Sun ﬂ ower ( Helianthus annuus L.) genetic resources, production and researches in Turkey ☆

– Sun ﬂ ower is one of the leading oilseed crops and it is widely grown in the Thrace region of Turkey. In 2017, in Turkey as a whole, oilseed and confectionary sun ﬂ owers were grown on 779.622 ha with a total production of 1 964 385 t of seed, and average yields of 2.64 t ha (cid:1) 1 for oilseed and 1.67 t ha (cid:1) 1 for confectionary types. Turkey is one of the important countries for crop diversity and has been described as a microcenter for some crops, which originated in different parts of the world. Landraces of sun ﬂ ower ( Helianthus annuus L.) show signi ﬁ cant diversity in Turkey and have been collected in the framework of the “ National Industrial Plant Genetic Resources Project ” (NPGRP). Nine hundred and thirty two oilseed and confectionary sun ﬂ ower accessions are in longterm conservation in the National Seed Gene Bank of Turkey. The mission of the National Sun ﬂ ower Research Project is to develop improved germplasm and hybrid varieties by conventional and biotechnical breeding techniques in Turkey. New germplasm and breeding lines have been developed to improve oilseed and confectionary sun ﬂ ower hybrids with desired characters including high yield and oil quality, resistance to diseases such as: Plasmopara halstedii (Farl.) Berl de Toni., Puccinia helianthi Schw., and Orobanche cumana Walr. Adverse conditions are also taken under consideration. These studies are integrated with agronomic and other related research.


Introduction
Turkey is an important country concerning plant genetic resources and center of origin or micro gene center for several crop species (Harlan, 1951) that did not originate in the country, but shows diversity for many characteristics (Tan, 2009;Tan, 2010a, b;Karagoz et al., 2010). Two centers of origin (Mediterranean and Near Eastern) overlap in Anatolia. About 3700 of the 11 707 plant taxa found there are endemic to Turkey (Guner et al., 2012). The National Industrial Crops Genetic Resources Research Project aims to survey, collect, conserve long term, characterize, regenerate and utilize the industrial crop genetic resources of Turkey. This collection is a source of germplasm to be used in breeding programs.
Helianthus annuus L. originated in North America, where wild sunflowers provide important genetic diversity for crop improvement (Heiser et al., 1969;Heiser, 1978;Putt, 1978;Zeven and de Wet, 1982;Miller, 1987;Gobbelen et al., 1989;Schneiter, 1997). Landraces are also important sources of genetic variability, because they have adapted to local environments as a result of natural selections over centuries. Thus, the evaluation of existing confectionary and oilseed sunflower land races is essential for increased utilization. Characterization studies indicated that confectionary land races are highly variable for morphological characters (Tan, 1993;Tan, 2002;Tan, 2010a, b;Tan and Tan, 2010;2011;Tan et al., 2013a, b;Tan et al., 2016a, c;Tan et al., 2017b;.

Sunflower genetic resources in Turkey
Crop genetic bases became narrowed since landraces were replaced by modern cultivars (Tanksley and McCouch, 1997). Therefore, in the framework of National Plant Genetic Resources Program (NPGRP), since the 1960s, Turkish landraces of many species have been surveyed, identified then collected before they disappeared and conserved at the National Seed Gene Bank at the Aegean Agricultural Research Institute (AARI) in Izmir, Turkey (Tan, 2000;. The sunflower genetic resources collections are included in this seed bank as part of the "Industrial Crops Genetic Resources Project" (Tan and Tan, 1998a, b;Tan, 2000;Tan, 2009;Tan, 2010, Tan, 2010a, b;Tan and Tan, 2011;Tan et al., 2013a, b;Tan et al., 2016a, c;Tan et al., 2017c).
These landraces or primitive cultivars are very important sources of genetic diversity, with their adaptability to local environments as a result of natural or farmer selection over centuries. To date, over 932 oilseed and confectionary sunflower accessions collected from sunflower fields, farmer storage and markets are long term ex situ conserved at the National Seed Gene Bank of Turkey (Anonymous, 2017a;. Figure 1 shows the collection areas of sunflower land races in Turkey (Anonymous, 2017a;Tan et al., 2017c;. The oilseed and confectionary sunflower genetic resources received from the National Seed Gene Bank of Turkey were observed for 43 morphological, phenological and technological characters identified by UPOV (Anonymous, 2000) and IBPGRI (IBPGR, 1985).
The data were evaluated by Principal Component Analysis (PCA), and Cluster Analysis and the eco-geographical distribution and agro-morphological variation of both oilseed and confectionary sunflower landraces at National Gene Bank have been published (Sneath and Sokal, 1973;Clifford and Stephenson, 1975;Tan, 1983). The distribution areas of sunflower samples showed significant variation within and between accessions. Distinct groupings were determined in principal components and the results of analyses exhibited broad morphological variation for land races Tan, 2010, 2012;Tan et al., 2013a, b;.
This genetic diversity and its characterization are very important for hybrid sunflower variety breeding because parental lines with diverse origin have higher potential heterosis, then hybrids made from closely related parents (Kaya, 2010;Kaya, 2014a;Kaya, 2016). Thus, both confectionary and oilseed sunflower land races have been evaluated and utilized in breeding programs at AARI and TARI (Thrace Agricultural Research Institute).

