16 WHEAT KESISTANCE TO TOXIC SALTS. 



Sea is a great salt marsh covering a considerable area. On the other 

 side of the river, for a couple of hundred miles along its course, there 

 are both salt marshes and lakes. The great Khaki salt marsh along 

 the borders of the Kirghiz Steppe covers several hundred square 

 miles. Northward and westward from this marsh there is a series 

 of small salt lakes, the largest of which is Elton Salt Lake. It 

 would naturally be expected that in a region with such extensive 

 salt marshes and lakes the arable soil would likewise contain a large 

 proportion of salt. 



MARAOUANI. 



The Maraouani variety of durum winter wheat {Tritkuni durmn) 

 has been grown in northern Africa probably for centuries. As far as 

 can be ascertained, it originated there and has long been one of the 

 most valuable sorts of that country. The seed used in these experi- 

 ments came directly from the Cheliff Valley, an arid region with 

 very little rainfall, in the western part of Algeria. The wheat land 

 there is cultivated for the most part Avithout irrigation. The soil is 

 largely a heavy clay loam, and probably contains in nearly all sec- 

 tions a more or less excessive amount of readily soluble salts. Mara- 

 ouani is very hardy, is resistant to rusts, and has the reputation of 

 being the best of the durum Avheats now grown in that region. In 

 the Department of Oran it is most successful when sown in Novem- 

 ber; it then matures about June. It is thought by expert cerealists 

 that this variety would succeed well in the spring-wheat regions of 

 the northern United States and as a winter wheat in the Southwest. 



METHODS OF EXPERIMENTS. 



Wheat seeds are small compared with lui)ines, beans, peas, etc., 

 Avith Avhich most of the work of other experimenters has been done. 

 The rootlets of the Avheat seedlings are so small that at first it was 

 feared that some difficulty would be experienced in marking off the 

 rapidly growing zone with india ink, the readiest method for accu- 

 rate determination of the death point. In view of this difficulty the 

 work was begun Avithout marking. It required but a fcAV trials, hoAV- 

 ever, to proA^e that it Avould be practicallv impossible to obtain satis- 

 factory results in such a Avay. Wheat rootlets have a hard surface 

 and do not become flaccid in salt solutions unless these are of a con- 

 centration much beyond the toxic limit, in Avhich case the roots be- 

 come yelloAV and the cells somcAvhat broken doAvn. HoAvever, one 

 or two attempts at marking shoAved that Avith a little practice and 

 care this could be effected Avithout inflicting any injury. By ruptur- 

 ing the epidermis A^ery slightly a sufficiently conspicuous mark, Avhich 

 Avill last forty-eight to seventy-two hours, can be made Avithout injury 

 to the roots. 



