Development of Cherry and Peach Fruits as Affected by Destruction of the Embryo

Abstract

Fruit development in the cherry and peach falls in 3 clearly marked stages: I, rapid increase of the pericarp from about the time of fertilization to mid-season; II, retarded increase of the pericarp during mid-season; and III, 2d rapid increase to fruit maturity. Embryo development is arrested during I and is rapid during II. With early-ripening vars., III is initiated during rapid development of the embryo, and early-ripening vars. characteristically have abortive embryos. In late-ripening vars., III does not begin until the embryo is full size, and such vars. have a high proportion of viable seed. Three vars. of sour cherry (Prunus cerasus) and 6 vars. of peach (P. persica) were studied during the growing seasons of 1934 and 1935, using the sour cherry vars., Early Richmond, Montmorency, and English Morello, representing early, mid-season, and late vars., respectively; and Triumph, Greensboro, Arp and Lola peaches representing early vars., and Elberta and Chili representing late vars. Embryos were destroyed at various stages of fruit development by jabbing through split pits with a needle and by drilling through the pericarp into the seed and embryo from several positions, the most effective of which was through the apex of the fruit towards the base. Fruits were also wounded in the fleshy pericarp and stony pericarp, without interfering with the seed; and other fruits which were wounded in the pericarp by insects were also studied. Destruction of the embryo early in the development of the fruit (Stage II or earlier) resulted in abrupt check in fruit development, shriveling, and abscission. Destruction of the embryo in the transition between Stages II and III resulted in growth of the fruit at the normal rate but for a limited period, ending with hastened ripening and failure to reach full size. Destruction of the embryo in Stage III resulted in increased growth rate and earlier ripening, and occasionally increased size over the size attained by normal fruits at maturity. Wounding of the fleshy and stony pericarps, either alone or together without injuring the seed, did not alter the growth rate of the fruit. The nearer the date of normal fruit maturity at which the embryo was destroyed, the more rapid the growth increase of pericarp.