Productivity of common wheat (Triticum aestivum L.) grown after various predecessors and nitrogen fertilization rates

M. Gerdzhikova*

Department of Plant Growing, Faculty of Agriculture, Trakia University, 6000 Stara Zagora, Bulgaria (Manuscript received 12 December 2016; accepted for publication 20 February 2017)

Abstract. During the period 2008-2011 the influence of the predecessors wintering peas, spring peas, sunflower and common wheat and different levels of nitrogen fertilization: 0 (N0), 40 (N40), 80 (N80), 120 (N120) kg/ha after legumes and 0 (N0), 60 (N60), 120 (N120), 180 (N180) kg/ha after the other predecessors on the productivity of common wheat was studied on the experimental field of the Department of Plant Growing, Trakia University. It was found that with cultivation of common wheat without fertilization after legume predecessors higher yields by 9.4 % were obtained compared to the other predecessors. The highest yields were obtained at fertilization with the highest nitrogen rates: after legume predecessors 4069.8 kg/ha grain; after sunflower and wheat 3853.2 kg/ha of grain. The strongest influence on the productivity of common wheat had nitrogen fertilization as a factor with 79.80 %. The yield of wheat grain correlates very well with the level of nitrogen fertilization and can be determined approximately by regression equations based on the quantity of nitrogen as an independent variable.

Energy productivity, fertilization rate and profitability of wheat production after various predecessors II. Profitability of wheat production

Z. Uhr1*, Е. Vasileva2

1Institute of Plant Genetic Resources, 2 Druzhba, 4122 Sadovo, Bulgaria
2University of Agribusiness and Rural Development, 78 Dunav, 4000 Plovdiv, Bulgaria

(Manuscript received 27 July 2015; accepted for publication 13 October 2015)

Abstract. In the course of our study on the adaptation of modern genotypes common winter wheat (Triticum aestivum) to the requirements of sustainable agriculture data were received concerning the influence of the predecessor and nitrogen fertilizer rate on energy efficiency and recyclable nitrogen fertilization and profitability of productivity.We share these data with the scientific community, as they are up-to-date and informative in both theoretical and practical aspects. The analyses are based on data from field experiments fertilizer derived after predecessor cereals – regular crop of sorghum, millet, maize and legumes after predecessor – separate sowing of chickpeas. Energy efficiency of nitrogen fertilization was calculated as the ratio between the energy supplied in the additional grain yield and energy input in the form of fertilizers. Refundable efficiency of nitrogen fertilization is the additional amount of nitrogen accumulated in the grain, with respect to the applied nitrogen fertilization. Economic profitability of production is evaluated by coefficient R = P/Ra (ratio of benefits/costs). The results show that energy efficiency and recyclable nitrogen fertilization are on average five times higher after cereal than after legumes predecessor, and decreased with increasing the fertilizer rate, the decrease was statistically significant only for the first item (exponent). Profitability ratio of production after the introduction of legumes predecessor in crop rotation increases by an average of 42% and retains maximum values of fertilization levels 0.06, 0.12 and 0.18 t/ha nitrogen. Profitability of wheat production using pre-legumes crop is not determined by the parameters nitrogen fertilizer rate and energy efficiency of nitrogen fertilization and refundable efficiency of nitrogen fertilization.

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Energy productivity, fertilization rate and profitability of wheat production after various predecessors I.Energyproductivityofwheat

Z. Uhr1*, E. Vasileva2

1Institute of Plant Genetic Resources, 2 Druzhba, 4122 Sadovo, Bulgaria
2University of Agribusiness and Rural Development, 78 Dunav, 4000 Plovdiv, Bulgaria

Abstract. As a consequence of a long-year comparative study of quality, productivity and physiological characteristics of Bulgarian varieties of common winter wheat(Triticumaestivum),wecarriedouta studyontheadaptationofmoderngenotypestotherequirementsofsustainableagricultureandrespectivelytheir effectiveness of breeding methods with respect to these requirements. In the course of this study were also accumulated additional data concerning the influence of the predecessor and nitrogen fertilizer rate on energy productivity of crop, energy and recyclable efficiency of fertilization and profitability of production. In two consecutive publications we summarize and share with the scientific community the data that we have received. The results are up-to-date and useful in both theoretical and practical aspects. The analysis is based on data from field fertilizer experiments carried out with predecessor cereal – regular crop of sorghum, millet, maize and legumes after predecessor–separate sowing of chickpeas. Energy productivity is calculated as a function of yield (grain, straw and total biological yield, (t/ha), multiplied by the energy equivalent unit (MJ/kg). Maximum values of gross energy productivity by grain yields are reported by fertilization rate with 0.18 t/ha nitrogen fertilizer after cereal predecessor and after 0.06 t/ha after legumes. After cereal predecessor the effect of increasing the fertilizer rate to 0.18 t/ha N improves energy productivity of grain by 160% compared to the control N0. After legumes predecessor at N 0.0 t/ha energy productivity with grain was 12%, and in N 0.06 – 21% higher than the maximum (at 0.18 t/ha) after cereal predecessor. Legume predecessor unifies differences between genotypes and fertilizer levels on energy productivity of grain and increases energy productivity of straw by 16% on average. Maximum values of gross energy productivity of straw are reported in fertilization with 0.12 t/ha after wheat and 0.24 t/ha fertilizer nitrogen after legume predecessor. Increasing the fertilizer rate from 0.0 t/ha to 0.18 t/ha nitrogen reduces the difference in the gross energy productivity of crops after legumes and cereal predecessor from 105% in 0.0 t/ha to 10% in 0.18 t/ha. The differences between both varieties regarding the studied parameters are statistically significant at P < 0.001.

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Possibilities for increasing the yield and quality of asters (Callistephus chinensis L.) cut flower

N. Miteva, O. Tafradziiski
Abstract. Asters (Callistephus chinensis L.) are one of the basic annual sorts for growing in the open with big economic importance for getting cut flower. This is defined not only by their high decorative qualities because of the variety of structure and colouring of the raceme but also by their usage. The aim of the present paper is to study the influence of nitrogen fertilization on the vegetation and generational activities of the plants. Experiments were carried out as field tests. The results show that a higher dosage of nitrogen stimulates plant growth. It has also been established that mineral fertilization has a positive effect on the size of the raceme – larger racemes with bigger tubular discs are formed with many more lingulated petals, defining the fascicularity of the plants.

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