FIELD CROPS. • 



31 



Rate of growth and chemical composition of the com plant, 



E. H. FAKRiNGrTON {Illinois Sta. Bid. 31, pp. 3G1-381). 



Sii)iopsis. — Tabulated data giving the height of plants, weight of dry matter, and 

 uieteoiological conditions for each week of the growing season for the years 1889, 

 1890, 1891, and 1892. The composition of the green plant for each week of the 

 growing season of 1892 is given in tables and general notes. The data show 

 that the increase in dry matter continued about 4 weeks after the plant had 

 reached its maximum height. An experiment in germinating corn seeds showed 

 that the loss of dry matter during germination was considerable. 



1b these experiments the following varieties of corn were used: In 

 1889, Edmunds, planted May 4 5 in 1890, Burr White, planted May 5; 

 in 1891, Leamiug, planted May 9; in 1892, Burr White, planted June 

 3. From 6 to 226 stalks were measured each week, and 3 samples, each 

 consisting of 3 plants, were analyzed weekly. The average percentage 

 of the total height and dry matter made each week after the time when 

 the plants were 1 foot high was as follows, the figures being the aver- 

 age results for 4 years: 



Percentage of groivth in height and increase in dry matter, 1889-92. 



The proportionate growth for corresponding weeks in 1889, 1890, 

 and 1891 was quite uniform. In 1892, when the corn was planted late, 

 a greater percentage of the growth was made later in the season than 

 in the other years. 



"The higher the temperature the better the corn growth, and according to the 

 observations made heat seemed to be more beneficial than rain. The most rapid 

 growth in height was made when the corn was between 3 and 6 ft. tall. It grew 2 

 ft. per week for 2 weeks in succession the last of June, 1890. The excessive rain of 

 April, May, and June, 1892, prevented the same growth of corn as in the previous 

 years during these months, but about 3 in. in height per day was made in the last 

 week in July, 1892. The table shows that in the first 3 years the corn reached its 

 maximum height 8 weeks after it was 1 ft. high, but in 1892 it kept on increasing in 

 height for 10 weeks from this time. 



"No uniform relation between growth of plant and meteorological conditions can 

 be (Exactly traced from these figures, which cover a period of 4 years of observations." 



In 1892, when the corn was planted about a month later than usual, 

 the green corn plants were analyzed each week. The figures show that 

 the plants attained their maximum height August 19, their greatest 

 weight of water August 20, and their greatest weight of dry matter 

 September 10. 



"When a corn plant has reached its total growth in height it has attained only 

 one half the weight of dry substance it will gain if left to grow to maturity. . . 



