In vitro propagation of oil-bearing rose (Rosa damascena Mill.)

V. Badzhelova*

Institute of Roses, Essential and Medical Cultures, Kazanlak, Bulgaria (Manuscript received 12 June 2017; accepted for publication 25 August 2017)

Abstract. The purpose of this research is to develop effective protocol for clonal micro propagation of the oil-bearing rose (Rosa damascena Mill.). Explants used in the experiment are 1.0 to 1.5 cm long nodal segments from specially cultivated mother plants. These explants were subjected to a combined method of sterilization with 0.2% solution of HgCI2 for 3 minutes followed by 0.50% solution of NaClO for 20 minutes and 0.25% solution of NaClO for 30 minutes. The best results of multiplication were obtained in basic MS medium with added BAP quantity of 0.5 to 3.0 mg/L. After being separated from the mother plants the young shoots are placed directly in compost mixture for rooting and adaptation. Thus the process of multiplication is shortened, avoiding the period of in vitro rooting.

Parthenogenetic responsiveness of sunflower hybrid combinations with expressed tolerance to herbicides

M. Drumeva*, P. Yankov

Department of Plant Production, Faculty of Shipbuilding, Technical University Varna, 1 Studentska, 9010 Varna, Bulgaria (Manuscript received 6 March 2017; accepted for publication 3 July 2017)

Abstract. For accelerated development of fertility restorer lines with imidazolinone tolerance in sunflower (Helianthus annuus L.), the gamma-induced parthenogenesis, which combines classical breeding approaches and in vitro techniques, was applied. As initial materials six imidazolinone-tolerant hybrid combinations (F1203, F1216, F1246, F1248, F1295 and F1332), obtained from Dobrudzha Agricultural Institute, General Toshevo, were used. To initiate parthenogenetic development mixed pollen from different fertility restorer lines was applied. The mixed pollen was irradiated with a dose of 600 Gy. A total of 166 parthenogenetic immature embryos were obtained, and 84 young plants developed from them, 42 of the plants were fertile. Best parthenogenetic response, expressed as a number of embryos obtained, was observed by hybrid combination F1295, followed by hybrid combination F1332. The lowest parthenogenetic responsiveness is reported in hybrid combinations F1246 and F1248, where the total number of parthenogenetic embryos obtained was 5. In hybrid combinations F1295 and F1332, as well as in F1216, the method of gamma-induced parthenogenesis can be efficiently used for accelerated production of parental lines for heterosis breeding in sunflower. In hybrid combinations F1203, F1246 and F1248, which showed low parthenogenetic responsiveness, conventional methods for developing lines from these hybrids are recommended.

Evaluation of high yielding mutants of Hordeum vulgare cultivar Izgrev

B. Dyulgerova*, N. Dyulgerov

Institute of Agriculture, 8400 Karnobat, Bulgaria

(Manuscript received 7 February 2017; accepted for publication publication 31 May 2017)

Abstract. Seeds of Hordeum vulgare L. cultivar Izgrev were treated with different concentrations of sodium azide to induce genetic variability for the selection of genotypes with improved traits. After passing through different stages of selection, 18 promising mutants were selected for further studies. Eighteen mutants and their parent and national standard cultivar Veslets were evaluated in Complete Block Design with four replications. The research was conducted in 2013 – 2014 and 2014 – 2015 growing seasons in the experimental field of the Institute of Agriculture Karnobat, Southeastern Bulgaria. The characters studied included days to heading, plant height, lodging, peduncle length, spike length, awn length, spikelet number per spike, grain number per spike, grain weight per spike, 1000 grains weight and grain yield. Wide variation among mutant lines was observed for different traits. Mutant lines M4/16 and M3/14 produced significantly greater grain yield than the parent and standard cultivar. Positive changes in lodging tolerance, grain number per spike, grain weight per spike, 1000 grains weight were also observed. This study showed positive effects in the use of mutation in inducing improvement for grain yield and some yield related traits.

Characterization of a new winter malting barley cultivar Ahil

B. Dyulgerova*, Dr. Vulchev, T. Popova

Institute of Agriculture, 8400 Karnobat, Bulgaria

(Manuscript received 7 February 2017; accepted for publication 30 May 2017)

Abstract. Ahil is a new winter malting barley cultivar developed by the method of experimental mutagenesis at the Institute of Agriculture, Karnobat, Bulgaria. Biological and agronomic characteristics of the cultivar were also investigated for several years and at the Executive Agency of Varietal Testing, Field Inspection and Seed Control trails in the period 2012 – 2013. Averaged for 6 locations in Bulgaria grain yield of the new cultivar was significantly higher than the yield of standard cultivars with about 5%. At the Institute of Agriculture grain yield was 17% higher than the average standard for the period of 5 years. The cultivar has high winter hardness, lodging resistance, resistance to powdery mildew and medium resistance to brown rust. Ahil has good malting quality.

