Ash Composition of Upland Rice 



359 



ing the degree of accuracy with which each sample represented, in respect 

 to weight and moisture content, the average of all the plants at each 

 period. In calculating the probable error, one cylinder of 29 plants was 

 taken as a unit. The development of the plants at the different stages 

 was as follows: At 18 days the plants were stooling to some extent; at 

 73 days they were just about to flower; at 103 days panicles were out, 

 but the seeds were only partially formed; at 123 days seeds were fully 

 formed and ripe. 



Table I. — Weights of the different parts of ike upland rice plant analyzed at various 



periods 



18. 



26. 



48. 



73- 

 103. 

 123. 



Age of plant. 



Dry weight 



of sjeen 



stalks and 



leaves per 



plant. 



Gni. 



O. 132 

 .581 



4-38 

 11.47 

 21. 76 



Dry weight 

 of withered 

 stalks and 

 leaves per 

 plant. 



0-9S 



4-53 



23-34 



Dry weight 

 of panicles 

 per plant. 



3-24 

 12. 12 



Dry weight of 

 whole plant above 

 ground per plant. 



Gm. 



O. 132 



58 1 ±0.035 

 38 ±0. 25 

 42 ±1. 20 

 53 ±0.99 

 46 ±1. 90 



Percentage of 

 dry matter in 

 whole plant 

 aboveground. 



18.7 



20. 2 ±0.08 



14. 6zfco. 05 

 20. 9±o. 10 

 25. 8±o. 99 

 36. 2±o. 16 



It will be noted that the percentage of dry matter in the green plant 

 did not rise until the plant had begun to form seeds. Previous to this 

 time the percentage of dry matter in the plant was somewhat irregular, 

 but tended to remain about 20 per cent. The variations in the moisture 

 content of the first four samples are so many times the probable error 

 of each result that they could not be due to poor sampling. There is 

 little doubt that weather conditions affected the amount of moisture 

 or dry matter in the green plant during the first four stages of growth, 

 while the moisture content of the last two samples was controlled chiefly 

 by the physiological changes in the plant — accumulation of carbo- 

 hydrates and death of old leaves. This seems evident from the records 

 of rainfall. During the eight days preceding the cutting of each sample 

 the number of days with rain and the total precipitation for the eight 

 days were as follows: Previous to the i8-day-old sample, 5 days with 

 rain, 2.80 inches; previous to the 26-day-old sample, i day with 0.90 

 inch; previous to the 48-day-old sample, 6 days with 4.63 inches; and 

 previous to the 73-day-old sample, i day of rain with a precipitation of 

 0.32 inch. The weather was thus relatively wet, dry, wet, dry; and the 

 percentages of moisture in the green plant were respectively high, low, 

 high, low. 



The ash analyses of the various samples are given in Table II. The 

 panicles included the seeds and supporting stems. Withered leaves 

 of the 73- and 103-day-old samples were analyzed separately from the 

 green leaves and stalks, but no such separation was made for the 123-day- 



