RESPIRATORY ACTIVITY AND DURATION OF LIFE OF APPLES GATHERED AT DIFFERENT STAGES OF DEVELOPMENT AND SUBSEQUENTLY MAINTAINED AT A CONSTANT TEMPERATURE

Abstract

In Part I of this series (9) it was shown that the respiratory activity of an apple gathered at "maturity" in the autumn and subsequently kept at a constant temperature was characterized by a rise followed by a fall. This rise in respiratory activity was attributed to a change of state in the protoplasm. It was considered to mark the onset of senescence and was termed the "climacteric. " It is interesting to inquire whether the senescent rise occurs in fruit picked in an immature condition. Outline of the main experiment, 1925 In 1925, Bramley's Seedling apples were taken at intervals during their period of growth from selected trees in an orchard near Cambridge. They were immediately brought into the laboratory and placed in glass containers lheld at a constant temperature of 12° C. and ventilated by a constant stream of C02-free air of constant humidity. Under these conditions the rate of CO2 production was followed for as long a period as the fruit remained sound; i.e., free from the attack of fungi. The details of the various gatherings are given in table I. The temperatures in the orchard are given in table II. The glass containers used in these experiments were approximately 700 ml. in volume and were originally designed to hold one fully grown apple. Single apples were the experimental units in the case of the later gatherings. In the case of the earlier gatherings the experimental units consisted of more than one apple (table I). They were ventilated at a rate of about 4 lilers an hour, the incoming CO2-free air being passed through soda lime and through a wash bottle containing a 7 per cent. solution of sodium hydroxide. The number of fruits per container was so arranged that the rate of evolu-1 This is the second of a series of papers on the general subject of "Physiology of