Nitrogen uptake and expense in durum wheat depending on genotype and nitrogen fertilization

G. Panayotova1*, M. Almaliev2, S. Kostadinova2

1Department of Plant Production, Faculty of Agriculture, Trakia University, 6000 Stara Zagora, Bulgaria 2Department of Agrochemistry and Soil, Faculty of Agronomy, Agricultural University, 4000 Plovdiv, Bulgaria

(Manuscript received 29 September 2016; accepted for publication 30 January 2017)

Abstract. Nitrogen uptake and expense of durum wheat were studied under the conditions of fertilized field experiment on soil type Pellic vertisol. The seven genotypes – Progress, Vazhod, Victoria, Predel, Deana, Zvezdica and Elbrus selected at the Institute of Field Crops – Chirpan, Bulgaria, were grown in two field crops rotation of cotton and durum wheat under rainfed conditions for a period of three vegetations in years 2011-2013. The spring treatments of nitrogen as NH4NO3 were as follows: N0, N60, N120 and N180. The total N uptake in the above ground biomass of durum wheat increased with the amount of applied nitrogen and during climatically favorable years reached 220 kg N.ha-1. A tendency was found that the new genotypes uptook more N, compared to varieties Progress and Vazhod. The N expense of the new cultivars Predel and Zvezdica showed the highest amount of N per 1 ton of grain, 40.7 and 41.1 kg, respectively. Strong positive correlation was found between N fertilization and N uptake and expense for 1 ton of grain. The regression model indicated that N uptake with the grain and straw and N expense depending on N fertilization occurred with delay. With N fertilization of durum wheat at rates of up to 180 kg N.ha-1 each kilogram of applied N fertilizer increased the average expected N uptake with 7 kg.ha-1 and N expense with 0.66 kg.ton-1 grain.

Productivity and adaptability of new genotypes field pea (Pisum sativum L.) cultivated under environmental condition of Southern Romania

R. Sturzu*, A. M. Ene, Cr. Melucă, J. M. Cojocaru

Agricultural Research and Development Station Teleorman, Drăgănești Vlașca, 147135 Teleorman, Romania (Manuscript received 11 October 2016; accepted for publication 19 January 2017)

Abstract. The purpose of the paper was to identify new peas genotypes, created in Agricultural Research and Development Station, Teleorman, South Romania, with improved productivity and adaptability to the environmental conditions of that region. The study was carried out with 25 field pea varieties for a period of three years (2013-2015). The experiment was conducted in randomized complete blocks design in three replications. The results of variance analysis showed that there was significant difference among pea genotypes by grain yield. The average yield over three years showed that lines M 1357, M 1410, M 1418 and M 720 achieved higher yield levels compared with the control genotype Vedea and with the average yield of all tested genotypes. Yields stability was estimated by coefficient of variability. Correlation analysis showed that the strongest relations there are between productivity elements: number of pods and seeds per plant (r = 0.905), number of pods and seeds weight per plant (r = 0.655), number of seeds per plant and seeds weight (r = 0.815), plant height and first pod insertion height (r = 0.921). There are significant negative correlations between 1000 seeds weight and number of grains per plant (r = – 0.229), number of pods per plant and 1000 seeds weight (r = -0.346), the first pod insertion height and number of pods per plant (r = -0.530), and the number of grains per plant (r = -0.412). The results obtained in this study suggest that, the new field pea genotypes are suitable for spreading and cultivating in Southern Romania.

Use of recurrent selection of early flowering in late maize synthetic population. Results of second cycle of breeding

N. Petrovska*, V. Valkova

Maize Research Institute, 5835 Knezha, Bulgaria
(Manuscript received 10 June 2016; accepted for publication 28 September 2016)

Abstract. During the period 2012 – 2014, a second cycle of recurrent selection of early flowering in a synthetic maize population “Exotic-07” was conducted and finished on the experimental field of Maize Research institute – Knezha. The experiments are carried out by a block method, on a test plot of 10 m2, with three replications, and the respective for the region agricultural equipment. Twenty-three progeny from the first and second cycle, the source and improved exotic maize populations, as well as their testcrosses with the lines ХМ 4416 and PAU 1617 are tested. A phenotypic cycle assumes a leading position in terms of dates of plant silking as the forms of the earliest flowering are used as pollen in the population. The selected early flowering forms are sown for inbreeding and forming an improved maize population. As a direct result of the work of improvement, progeny with a period of days until silking averagely shorter with 5 days and grainmoistureloweredby1.1%areobtained.Theaimofthisstudyistopointoutinbredlineswithashortervegetativeperiodandusethemasparental forms for obtaining high-yielding mid-late maize hybrids.

