Sunflower is the most important oil crop in the Republic of Croatia. In the last two decades, it has been grown on average on 33,506 ha with a average grain yield of 2.66 t/ha. Weeds represent one of ...the most important causes of biotic stress, and their action is reflected in the competition for nutrients, water, light and space. The weed flora in sunflower crops in Croatia is extremely diverse, and we will most often meet: Polygonum persicaria L., Polygonum lapathifolium L., Ambrosia artemisiifolia L., Chenopodium polyspermum L., Amaranthus retroflexus L., Solanum nigrum L. emend Miller, Abutilon theophrasti Medik, Datura stramonium L., Xanthium strumarium L., Convolvulus arvensis L., Cirsium arvense (L.) Scop., Echinochloa crus-galli (L.) Pb., Setaria glauca (L.) Pb., Setaria viridis (L.) Pb., Digitaria sanguinalis (L.) Scop., Panicum spp. and Sorghum halepense (L.) Pers. For many years, weed control was based on the intensive use of chemical preparations, which were most often used after sowing and before emergence, in double or triple combinations. In addition to a number of advantages of using chemicals in sunflower production, the problem of broadleaf weeds was not satisfactorily solved until the advent of Clearfield, Clearfield plus and Express sun technology, i.e. hybrids tolerant to herbicides from the group of imidazolinone (imazamox) and sulfonyl-urea (tribenuron-methyl) at the beginning of this century. Integrated plant protection, including integrated weed management, with its holistic approach and greater application of direct and indirect non-chemical measures, is only environmental quality solution for controlling weeds in sunflowers.
Multi-year studies are crucial for the evaluation of sunflower hybrids and
quantifying the environmental effect in the expression of genetic potential.
In order to assess the adaptation of eight ...hybrids and test the impact of
water availability on plant height (PH), head diameter (HD), 1000-grain
weight (TWG), hectolitre mass (HM), seed yield (SY), oil content (OC) and
oil yield (OY), a two-year study was conducted with irrigation as treatment.
Analysis of variance (ANOVA) and principal component analysis (PCA)
confirmed the year influence on all tested agronomic traits. According to
the three-way ANOVA, irrigation significantly affected all tested traits
except HD, OC and OY. All agronomic traits had lower values in both rainfed
and irrigated treatment in 2014, confirming the influence of the
environment. The hybrid was a significant source of variation for all
traits. ANOVA and PCA grouped hybrids 1, 7, and 8 in one group and 2, 3, 4,
5, and 6 in another. The first group had lower PH, HD, TGW and SY values and
higher HM, OC and OY values, and the second group had reversed traits
values. Furthermore, the PCA biplot indicates SY was positively correlated
with PH, HD, TGW and OY and HM was positively correlated with OC. This
facilitates the breeding process because it enables indirect breeding for
economically important traits such as seed yield, oil content and oil yield.
As treatments were significant sources of variation for PH, HM, TWG and SY,
sunflower irrigating is considered justified and can be used as an
additional agrotechnical measure to target the agronomic traits.
Understanding the expression of traits under rainfed and irrigation
conditions will greatly help design effective breeding programs by creating
hybrids suitable for cultivation in semi-arid environments.
In Croatia, it began to expanding with the construction of oil factories in Zagreb and Čepin in the mid-1930s. ...the appearance of Russian varieties, mainly seeds of local populations were used for ...sowing, but also varieties created in institutes in Zagreb and Novi Sad (Krizmanić, 2012). The dominant problem of sunflower varieties in that period was its susceptibility to diseases, primarily downy mildew, black stem and white rot. ...after increase in production areas under sunflower, due to the appearance of the diseases, they decreased again (Vratarić, 2004). According to humidity, RFm classifies the months into: perarid (pa, less than 1.6), arid (a, 1.7 - 3.3), semiarid (sa, 3.4 - 5.0), semihumid (sh, 5.1 - 6.6), humid (h, 6.6 - 13.3) and perhumid (ph, more than 13.3). According to the research of Iljkić et al.
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In order to determine the influence of the sowing date on the most important agronomic sunflower traits, an experiment was conducted according to a random block design at the Osijek location. ...INTRODUCTION Sunflower (Helianthus annuus L.) is primarily grown because of the oil used in human consumption, but also as a raw material for the processing industry, animal feed, and beekeeping. Considering the occurrence of increasingly dry vegetation seasons, especially in the summer, with less precipitation, higher temperatures, extremely high daily maximums, but also fluctuations in weather parameters over a short period (daily, weekly) (Mijić et al., 2017; Jug et al., 2018), determination of the most favorable sowing date is a very important part of the application of quality agrotechnical measures (Balalić et al., 2007). ...this study aimed to determine the effect of sowing date on the most important agronomic traits of sunflower: plant height, head diameter, grain yield, oil content and oil yield of 25 sunflower hybrids at the Osijek location during 2015 and to identify the best hybrid combinations for further breeding work. According to Škorić (2012), the head diameter in sunflower hybrids is generally 20 to 30 cm.