Sunflower production in Turkey
An increasing world population makes necessary increased availability of human foods. Vegetable oils are an important source of energy. Production of sunflowers with high yield, oil percentage and oil quality will help to reduce the oilseed production gap in Turkey, which is one of the leading countries for sunflower production. Data presented in Table 1 shows that oilseed and confectionary sunflowers were grown on 77 9622 ha producing with 1 964 385 t of seed and an average yield of 2.64 t/ha oilseed and 1.67 t/ha for confectionary types in 2017 (Anonymous, 2017b).
Hybrid varieties constitute approximately 95% of production, but farmers generally prefer to use low yielding landraces when they grow confectionary sunflowers. Major provinces producing oilseed and confectionary sunflower in 2016 are given in Tables 2 and 3.
The Thrace region produces 49.3% of Turkish oilseed sunflowers in Tekirdag, Edirne, Kırklareli, and Canakkale provinces. This is followed by the Mediterranean, Central Anatolia, Southeastern Anatolia, Black Sea, South Marmara and Aegean regions. These provinces produce a total of 39.7% of production (Anonymous, 2017b). Linoleic (conventional) types represent 97% of sunflower production, high oleic types 3%. The main confectionary seed production areas are in Central Anatolia and the Aegean Region (Anonymous, 2017b).
Sunflower contributes 1 800 000 tons to the total production of 2 700 000 tons of all oilseed crops in Turkey. This production is not sufficient to cover local oil consumption,  partly because, although 9 71 000 tons of oilseed sunflower are used directly, 600 777 tons are exported (Tab. 4). To cover the oilseed deficit, Turkey paid 3.5 Â 10 9 US $ in 2016 to import oilseed and its derivatives, including 738 417 tons of sunflower oil at a cost of 1.015 Â 10 9 $ (Tab. 4). While 382 263 tons of oilseed sunflower were imported with a value of 264 Â 10 6 $; 48 259 tons were exported (Tab. 5). It would be useful to increase, perhaps even double sunflower production in Turkey. Turkey oil seed processing capacity is 1 750 000 tons but only 55% of the capacity of the 110 oil plants is utilized. Seed processing capacity and sunflower oil consumption in Turkey are given in Table 6. Turkish refinery capacity is 4 million tons per year, but the utilization rate of the existing 110 facilities was 70% in 2016 (Anonymous, 2017c). The production of additional oil seeds would create added value. There are some additional potential sunflower production areas such as Aegean Region and South East Anatolia with suitable ecological conditions for both main and second crop sunflower production in Turkey.
Turkey imports the oilseed sunflower seeds mainly from Bulgaria, Ukraine, Romania, Russia and Moldova. On the other hand, almost half of the raw sunflower oil import is from Ukraine, while the other part is from Russia, Argentina, Romania and Bulgaria. The most exported countries of refined sunflower oil are Iraq, Syria, Lebanon and Thailand (Anonymous, 2017c).
To date, oilseed and confectionary sunflower open pollinated variety, parental lines (CMS, maintainer, and restorer lines) and hybrid varieties have been developed and evaluated in yield trials under main and catch crop production seasons. Variety performance tests and yield trials indicated that sunflower can give with satisfactory yield performance (2.50-5.5 t/ha) in both seasons in Thrace, Aegean, and Mediterranean Regions of Turkey (Kaya, 2010;Tan, 2010a, b;Kaya, 2014b;Tan, 2014;Tan et al., 2016b;Kaya, 2016;Tan et al., 2017a, b). The Aegean Region that has suitable ecological conditions for both cropping systems should be considered for sunflower production, in order to decrease the vegetable oil gap in Turkey.
High oleic and herbicide resistant (IMI and SU groups) sunflower varieties are being developed. There are research programs to develop oilseed and confectionary sunflowers for both main and catch crop production seasons. Sunflower germplasm has been developed from sources such as cultivars and breeding populations and tested for general and specific combining ability. Inbred lines, candidate and commercial varieties are evaluated in preliminary and yield trials on a regional basis for both main and catch production seasons in the Aegean Region and other parts in Turkey. In addition, agronomic studies are made on effects of sowing date, plant population, fertilization, irrigation and honeybee pollination on seed yield, oil content, oil quality, silage quality and other plant characteristics.
There is a lack of certified confectionary seed production with desired quality for this type of crop. Consequently, land races are generally used for confectionary sunflower production in Turkey. However, they are not suitable for combine-harvesting because they are not uniform in terms of plant height and physiological maturity Tan and Tan, 2010). New high yielding oilseed and confectionary sunflower hybrids have been improved and registered for the direct benefit of the agricultural sector and increased sunflower production in the country (Kaya, 2010;Tan, 2010a, b;Aldemir et al., 2016;Altunok et al., 2016;Tan et al., 2016b, Tan et al., 2017a.
New high yielding oilseed and confectionary sunflower hybrids have been improved and registered for the direct benefit of the agricultural sector and increased sunflower production in the country.

Conclusion
Sunflower is one of the main oilseed crops that contribute to the economy of Turkey for both human and animal nutrition, creating employment and internal and external trade. Production needs to be increased by breeding high yielding varieties tolerant and or resistant to biological and physiological constraints. Sunflower landraces having diversity will also contribute improving high yielding oilseed and confectionary sunflower hybrids.