Nitrogen, phosphorus and potassium content in maize dry biomass under the effect of different levels of mineral fertilization

L. Nenova*, M. Benkova, Ts. Simeonova, I. Atanassova

Institute of Soil Science, Agrotechnologies and Plant Protection “N. Pouskarov”, 7 Shosse Bankya str., 1331 Sofia, Bulgaria

(Manuscript received 20 August 2019; accepted for publication 8 November 2019)

Abstract. The aim of the study was to assess the influence of different fertilizer doses on the content of macroelements (nitrogen, phosphorus and potassium) in dry biomass and grain of maize during the 2016 – 2018 period. A field experiment with fertilization of maize was carried out on Alluvial-meadow soil (Fluvisol) in the region of Tsalapitsa village, near Plovdiv. Three variants of mineral fertilization were studied V2 (N15P10K0), V3 (N20P15K0) and V4 (N25P20K0), and a control variant V1 (N0P0K0) – without fertilization. It was established that N% content in maize dry biomass was affected significantly by the variants of fertilization (18% of the variance). Significant differences (P≤0.05) between the control variant and all the variants of fertilization were established. Increasing the fertilizer dose, nitrogen content in dry biomass increased, too. The highest was the average content of nitrogen in maize leaves (0.94%), followed by the cobs (0.71%) and the lowest was the content in the stems (0.58%). Phosphorus and potassium content of dry biomass were affected significantly by the year of the study (10% and 9% of the variance, respectively). At the 7-8th leaf growth stage of maize, the highest nutrients content (N, P, K) in dry biomass were reported. With aging of plants the nutrient content in their biomass decreased. Nitrogen, phosphorus and potassium content in maize grain was significantly affected by the year of the experiment. Mineral fertilization had impact mostly on the nitrogen content of the grain, which was the highest in V3 variant, accepted as optimal – 0.66% on average.

Variation in the chemical composition and physical characteristics of grain from winter barley varieties

B. Dyulgerova*, N. Dyulgerov, D. Dimova

Institute of Agriculture, 8400 Karnobat, Bulgaria
(Manuscript received 4 July 2017; accepted for publication 28 August 2017)

Abstract. The aim of the study was to evaluate the range of variation in chemical composition and in physical parameters of grain associated with feed quality of barley under the conditions of Southeast Bulgaria. A set of 21 winter six-rowed barley varieties from different geographic origins were investigated. The study was conducted in the Institute of Agriculture – Karnobat, during the period 2013/2014 – 2014/2015. Grain samples of the studied varieties were analysed for crude protein, lysine, starch, crude fat, crude ash, crude fiber, hectoliter weight and 1000 grains weight. The coefficient of variation was the highest in crude fat (21.52%) followed by lysine (9.52%). Low variation among varieties was found in nitrogen-free extract (CV=1.56%) and hectoliter weight (CV=2.77%). Correlations of crude protein with lysine, starch and crude fiber were negative. Starch content was positively associated with crude fat and hectoliter weight. Significant negative correlation of nitrogen-free extract with crude fat and crude fiber was found. Differences in chemical composition and physical parameters of grain indicated that the studied varieties can provide a source of germplasm for breeding winter barley varieties with improved feed quality.

Occurrence and Distribution of Fusarium species in Wheat Grain

G. Beev, S. Denev, D. Pavlov

Abstract. Wheat fungal infections caused by Fusarium spp. is of great economic importance in cereal growing countries including Bulgaria. These infections greatly reduced crop yields and significantly decrease grain quality, because of mycotoxins production, that make grain unsuitable for human food and livestock diets. To establish the occurrence and distribution of Fusarium spp. were tested 21 samples of wheat from Stara Zagora area. To determine the internal contamination by microscopic fungi of grains, the agar plate method was applied. One hundred grains were tested for each sample. The grains were sterilized with 70 % ethanol, rinsed with sterile water, dried and placed on Petri dishes containing Chapeck-Dox`s agar medium. After incubation, the number of fungal genera detected in each sample was calculated. Conclusive identification of Fusarium spp. was made after transfer of selected isolates on SNA (Synthetischer nährstoffarmer agar) on the basis of their morphological and cultural characteristics. As a result of mycological investigation, fungi of 9 genera were obtained: Fusarium, Aspergillus, Penicillium, Alternaria, Mucor, Rhizopus, Cladosporium, Rhizoctonia and Nigrospora spp. From contaminated with Fusarium spp. wheat samples were identified 62 isolates attributed to the 8 sections. Most common isolated species were Fusarium verticillioides, followed by Fusarium poae and Fusarium solani. Particular interest is the species Fusarium equiseti, which is isolated for the first time from Bulgarian wheat.