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Path coefficient analysis was applied to gain information on direct and
indirect effects of studied traits (seed oil content, kernel oil content,
seed protein content, kernel protein content, head ...diameter, kernel ratio and
plant height) on sunflower seed yield. Traits which exhibit the highest
effects on seed yield will be used as a selection criterion in confectionary
sunflower breeding. The research was conducted during three vegetation
seasons on 22 experimental confectionary sunflower hybrids, created in
breeding program the Institute of Field and Vegetable Crops. Among the
largest number of examined traits, significant and highly significant
correlations were found. With the analysis of simple correlation coefficients
a low interdependence was determined between, kernel protein content, plant
heights with seed yield. Negative but weak correlation was determined between
kernel oil content, seed protein content, kernel ratio with seed yield.
Established a negative strong correlation of head diameter (-0.190*) and
negative very strong correlation of seed oil content (-0.351**) with seed
yield. The seed oil content had a very strong direct negative effect on seed
yield (DE=-0.831**). The head diameter, plant height, seed protein content had
weak negative direct effect on seed yield. Kernel protein content and kernel
oil content has demonstrated a weak direct positive effect on seed yield.
Path coefficient analysis for seed yield showed very strong direct effect for
kernel ratio (DE=0.487*) on seed yield, it shows that the kernel ratio is
important selection criterion for confectionary sunflower breeding.
S ciljem utvrđivanja utjecaja vremenskih uvjeta na komponente uroda ulja suncokreta, u radu su analizirani trogodišnji rezultati poljskih pokusa. U pokusima posijanim u Osijeku 2013., 2014. i 2015. ...godine bilo je 15 hibrida suncokreta: dva strana hibrida i 13 hibridnih kombinacija Poljoprivrednog instituta Osijek. U periodu prije sjetve (siječanj – ožujak), najveća je količina oborina bila 2013. (213,1 mm), zatim 2015. (167,9 mm), a najmanja 2014. (109,5 mm). U vegetacijskome periodu (travanj – rujan), u 2014. bilo je najviše oborina (487,3 mm), u 2013. 475,7 mm, a u 2015. najmanje (251,6 mm). U 2013. godini, u vegetacijskome periodu, srednja mjesečna temperatura zraka bila je 19,1°C, u 2015. 19,9°C, a u 2014. 18,6°C. Od navedenih godina, statistički značajno na nivou P=0,05, najviše vrijednosti analiziranih svojstava zabilježene su 2013. godine: urod zrna 6,47 t ha-1, sadržaj ulja 51,69% i urod ulja 3,05 t ha-1. Urod zrna, sadržaj ulja i urod ulja bili su manji 2015., a najmanji 2014. godine. Najveće vrijednosti uroda zrna i ulja (6,95 i 3,39 t ha-1) imao je Matej, novopriznati hibrid suncokreta Poljoprivrednog instituta Osijek, a po sadržaju ulja od 53,44% bio je na trećem mjestu. Za visoke urode zrna i ulja suncokreta, pored optimalne temperature zraka, jako je bitna količina i raspored oborina prije, a također i tijekom vegetacije.
With the purpose of determining the influence of weather conditions on the yield components of sunflower, the results of three-year field trials are analysed in the paper. In the trials sown in ...Osijek in 2013, 2014 and 2015, there were 15 sunflower hybrids: two foreign hybrids and 13 hybrid combinations of the Agricultural Institute Osijek. In the period before sowing (January – March), the highest amount of precipitation was in 2013 (213.1 mm), then in 2015 (167.9 mm), and the lowest in 2014 (109.5 mm). In the growing period (April – September), the highest amount of precipitation (487.3 mm) was in 2014, 475.7 mm in 2013, and in 2015 it was the lowest (251.6 mm). In 2013, during the growing period, the mean monthly air temperature was 19.1°C, in 2015 19.9°C, and in 2014 18.6°C. Of these years, statistically significant at the P=0.05, the highest value of the analysed traits was recorded in 2013: grain yield of 6.47 t ha-1, oil content 51.69% and oil yield 3.05 t ha-1. Grain yield, oil content and oil yield were lower in 2015, and the lowest in 2014. Matej, a newly recognized sunflower hybrid of the Agricultural Institute Osijek had the highest values of grain and oil yield (6.95 and 3.39 t ha-1), and by its oil content of 53.44%, it was in the third place. For high grain and oil yields of sunflower, in addition to the optimal air temperature, the amount and distribution of precipitation before and also during the growing season are very important.
