February, 1921. 



SCIENTIFIC AGRICULTURE 



77 



served at Ottawa during the period of this i-xperiment. 



July 21.st .... 74.4 degrees Fahrenheit 



" •22nd . .. 77.9 



" 2ard . . . 79.2 



" 24th . .. 78.4 



" 2r)th ... 80.3 



■• 26th ... 79.2 



" 27th . .. 72.5 



" 28th . .. 6.5.9 



" 29th . .. 70.7 



•• 30th . . . 82. 8 



'• 31st . .. 82.2 



Aug. 1st . . . . 84.8 



2nd . . . 78.0 



3rd . .. 67.7 



4th . .. 65.9 



5th . . . 66.5 



6th . . . 71.5 



7th . . . 69.9 " . " 



8th . . . 70.6 

 9th . . . 70.0 

 " 10th . . . 67.3 

 " 11th . . . 68.0 

 " 12th . .. 70.8 

 " 13th . .. 72.0 

 " 14th . . . 70.7 

 " 15th ... 71.3 

 Taking into eonsideration these temperatures we can 

 construct a theoretical curve (the broken line) repres- 

 enting what probal)ly would have been the normal 

 course of the development of the wheat kernel under 

 uniform conditions of temperature. This curve .shows 

 a rapid increase in the amount of material deposited 

 daily from July 21st up to July 28th or 29th when, had 

 the w-eather l)een normally warm, about 2 grammes jier 

 day of solid matter would have been added to each 

 1000 kernels. But the weather happened to be quite 

 cool on the 28th and 29th, so that the amount deposited 

 was certainly less than the noi-mal for those days. 

 Furthermore the excessive heat on August 1st caused 

 more than the usual activity on that day. The period 

 of very great daily gains extends from about July 25tb 

 to August 2nd. It seems fair to conclude that July 

 29th w'ould have been the date of maximum activity, 

 under conditions of even temperature — that is to say 

 approximately seventeen days before the date <if 

 cutting. 



A deposition in the wheat of two grammes per 1000 

 kernels would be equal to about 1/16 of the total crop, 

 or about 120 pounds to the acre on a fairly good field. 

 We must remember however that not all the heads 

 would be in exactly the same stage of development at 

 any one time. The amount of material added per day 

 would therefore not be quite so great as appears from 

 the figures given here. Nevertheless, I think it safe to 

 say that in a good field, with favourable weather con- 

 ditions occurring at the time of maximum physiological 

 activity, about 100 i)ounds of material per acre would 

 be transferred daily, for a few days, to the wheat 

 kernels. 



It is evident that during the early period of tlie 

 development of the wheat kernel — 20 to 25 days be- 

 fore cutting in this case — the materials of which the 

 grain is composed are deposited in it at a rapid rate. 

 This rate increases in rapidit.v until about 17 days be- 

 fore harvest. It remains stationary for a short time 

 and then decreases quite ipiickly, being reduced almost 

 to nothing several davs l)efore the ordiiuii-v time of cut- 



ting ill Ontario. It would appear, therefore, that, in 

 an ordinary Ontario summer, there would be very little 

 loss of croj) in cutting wheat aljout a week iiefore the 

 ordinary date, and allowing it to finish the ripening 

 process under the relatively favourable conditions 

 which obtain in an ordinary stook. In those parts of 

 Canada where tiie summer weather is cooler than at 

 Ottawa the harvesting could i>rol)ably lie done without 

 appreciable loss in yield at a relatively earlier period 

 — perhap.s two weeks before the grain would have been 

 ripe. This indeed is a common practice in nearly all 

 those districts, east or west, where the summer season 

 is rather short. 



Through the kindnes.s of Dr. Frank T. Shutt, Dom- 

 inion Chemist, the writer is able to give the results of 

 protein determinations made in his laboratories with the 

 samples of wheat which we are considering. The samples 

 from the heads gathered with three inches of .straw and 

 those from the heads gathered with full length of straw 

 w-ere analyzed separately. The results of tjie two series 

 are similar. The average results are given in the fol- 

 lowing table. The figures have been recalculated on 

 the basis of wheat containing ten per cent, of moisture. 

 Analyses of Marquis Wheat. 



Orammes of protein 

 in 1000 kernels. 

 July 21st 20.02 884 



" 24th 16.42 1337 



" 27th 14.09 1.925 



" 30tli 14.62 2.783 



Aug. 2nd 15.09 3.814 



■" 4tli 15.41 4.287 



" 6th 15.57 4.610 



" 8th 15.87 4.890 



" 11th 15.89 4.940 



" 13th 16.03 5.045 



" 15th 1.5.92 5.104 



It is noteworthy that the percentage of protein rapid- 

 ly decreased from July 21.st to July 27th, then slowly 

 increased untd August 13th. Tiie actual amount of 

 I)rotein pr.-sent, however, increased rapitUy from July 

 21st to August 6th and then increased more slowly 

 until the end of the test. 



Evidently, therefore, in the earliest stages of the 

 formation of the kernel, protein is added with much 

 greater relative s()eed than later on. Between the 21st 

 and 30th of July, although the amount of protein added 

 was very great, the addition of other constituents 

 (chiefly carbohydrates of course) was -even more rapid. 

 The period during which carbohydrates were deposit- 

 ed most rapidly is also the period during which protein 

 was deposited most rapidly. Towards the end, both 

 l)rocesses became much slower but the deposition of 

 both i)rotein and carbohydrates did not cease in this 

 case until after August 15th, by which time the grain 

 was fit to cut and was well advanced towards ripeness. 

 The process of ripening has been described as merely 

 a drying out of the kernel. This is evidently not the 

 ease if we use the word "ripening" in the .sense it 

 usuall.v bears in Canada. Simple drying out may be 

 the final stage, but up to a very late date protein and 

 other materials are being deposited in the kernel. The 

 amount of such dejiosition is, however, so small that 

 farmers ai-c fully justified in cutting their grain quite 

 early whenever they have good reasons for doing so. 



The study of this important problem of the effects 

 of early cutting on wheat is being continued by the 

 writer. 



