The Effect of Different Seeding Rates on Grain Yield and Yield Components in SomeFlax (Linumusitatissimum L.) Varieties

Flax (Linumusitatissimum L.)is a multi-purpose annual industrial plant, whose seeds are used and fiber is obtained from its stems. The flax'sfibers obtained from its stems, its seeds, oil, and residue have been used indifferent sectors. The oil, which is approximately found in the rate of 35-46% in the flaxseed, has been used in chemical industry areas such as paint and varnish production due to having high amount of linoleic (16-75%) and alpha-linolenic (17-59%) acids in it and due to being a polyunsaturated oil (M. Zuk et al., 2015).

The need for the oilseeds has been increasing every year throughout the world, and the flax has also been contributing to the production of the oilseeds in addition to the produced major oil plants. The flax, which is produced approximately 2.5 million tons in the world, is mostly cultivated in Canada, Kazakhstan, China, Russia, USA and India (FAO 2017). Considering the existence of agricultural areas in the world, since the horizontal growth is not possible, vertical growth should be considered; and selection of the plant types and agronomic applications should be emphasized to increase the yield in the unit area. There are three major components of yield in the production of flaxseed, namely, number of capsules, number of seeds in capsules and seed weight (Lafond 2001). Knowing the amount of seed is one of the most important facts of the agronomic applications (Casa et al., 1999). It has also been confirmed in scientific studies that the grain yield varies depending on agronomic applications and environmental factors, i.e. while the yield was 3,310-4,360 kg/ha in England (Turner 1991), it was 950-2,795 kg/ha in Germany (Diepenbrock and Parksen 1992).

Studies have shown that the amount of seeds is important in flax and that the flax varieties can react differently to the plant density (Gabiana 2005). Studies on the number of seeds to be sowed in the unit area in the oilseed flax found the ideal rate as 200-400 plants/m2 for the grain yield (Turner 1991; Diepenbrock and Parksen 1992; Gubbles and Kenaschuk 1989; Lisson and Mendham 2000) and reported that this plant density increased the photosynthesis capacity of the plant as a result of the length of the green leaf area during capsule and seed development (Diepenbrock and Parksen 1992). On the other hand, Hassan and Leitch (2000) reported that when the plant density increased, plants entered into competition with each other, resulting in fewer and shorter branches with smaller leaves, limited plant growth and decreased number of capsules. In another study, it was observed that high sowing norm increased plant height, leading to the problem of leaning in plants (Lisson and Mendham 2000). Leitch and Sahi (1999) reported that when the plant density in the unit area increased, the individual plant size decreased, while the total dry matter ratio obtained from the unit area increased. In some studies on flax, the difference between the numbers of plant parts in the unit area did not make a difference in both dry matter and grain yield as a result of plants' denser branching and filling the existing gaps due to increased plant size (Khan and Bradshaw, 1976). It is observed that the effects of climate and soil factors are great on the difference found in terms of the effects of plant density on grain yield and yield components in the conducted researches. It is important to determine the most suitable plant frequency by carrying out studies in all of the ecologically different production areas. In this study, it was aimed to determine the ideal amount of seeds in Tekirdağ conditions, considering the yield and yield components of different flax varieties.