LIFE HISTORY INVESTIGATIONS. 139 



IMPORTANCE OF LIFE HISTORY INVESTIGATIONS IN DEMON- 

 STRATING THE FEASIBILITY OF DATE CULTURE. 



The importance of a detailed study of the climatic and soil require- 

 ments of the date palm is clearly shown in treating of the regions in 

 the United States adapted to its culture, as well as in the discussion of 

 the heat requirements and of the alkali resistance of this remarkable 

 plant. No other crop plant can withstand so much alkali in the soil 

 or in the irrigation water, and tens of thousands of acres of alkali lands 

 in the irrigated areas in the Southwest can be reclaimed and put to 

 profit only by growing dates. This renders it of the greatest impor- 

 tance to determine the extreme geographical limits of the regions 

 where dates can be produced with profit in order that this invaluable 

 plant may be utilized on alkali lands wherever possible. 



Not only is it possible as a result of life history investigations to 

 indicate with some degree of precision the regions where dates can be 

 grown, but also to predict the types of varieties which alone can 

 succeed in each region, and further, to indicate in which of the date- 

 growing countries of the Old World such types can most likely be 

 secured. For example, in order to secure hardy late-ripening sorts 

 able to withstand the winter cold in Texas and southern Nevada, 

 search should be made in the oases of central Persia, near the 

 northern limit of date culture, where the winters are so severe that 

 even old, bearing palms are sometimes killed, but where the summers 

 are nevertheless very hot. North Africa on the contrary, is the least 

 promising region to search for such sorts because of the mildness 

 and equability of the winter climate, even in the oases situated on the 

 slopes of the Atlas Mountains limiting the Sahara to the north. 

 On the other hand, early maturing sorts, suitable for culture in the 

 interior valley region of California and in the flood-plain of the 

 Colorado River in Arizona and California, where the winters are 

 relatively mild and the summer heat deficient, are most likely to be 

 secured in just these oases on the slopes of the Atlas Mountains, 

 though such varieties may be expected to occur in oases at high 

 altitudes in the interior of the Sahara and in Arabia. Choice late 

 sorts of date palms, suitable for culture in the hotter valleys of 

 Arizona and in the Salton Basin, California, are most likely to be 

 found in the oases at low altitudes in the interior of the deserts of 

 Sahara, Arabia, and Persia. 



It is also possible, from a study of the life-history factors of the date 

 palm, to warn intending planters against attempting its culture in 

 regions where it can not succeed. Thus it becomes possible to estab- 

 lish a new fruit industry in a rational manner without having to await 

 the tardy results of costly and often badly conducted trials made with- 

 out adequate foreknowledge of the requirements of the plant. Such 

 trials often lead to elusive hopes on the one hand and to unjust 



