Effect of winter irrigation on flowering , fruit set of olive (Olea europaea L.) cv Zard Roudbar

Following to drought in the state during the years 1997 and 1998 and decrease of rain fall in Autumn and Winter and therefore to decrease of soil moisture in primary stages of Roudbar olive flower development and increase in shot berry percentage compared with last years, attention was paid to the necessity of study of the effect of Winter irrigation of Roudbar olive gardens on flowering characteristics and yield increase .on the strength, A study preformed in complete randomized block design with five treatments and three replications with stress on time factor on Roudbar local olive trees,cv Zard during agronomical years of 1999 and 2000. Each experimented unit consisted of two trees (high product and low product and low product), totally thirty trees used to complete this experiment. For each of the used trees one guard plant tree was considered. In this study each square meter of canopy was irrigated by five hundred liters of water in two phases (8th,22nd) during Winter. For assessment of the projeظct results, inflorescence length, number of flowers in inflorescence , fruit set percentage , intact fruits and shot berry pe rcentages were counted in the selected branches (four branches in four different directions of the tree). The study results showed that winter irrigation had significant effect on increase of inflorescence size, number of flowers in inflorescence, fruit formation percentage, intact fruit and shot berry percentages in such as way that a significant difference was observed among different treatments and control trees with a view to inflorescence size, number of flowers in inflorescence, fruit set percentage and intact fruits percentage. A significant difference was observed among different times of Winter irrigation with a view to inflorescence size, fruit set percentage and intact fruits percentage. Treatments of control trees and irrigation irrigation had least effect on increase of inflorescence size, number of flowers in inflorescence , fruit set and intact fruit percentage. The study results showed that with decrease of irrigation, the shot berries percentage were increased too. Keywords: Olive irrigation, Flowering, Flower development, Fruit set, Yield