Effect of Prolonging Daylight, Foliar Application of Salicylic Acid and Micronutrients on Inflorescence Characteristics and Leaf Anatomy of Gerbera jamesonii Plant Photoperiod Extension

This study was conducted in the fields and laboratories of the Department of Horticulture and Landscape design, College of Agriculture and Forestry, University of Mosul. The experiment included a study of exposing plants to natural daylight or with prolonging daylight with red and blue light, which obtained from diodes, Figure 1 for four hours (one hour before sunrise and continuing one hour after, then two hours at sunset, one hour before sunset and continuing for one hour after sunset), and spraying with salicylic acid at 300 mg l^-1, or spraying with a mixture of micronutrients, include FeSO₄, ZnSO₄ and CuSO₄, at a concentration of 40 mg l^-1 for both iron and zinc, and copper was added at 10 mg l^-1 or an interaction between salicylic acid and micronutrient. The results showed that growing plants with prolonging daylight combined with spraying with salicylic acid and a mixture of micronutrients led to the significant increase in values ​​for inflorescence yield, inflorescence stalk length, and the ratio of ray to disc florets, as well as the glucose content of the flowers. The anatomical study showed that the above treatment led to an increase in the thickness of the spongy layer and the lower leaf epidermis. On other hand, the diameter of the vascular bundle in the midrib vein of the leaf and the total number of vascular bundles and small vascular bundles also increased. The above treatment also led to an increase in the diameter of the vascular bundle in the leaf petiole, the outer sclerenchyma layer, and the xylem.