Effect of foliar fertilization on flowering of Olea europaea L. ‘Chemlali’

Olive is a traditionally important crop grown extensively in the Mediterranean basin. Floral quality and effective pollination have a significant influence on fruit set and on final crop. In the present work, we studied the effect of foliar fertilization on floral phenology, flowering parameters, pollen viability, and in vitro pollen germination of Olive 'Chemlali' grown under rain-fed conditions in Saheline (Monastir, Tunisia). For this purpose, four foliar treatments were applied: TC (control, without foliar nutrition), T1 (rich in nitrogen, applied on 18 of February before the start of vegetative growth and 10 days later), T2 (rich in boron, magnesium, sulfur and manganese, applied on 25 of March, before the begin of flowering and 10 days later) and finally T12 a combined treatment of T1 and T2. The number of flowers cm-1 of fruiting branch ranged between 5.49 (T1) and 8.51 (T12). The combined treatment T12 showed the earliest flowering on 30th April and the highest number of flowers inflorescence-1. The simple treatment T1 showed the highest number of perfect flowers. The maximum number of branched peduncles developing in the inflorescence was four for all treatments. Perfect flowers were more frequent in a terminal than in a lateral position. Pollen viability varied between 82.83 and 85.97%. The simple treatment T2 showed a high fertility of pollen under in vitro conditions. The results indicated that all foliar fertilization enhanced the flowering status of olive tree cultivated under rain-fed conditions of central Tunisia.