Mar. t, 1920 



Effect of Length of Day on Plant Growth 



587 



Table IX. — Effect of various degrees of shading in combination with differences in water 

 supply on the growth and development of soybeans, IQ18 



Treatment. 



Shade. 



I a by 12 netting. 



Do 



Do 



6 by 6 netting . . 



Do 



Do 



12 by iznetting. 



6 by 6 netting. . . 

 12 by 20 netting. 



Not shaded 



Not shaded a. . . . 

 12 by 12 netting. 



Do 



Do 



6 by 6 netting . . . 



Do 



Do 



Not shaded 



Do 



Do 



12 by 12 netting. 



6 by 6 netting. . . 

 12 by 20 netting. 



Wet. 



Medium 



Dry 



Wet 



Medium 



Dry 



Actual rain- 

 fall. 



do 



do 



do 



. ...do 



Wet 



Medium 



Dry 



Wet 



Medium . . . 



Dry 



Wet 



Medium 



Dry 



Actual rain- 

 fall. 



do 



do 



Duration. 



Germination till ma- 

 turity. 



....do 



....do 



....do 



....do 



do 



do 



...do 



...do 



...do 



...do 



Blossoming till ma- 

 turity, 

 .do 



.do. 



do. 



do. 



do. 



do. 



do. 

 .do. 



do. 



do. 

 .do. 



Num- 

 ber of 

 plants 

 grown. 



46 



58 



Aver- 

 age 



height. 



Weight 



per 

 stalk, 

 defoli- 

 ated. 



Gr. 

 9.8 



9-6 

 6.7 



Q.e 



8.7 

 8-3 



10. ft 

 9-7 



Weight 

 of hulls 



per 

 plant. 



Weight 



of 

 beans 



per 

 plant. 



Per- 

 centage 

 of 

 beans 

 in seed 

 pods. 



63-5 



64-5 

 65.8 



63.8 

 63.0 

 69.4 

 66.1 



65.6 

 66.9 



65-7 

 70. a 

 69.9 



65.0 

 69- S 

 66.3 

 66.3 

 63- 9 

 64-9 

 66.3 

 64- 3 

 67. '« 



64.4 

 67.a 



» This planting differed from the control immediately preceding only in that the plants were spaced 5 to 

 6 inches apart in the row while in all other cases they were spaced 2 to 3 inches apart. 



In the 1 91 8 experiments the plantings were made from June 4 to 6. 

 Two different degrees of shading were used in combination with three 

 different rates of water supply in each of two series, one covering the 

 period from germination to maturation and the other extending only 

 from blossoming till maturation. In addition, two corresponding series 

 were run, in each of which three different degrees of shading were em- 

 ployed without variation in the water supply, the plants in this case 

 being grown in open field rows without use of boxes, so that the actual 

 rainfall of the season was received by the soil. As controls, a series was 

 arranged without shade but with the three rates of water supply, which 

 extended only from the blossoming period till maturation, the plantings 

 being in buried boxes as in the other experiments having to do with water 

 supply. An additional control consisted of a planting in the field with- 

 out any special treatment as to either shade or water supply; and, inci- 

 dentally, a similar planting was made which differed only in that the 

 plants were spaced 5 to 6 inches apart instead of the standard distance 

 of 2 to 3 inches used in all other cases. The shades for the two periods 

 of shading were placed in position, and the special water treatments were 

 begun on June 12 and 13 and August 9, respectively. The results of the 

 tests are summarized in Table IX. It appears that the effect of the 

 shade on the size, weight, and relative proportions of the plant parts is 



