42 EXPERIMENT STATION RECORD. [Vol.40 



of the stems or cuttings of plants with a large amount of storage carbohydrates 

 and particularly those parts where such storage is localized, when supplied 

 with moisture or moist conditions, produce roots abundantly. This would be 

 of particular interest in vegetative propagation. . . . Fertilizers containing 

 available nitrogen or that which may be made available are mainly effective 

 in producing vegetative response. They may either increase or decrease fruit- 

 fulness, according to the relative available carbohydrate supply. 



" Irrigation or moisture supply is effective in increasing growth or fruitful- 

 ness only when accompanied by an available nitrogen supply and vice versa. 

 The effectiveness of the nitrogen value of leguminous cover crops is*dependent 

 upon the accompanying moisture supply. Cultivation is largely effective in con- 

 serving moisture and rn promoting the supply of available nitrogen. If in any 

 given soil, moisture and available nitrogen are already present in quantities 

 such that the plants growing upon it are largely vegetative, a decrease in culti- 

 vation will tend toward fruitfully 



" Nbnteguminous companion crops or cover crops remove from the soil both 

 available nitrogen and moisture. In regulating vegetation and fruitfulness by 

 this means the relations of the available moisture, nitrogen, and carbohydrates 

 largely determine the result. Pruning is largely effective in promoting or 

 retarding fruit fulness by its effects in balancing the carbohydrate supply within 

 the plant, or the means for its manufacture, with the available moisture and 

 nitrogen supply. Girdling or ringing of the cortex or bark is effective through a 

 modification of the carbohydrate-nitrate relationship. In practice the entire 

 range of effects due to such a relationship may be expected from its application. 



"Fruit production is seemingly a specialized vegetative function usually more 

 or less closely associated with the function of gametic reproduction. Parts con- 

 cerned in reproduction range from but little modified vegetative parts to those 

 highly modified portions classified as fruits. The degree in which such modifi- 

 cation is expressed is dependent upon physiological changes within any specific 

 plant, and may vary widely within the same variety or even the same individual. 

 At least some of the instances of sterility considered to be the result of physio- 

 logical incompatibility may be due to the state or condition of nutrition of the 

 plant itself. 



"Until more exact information is available, both environmental and hereditary 

 factors must be considered in any attempted explanation of the reproductive 

 or vegetative behavior of plants." 



[Horticultural investigations], F. M. ROLFS (Oklahoma Sla. Rpt. 1917, pp. 

 32-35). — Notes are given on the present status of various Adams and Hatch 

 fund projects under way at the station. 



Report of the assistant horticulturist, T. B. McCi.ei land (Porto Rico SI". 

 Rpt. 1917. pp. 24-28, pis. 3). — During the year an experiment was undertaken in 

 the restoration of coffee plantations seriously infested with a leaf disease, 

 Stilbclla flavida, which is more prevalent at the higher altitudes in Porto Rico, 

 where climatic conditions are much more favorable for the growth of coffee than 

 nearer the coast. In many places the trees have been so debilitated through 

 long-continued defoliation that the crop is greatly reduced and the plantation 

 made unprofitable. In addition to improvements in cultural practices different 

 species of introduced coffee have been set in patches of Coffca arabica affected 

 with Stilbella in an attempt to find a resistant species. 



In continuance of the work with Murta coffee (E. S. R., 3S. p. 740), 700 seeds 

 were planted from blossoms which had been protected from foreign pollen. The 

 resulting progeny gave evidence that the Murta form is inherited along Btea- 

 delian lines. The grains of the Murta coffee are similar in size and appearance 

 to the typical Arabian coffee. The very short internodes of this type allow the 



