PFA in walnut at the Central Valley of Chile

Female flower abortion caused by lack and excess of pollen was studied during 3 seasons (2014 to 2016), at San Bernardo, and at Paine orchards, close to Santiago, Chile. Cultivars studied were ‘Serr’, ‘Chandler’, ‘Howard’, and ‘Franquette’. The first season ‘Serr’ showed 37.2% abortion, where 27.8% was due to excess of pollen. ‘Serr’ was the most affected cultivar for this cause, compared with the other cultivars under evaluation. In the season 2015-16 ‘Serr’ presented 56.3% abortion and excess of pollen was 36.7%. In the 2016-17 season, ‘Serr’ showed 38.3% abortion. Excess of pollen induced 32% of that abortion, compared with ‘Franquette’, which had only 5% abortion; 4% caused by excess of pollen. The differences between cultivars are probably genetic. However, differences between seasons are due to chilling accumulation each winter time.