Date of ear emergence: a factor for notable changing the grain yield of modern winter wheat varieties in different environments of Bulgaria

N. Tsenov1*, T. Gubatov1, I. Yanchev2

1 Department of Wheat Breeding and Technology, Agronom Breeding Company, 9300 Dobrich, Bulgaria
2 Department of Plant Science, Faculty of Agronomy, Agricultural University, 4000 Plovdiv, Bulgaria

(Manuscript received 2 November 2020; accepted for publication 15 January 2020)

Abstract. Wheat is a crop with a very long growing season, during which it is subjected to prolonged exposure to many environmental factors. For this reason, the interaction of genotype with conditions is very common for any character of wheat. This study aims to determine whether the grain yield is affected by the change of the ear emergence date (EED) in various environments. In a four-year period, 30 current for national real grain production winter wheat varieties were studied. The EED and grain yield (GY) were studied as quantitative traits within five locations of the country having various soil and climatic conditions. Using several statistical programs, genotype x environment interaction of two traits was analyzed. The emphasis on data analysis was whether changes of traits due to the conditions were related and that the optimization of the ear emergence date could serve as a breeding tool for increasing grain yield. The date of ear emergence and grain yield are traits that are reliably influenced by growing conditions. The change in the date of emergence is mainly of the linear type, while the grain yield shows linear and nonlinear type changes in the same environmental conditions. It was found that the key roles in the change of characteristics are the conditions of the year, with the relatively weakest impact of the genotype on them. There is a positive relationship between the two traits, although their change depends on environmental factors. Although they change to different degrees and in relation to each other, there is a positive correlation between them. The more favorable the environmental conditions, the weaker the relationship between these two traits and vice versa. Under changing climatic conditions, the change in the relationship between the two traits is a signal of the need to create different varieties by date of ear emergence in order to obtain higher yields in the future.


Variability and stability of yield and quality of grain of several bread wheat cultivars

N. Tsenov, I. Stoeva, T. Gubatov, V. Peeva

Abstract. Breeding for grain yield and quality is central in research work on wheat in Bulgaria. Combining the two genetic systems is difficult and requires long and systematic efforts. The aim of this investigation was to analyze the ecological plasticity and stability of grain yield and quality of cultivars already in production. Such information would be valuable with a view of their proper distribution. The quality and production potential of cultivars Aglika, Slaveya and Iveta were determined applying several different approaches for analysis of the genotype x environment interaction. Data were used from several different trials involving these cultivars in a group of 33 Bulgarian varieties during two successive years at eight locations in Bulgaria. The data on the different quality indices are from trials conducted at DAI during a period of six years. The focus is on the complex evaluation of grain yield and quality with respect to their level of realization and plasticity under different combinations of environmental conditions in two groups of trials. Grain yield and its components of the three investigated varieties were significantly higher in comparison to the standards. The model cultivars Sadovo 1 and Pobeda had larger grain and higher tillering capacity although their yields were lower. Number of grains per spikes, which determines the higher productivity of the investigated cultivars, had values with 30 % higher than the values of the model varieties. The values of the indices determining wheat grain strength and bread making quality (valorimetric value, dough resistance and sedimentation) of the three cultivars were significantly higher than the values of the standard Pobeda, which confirmed their genetic potential of strong wheats. No significant variations between cultivars and standard varieties were observed for the indices test weight and wet gluten. The investigated cultivars Aglika, Slaveya and Iveta are a good breeding achievement because they successfully combine high yield with high grain quality. In this respect all three cultivars considerably exceed the level of variety Bezostaya 1, which was at the basis of the successful breeding for combining high yields with high grain quality in the recent past. Cultivar Slaveya, although well established in the group of fillers, demonstrated quality indices of strong wheat. The cultivars possess good adaptability and plasticity under changeable environments with regard to grain yield and its main components. According to the complex indicator of quality level (bread making strength index), all three genotypes demonstrated excellent plasticity and adaptability ranking first among over thirty analyzed cultivars developed in Bulgaria.


Relation between time to heading and date of maturity of winter common wheat varieties (Triticum aestivum L.)

The changed duration of the time to heading and maturity is an important element of the wheat’s adaptability to specific production conditions. The
question whether a variety early by its heading date remains early by its maturation date is a significant one, but the data on this problem is rather limited.
Therefore the aim of this investigation was to find out if there is any specificity between the varieties by their response to the environment with regard to heading
date and maturation date and if there is any relation between these periods in the common wheat varieties different by their earliness. After preliminary
observations in the trial field of DAI, General Toshevo, ten early and ten late wheat varieties and lines were selected and analyzed. The dates to heading and
physiological maturity were studied. They were identified visually at stage 55 and 94, respectively, by the scale for wheat growth and developments during 2004
– 2009. The genotype, the year conditions and the sum of temperatures (GDD) interacted significantly with the dates of the two traits and therefore affected their
variation. The heading date varied in a similar way in positive or negative direction in both variety groups. The correlations between the dates to heading and
maturity were high and significant regardless of the variety group (r=0.858, r=0.755, respectively). The period between heading and physiological maturity
(grain filling) varied according to the temperatures of the respective year. The date to heading can on the whole be used as a criterion for distinguishing wheat
varieties by their growing period durability. The time from heading to grain maturity was clearly less affected than the time to heading and depended mostly on
the genotype.

Relation between time to heading and date of maturity of winter common wheat varieties (Triticum aestivum L.)

N. Tsenov

Genotype x Environment Interaction and Stability Analysis of Some Narbonne Vetch (Vicia narbonensis L.) Genotypes

The objectives of this research are to determine genotype x environment interactions and stability of seed yield and some plant characters of
Narbonne vetch (Vicia narbonensis L). Thirteen Narbonne vetch genotypes were grown at two different locations during 2000-2002 years. This research was
carried out as randomised completed block design with three replications. Significant differences were found (P≤0.01) among Narbonne vetch genotypes for
plant height (57.54-77.98 cm), pod number per plant (10.97-20.09), and seed yield per plant (7.22-22.64 g). Genotype x environment interaction was found to
be significant (P≤ 0.01) in all investigated characters. Mean values of genotypes (x), regression coefficient (b) and deviation from regression (S2d) were i
evaluated as stability parameters. According to stability analyses, genotype 133 and 600 showed upper performance about seed yield per plant in two
locations. On the other hand, genotypes I would recommend for suitable locations which were loamy and limy soils and rainy and cool season climatic

Genotype x Environment Interaction and Stability Analysis of Some Narbonne Vetch (Vicia narbonensis L.) Genotypes

A. Orak, I. Nizam