74 



SCIENTIFIC AGRICULTURE 



February, 1921. 



The Effects of Premature Harvesting on the 



Wheat Kernel 



By CHAS. E. SAUNDERS, Ph.D., Dominion Cerealist. 

 (Read before The Western Canadian Society of Agrono my anil jnililished tliniugh tlie conrtesy of tliat Society) 



It has long been know that, under ordinary condi- 

 tion.s, grain may be cut many days, perhaps even two 

 weeks, before it is fully mature and may still give good 

 and fairly plump kernels wlien allowed to ripen in the 

 stock. A great deal, however, has j'et to be learned 

 about the effects of premature cutting, especiallj^ such 

 cutting as deprives the grain altogether, or to a large 

 extent, of any food supply from the leaves or straw. It 

 should be noted that, when grain ripens in the stook, 

 especially under fairly cool and not too dry conditions, 

 there is a considerable opportunity for the food supply 

 in the plant to be transferred to the kernels, much in 

 the same way as would have occurred had the plants 

 been left intact. We have here two distinct problems: 

 first, a problem which is primarily practical, namely 

 to decide how far in advance of ripeness grain may 

 wisely be cut Avhen there is believed to be danger of 

 frost, high wind, or some other destructive agejicy, 

 and, second, to study the physiological processes oper- 

 ating towards the end of the period of development of 

 the grain. This second problem, which appears to be 

 rather of a purely scientific than a practical character, 

 becomes most practical in its nature when Ave have to 

 consider the effects of a rust epidemic Avhereby the 

 kernel is prematurely deprived of much of the material 

 which would have gone towards building it up. In 

 spite of all the work which has been done, we are today 

 unable to confidently answer the question which 

 farmers put to us when rust appears : " Is it Avise to cut 

 grain immediately Avhen the leaves and stems are badly 

 attacked?" 



Investigations on the effect of premature cutting 

 have been carried on in the experimental farm system 

 for a few years past, and the Avriter presents in this 

 paper the results of one series of observations. In the 

 summer of 1917, Mr. G. G. Moe, (then the Avriter"s 

 chief assistant and noAV assistant professor of 

 Agronomy at the University of British Columbia) 

 gathered a number of heads of Marquis Avheat 

 at different dates. The folloAving Avas the method 

 used. In order to make sure - that aa^c Avere 

 dealing Avith heads of uniform degree of ma- 

 turity, about 1100 heads Avere marked on the same 

 day, each head showing a fcAv anthers, but only a feAv. 

 Starting on July 21st, Avhen the Avheat Avas still per- 

 fectly green, 100 of these marked heads Avere gathered 

 every second or third day until August 15th Avhen the 

 Avheat Avas considered to be ready for ordinary harvest- 

 ing. These heads Avere gathered in four groups accord- 

 ing to the length of straAv retained. All Avere taken 

 indoors and hung up in a reversed position in a Avarm. 

 Avell-ventilated loft. In the autumn all heads were very 

 carefully threshed out by hand, every kernel being 

 saved. When the heads Avere being harvested, notes 

 •were not alAA-ays made on the appearance of the plants, 

 but the following particu'irs Avill give some idea as to 

 the character of the kernels from some of the lots gath- 

 ered. The descriptions apply to the kernels Avhen 

 thoroughly dry. 



July 21st: all kernels very small and extremely shriv- 

 elled, very hard to remove from the heads; 

 July 24th : kernels much larger but still probably im- 

 possible to thresh Avith a machine ; 

 July 27t]i : kernels very small but might perhaps have 



been threshed by a machine : 

 July 30th : kernels shrivelled but could be threshed 



out by a machine ; 

 Aug. 4th : kernels not plump but might be accepted 



for milling purposes ; 

 Aug. 8th : kernels fairly plump though not large ; 

 Avould be accepted for milling. 

 The kernels gathered on the other dates do not re- 

 quire special description. It should be noted, hoAvever, 

 that the season Avas ijot favourable to the development 

 of large kernels, so that even those harvested on the 

 latest date (Aug. 15th) Avere rather small. 



As a rule, the tAventy-fiA'e heads in each group con- 

 tained nearly 700 kernels, but the results have all been 

 calculated on the basis of 1000 kernels. The following 

 table gives the Aveight of a thousand kernels from each 

 bunch of heads, on ea^ch date. 



Marquis wheat harvested at different dates, and Awith 

 different lengths of straw. 



Weight in grammes 

 Date. Amount of straAv retained, of 1000 kernels. 



Jul}' 21st tliree inches 3.650 



half length 4.320 



full length 5.136 



fuUl length Avith roots. 5.075 



July 24th three inches 8.176 



half length 8.391 



full length 8.114 



" . full length Avith roots. 9.127 



Julv 27th' three inches 13.624 



half length 13.766 



full length 13.688 



full length with roots. 13.956 



Julv 30th three inches 19.122 



half length 19.595 



full length 18.940 



full length Avith roots. 20.053 



Aug. 2n(l three inches 25.152 



half length 25.042 



full length 23.391 



" full length Avith roots. 25.152 



Aug. 4th three inches 27.546 



half length 27.336 



full length 28.082 



full length with roots. 27.209 



Aug. 6th three inches 29.963 



half length 30.564 



full length 29.260 



full length Avith' roots. 29.598 



Aug. 8th three inches 30.770 



half length 30.824 



full length 30.859 



full length Avith roots. 31.420 



