Later, in 1959, Poapst, Ward, and Phillips (64) reported more complete 
findings in which they stated that of all the criteria of maturation which they 
had tried, including ground color, blush, acidity, soluble solids, firmness, 
respiration, or peroxidase activity, the use of the starch patterns described 
by Davis and Blair (13) was the most satisfactory. They suggested a formula 
for calculating date of mean maturity which they considered the middle condition 
of abscission, 
Their relationship between index and starch pattern charts revealed an 
inherent error in the design of the Blair and Davis maturity chart in that ex- 
trapolated data failed to reach an index 9 and this bias varied from year to 
year. The reason for the difficulty was said to be embodied in the chart in 
that early changes represent major losses in starch content and later changes 
represent minor losses, 
Respiration 
One of the indices of the physiological and chemical changes in the 
apple is provided by intensity of respiration, as indicated by the rate of 
production of carbon dioxide. 
West (89) reported a respiratory curve of the life of a Bramley Seedling 
apple. While fruit are on the tree, the rate of respiration drops from a maxi- 
mum high in the stage of cell multiplication through a low period during cell 
enlargement. At harvest the rate of respiration rises again with the onset of 
the climacteric, falling off during senescence with a final quick rise at the 
death of the apple. 
The height of any climacteric peak seems to vary with the picking date 
for different varieties. Smock and Gross (75) reported that late pickings of 
a given variety often had a higher climacteric peak during storage than early 
pickings. Kidd and West (33) found that this climacteric could also occur on 
the tree. 
Hulme (29), in developing the ratio of rate of respiration to protein 
content, R/P, showed that subsequent to about 60 days from petal fall until the 
onset of the respiration climacteric, the rate of respiration of an apple on 
the tree is proportional to its content of protein. He stated that with the 
less developed apples the R/P ratio appeared to decrease from a relatively high 
value a few days after petal fall. Also, the mature preclimacteric apples 
showed an approximately constant R/P for a given variety, at least when cultural 
practices were not very different. Hulme suggested that the R/P ratio has a 
value characteristic of a variety and that the value tends to be higher for the 
dessert varieties rather than those for culinary use, 
Robertson and Turner (67) reported changes in respiration in Granny Smith 
apples following varying days from full bloom. 
Krotkov, Wilson, and Street (36), assigning less credence to rate of 
respiration as an index of maturity, suggested that pH of the juice of an apple 
might be a better indicator of the ontogenetic stage of the apple fruit than 
its respiration rate, carbohydrate content, or acid content. 
Hulme (30), working with Cox's Orange Pippin, developed the theory that 
the difference in time between the onset of the respiration climacteric in 
harvested fruit held at 12°C. (53.6 F.) and’ at’‘15° C. 759° F.) varied trom 
the date of picking fruit over a period a few weeks before to a few weeks after 
the commercial harvest date. This "time gap"’ had a minimal value which could 
vary from season to season. He suggested, however, that this "point of minimal 
12 
