Productive and Quality Characteristics of Soybean in Agroecological Conditions of Sombor , Serbia

The objective of this paper was to examine and present the results of soybean grain yield, protein and oil content during a two-year period (2009 to 2010) in agro-ecological conditions of Sombor, Serbia. Data were statistically analysed by analysis of variance, using the method of two factorial trials (variety, year). LSD was used to compare means for significant differences. Significantly higher yields were recorded in 2010 compared to 2009. Average yield amounted to 4,196 kg ha-1 for analysed soybean varieties, and ranged from 2,889 kg ha-1 (2009) to 5,503 kg ha-1 (2010). The year 2010 was favourable for protein synthesis. The highest protein content was achieved by Bečejka variety (38.38%) and Proteinka variety (38.33%) in 2010. Proteinka had statistically significantly higher average protein content compared to other tested varieties in the two-year average. The tested soybean varieties had average oil content of 20.93%. The highest oil content was found in Sava variety (23.03%) in 2009. Statistically significantly higher oil content was recorded in 2009 compared to 2010, while variety and their interactions had statistically significant effect (p <0.05, p <0.01) on yield and grain quality of soybean. Irrigation and appropriate cultural practices are the only measures that could mitigate limitation factors and increase yields.


Introduction
From a little-known plant that was cultivated in the early twentieth century in a few countries, soybean (Glycine max.(L.) Merr.) became one of the most widely grown field crops in the world at the end of the 20th century (Miladinovic et al. 2008).In recent years, 90% of the world production has been concentrated in a few countries (USA, Brazil, Argentina, China, India, etc.).Areas and yields have had a growing tendency (and hence higher production) in recent years, in our country and abroad (Popović 2010).Regarding the favourable grain composition, soybean has been classified into the group of the most important plant protein and oil sources in the world.Because of high protein content with a high ratio of essential amino acids ( Jayakumar et al. 2010), as well as high concentration of antioxidants (Cahoon 2003), and unsaturated fatty acids (McCord et al. 2004), soy has been recognized as functional food.Soybeans have multi-purpose: human and animal nutrition, proteins, oil and bio-diesel production.
The climate has a major effect on plant growth and development, and often represents a limiting production factor.Very important factors that influence the chemical composition of soybean grains are the prevailing environmental conditions during the growth phase, as well as specificities of a variety, in accordance with the results of Hurburgh (2000).Proper variety selection, besides the best cultivation technology use, has major influence on the yield increase and soybean grain quality in different environmental conditions (Miladinović et al. 2008, Vidić et al. 2010, Popović et al. 2013).
Growing high yielding varieties resistant to diseases, pests and other adverse environmental conditions is very important for successful soybean production.Proper and timely agricultural practices can mitigate negative conditions that have a major impact on yield and soybean grain quality (Popović 2010).The aim of this study was to determine the productivity and soybean grain quality of varieties of Novi Sad in the region of Sombor, in agro-climatic divergent years.

Materials and Methods
Examination of varietal productivity during divergent examination years was on the PSS Sombor plot, experimental field Toplana, where experiments were performed during 2009 and 2010 on the chernozem meadow soil type.Four soybean varieties from the maturity group 0 (Galina, Valjevka, Bečejka and Proteinka) were used as material, as well as two varieties of the maturity group I (Balkan and Sava), which are at the same time the current assortment in our country.Field trials were designed as a two factorial trial with 3 replications using plots of 10 m 2 .Corn was the preceding crop.
Each year standard agricultural practices for soybean were applied.Before primary tillage, 400 kg ha -1 of NPK fertilizer with 15:15:15 formulation was applied.Sowing was carried in the first half of April, with micro-experiments planter on 50 cm row spacing.Microbiological preparation NS Nitragin was applied during sowing.Crop density was 500,000 plants per hectare for the 0 maturity group and 450,000 plants per hectare for the maturity group I.
Harvest was performed in technological maturity with the micro-experiments combine.After harvest, grain yield (kg ha -1 ), protein and oil content (%) were measured from each plot and converted to level of 14% of grain moisture.Chemical composition of soybean grain was determined by infrared spectroscopy technique with PERTEN DA 7000 apparatus (Spectrophotometer NIR / VIS) and non-destructive method.Experimental data were analysed by descriptive and analytical statistics, using the statistics software package Statistica 12 for Windows.The significance of differences among the mean values of different factors studied in the paper (year, genotype, interaction) was tested by adapted two-way ANOVA.All evaluations of significance were made on the basis of the LSD test at 0.05% and 0.01% significance levels.The stability of the analysed parameters was measured by the coefficient of variation (Cv).

