Mar. I, igso 



Effect of Length of Day on Plant Growth 



589 



for most crop plants. The results of the moisture determinations in the 

 boxes are shown in Table XI. 



Table X. — Quantities of water added to boxes and the rainfall during the period of the 

 tests dealing with effect of difference': in soil moisture on the development of soybeans, 

 1916 



Week ending- 



July 24 



31 



Aug. 7 



14 



21 



28 



Sept. 4 



II 



Total. .. 

 Equivalent to 



Box I, 

 ■wet from 

 germina- 

 tion to 

 maturity. 



Gallons. 

 32 

 20 

 20 



18 



37 



177 

 123. 6 



Box 2. 

 dry from 

 germina- 

 tion to 

 maturity. 



Gallons. 



02. 



Box 3. 

 wet from 

 germina- 

 tion to 

 blossom- 

 ing; dry 

 thereafter. 



Gallons. 

 32 

 20 

 20 



114 

 15.2 



Box 4, 



dry from 

 germina- 

 tion to 

 maturity; 



wet there- 

 after. 



Gallons. 



60 

 08 



Rainfall 



(on field 



planting 



only). 



Inches. 



'•77 

 2. 14 



•56 

 •23 

 •38 

 .92 



•03 

 .70 



73 



1 1nches. 

 Table XI. — -Moisture content of soil in boxes used for growing soybeans, 1916 



Date of examination. 



July 17. 



Aug. I 



8 



15 



Box I, wet 

 from germi- 

 nation to 

 maturity. 



Per cent. 



13-0 

 20. 6 

 20. 6 



14.7 



Box 3, dry 

 from germi- 

 nation to 

 maturity. 



Per cent. 

 13.0 

 II. O 

 II. o 



9-5 

 10. o 



Box 3, wet 

 from germi- 

 nation to 

 blossoming; 

 dry there- 

 after. 



Per cent. 

 13.0 

 21. 2 

 13.8 



15- s 

 10.8 



Box 4, dry 

 from germi- 

 nation to 

 maturity; 

 wet there- 

 after. 



Per cent. 



13.0 

 II. O 

 II. o 



9-5 

 16.8 



The comparative growth and development of the plants under the 

 different treatments are indicated by the data presented in Table XII. 

 It appears that the control plants in the field were somewhat larger and 

 considerably more productive than the best plants in the boxes, which 

 were those receiving the larger water supply from germination to ma- 

 turity. These differences were possibly due to the larger volume of soil 

 available to the plants in the field. There are large reductions in the 

 size and productiveness of the plants in the boxes resulting from a defi- 

 ciency in the water supply. It appears also that a more favorable water 

 supply during the period preceding the flowering stage resulted in greater 

 vegetative development, while a more favorable water supply after the 

 flowering stage gave a larger yield of seed. In spite of the well-defined 



