Grain yield response of some agronomy practices on contemporary common winter wheat cultivars (Triticum aestivum L.)

M. Nankova*, A. Atanasov
Dobrudzha Agricultural Institute, 9520 General Toshevo, Bulgaria
(Manuscript received 28 June 2018; accepted for publication 5 September 2018)

Abstract. During2014–2017,theinfluenceofsomemainagronomyfactorsonthesizeoftheresultantagronomiceffectfromtheirapplicationtocontemporary common winter wheat cultivars was investigated. The study was carried out in the experimental field (Haplic Chernozems soil type) of Dobrudzha Agricultural Institute – General Toshevo. The trial was designed by the split plot method, in four replications, on harvest area of 12m2. Cultivars Sadovo 1, Pryaspa, Kami, Kalina, Kiara, Kossara and Katarjina were grown after winter oilseed rape, spring pea, sunflower and grain maize at four levels of nutrition regime. The nutrition regime was differentiated depending on the previous crop. After spring pea, 30, 60 and 90 kg N/ha were used, and after the rest of the previous crops – 60, 120 and 180 kg N/ha. With the exception of the check variant all fertilizer variants were against background fertilization with 60 kg P2O5/ha and 60 kg K2O/ha. The positive reaction from the complex interaction of the tested agronomy factors was best expressed in 2015 – 2409.2 kg/ha, while during the extremely unfavorable year 2016, the effect was only 628.2 kg/ha. The independent and combined action of the mineral fertilization and the year conditions had determining influence on the size of the agronomic effect (AE). The positive effect from the mineral fertilization on the values of AE was accompanied by slight differentiation between the tested fertilization norms. Within this study, the highest mean value of AE was determined after fertilization with N180P60K60 – 2274.2 kg/ha. The variation in the mean size of AE depending on the type of previous crop was high – from 900.6 kg/ha (pea) to 2031.2 kg/ha (oilseed rape). The applied agronomy practices caused differentiation in the mean values of AE according to the type of cultivar. The cultivars Kiara (1796.1 kg/ha) and Kalina (1704.5 kg/ha) were with the highest size of AE. They exceeded the AE values of the two standard cultivars Sadovo 1 and Pryaspa by 30.26% and 23.62%, respectively. Averaged for the research, it was found that AE was in positive statistically significant correlation with grain yield and its physical properties.

Intensity of spike increase in Triticum aestivum L. cultivars depending on some agronomy factors

M. Nankova1*, A. Ivanova1, N. Tsenov2

1Dobrudzha Agricultural Institute, 9520 General Toshevo, Bulgaria 2Agronom I Holding, 9300 Dobrich, Bulgaria

Abstract. Under conditions of Haplic Chernozems, the dynamics and the intensity of dry matter increase in the spikes of the common winter wheat cultivars Pryaspa, Enola, Iveta, Bolyarka and Dragana were followed in the trial field of Dobrudzha Agricultural Institute, General Toshevo during 2009 – 2011. The investigation was carried out during stages 57-59, 69, 73, 83 and 94-95 according to Zadoks in a stationary field trial designed by the split plot method. The cultivars were grown after 4 previous crops – pea, oilseed rape, sunflower and grain maize at four levels of nutrition regime formed after main mineral fertilization. The nitrogen fertilization norms after oilseed rape, sunflower and grain maize were 60, 120 and 180 kg/ha, and after pea – 30, 60 and 90 kg/ha, respectively. The phosphorus and potassium fertilization was applied as a background, with 60 kg/ha. Each of the previous crops had a check variant without mineral fertilization. The dynamics of spike increase was influenced most by the meteorological conditions of the investigated years. The strength of effect of this factor increased in the course of vegetation. Mineral fertilization and the type of cultivar were next in significance. The role of the previous crop in the course of vegetation was low, being statistically significant only at the final stage. Similar tendency was observed in the daily rate of spike increase, but at the beginning of heading the cultivar had a better expressed effect in comparison to mineral fertilization. The intensity of spike increase was highest after nitrogen fertilization with 120 and 180 kg/ha. The cultivars had higher daily rate of spike increase during inter-stage periods 73–69 and 83–73 according to Zadoks. The spikes of cultivar Dragana increased with the highest mean daily rate from heading to maturity (16.126 kg/da/day). Depending on the type of previous crop, the mean values of daily intensity varied from 13.418 kg/da/day (maize) to 15.106 kg/da/day (pea). The differentiation with regard to the meteorological conditions of the year was very well expressed; the spikes increased with highest rate in 2011 – 20772 kg/da/day, averaged for heading-maturity. High values were determined of the correlations between the dry matter formed in the spikes during the separate stages of development and the rate and intensity of dry matter accumulation.

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Dry matter accumulation in the varieties of wheat (Triticum aestivum L.) according to previous crop

A. Ivanova, N. Tsenov
Abstract. The constant interest in common wheat investigations is determined by the main share this crop has in agriculture and by the unique properties it possesses. This investigation was carried out under field conditions for a three-year period (2009 – 2011) in the trial field of Dobrudzha Agricultural Institute – General Toshevo (DAI). The trial was designed according to the split plot method in four replications, the size of the trial plot being 12 m2. Five common wheat genotypes developed at DAI were subjected to investigation (Iveta, Enola, Pryaspa, Bolyarka, Dragana). The trial involved four previous crops: oilseed rape, pea, sunflower and maize, and three norms of mineral fertilization depending on the type of previous crop. Fertilization with phosphorus and potassium was used as a background (Р К ), kg/ha and nitrogen was tested at the following fertilizer norms: N , N and N kg/ha after previous crops oilseed rape, 60 60 60 120 180 sunflower and maize, and N , N and N kg/ha after pea, with check variant N P K . The effect of the type of previous crop on dry matter accumulation in the 30 60 90 0 0 0 investigated common wheat varieties was analyzed. It was found that dry matter accumulation continued throughout the entire growth season, the year conditions being decisive for its amount. Dry matter accumulation during the individual stages of growth and development was specific for each investigated cultivar. The investigated cultivars accumulated higher total biomass than the standard Pryaspa. After the early previous crops (oilseed rape and pea), the amounts of dry matter formed were higher at the end of the growth period (after heading). After the late previous crops (sunflower and maize) the new wheat varieties formed higher total biomass as early as the beginning of spring growth. After predecessor pea the highest amounts of dry matter were formed.

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