FRUIT SET IN CONTROLLED CROSSES OF ALMOND CULTIVARS

Abstract

Generally, in controlled almond crosses made for scion breeding programmes, flowers are pollinated earlier than in natural conditions. Branches are not bagged, flowers are emasculated before anthesis (at balloon stage) and then pollinated immediately, to reduce chances of outcrossing and to ensure crossing, as a delay in the artificial pollination can prevent it due to unsettled climatic conditions. Usually, it is not necessary to repeat the pollination to obtain an acceptable fruit set if the weather is favourable. A second pollination, 2-3 days after emasculation, coinciding with natural flower's anthesis, could be convenient to increase the fruit set in some cultivars. In this work, average fruit set obtained, applying one single artificial pollination, is compiled from 30 cultivars or selections used repeatedly as female genitors in the IRTA’s breeding programme. Considerable differences have been recorded among cultivars, repeated in different years and crosses. Cultivars have been classified in 3 groups, according to their average fruit set: low ( 30 %). Cultivars with low fruit set should receive a second artificial pollination, or be only used as male genitors, while cultivars with high fruit set are good as female parents. 'Anxaneta' can be cited as an example of a cultivar with a very low fruit set in this type of crosses (6 %, using about 14.000 flowers in 29 crosses made during 9 years), being however very productive in natural pollination conditions. Opposite to it, 'Lauranne' is a good example of excellent fruit setting (45 %, using about 12.000 flowers in 18 crosses made during 8 years).