1118 EXPERIMENT STATION RECOED. 



tors tban the time of cutting after the srain reaches the hard-dough stage are hi- 

 volved. 



Investigations on the winterkilling of cereals, Buhlekt (Laiidic. Jalirb., 

 ■i-j {UIOH). \<>. (>. III). SS7-<SS7). — M()ri)hol<)gi(al, anatomieal, and cheniieal studies 

 were made to determine whetlier tlie winter resistance of plants may be recog- 

 nized by outer cliaracteristics. inner structure, or chemical composition. 



The mori)hological work was done with Jobannis and Zeeland rye and Preus- 

 sen and Eckendorf smooth square-head wheat. The less resistant varieties were 

 apparently better developed than the more hardy sorts. The dry matter in the 

 parts above ground of Eckendorf smooth square bead weighed on an average 

 per plant 0.01G4 gm., as compared with 0.0150 gm. for Preussen, the hardier 

 variety, and for Zeeland rye 0.0221 gm. as compared with 0.017G gm. for 

 Jobannis. The average weight per ])lant of the dry matter in the underground 

 parts was as follows : Eckendorf smooth S(inare head 0.021() gm., I'reussen 

 0.0192 gm., Zeeland rye 0.0177 gni.. and Johainiis rye 0.0134 gm. 



The wheat showed the greater root development and the rye the greater leaf 

 development. It also appears that the less hardy varieties bad the greater 

 root development, the relation of above to underground substance being on an 

 average as follows : in Eckendorf smooth square bead wheat 1 :1.317, in Zeeland 

 rye 1 : 08, in Preussen wheat 1 : 1.28, and in Jobannis rye 1 : 0.761. The root 

 length of the less I'esistant varieties was also greater tban in the bai'dy sorts, 

 the main roots measuring 927 mm. in Eckendorf smooth square-bead wheat, 

 873 mm. in Zeeland rye. (528 mm. in Preussen wheat, and 079 mm. in Jobannis 

 rye. 



The relation between leaf surface and root length was closer in Eckendorf 

 smooth square head and Zeeland rye tban in the other 2 varieties. Measure- 

 ments also indicated that the leaves of the hardy varieties were relatively longer 

 and narrower tban the leaves of the more tender sorts, and this character is 

 believed to assist the foliage in assuming a protective position against frost and 

 also enabling it to lie closer to the surface on uneven ground. The thickness of 

 the leaves of the 4 varieties showed but slight differences. 



The anatomical investigation showed that the plasmolytic effect of frost 

 varied considerably between individuals and varieties and also between different 

 species of plants. Plasmolysis as the x-esult of frost was frequently observed 

 in the leaves of grains, while it was not found in pine needles. The use of 

 potassium nitrate solutions in bringing about plasmolysis also showed different 

 degrees of resistance. Winter barley was less resistant to the action of the 

 solution than winter rye, while pine needles were excei»tionally resistant. 



The chemical study of the juice of normal and frosted plants showed that the 

 composition was about the same, hut that through the action of sodium chlorid 

 or zinc sulphate a greater precipitation of albumen was effected in the juice 

 from normal jilants. When the juice of normal plants was kept at a tempera- 

 ture ranging from +.'")° to — 40° ('. it was noted that chemical changes took 

 place under the action of low temperatures, but that the juice of ditl'erent plants 

 behaved differently in this i-esiiect. The frozen juice ui»on melting showed a 

 precipitate containing considerable albumen and traces of lime and phosphoric 

 acid. This precipitate was formed in the juice of spring barley at — 7°, of 

 winter barley at — 12°, and of winter rye at —15°, while the juice from pine 

 needles was subjected to a temperature of — 40° for days before precipitation 

 was observed. It was further noted that the albumen of plants little resistant 

 to frost was more readily precipitated in the presence of potassium chlorid, 

 sodium chlorid, and zinc sulphate solutions than the albumen of plants capable 

 of withstanding low temperatures. 



