CLIMATE AND PLANT GROWTH. 



55 



Furthermore, the curve representing these percentages bears an 

 intimate agreement with both of the temperature summation curves. 

 This increased conservatism in the use of water in wheat leaves may, 



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Temperatare aboi/^e 4-0' 



— h/afer re<^u/remerrts- per mTrr. Leaf Length {iV/7eaf) 



P/7ys/o/oqica/ Tenrperafure Efficierrcy 



■ fVater' reef^ifemenfs per mm.LeafLer)<^/-h(Srome-q/'ass) 



Fig. 30. — Water requirements per unit (1 mm.) of leaf length of brome grass and wheat 



in a way, account for the high yielding qualities of wheat, other 

 conditions remaining the same, in regions where the summers are 

 relatively cool. 



