Development of the Almond Nut (Prunus dulcis (Mill.) D. A. Webb). Anatomy and Chemical Composition of Fruit Parts from Anthesis to Maturity

Abstract

The growth of the fruit of two varieties of almond (Prunus dulcis (Mill.) D. A. Webb) was studid from anthesis (week 0) to maturity (week 32). The dimensions, fresh weight, moisture content, anatomy and chemical composition of the pericarp, testa, embryo, endosperm and nucellus are recorded diagrarnmatically, graphically and by micrographs for one variety. Of the two ovules present at flowering only one normally developed further. By 12 weeks after flowering the whole fruit had reached full size. The space encloscd by the pericarp was filled by nuallus until weck 10, with subsequent enlargement of both endosperm and embryo. From week 16 to week 20 the embryo increased to full size with a concumnt decrease in the size of the endosperm. Sixteen weeks after flowering, the embryo began to accumulate protein and lipid, little of which originated from either the nucellus or endosperm. The embryo contained no starch or reducing sugar but up to 3% sucrose in the early stags which dtcreascd as lipid and protein increased. Starch and sucrose levels were high in the testa at week 16 but subsbquently dropped, starch more rapidly than sucrose. The role of the testa in transport of metabolites to the embryo is discussed.