The yield of achenes and the yield components of the head are specific to each sunflower hybrid, but they are influenced by the different growing factors (environmental and technological factors). Soil and climatic conditions are among the environmental factors with a great influence on the sunflower yield. Row spacing and plant population are of great importance among the technological factors. In this respect, the present study was aimed to study the influence of row spacing and plant population on yield of achenes and yield components of the head under different soil and climatic conditions from South Romania. Researches were performed in field experiments in the years 2013 and 2014, in two locations from South Romania, respectively Fundulea (44^o28’ N latitude and 26^o27’ E longitude) and Moara Domneasca (44^o29’ N latitude and 26^o15’ E longitude). In each location and experimental year there were studied four sunflower hybrids (Pro 111, Pro 953, LG56.62, and P64LE19), each of them under three row spacing (75 cm, 50 cm, and twin-rows of 75/45 cm) and under three plant populations (50,000, 60,000, and 70,000 plants ha^-1). The row spacing influenced differently the yield components of sunflower head according to the soil and climatic conditions. The highest yields were obtained at row spacing of 75 cm under favourable growing conditions and at row spacing of 50 cm under less favourable growing conditions. The increasing of plant population from 50,000 to 60,000 and further to 70,000 plants ha^-1 decreased the values of yield components of the head. In the same time, the increasing of plant population increased the yield under favourable growing conditions and decreased the yield under less favourable growing conditions.

Sunflower (Helianthus annuus L.) is one of the most important oil crop in the world with a harvested area in 2016 which was 3.9 times more than in 1961. The almost continuous increase of the harvested area at world level is due to the sunflower crop advantages for the farmers and to the increased yielding capacity and oil content in the seeds, all these associated with an increased demand on the market for the sunflower oil. The high yielding capacity associated with high oil content in the seeds is due to the remarkable achievements realized through the breeding programs performed at sunflower crop in the last century. These achievements are related especially to the creation of the high-yielding F1 hybrids with excellent performances. The aim of the present paper is to make an analysis and to give an insight into the situation, evolution, and historical milestones regarding the sunflower varieties and hybrids registered for cultivation in Romania in the last century. In this respect, there were analyzed different informational sources during the last century with respect to the sunflower crop in Romania, but especially the whole collection of the Romanian Official Catalogues of the Varieties of Plant Species. The official journey in Romania of the sunflower as an oil crop started in 1910 and has registered up to present a spectacularly evolution both in terms of cultivated area and varieties and hybrids cultivated.