%, the vigor index of primary radicle and plumule by 81.1 and 82.1% as well as the germination index by 83.1%. The inhibitory effect was on average 58.3%. It was found that the damaged seeds with parasitoid emergence hole provided better possibility for growth and development of plants whereas the damaged seeds with bruchid emergence hole had significantly low germination, vigor and sowing characteristics. These seeds could not provide the establishment of well-garnished stand and stable yields. As tolerant to damage by Bruchus pisorum was distinguished Glyans variety for which the values of parameters related to germination and vigor of seeds were influenced in the lowest degree from the damage unlike the sensitive Pleven 4 variety. Dominant factor influencing germination ability of seeds for all analyzed parameters was the type of seeds compared to varietal appurtenance.

Development and reproduction of spider mites Tetranychus turkestani (Acari: Tetranychidae) under water deficit condition in soybeans

SUMMARY One of the major pests of soybeans in Bulgaria is the spider mite Tetranychus turkestani Ug et Nik (Acari: Tetranychidae) and different results have been reported about the impact of water stress on its development and reproduction. Soybean plants exposed to natural infestation by spider mites, water deficit and treatment with imidacloprid were examined under greenhouse conditions at the Institute of Forage Crops, Pleven, Bulgaria, over the period 2011-2012. The development of mites and their eggs was faster when plants were exposed to water deficit, which created favorable conditions for high density and reproduction of T. turkestani. There was a vertical distribution of protonymphs, deutonymphs and adults as their numbers and egg counts were significantly higher under conditions of water deficit on the upper and middle plant parts, compared with their bottom parts, and imidacloprid treatment had a stronger and more prolonged activity against mites, compared to its influence on well-watered plants. Spider mites on water-stressed plants caused a 24.8% reduction in the contents of plastid pigments, and carotenoids, and 21.5% decrease on well-watered plants.

DENSITY AND REDUCTION OF THE STAND AT ALFALFA VARIETIES (MEDICAGO SATIVA L.)

With purpose to study the density and reduction of stand at 9 alfalfa varieties (Europe, Prista 2, Prista 3, Prista 4, Obnova 10, Pleven 6, Dara, Multifoliate and Dama) during 2006–2009 period in IFC–Pleven is carried out an experimental activity. The average density of stand at studied alfalfa varieties during the first year of development was 1313 plants/m. The reduction during next three years was disproportionately and was the strongest pronounced during the second year–by 58.3% to the density of the stand in the previous year. During the third experimental year the reduction of alfalfa was still strong pronounced albeit with a lower value (51.1%) and during the fourth year it was 5 times less than that during the previous two years at average value of 10.6%. In the end of four–year experimental period the reduction at different varieties was in limits from 68.6% (Obnova10) to 85.7% (Dara) at average value for the species of 81.8%. It is established correlations with high negative value among the stand density and root mass weigh/plant (r=–0.811) and diameter of root collar (r=–0.692), and a correlation with medium negative value between the stand density and number of stems/plant (r=–0.488)

Evaluation of genotypic and genetic variances of quantitative traits in pea (Pisum sativum L.)

A new approach has been applied for identification of the changes in gene spectra, in accordance with the graphic model of Hayman, which allows making a comparison of varieties, presented in the graphics, as well as, a new method for interpretation of the change in location of certain varieties, with respect to given signs, at different environmental limits. In the genetic control of the characteristics of plant weight and seed weight per plant, a major role plays gene over-domination. The results obtained indicate a possibility of assessment of field peas genotypes by genetic-physiological systems in different environmental limits. No universal donor has been established between hybrids for attraction and adaptability. From selection point of view, of interest are the hybrids №11 (E.F.B.33 A— Mir) with respect to green biomass (forage) and №12 (E.F.B.33 A— Pleven 10), and with respect to seed №9 (Pleven 10 A— E.F.B.33). Assessment of the source material, according to genetic-physiological systems, allows, with a higher degree of probability, to select an appropriate genotype, which exceeds the parental forms, in terms of productivity and ecological stability, and also to accelerate the process of creating new pea varieties.

ECONOMIC EVALUATION OF FORAGE PEA ORGANIC PRODUCTION

The presented evaluation provides an opportunity to be compared the economic results at different variants of forage pea organic production. From the recommended indicators in economic literature in the current evaluation are calculated following ones: total production (€/da), production costs (€/da), cost price (€/kg), net income (€/da) and rentability (%). In the organic production are used four products: foliar fertilizer Biofа, growth regulator and fungicide Polyversum, bioinsecticides Pyrethrum and NeemAzal which are applied alone and in combination. Comparisons are chemicals (regulator Flordimex, insecticide Nurelle D) that are used in the standard conventional technology. All variants of organic production are cost–effective and enable the realization of good economic results. With the highest economic effect is the application of organic fertilizer Biofa in combination with bioinsecticide Polyversum. In the production of hay, this combination provides profitability of 79.30 %, exceeding the profitability of the standard variant in conventional production (75.00 %); the profitability in grain production (137.05 %) is somewhat lower than that of the conventional variant (140.00 %). Overall, the profitability in different variants of pea organic production for grain and hay is with average values of 109.91 % and 51.67 %, as values for the conventional production are 128.905 and 68.43 %, respectively. Although the result of the economic evaluation is chosen a certain optimal variant of pea organic production, open to future studies remain questions concerning the effectiveness of various organic products in different forms of production organization. Keyword: economic evaluation, rentability, organic production, pea.

