THE RELATION OF CLIMATE TO POMOLOGY 243 



211. The effect of climate on development of fruit. — 



Shaw ^ luis shown that the variation in apple varieties is 

 due to three principal causes: (1) cultural practices, (2) soil 

 variation, (3) climate. Of the climatic influences, he places 

 temperature as the most potent. 



From his researches he draws the following significant 

 conclusions: (1) "Variation in form in the Ben Davis, and 

 probabl}^ in other sorts as well, is due principally to the tem- 

 peratm-e during a period of about two or three weeks fol- 

 lowing blossoming. The lower the temperature the more 

 elongated the apple. This elongation is seen in apples grown 

 near large bodies of water, which lower the temperature at 

 this season of the year, and in seasons where the tempera- 

 ture is low owing to seasonal fluctations. This influence 

 is also seen in the form of apples in different parts of the 

 tree. Those in the lower north portion are more elongated 

 than those from the warmer, upper south portion. " (2) " Sea- 

 sonal temperature affects the size of apples, a cool season 

 resulting in smaller fruit. This is marked only in full sea- 

 son varieties, and is especially noticeable in the more north- 

 erly portions of their distribution. On the other hand, in 

 the extreme south a variety is apt to be smaller than when 

 grown in a somewhat cooler climate." 



212. Climatic factors which delimit the geographical 

 distribution of fruits. — As pointed out earlier in the chap- 

 ter, climatic factors limit the growing of deciduous fruits as 

 the northern and southern boundaries of the temperate 

 zone are approached. These factors are defined by Shaw as 

 follows: "The northern limit of apple-growing is fixed by 

 the minimum winter temperature, and the southern limit 

 by the heat of the hottest part of summer, occurring usually 

 in July or August. 



"The attainment of the highest quality, appearance and 

 1 Mass. Agr. Exp. Sta. 22nd Ann. Rept. 1910. 23rd Ann. Rept. 1911. 



