Phenology aspects of some sunflower hybrids.
Abstract: Cultivated sunflower (Helianthus annuus L. is an unusual plant. It is distinguished from all other cultivated plants by its single stem and conspicuous, large inflorescence. A sunflower plant is influenced by both the growth stages from planting to maturity, as well as temperature, day length, nutrition and humidity. Hybrid maturity and crop area also have an effect on the length of the growing season. The study investigated the phenology of three sunflower hybrids grown in the western part of Romania. The yield of these hybrids from the morpho phenological perspective is being sought in order to identify their adaptability to the cultivated area. To grow best, sunflowers need full sun. They grow best in fertile, moist, well drained soil with heavy mulch. The results obtained from the measurements show that the studied hybrids behave differently from the environmental conditions encountered in the western part of Romania. In order to reach the objectives, the most important characteristics were measured which reflected the behavior of the hybrids in relation to the environmental factors, namely, the height of the plant, the length of the roots, the number of leaves, the length and width of the leaves, the diameter of the stem, the diameter of the flower buds and the diameter of the inflorescence. Those characteristics determine somewhat the use of the plant as a source of edible oil, as food for people and animals, or as forage. Floriculturists are interested in the variability in flower color, petal structure, and petal size. Descriptive classes are proposed herein for some morphological characters to improve the uniformity of descriptions of inbred lines and cultivars. Many descriptive characters are affected by the environment, so measurements should be made of plants grown under optimum field conditions. The statistical calculation was performed in Microsoft Office Excel 2016, establishing the coefficient of variation, the standard deviation of the mean and the average of the observed variants.