182 FUNDAMENTALS OF FRUIT PRODUCTION 



ness, fertility, and lessened vegetation.""^ The third condition, in 

 which "a further reduction of nitrates without inhibiting a possible 

 increase of carbohydrates, makes for a suppression both of vegetation and 

 fruit fulness,""^ is evidently the manifestation of the effect of a limiting 

 factor, nitrate supply. In addition to these three, a fourth condition 

 was found. "Though there be an abundance of moisture and mineral 

 nutrients, including nitrates, yet without an available carbohydrate 

 supply, vegetation is weakened and the plants are non-fruitful. . . . 

 The available carbohydrate supply or the possibility for their manu- 

 facture or supply, constitute as much a limiting factor in growth as the 

 available nitrogen and moisture supply.""^ 



Those instances (3 and 4), in which nitrogen or carbohydrate supply 

 are limiting factors of growth, reveal the necessity of a proper balance 

 between carbohydrate and nitrate supply for the best vegetative 

 development. 



"In other words, this experiment indicates first, that the limitation of the 

 nitrates resulted in the suppression of growth and the accumulation of the more 

 complex carbohydrates; second, that the limitation of the carbohydrates, even 

 with large quantities of available nitrates in the soil, results in a suppression of 

 growth; third, that a rapid vegetative extension results from an adjustment of 

 the carbohydrates and nitrates relative to one another so that both may be 

 utilized in the formation and expansion of such structures; and fourth, that such 

 a relationship can be secured either by increasing the nitrates without decreasing 

 the carbohydrates, or by decreasing the carbohydrates without increasing the 

 nitrates. While it is apparent that the amounts of these compounds relative to 

 one another would be the same in both the above cases, the total amounts would 

 be greater in the former and less in the latter, a condition faithfully reflected 

 in the amount of growth produced. "^^* 



In this passage Kraus and Kraybill show that there is a distinct 

 nutritive relation between the supply of nitrates and of carbohydrates, 

 for vegetative growth and development. A carbohydrate supply 

 is therefore not only just as essential for the manufacture of protoplasm 

 as are nitrogen and the essential mineral elements, but it combines 

 with them in definite proportion for the building up of the plant tissue. 



The Significance of Carbohydrate Accumulation. Manufacture in 

 Excess of Utilization. — The differences between the conditions char- 

 acteristic of vigorous vegetative growth which is unfruitful and vegeta- 

 tion accompanied by fruitfulness are of interest. There is no evidence 

 to show that the utilization of nutrient substances is any different in a 

 plant showing fruit bud differentiation from that in one which does not, 

 or that the nutritive relation between carbohydrate and nitrate supply 

 in particular is altered. Kraus and Kraybill's work shows that, in so 

 far as the materials determined by them are concerned, the chief differ- 



