30 
BULLETIN 57, HAWAII EXPERIMENT STATION 
The comparatively small increases in the yields during June and 
July, the sudden increase beginning with August, and the appearance 
of Group 1 in appreciable numbers indicate a cyclic rather than a 
continuous growth of the plant. (Fig. 16.) From February until 
May few new rootstocks appeared and practically all the stalk growth 
was mature, Group 3 consisting largely of spikes. New stalk growth 
appeared in June and many new rootstocks in August. If these 
phenomena are inherent in the plant, the first cycle of growth ended 
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Fig. 15.— Tenth-acre harvests and classifications of "two-seed" plat 
about June, and the two or three earlier months constituted the 
maturing period. The sudden new growth of stalks in June and new 
rootstocks in August might then indicate the beginning of the second 
cycle of growth. 
Climatic factors undoubtedly have their effect on growth. Except 
for young fields planted six to eight months or less, observations 
show a similarity in the growth of fields of different ages in the same 
locality. Among the climatic factors, destructive winds have a 
bearing on the crop. During December, 1925, for example, a severe 