Weather conditions
The data from Sombor meteorological station were used for the analysis of weather conditions.The total amount of precipitation for the studied period was 476 mm and ranged from 258 mm (2009) to 694 mm (2010), Fig. 1.During 2009 average air temperature was 19.45ºC, which was 1.4°C higher than the average temperature in 2010.
High air temperatures and precipitation deficit during April and May of 2009 caused delays in soybean growth.End of May and early July were followed by precipitation which had a favourable effect on soybean growth and development.There was an arid period from mid-July to September.Soybean had lower aboveground mass and relatively stronger root system.As soybean plant is very sensitive to the lack of soil moisture during flowering and grain filling, it reflected on the yield.In contrast to 2009, monthly precipitation distribution during the humid 2010 was more favourable and it reflected on soybean plants growth and contributed to the achievement of higher yields.

Soybean grain yield
Year, variety and their mutual interactions had a statistically significant effect (p <0.05, p <0.01) on soybean grain yield.All the tested varieties achieved high, relatively yield.Yields ranged from 3.918 kg ha -1 (Proteinka) to 4,450 kg ha -1 (Balkan).There was statistical significance among the achieved yields for the tested varieties.The average yield for all soybean tested varieties in the two-year period was 4,196 kg ha -1 (Table 1 and 2).Since the studied years were agro-meteorologically divergent, 2009 relatively arid and 2010 humid, large fluctuations in the yields and stability were recorded.
In 2010 yields were significantly higher (5,503 kg ha -1 ) compared to the yields in 2009 (2,889 kg ha -1 ), Tab. 1. Irrigation is the only measure that can fully solve the problems of drought in the years such as 2009.Pejić et al. (2012) reported that soybean yields are projected to significantly increase under irrigation.Hrustić et al. (2002) and Miladinović et al. (2008) reported that there was the greatest negative influence on yield and grain quality due to lack of water during the time of formation and grain filling (R5-R6).These stages take place in August, when lack of precipitation is common in our environmental conditions.
The average Standard Error for yield for all soybean tested varieties in the two-year period was 238.31 (Table 2).

Protein content
The average protein content was 37.01% for all tested soybean varieties in 2009-2010.During the analysed period Proteinka (37.82%)Tab. 3,4).The average Standard Error for protein content for all soybean tested varieties in the two-year period was 0.18 (Table 4).
Year 2010 was favourable for protein synthesis.Stable protein content was recorded within years for tested varieties, C V = 1.39% ( 2009) and Cv = 2.44% (2010), Table 3.Based on the LSD-test variety and interaction genotype x year (G x Y) had a statistically significant effect (p <0.05) on protein content in soybean grain.Analysed years were not statistically significant (p >0.05),Table 3.1.
Monitoring of variety x year interaction shows that the average protein content was higher in 2010.Significantly higher protein content, compared among all tested varieties, was achieved by Bečejka (38.38%) in 2010 with the exception of Proteinka (38.33%) which had relatively uniformed protein content.The higher protein content in 2009 was found in Proteinka (37.32%), (Table 3,4).
The average protein content of maturity group 0 varieties (37.08%) was higher than the maturity group I varieties (36.94%),Table 3.

Oil content
The average oil content was 20.93% for all analysed genotypes in the period 2009-2010.Year had a statistically significant effect (p<0.01), on the oil content in soybean grain (Table 5, 5.1).
The realized average oil content for all varieties in 2009 (22.16%) was statistically significantly higher than in 2010 (19.78%).The higher oil content in 2009 was achieved by Sava variety (23.03%), and the higher oil content in 2010 was achieved by Valjevka variety (20.32%),Table 5.
The average Standard Error for oil content for all soybean tested varieties in the two-year period was 0.22 (Table 6).
The average oil content in 2009-2010 of 0 maturity group varieties (20.85%) was lower compared to the maturity group I varieties (21.09%),Tables 5, 6.
Year and variety x year interaction had a statistically significant effect (p<0.05), Tab. 5, on the oil content in soybean grain.
Our results are in accordance with the results of Popović et al. (2012), where the authors stated that there are always several factors which both independently and in interactions cause the success of certain soybean variety application in soybean production, and therefore the success of the production.Besides genetic factors, agroecological factors had a major impact on the variability of analysed variety traits.Highly significant interaction year x variety showed that there were differences in the expression of analysed traits in soybean.
The same authors report that average yield for the same variety amounted to 3,657 kg ha -1 , 38.04% protein content and oil content of 20.54% at Rimski Šančevi locality during 2009-2010.Based on the previous, it can be concluded that besides genetic and agro-ecological factors, variability of examined soybean traits, as well as growing locality, affected soybean production the most.

Figure 1
Figure1a, b.Mean daily temperature ( o C) and total precipitation (mm) during the growing season in soybean growing period inSombor, Serbia (2009-2010)

Table 5 .
1. Analysis of variance of oil content

Table 6 .
Descriptive statistics for oil content