The aim of this research was to investigate the variability of photosynthetic performance index (PIABS) and leaf temperature values measured in V6 development phase on 13 sunflower hybrids, grown in ...stressful conditions. The pot trial was made up of two treatments, one (T1) with 60% Field Water Capacity (FWC), and the other one (T2) with 80% FWC. Significant differences between T1 and T2 treatments were established for both of these parameters which prove their dependence on the water content in the soil, while the influence of hybrid was evident only in the case of PIABS. Although in T1, as opposed to T2, all sunflower hybrids reacted by increasing leaf temperature, reaction to stress conditions measured with PIABS parameter was not uniform. Some of the hybrids reacted by decreasing PIABS values, while others reacted by increasing their PIABS values. Therefore, it can be concluded that changes in parameters were independent of each other, which was confirmed by correlation analysis. Investigated parameters are suitable for determining the existence of undesirable environmental conditions that cause stress in plants and can be used in breeding of sunflower to withstand abiotic stress conditions, i.e. in selection of stress tolerant hybrids.
Global warming and the associated climate change are imposing abiotic stress on plants. Abiotic factors are crucial for plant productivity, survival, and reproduction. Eight sunflower hybrids were ...tested in conditions of different water availability and with combinations of different temperatures and irradiation. The changes in the photosynthetic efficiency were measured in the morning (control conditions: 2013, 25.8 °C and 349.1 W m−2; 2014, 21.8 °C and 296.4 W m−2) and afternoon (the combination of increased temperatures and high irradiation: 2013, 34 °C and 837.9 W m−2; 2014, 29.4 °C and 888.9 W m−2) at a flowering stage in rainfed or irrigated conditions. The measurement time (morning and afternoon conditions) had a statistically significant effect on all the tested parameters. The performance index (PIABS) in 2013 and the maximum quantum yield of photosystem II (TR0/ABS) in 2014 are the only parameters significantly affected by the irrigation. As a result of the combined effect of increased temperatures and high irradiation, PIABS values decreased by 73–92% in rainfed conditions and by 63–87% in irrigated conditions in 2013, depending on the hybrid, while in 2014, the decrease varied between 70 and 86%. The TR0/ABS decrease was 7–17% in 2013, depending on the hybrid, and 6–12% in 2014, both in rainfed and irrigated conditions. The principal component analysis confirmed the effect of the combination of increased temperatures and high irradiation on hybrids, sorting them exclusively according to the time of measurement. All investigated parameters highly fluctuated between hybrids but without observable trends for the morning and afternoon conditions, as well as for irrigation. Plants’ reaction to the combination of increased temperatures and high irradiation manifested as a change in their photosynthetic efficiency, i.e., the photosynthetic apparatus’ functioning was impaired.
In this research we have determined germination energy and germination of seeds of sunflower hybrids ‘Luka’ and ‘Apolon’, at the beginning of storage and 6, 12 and 18 months after of storage period ...(2011-2012) in the floor concrete storage at two different air temperatures and humidity (S-1: air temperature 15-18°C and relative air humidity 65-70%) as well as in climate chamber (S-2: air temperature 10-12°C and relative air humidity 60-65%), stored in four treatments (Control: processed-untreated seed; T-1: treated with A.I. metalaxyl-M; T-2: treated with A.I. metalaxyl-M + A.I. imidacloprid and T-3: treated with A.I. metalaxyl-M + A.I. clothianidin). Based on the obtained results we have determined that sunflower hybrid ‘Luka’, compared to hybrid ‘Apolon’, in the given storage conditions and with the same seed treatment has 5-8% higher germination energy and seed germination and that in climate chamber both hybrids have 5-7% higher germination energy. Seed treatment of both sunflower hybrids with A.I. imidacloprid maximally reduced initial germination energy and seed germination in all tested periods and conditions of storage. On the average, natural seed, after 18 months of storage did not have better seed quality compared to seed treated with A.I. metalaxyl-M while other treatments had more significant influence on reduction of germination energy and seed germination, 6-15%. On the average, compared to other variants, seeds treated with A.I. metalaxyl-M after 18 months of storage in both storage conditions had higher germination energy by 4-15%, and seed germination by 2-12%.
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