YIELD OF BROOMCORN (SORGHUM VULGARE VAR. TECHNICUM [KÖRN.]) CULTIVATED IN SOUTHERN BULGARIA

A three years’ comparative trial was conducted in Agricultural Experimental Station in the Eastern Rhodopes – Kardzhali, Bulgaria to assess the productive potential of five broomcorn genotypes – cultivar Prima and populations S14, G16, L18 and MI16N. Fresh biomass yield was formed by two to three cuttings per season, depending on annual precipitation quantities. The average duration for cutting formation for the region is from 35 to 45 days. When grown in Southern Bulgaria (Kardzhali region) broomcorn landraces can produced up to 9974 kg/da fresh biomass and up to 1977 kg/da dry mass, depending on the cultivation year. The highest yield of fresh and dry biomass was obtained from the local population MI16N, which exceeds the standard variety Prima from 131.8% to 185.1% and an average of 159.1%. This study demonstrates the potential of growing broomcorn for fodder in the conditions of Southern Bulgaria

Trace Element Content of Polyfloral Honey and Beeswax from the Vicinity of Non-Ferrous Metal Plant

Bees and their products occupy an important place in the trophic chain “toxicant-soil-plant-bee-bee product-man”, so it has been suggested that bees and bee products should be considered as not a costly method for monitoring of the environmental pollution. Aim of the present study was to analyse trace element content of polyfloral honey and beeswax, produced in three beehives, situated in the vicinity of non-ferrous metal plant and to assess the hazardous risk at consummation. For the purposes of the study, three beehives in this area have been chosen, as follows: BH1 – located at distance of 3.8 km from the smelter, SW; BH2 – at 4 km distance, NE; BH3 – at 4.6 km distance, SE. Content of Al, Cr, Co, Cu, Fe, Mn, Ni, Pb, Sr and Zn was determined by ICP-MS. Data revealed approximately low content of heavy metals and toxic elements. Beeswax samples were found to contain significantly more Cr, Cu, Fe, Pb and Zn, in comparison with the honey samples (p BH1 > BH3

Effect of Grain Moisture Content on Popping Yield of Sorghum Genotypes

This paper aimed at providing popping characteristics of different red and white sorghum genotypes according to different moisture content at traditional methods of popping using high temperature for a short time (HTST). To increasing grain moisture level, seven sorghum genotypes - mutant and hybrid lines (M1(6282), 16113, 16121, 1641, 1643, 1651, 1673) were soaked to 0, 60, 120 and 180 min in distilled water. The popping rate and expansion ratio were recorded. The results showed that conventional method of popping is a good main to produce pops sorghum after increasing moisture of grains. Moistening of grains from 13-16 % increased 5.3-10.2% popping rate of all sorghum genotypes. The mutant line M1(6282) with red coloration of pericarp had the highest popping rate and expansion ratio at 16% moisture i.e. 85% and 3.88 %, respectively. There was correlation between diameter of grains and parameters expansion ratio (from 0.604 to 0.724), popping rate (from 0.815 to 0.878) and moisture grains (from 0.815 to 0.878)

Popping characteristics of sorghum genotypes (Sorghum bicolor (L.) Moench)

Twelve genotypes (varieties, hybrids, mutant and hybrid lines) of sorghum (Sorghum bicolor (L.) Moench) were studied. The objective of the study was to determine the popping performance and to establish the relationships with some biochemical parameters (content of crude proteins, starch, moisture) and grain characteristics (pericarp color, grain width, 1000-grain weight). Popping yield of sorghum grain genotypes was in range 32.0% - 72.0%. The highest influence on popping yield had 1000-grain weight (r = 0.831), starch content (r = -0.356), followed by moisture content (r = 0.212) and crude proteins (r = 0.282). It was found that the endosperm of the seeds expanded poorly in most genotypes with white coloring of the pericarp (from 33.3 to 90.1%), while for those with a dark-colored seed pericarp, the expansion was from 50.0% to 160.0%. Mutant line M1 (6282) (dark brown color of the pericarp) and hybrid line 1643 (white color of the pericarp) stood out with relatively better popping characteristics and particle size of popped grains. This study demonstrated one of the qualities of sorghum grain- poppability and opportunities for enrichment of the genetic diversity for the breeding program in this culture

ALLELOPATHIC POTENTIAL OF SOME WEEDS IN THE RICE FIELDS OF THE KOCHANI REGION

During the period 2021-2022, the allelopathic effect of three weed species Scirpus mucronatus L., Scirpus maritimus L. and Heteranthera reniformis Ruiz & Pav. was studied under laboratory conditions at the Institute of Forage Crops, Pleven from the rice fields in the Kochani region and determining the allelopathic tolerance of four rice varieties Ronaldo, Opale, San Andrea and Halilbay grown in the Republic of Macedonia. It was established that the developed in vitro test ensures the obtaining of reliable results for the allelopathic effect of S. mucronatus, S. maritimus and H. reniformis and the allelopathic tolerance of the Ronaldo, Opale, San Andrea and Halilbay rice cultivars included in the study. The use of agar-gel as a carrier of allelochemicals and development environment has sufficient water supply and compacted structure to support the optimal development of the accessions included in the experiment development index (GI%) varied from 21.5 to 129.2%) and proof of allelopathic interference in rice. In terms of allelopathic tolerance to weed species, rice varieties can tentatively be ranked in the following order: Halilbay (GI% average 47.5%) → Ronaldo and Opale (GI% average 62.3%) → San Andrea (GI% average 94.1%)