Heterosis and degrees of dominance of grain yield and grain yield elements in maize hybrids in different groups of ripeness

M. Ilchovska*

Maize Research Institute, 5635 Knezha, Bulgaria
(Manuscript received 10 Juny 2016; accepted for publication 29 November 2016)

Abstract. This study is conducted in the period 2014 – 2015 in the experimental field of the Maize Institute, Knezha by using an agro technique adopted for the region. For the purposes of the study four maize hybrids Kn 307, Kn 435, Kn 509 and Kn 625М are included at different degree of maturity – FAO 300-399; 400- 499; 500-599 and FAO above 600. The hybrids together with their parental forms are studied in competitive variety trials under conditions without irrigation at three densities of the crop 45000pl/ha; 55000рl/ha and 65000рl/ha. From the presented results obtained based on the data of manifestation of heterosis and the degrees of dominance of the hybrids clearly expressed heterosis is established for the traits grain yield, length of cob and number of grains per row. For the trait number of rows in the cob both presence and absence of heterosis is observed. The degrees of dominance in F1 also vary widely, from intermediate inheritance to incomplete positive dominance and over-dominance.

Heterosis manifestations by survival and larval duration of F1 Bombyx mori L. Hybrids reared with artificial diet

R. Guncheva1*, M. Panayotov1, P. Tsenov2, Y. Dimitrova2

1Department of Animal Science – Non-ruminants and other Animals, Faculty of Agriculture, Trakiа University, 6000 Stara Zagora, Bulgaria 2Sericulture and Agriculture Experiment Station, 3000 Vratsa, Bulgaria

(Manuscript received 2 July 2016; accepted for publication 22 November 2016)

Abstract. The aim of this paper was to study the influence of the degree of heterosis (compared to higher parent value- HP and mean parental values- MP) on the signs, survival and duration of development in F1 hybrids of Bombyx mori L. from different geographical origin, fed by artificial diet. The study was conducted at the Training Experimental Station of the Sericulture section of the Faculty of Agriculture at Trakia University. A total of 10 hybrids were tested featuring 6 breeds from the genetic bank of Sericulture and Agriculture Experiment Station (SAES)-Vratsa. Silkworms were reared with artificial diet containing 15% powder of dried mulberry leaf produced at SAES-Vratsa and prepared by methods, developed by the manufacturer, whereby 250g of dry substance and 675ml of distilled water are homogenized using a mixer. The mixture is cured thermally in a microwave for 10min. at ~800W. The receptivity of specimens was determined based on the results from the survival and the duration in the I-st age of the larval stage. In heterogeneous crossbreds higher survival rate in the first age is exhibited by hybrids in which a Japanese type breed was used as dam. Homogeneous crossbreds created with the participation of Japanese breeds excel in both analyzed traits those involving a Chinese type. For the survival trait heterosis manifestations to higher parent value (HP) and mean parental values (MP), were detected in the majority of hybrids (90.91%). Regarding the duration of development, heterosis effect to MP was observed in all F1 hybrids, while to HP heterosis is exhibited by 60% of the tested F1 hybrids.

Breeding programme for developing new sweet cherry cultivars in the Fruit Growing Institute, Plovdiv, Bulgaria

S. Malchev*, A. Zhivondov

Fruit Growing Institute, 12 Ostromila, 4004 Plovdiv, Bulgaria
(Manuscript received 2 June 2016; accepted for publication 21 September 2016)

Abstract. Sweet cherry is a major structural species in Bulgaria. According to the Ministry of Agriculture and Food, in 2010 it occupied 21% of the fruit tree areas, which defined it as a leading fruit crop. It represents 16% of the total fruit production in the country, as is the relative share of peach, being surpassed only by apple and plum production. The increased interest in establishing new cherry plantations necessitates the provision of new market-oriented cultivars with a better sensory profile of the fruits, resistant to biotic and abiotic stress factors, suitable for creating modern intensive cherry plantations. The Bulgarian sweet cherry cultivars are chronologically discussed and a thorough description of the development of the sweet cherry breeding programme, launched at the Fruit Growing Institute in Plovdiv in 1987, is presented. Current objectives comply with the world’s major breeding trends and the changing market requirements. The paper reflects the main objectives of the programme and the finalized products obtained in the last twenty years of the past century and first decade of the new millennium, i.e. the new cultivars ‘Kossara’, ‘Rosita’, ‘Rozalina’ and ‘Thrakiiska hrushtyalka’ and some promising hybrids.