Jan. 1922J annual report. 11 



in the problems of apple culture testifies. Recognizing this fact. H. R. Kray- 

 bill and T. O. Smith (Agricultural Chemistry) began investigations last 

 year in the subject of plant metabolism, a field in which Mr. Ivraybill has 

 been associated in previous work. 



The literature of this subject has placed particular emphasis upon the 

 relation of different amounts of available nitrogen and carbohydrates to 

 growth and fruit production. In general there seems to be associated with 

 fruit production a more or less definite relation of available carbohydrates 

 to nitrogen. The quantity of nitrogen available to the plant has been modi- 

 fied by varying the supply of nitrogen in the soil or the nutrient solution; 

 and it is probable that modifying the available supply of other elements 

 to plants will also affect the relation of available carbohydrates and nitro- 

 gen. It is also evident that before we can clearly understand the relation 

 of nutrition to fruit production all of the factors which affect the nutrition 

 of the plant must be taken into consideration. 



In carrying out this project the tomato plant is being used, because it is 

 suitable for experiments under more or less controlled conditions and be- 

 cause of its similarity to the fruit tree in responses of growth and reproduction. 

 During the past year two sets of plants have been grown in sand in the green- 

 house. The first set consisted of four lots, receiving the following nutrient 

 solutions respectively: — Lot 1 — complete nutrient solution; Lot 2 — nu- 

 trient solution without nitrogen; Lot 3 — nutrient solution without sulphur; 

 Lot 4 — nutrient solution without phosphorus. The second set was a du- 

 plication of the first set but carried on at a different season of the year. 



Samples of the leaves and stems of the plant from the different lots have 

 been preserved and are being analyzed. Photogi-aphs were taken of typical 

 plants from the different lots, and the number of blossom clusters, blossoms, 

 fruit set, and fruit dropped was recorded. Catalase studies of samples of 

 the plants under the different conditions, and micro-chemical examinations 

 for starch and nitrate nitrogen were made. 



Control of Root Maggots. 



For a number of years investigations in the control of the cabbage mag- 

 got by insecticides have been carried on here by W. C. O'Kane (Entomology) ; 

 and the data secured has shown a marked efficiency for a tobacco-dust- 

 lime mixture, composed of equal parts of finely ground tobacco-dust and 

 limestone, commonly known as agricultural lime. 



The investigations of the present season were arranged to throw light 

 on the underlying causes responsible for the definite effects observed in pre- 

 vious years. Determinations were sought as to the following: whether 

 the mixture affected the vitahty of the egg stage and, if so, to what degree; 

 what effects may exist on the larval and the pupal stages; what results might 

 be brought about by the addition of moisture, as in rain-fall; whether the 

 dry mixture exerts a repellent action on the adults. Along with these ex- 

 periments others were planned to determine the possible reaction of the adults 

 to a poison bait of bananas and sodium arsenite. indicated in last year's 

 studies. 



