An examination of the sampling observations on wheat of the crop-weather scheme

The paper gives an account of the results obtained from the data provided by the first three years of the Sampling Observations on Wheat of the Crop-Weather Scheme.Section I describes the Sampling Observations on Wheat of the Crop Weather Scheme which have been initiated in order that the effect of weather conditions may be studied at all stages of the wheat crop’s growth from germination to maturity.In Section II several curves are given which illustrate the progress of the wheat crop. The shoot-number curves bear a marked resemblance to one another subsequent to the period when the shoot number is a maximum in spite of the wide divergences which exist between the maximum shoot numbers themselves.Section III indicates the statistical processes involved in the analyses given in the succeeding sections.Sections IV-VIII are devoted primarily to discussions of the effects of various meteorological factors on specific stages of the crop’s growth. The following results have emerged:The length of the interval from sowing to appearance above ground is shown to be largely dependent on the mean soil temperature during this interval, the relation being well expressed by a quadratic regression. The growth rates of the plants at this time are shown to be in good agreement with those which would be obtained by applying Van ‘t Hoff’s law. Neither the rainfall nor the variation in temperature during the period appear to affect its length.Squarehead’s Master appears above ground consistently later than Yeoman, but the amount of this lag is apparently uninfluenced by variations in soil temperature.