EXPERIMENT STATION REPORTS. 207 



1 would call yoiii' attoiilioii to tho fact that the work is Itadly hampered 

 for waut of laboratory room and by lack of greeiilumse space. 



Eespectfiilly submitted, 



G. H. COONS, 

 Associate Botanist. 

 I'rofessor E. A. Bessey, 



Botaiij^ Department, M. A. C. 

 Dear Dr. Bessey : 



I herewith submit the report of the work in Plaut I'hysiology for the 

 year ending June 30, 1922. 



The work in Plant Physiology was somewhat reduced because of my 

 absence from the College. By arrangement, the Adams 2d project Avas 

 discontinued for the period of my leave and the services of my assistant, 

 Mr. S. Gershberg, discontinued. As my work at Johns Hopkins rather 

 unexpectedly turned out to be in the same general line that I have followed 

 here, I assume it will not be out of place to append a brief memorandum 

 to the present report. 



(1) A study, conducted in the fall of 1921, of 15 culture solutions of 

 Type I (1.00 atm.) with pure line ]\[arquis wheat, seedling phase, using 

 5 plants in each of ten 2-quart jars for each solution, renewing all solu- 

 tions every other day, determining the dry weight of the 750 plantlets 

 individually and studying the results statistically. The results are the 

 most valuable thus far obtained by the water culture method. 

 -. (2) A study identical with that above Avith the exception that the 

 experiment was carried on early in the spring while the other was in the 

 winter time. Both experiments were run in the greenhouse. 



It was interesting to note that climatic conditions played an important 

 part in detenuining the distribution of good and poor growth on the 

 triangular diagram. For example, the peculiar injury called ''magnesium 

 injury" was marked in April and May but failed to appear in December. 

 In December, a ratio of salts high in magnesium and low in both potas- 

 sium and calcium proved to be the best for growth of seedlings, while 

 in April a ratio of the same salts all in about equal quantities produced 

 the best yields for seedlings. The general conclusions from this study 

 follow : 



l.Variability in plants frequently obscures any relation that may hold 

 betw^een the physiological values of the different solutions tested. This 

 difficulty is to be overcome partly by using pure line seed, partly by im- 

 proved methods of germination, and selection of original seedlings but 

 probably mainly by employing larger numbers of seedlings with the same 

 treatment. The best results have been obtained with pure line seeds, 

 germinated in a special way, and with 50 plants for each solution. 



The general conclusion follows that in view of the many kinds of condi- 

 tions atfecting the salt relations it is practically impossible for a single 

 worker to secure results involving all the influential conditions in a known 

 way. Co-operatian of several workers with carefully controlled conditions 

 is absolutely essential if definite knowledge is to be obtained. 



It is suggested that the next great step in the study of salt nutrition 

 of plants should be an attempt to provide at one or more places the 

 necessary equipment for adequately controlling temperature, evaporation, 

 the CO:; content of the air, the oxygen and CO^ content of the nutrient 



