Ola Kajo*¹ and Riham Ihsan¹

1 Field Crops Department, Faculty of Agriculture, Lattakia, University, Lattakia, Syria.
(*Corresponding author: dr. Samar Saleh, Email: ola.kajo@latakia-univ.edu.sy phone: 0932663764)

Received: 19/11 /2025       Accepted: 12/07 / 2026

Abstract: 

This study was conducted in Jableh region of Latakia Governorate during the 2024 agricultural season to investigate the effect of planting date and foliar application of Humic acid on the productivity and its components of sunflower (local variety). Humic acid was applied at a concentration of 2 g/Liter with either one or two foliar sprays, in addition to the control treatment (without spraying). The first spray was applied 30 days after planting and the second spray after 40 days (at the beginning of floral bud formation) for both planting dates. The experiment was carried out using a randomized complete block design (RCBD) with three replications.  The following parameters were measured: plant height (cm), number of leaves, head diameter (cm), number of seeds/heads, 100-seed weight, seed yield/plant, and seed yield per unit area. Results showed a significant effect of planting dates, with the first planting date (May 15) outperforming the second planting date (June 15) in most of the studied traits. Regarding the effect of Humic acid, foliar application, especially with two sprays, improved growth parameters (plant height 257.35cm, number of leaves 41.80 cm) as well as yield traits (head diameter 25.37 cm, number of seeds 1220, 100-seed weight 20.34g), which positively affected seed yield per unit area. The interaction between planting date and Humic acid application showed that the highest seed yield was recorded with the first planting date (May 15) combined with two foliar sprays of Humic acid, reaching 5854 kg/ha.

Keywords: Sunflower, Planting date, Humic acid, Yield, Oil.

Full paper in Arabic: PDF