NUTRITIVE VALUE OF FORAGE OF VETCH CULTIVARS (Vicia sativa L., Vicia villosa ROTH.)

The chemical composition, plant cell–wall fiber components content, in vitro enzyme digestibility, potential protein and energy feeding value of forage of seven vetch cultivars were evaluated. Vicia sativa L. (cultivars Liya, Lorina, Vilena, Moldovskaya, Obrazets 666) and Vicia villosa Roth. (cultivars Violeta and Viola) were planted at the experimental field of the Institute of Forage Crops, Pleven (Bulgaria) during 2012–2014 period. The origin of Obrazets 666 is Bulgaria and of the rest six cultivars–Moldova. Vicia villosa cultivars revealed a greater content of CP and fiber components, measured as NDF, ADF and ADL (211.4, 451.9, 378.5, 74.0 g kg DM respectively) in comparison with Vicia sativa cultivars (189.5, 409.2, 352.4, 67.9 g kg DM respectively). Quality of the herbage in terms of digestibility was 63.9% IVDMD for Vicia sativa and 52.9 % IVDMD for Vicia villosa. The nutritive value based on arithmetical rank sum of all studied parameters (chemical composition, in vitro enzyme digestibility, protein and energy feeding value) showed better forage quality of V. sativa compared to V. villosa. With the highest nutritive value was distinguished cultivars Liya, Vilena and Moldovskaya, which could be used as germplasm in future breeding programmes for quality improvement. Keyword: fiber, digestibility, vetch, feeding value.

OM NeemAzal–T/S AND Pyrethrum AND THEIR EFFECT ON THE PEA PESTS AND SEED QUALITY

A study was conducted on the influence of biological insecticides (NeemAzal and Pyrethrum, applied alone and in combinations with organic products) to Bruchus pisorum L. (Coleoptera: Chrysomelidae) population density and rate of damaged seeds. The change of chemical composition in damaged by pea weevil and Cydia nigricana Fabr. (Lepidoptera: Tortricidae) seeds was found. The treatments were performed in budding and budding and flowering stages. The toxic effect of biological insecticides Pyrethrum and NeemAzal after treatment in budding and flowering stages was considerably higher in comparison to the single use. The weevil density was decreased at the greatest rate after treatment with Pyrethrum + Biofa (37.5%) among biological treatments. The biological and synthetic products use had positively influence on the crude protein, crude fiber and phosphorus content. The treatment in budding and flowering stages led to a stronger increase in the crude protein and phosphorus content to a single treatment. Keyword: NeemAzal, Pyrethrum, organic products, Bruchus pisorum, crude protein, phosphorus.

Effects of biological insecticides NeemAzal T/S and Pyrethrum FS EC and their interaction with organic products in treatments of pea aphid Acyrthosiphon pisum (Harris) (Hemiptera: Aphididae) on Pisum sativum (L.)

The efficacy and effects of two biological insecticides, NeemAzal T/S® and Pyrethrum FS EC, applied individually and in combination with Polyversum (a biological growth regulator and fungicide) and Biofa (an organic foliar fertilizer), in controlling Acyrthosyphon pisum population density were studied. Nurelle D (a synthetic insecticide), applied alone and in combination with Flordimex 420 (a synthetic growth regulator), was used as a standard. The products were applied once (at budding stage) or twice (at budding and flowering stages). Twenty-four variants were studied. The interaction of Pyrethrum with Biofa was the most efficient variant of the biological products, causing a reduction in aphid density that reached 48.2% after double treatment, while Pyrethrum+Polyversum (42.5%) was the second most successful treatment. The combination of Pyrethrum with Biofa achieved the highest efficacy and synergism and their efficacy approached that of the synthetic insecticide.

STABILITY EVALUATION OF MIXTURES AMONG PREPARATIONS WITH DIFFERENT BIOLOGICAL EFFECT ON BASIS OF GRAIN YIELD IN SPRING FORAGE PEA

During the period 2007–2009 in IFC–Pleven is carried out three–factor field trial with purpose to evaluate the stability of mixtures among preparations with different biological effect on basis of the grain yield in spring forage pea. It is used the split plot method. Factor A includes the three years of the study. Factor B (preparations) includes 8 levels: untreated control, Atonic (growth stimulator), Masterblend (combined leaf fertilizer), Atonic + Masterblend, Confidor (insecticide), Confidor + Atonic, Confidor + Atonic + Masterblend, Confidor + Masterblend. Factor C (stages of treatment) includes 3 levels: budding, budding + flowering, flowering. In result of the held experiment is found that the preparations with different biological effect Atonic, Masterblend and Confidor used alone and in mixtures increase the productivity in the spring forage pea (from 101,9 to 129,0%). With highest stability is distinguished the triple mixture Confidor + Atonic + Masterblend (applied at budding stage), followed by mixtures Confidor + Atonic and Confidor + Masterblend (applied at flowering stage) and at alone use of preparations–the leaf fertilizer Masterblend (applied at flowering stage). Technologically the most valuable variants which match high stability and high productivity in the different years are appeared all of them with twofold treatment of the studied preparations and their mixtures as it is recommended the use of mixtures Confidor + Masterblend and Confidor + Atonic.