A major gene for flowering time in almond

Almond (Prunus amygdalus Batsch) is the earliest temperate fruit species to bloom. This restricts the economic growing of almond to frost-free regions . Most almond-breeding programmes aim to develop late-flowering cultivars i n order to avoid frost damage and take advantage of higher temperatures whi ch are favourable for pollination and fertilization. Flowering time is gene rally considered to be inherited quantitatively but a single gene conferrin g Very late flowering in a qualitative way has been identified in several p rogenies tracing back to a single mutant, 'Tardy Nonpareil'. The effect of this allele has been studied in three progenies, showing that the effect of this major gene is modified by minor genes, quantitatively inherited, and probably influenced by inbreeding.