8 N. H. AGR. EXPERIMENT STATION [Bulletin 212 



there is a quite definite relation between the relative proportion of availaljle 

 nitrogenous compounds and carbohydrates to growth and reproduction. It 

 is not surprising, therefore, that it has been possible, on the basis of the inter- 

 nal changes produced in the plants, to explain the effect upon fruitfulness of 

 various cultural operations such as pruning, fertilization with nitrogen, culti- 

 vation, growing of cover crops, etc. In fact, more rational recommendations 

 regarding cultural operations in fruit production can be hoped for only by 

 means of a thorough understanding of the internal changes produced and their 

 correlations with external manifestations of the plants. 



If the other environmental conditions are maintained, increases in the 

 amount of available nitrogen lead to a decrease in the proportion of availa1)le 

 carbohydrates. This is in part due to the fact that considerable amounts of 

 carbohydrates are used up with the nitrogen in the synthesis of proteins. Anj' 

 decrease in the supply of available nitrogen on the other hand will lead to an 

 increase in the relative proportion of carbohydrates. This is in large part due 

 to the fact that the carbohydrates are not used up with the nitrogen in the 

 synthesis of proteins. Phosphorus and sulphur are also used in the sj'nthesis 

 of proteins. It would be helpful, therefore, to know in what manner modifica- 

 tions of the supply of phosphorus and sulphur affect growth and reproduction 

 as well as the metabolism of the plant. 



The present project was initiated by H. R. Kraybill and T. O. Smith (Agri- 

 cultural Chemistry) with the purpose of studying the effect of modifying the 

 supply of nitrogen, phosphorus and sulphur upon growth and fruit production. 

 The tomato plant has been used in aU of the work. In addition to the two sets 

 of plants mentioned in the last report another set has been grown during the 

 past 3'ear. Analysis of the first two sets of plants has been completed and that 

 of the third set is now under way. Careful records have been made of the 

 number of blossom clusters formed and the number of fruits set on each blos- 

 som cluster. Microchemical and anatomical studies have been made. 



The results with the first two sets show that the jilants which were grown 

 in a fertile soil and then transplanted to sand with a nutrient solution minus 

 phosphorus were feebly vegetative, deep green in color, and non-fruitful. 

 Compared with those grown in the complete nutrient solution they were higher 

 in total nitrogen, nitrate nitrogen and chlorophyll content and also higher in 

 free reducing sugars and total carbohydrates. The plants grown in sand with 

 nutrient solution minus nitrogen were also feebly vegetative and non-fruitful, 

 but had a pale green color and compared to tho.=e grown in the complete nutrient 

 solution were lower in total nitrogen, nitrate nitrogen and chlorophyll content, 

 and higher in free reducing sugars and total carbohydrates. 



The plants gro\^'n in sand with nutrient solutions minus sulphur were just 

 slightly less vegetative and fruitful than those grown in the complete nutrient 

 solution, and were slightly higher in total nitrogen, free reducing substances 

 and total carbohydrates. The effect of leaving the sulphur out of the nutrient 

 solution was not very marked. 



In order to study in more detail the effect of limiting the supply of phosphorus 

 and sulphur upon the metabolism of the plants, the nitrogen distribution of the 

 three fractions, separated by a modification of the Koch method of tissue 

 anah'sis, was determined. 



