ABSTRACT
The pollination of the olive is carried out mainly by wind and, thus, climatic conditions are critical for good fruit set. 1 , 3 Rain during the flowering period will cause a marked reduction in fruit set, while high temperatures, 4 , 5 particularly when accompanied by dry wind, cause abortion of young fruitlets. 6 The viability of pollen is very high when originating from male or complete flowers. 6 On the other hand, the amount of pollen produced is excessive and the distribution potential high; thus, no correlation between the viability of pollen and fruit set could be shown. Furthermore, as the number of flowers is very high, the set of 2 to 3% of the flowers on an olive tree is enough for a heavy yield, the degree of flower viability is dependent, not only on the environmental conditions, but to a great extent on the physiological state of the tree. The viability of the flowers, induced by a favorable winter, on trees which had a heavy crop in the previous year will be low. On the other hand, on trees which in the previous year had an average crop, the viability of flowers is negatively correlated to their number. On well-developed trees with weak flowering the percentage of fruit set might increase to 5 to 6% (Figure 1).