Allelopathic activity of some parasitic weeds

Allelopathic activity of Cuscuta epithymum L. (CVCEY), Cuscuta campestris Yuncker (CVCCA), Phelipanche ramosa (L.) Pomel (ORARA), Phelipanche mutelii (Schultz) Reuter (ORARM) and Phelipanche spp. (PHESS) on germination and initial development of test plats of Lactuca sativa L. cultivar 'Great Lakes' was studied under laboratory conditions. It was found that, water exracts of the parasitic weed species in concentrations 0.4, 0.8, 1.6, 3.2, 6.4 and 12.8% w/v have a relatively high inhibitory effect on the seed germination of test plants. The inhibiting rate of parasitic weed species from family Convolvulaceae ranges from 6.24 to 100.0% and for the species of family Orobanchaceae from 42.1 to 100.0%. Parasitic weed species from family Orobanchaceae (Ph. ramosa, Ph. mutelii and Phelipanche spp.) showed a considerably stronger allelopathic effect (GIaverage 17.9), as compared with the applied concentrations of water exracts of species from family Convolvulaceae (C. epithymum and C. campestris) (GIaverage 22.7)

A Preliminary Study of Soybean Genotype Responses to Glyphosate

The effect of four application rates of glyphosate (Roundup, 360 g a.i./l) – 180; 360; 720 and 1440 g a.i./ha on the survival, dynamics of growth, and accumulation of fresh biomass in g per plant was studied on eight newly-developed Bulgarian lines, varieties and candidate varieties of soybean bred by different methods under greenhouse conditions. The objective of this study was to determine and compare the sensitivities of different soybean genotypes to glyphosate. The studied soybean genotypes showed different levelsof glyphosate sensitivity due to their genetic differences. Glyphosate rates of 180, 360, 720 and 1440 g a.i./ha, applied at the stage of three trifoliate leaves (V4) of soybean had effect on the survival of the studied genotypes and can be presented conditionally in the following order: H (40.6%) < G (40.7%) < D (51.3%) < C (52.6%) < F (58.9%) < E (60.5%) < B (62.0%) < A (65.3%). The depression coefficients (B) of the studied characteristics dependedmainly on soybean genotypes and the applied herbicide rates. The tested glyphosate rates showed a high (GI 26.5-51.6%) to relatively low degree of toxicity (GI 16.0-18.7%) in the studied soybean genotypes

Preliminarno proučavanje odgovora različitih genotipova soje na glifosat

The effect of four application rates of glyphosate (Roundup, 360 g a.i./l) – 180; 360; 720 and 1440 g a.i./ha on the survival, dynamics of growth, and accumulation of fresh biomass in g per plant was studied on eight newly-developed Bulgarian lines, varieties and candidate varieties of soybean bred by different methods under greenhouse conditions. The objective of this study was to determine and compare the sensitivities of different soybean genotypes to glyphosate. The studied soybean genotypes showed different levels of glyphosate sensitivity due to their genetic differences. Glyphosate rates of 180, 360, 720 and 1440 g a.i./ha, applied at the stage of three trifoliate leaves (V4) of soybean had effect on the survival of the studied genotypes and can be presented conditionally in the following order: H (40.6%) < G (40.7%) < D (51.3%) < C (52.6%) < F (58.9%) < E (60.5%) < B (62.0%) < A (65.3%). The depression coefficients (B) of the studied characteristics depended mainly on soybean genotypes and the applied herbicide rates. The tested glyphosate rates showed a high (GI 26.5-51.6%) to relatively low degree of toxicity (GI 16.0-18.7%) in the studied soybean genotypes.Proučavano je delovanje četiri doze primene glifosata (Roundup, 360 g a.m./l) – 180, 360, 720 i 1440 g a.m./ha na preživljavanje, dinamiku rasta i akumulaciju sveže biomase (g/biljci) osam novih bugarskih linija, varijeteta i predloženih varijeteta soje oplemenjenih različitim metodama u uslovima staklenika. Cilj proučavanja je bio da se utvrdi i uporedi osetljivost različitih genotipova soje na glifosat. Proučavani genotipovi soje pokazali su različite nivoe osetljivosti na glifosat kao posledicu genetskih razlika. Doze primene glifosata od 180, 360, 720 i 1440 g a.m./ha u fazi tri troliska (V4) soje su uticale na preživljavanje proučavanih genotipova i uslovno se mogu predstaviti sledećim redosledom: H (40.6%) < G (40.7%) < D (51.3%) < C (52.6%) < F (58.9%) < E (60.5%) < B (62.0%) < A (65.3%). Koeficijent opadanja (B) proučavanih karakteristika zavisi prevashodno od genotipa soje i doze primene herbicida. Ispitivane doze glifosata pokazale su stepen toksičnosti u rasponu od visokog (GI 26.5-51.6%) do relativno niskog (GI 16.0-18.7%) za proučavane genotipove soje

