Variations in the Composition of Avocado Seed

SUMMARY Avocado seed are usually considered as waste or as a source of seedlings suitable for use as rootstocks. This paper emphasizes the changing composition of avocado seed and how as a storage organ certain constituents are translocated from it to other portions of the fruit or tree. The fresh and dry weight and some of the inorganic constituents were determined in the dry matter of the seed of fruits of a number of Mexican and Guatemalan varieties. When the inorganic elements were calculated in terms of grams per seed, the calcium, magnesium, and potassium content of the seed of the Mexican varieties average much less than those of the Guatemalan varieties examined. Avocado seed contain relatively low amounts of calcium and magnesium, somewhat higher amounts of phosphorus, and high amounts of potassium. Determinations were made of the fresh and dry weights and inorganic composition of seed of fruit collected at the same time from similar scion varieties grown on different rootstocks under the same orchard conditions. Calcium in the dry matter of the Fuerte avocado seed from fruit of trees on Topa Topa rootstock was greater than in that of seed from fruit of trees on Mexicola rootstock. A study was made of seasonal changes in the weights and composition of Fuerte avocado seeds from fruits of a tree on Mexicola as the rootstock variety. During the early stages of fruit maturity the fresh weight of the seed increases until about the middle of December and then decreases until about February 20. Variations in the grams of water per seed and in the dry weight per seed roughly follow (when plotted) the same trend as that of the fresh weight. Approximately half of the maximum content of potassium in the seed is translocated or removed from the seed during the period of fruit maturation. Although the calcium and magnesium contents of the seed are relatively low, their content is also greatly decreased as the fruit matures. Such losses from the seed may have some bearing on the time of securing seed for rootstock purposes. In previous reports (1,2) it was pointed out that the content of inorganic elements in the pulp, skin, and seed of avocado fruit parallels the results found for those elements in the leaf petioles and blades (3). Furthermore the high and low potassium values in the pulp of Fuerte avocado fruit obtained from various orchards …