OTIORRHYNCHUS LIGUSTICI L. (COLEPTERA: CURCULIONIDAE) II. METHOD FOR DETERMINATION OF THE DEGREE OF DAMAGE BY LARVA AND BIOCHIMICAL COMPOSITION OF THE ROOT SYSTEM IN DIFFERENT ALFALFA VARIETIES

DOI: 10.7904/2068 – 4738 – III(6) – 75

Ivelina NIKOLOVA, Nataliya GEORGIEVA, Anna ILIEVA

 Abstract: During the period 2006–2009 in the experimental field of IFC–Pleven were conducted studies with 8 varieties of alfalfa included in the Official variety catalog of Bulgaria (2005): Europe (France), Prista 2 (Obraztsov Chiflik, Ruse), Prista 3 (Obraztsov Chiflik, Ruse), Prista 4 (Obraztsov Chiflik, Ruse), Obnova 10 (IFC, Pleven), Pleven 6 (IFC, Pleven), Dara (IFC, Pleven) and Multifoliate (Obraztsov Chiflik, Ruse). For determination of the damage from the large alfalfa weevil Otiorrhynchus ligustici on the root system of plants was developed methodology depending on the root area and the damage area. The area of the roots was calculated by the formula S = (π * d * L) / 2, where π is 3.14; d–diameter of the root collar, L–length of the root. The area of the furrows оn the root system was product of length and width of the furrows. With the lowest percentage of furrows and tolerant to O. ligustici were Multifoliate, Prista 2 and Europe–respectively 10.38, 11.41 and 11.68%. Highly sensitive, with high percentage of damage were distinguished Dara, Prista 4 and Prista 3 (respectively 14.28, 14.05 and 13.58%). As a result of the caused damage the content of sugars and saponins increased as depending on the sensitivity of varieties the increase was different. In the tolerant varieties to the pest the increase in sugar content was less pronounced, but in the sensitive ones–stronger. In regard to the saponins the trend was reversed–the increase in the sensitive varieties was less and in the tolerant varieties–stronger which could be explained with the defensive reaction of plants to compensate the losses from damages of the pest.

Key words: alfalfa, varieties, method of damage degree, biochemical composition, Otiorrhynchus ligustici

OTIORRHYNCHUS LIGUSTICI L. (COLEOPTERA: CURCULIONIDAE) I. COMPARATIVE STUDY OF THE RESISTANCE OF ALFALFA VARIETIES

 DOI: 10.7904/2068 – 4738 – III(6) – 68

Ivelina NIKOLOVA, Nataliya GEORGIEVA

Abstract: From studies carried out during the period 2006–2009 in the experimental field of the IFC–Pleven with 8 alfalfa varieties included in the Official variety catalog of Bulgaria (2005): Europe (France), Prista 2 (Obraztsov Chiflik, Rouse), Prista 3 (Obraztsov Chiflik, Rouse), Prista 4 (Exemplary Chiflik, Rouse), Obnova 10 (EFC, Pleven), Pleven 6 (EFC, Pleven), Dara (EFC, Pleven) and Multifoliate (Obraztsov Chiflik, Rousse) it was found that in the year of the establishment of the stand there was partial damage from Otiorrhynchus ligustici. It was found that surface of caused damage was a major sign to determination ofthe degree ofinfestation from the insect pest as it increased from second tofourth yearon average from 5.6 to 42.1 cm2.Varieties of Multifoliate, Europe and Prista 2 were the least preferred and with low values of surface of damage, number and length of the gnawed furrows. These varieties can be used as sources of germplasm resistant to Otiorrhynchus ligustici.

Keywords: alfalfa, varieties, damage, Otiorrhynchus ligustici

 

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

DOI:10.7904/2068 – 4738 – III(6) – 18

Natalia GEORGIEVA, Ivelina NIKOLOVA

 Abstract: 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/m2. 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).

Key words: alfalfa, varieties, stands density, reduction

 

BIOCHEMICAL CHANGES IN LUCERNE ATTACKED BY LONGHORN BEETLE AND ROOT ROT

Dimitriya S. PETKOVA, Evgeniya D. ZHEKOVA, Anna V. ILIEVA, Iliana I. IVANOVA

Abstract. Eight alfalfa genotypes were investigated at IASS “Obraztsov chiflik”–Rousse during the period 2006–2009. The objective of the study was investigation of biochemical changes in alfalfa roots, attacked by lucerne longhorn beetle (Plagionotus floralis Pall.) and root rot. Biochemical analysis of healthy roots, roots damaged by larvae of longhorn beetle, roots attacked by root rot and green mass were made. The healthy status of roots was evaluated according to the scale of Lyubenets and Shtukina (1968). A moderate negative correlation was determined between total phenols and sugars in plants damaged by longhorn beetle. The content of proteins, fiber, calcium, magnesium and total phenols in plants damaged by longhorn beetle and root rot increased compared to healthy ones and a decrease of sugars was observed. The highest number of healthy plants and high productivity were registered in Synthetic population (SP) N 7 and it could be appropriate in selection for the purposes of breeding.

Keywords: alfalfa, Plagionotus floralis, root rot, biochemistry

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