940 EXPERIMENT STATION RECORD. 



yield. The author concludes that the increase of fertilizing material is 

 only profitable within certain limits, and that finally an optimum appli- 

 cation is reached which results in a maximum production of plant 

 substance. Beyond this a further increase of available plant food 

 material becomes detrimental to plant growth, due, it is stated, to too 

 great amounts of fertilizing- material being carried in solution in the 

 soil moisture, which retard the osmotic action of the roots, thus depriv- 

 ing the plant of its necessary supply of moisture and in consequence 

 causing the turgescence of the cell to decline and in extreme cases to 

 disappear. It was observed that with an increased amount of moist- 

 ure in the soil larger amounts of the fertilizer mixtures were necessary 

 to retard the growth of the plants. 



A study of the influence of light in different degrees of intensity, 

 designated as strong, medium, and weak light, was made; and similar 

 experiments of other investigators are cited in connection with the 

 reported results. It is shown that the productive capacity of culti- 

 vated plants both in quantity and quality is dependent upon the inten- 

 sity of light. In every case plants grown in a strong light were the 

 most productive. The results of experiments made by Briem and 

 Pagnoul are tabulated to show the effect of light on beets and pota- 

 toes. Beets grown in the light contained more sugar, and potatoes 

 more starch than those grown in the shade. The author calls atten- 

 tion to the practice of shading crops in tropical climates and concludes 

 that the intensity of light has its minimum, optimum, and maximum, 

 although no exact experiments to determine these points have been 

 made. 



A series of experiments was made to ascertain the combined action 

 of water and plant food, light and plant food, and light and moisture. 

 The results indicated that the effect of fertilizers on the productive 

 capacity of plants depends upon the moisture content of the soil to 

 such an extent that the highest absolute yield from the application of 

 fertilizers was obtained with a content of soil moisture corresponding 

 to the optimum; that the applied fertilizer material produced the 

 greatest increase in yield under the strongest light, and vice versa; that 

 soil moisture produces its greatest effect upon plant growth when the 

 plants are grown in the strongest light; and that the amount of water 

 needed to produce a maximum yield exerts its full force only when the 

 light passes to the plants unhindered. 



No experiments were made by the author to study the effect of tem- 

 perature on plant growth, but the results are tabulated and discussed 

 of experiments made by Haberlandt, Sachs, and Bialoblocki with the 

 common field crops, on the minimum, optimum, and maximum temper- 

 ature for germination, the time required for germination, and the rate 

 of growth of the root and plumule at different temperatures. 



Autumn catch crops, P. P. Deherain (Ann. Agron.,23 {1897), Wo. 

 12, pp. 501-575). — The results of experiments with vetch and peas as 