Determination of Allelopathic Effect of Some Invasive Weed Species on Germination and Initial Development of Grain Legume Crops

During the 2006-2007 period, the allelopathic effect of cold water extracts from Amaranthus retroflexus L., Chenopodium album L., Erigeron canadensis L. and Solanum nigrum L. on seed germinationand initial development of Glycine max L., Pisum sativum L. and Vicia sativa L. was studied under laboratory conditions in the Institute of Forage Crops, Pleven. It was found that: waterextracts from fresh and dry biomass of A. retroflexus, Ch. album, E. canadensis and S. nigrum had an inhibitory effect on seed ermination of G. max, P. sativum and V. sativa, the inhibition rate for the extracts from fresh biomass varying from 28.8 to 81.5% and for the extracts from dry weed biomass it was from 26.8 tо 89.2%; The values of LC50 varied from 13.5 tо 72.2 g l-1 for the extracts from fresh biomass and from 7.0 tо 84.1 g l-1 for the extracts from dry weed biomass and they could be conditionally grouped in the following ascending order: A. retroflexus < S. nigrum < E.canadensis <Ch. album and for extracts from dry biomass: A. retroflexus < E.сanadensis < Ch. album < S. nigrum; P. sativum was the most sensitive to the allelopathic effect of the extracts from fresh and dry weed biomass - LC50 varied from 13.5 tо 21.6 g l-1, followed by V. sativa - LC50 from 26.0 tо 11.7 g l-1 and G. max had relatively the lowest sensitivity - LC50 was from 46.6 tо 56.7 g l-1

Utvrđivanje alelopatskog delovanja nekih invazivnih korovskih vrsta na klijanje i početni razvoj zrnastih mahunarki

During the 2006-2007 period, the allelopathic effect of cold water extracts from Amaranthus retroflexus L., Chenopodium album L., Erigeron canadensis L. and Solanum nigrum L. on seed germination and initial development of Glycine max L., Pisum sativum L. and Vicia sativa L. was studied under laboratory conditions in the Institute of Forage Crops, Pleven. It was found that: water extracts from fresh and dry biomass of A. retroflexus, Ch. album, E. canadensis and S. nigrum had an inhibitory effect on seed germination of G. max, P. sativum and V. sativa, the inhibition rate for the extracts from fresh biomass varying from 28.8 to 81.5% and for the extracts from dry weed biomass it was from 26.8 tо 89.2%; The values of LC50 varied from 13.5 tо 72.2 g l-1 for the extracts from fresh biomass and from 7.0 tо 84.1 g l-1 for the extracts from dry weed biomass and they could be conditionally grouped in the following ascending order: A. retroflexus < S. nigrum < E. canadensis <Ch. album and for extracts from dry biomass: A. retroflexus < E. сanadensis < Ch. album < S. nigrum; P. sativum was the most sensitive to the allelopathic effect of the extracts from fresh and dry weed biomass - LC50 varied from 13.5 tо 21.6 g l-1, followed by V. sativa - LC50 from 26.0 tо 11.7 g l-1 and G. max had relatively the lowest sensitivity - LC50 was from 46.6 tо 56.7 g l-1.Tokom 2006. i 2007. godine, na Institutu za krmno bilje u Plavenu vršena su laboratorijska ispitivanja alelopatskog delovanja hladnih vodenih ekstrakata iz Amaranthus retroflexus L., Chenopodium album L., Erigeron canadensis L. i Solanum nigrum L. na klijanje i početni razvoj Glycine max L., Pisum sativum L. i Vicia sativa L. Utvrđeno je sledeće: vodeni ekstrakti iz sveže i suve biomase A. retroflexus, Ch. album, E. canadensis i S. nigrum delovali su inhibitorno na klijanje semena G. max, P. sativum i V. sativa, pri čemu je stepen inhibicije kod ekstrakata iz sveže biomase bio 28,8-81,5%, a kod ekstrakata iz suve biomase 26,8-89,2%; vrednosti LC50 su se kretale od 13,5 do 72,2 g l-1 za ekstrakte iz sveže biomase, odnosno od 7,0 do 84,1 g l-1 za ekstrakte iz suve biomase korova i uslovno bi se mogle prikazati u sledećem uzlaznom nizu kod ekstrakata iz sveže biomase: A. retroflexus < S. nigrum < E. canadensis <Ch. album, a kod ekstrakata iz suve biomase: A. retroflexus < E. сanadensis < Ch. album < S. nigrum; najveća osetljivost na alelopatski efekat ekstrakata iz sveže i suve biomase korova uočena je kod P. sativum – vrednost LC50 se kretala između 13,5 i 21,6 g l-1, a zatim kod V. sativa – LC50 je iznosila od 26,0 dо 11,7 g l-1, dok je G. max pokazala relativno najniži stepen osetljivosti – vrednost LC50 je varirala od 46,6 do 56,7 g l-1