wine this year should have had a great similarity with 1874. Neverthelss, the wine of 1873 was not of very good quality, which can perhaps be attributed to a too prolonged growth of the vine stems, caused by the humidity of the soil. If in general a good wheat year corresponds with a good wine year this rule is far from invariable. In regard to quality the vintage depends but too often on the late spring frosts. The extremely important part played by light in agriculture makes us regret that the actinometer should still be so little known. It perfectly replaces the thermometer for agricultural purposes, but the thermometer can not take its place. In his Annuaire for 1882 Marié-Davy gives the following study of the development of cereals, wine, and other crops: Cereals. The cereals offer a great number of varieties, and this number increases annually, but often the differences that we see between them are due to certain influences of the soil and climate which disappear by change of locality. However, there are some varieties whose qualities have been fixed by long-continued cultivation in the ordinary way or by long-continued selection, and which present decided advantages for the specific climates. The varieties brought from the south are more sensitive to cold. than those from the north, and can not be propagated without special precautions in higher latitudes or at greater altitudes than belong to the localities where these varieties were gradually developed. The varieties brought from the north are generally more precocious and suffer more from dryness. The expressions "early" or "late" have reference to their behavior in the new locality. The grain brought from the south comes to maturity at a later date than that raised in the north. Influence of heat and light on development of wheat.-We shall divide the development of wheat into four phases, whose dividing epochs are the processes of (1) sowing and germination, (2) heading out, (3) flowering, and (4) ripening. According to Gasparin the germination of wheat begins when together with the necessary moisture it also enjoys a temperature in excess of 5° C., and it sprouts when it has received a sum total of effective mean daily temperatures (above 5° C.) equal to 84° C. Its sprouts shoot above the soil a few days later. Some wheat sown by Marié-Davy April 23, 1880, was up on the 4th of May, the sum of the mean temperatures being 96°, so that the germinating sprout had taken about two days to grow from the seed to the surface. In the following table columns 2, 3, 4, and 5 show the duration in days of the period required for the germination of wheat supposed to be sown at Montsouris in the different years on four different dates-a, b, c, d-as stated at the heads of the columns. These durations are calculated to the nearest whole days, on the assumption that the sum of the mean daily temperatures in the shade must be 84° C. Aver [Date of sowing: a, October 1; b, October 15; c, November 1; d, November 15. age date of germination: a, October 7; b, October 22; c, November 14; d, December 18. Average date of heading: a, February 8; b, March 4; c, March 3; d, February 26.] Counting from the date when the mean daily temperature is 5° C. and the wheat begins to sprout to the date when the wheat begins to head, Gasparin adopts 430° C. as the sum of the mean daily shade temperatures. Marié-Davy finds from the date of actual sowing of the seed to the date of heading out a sum of 555° C. after rejecting all daily mean temperatures that are below 6° C. according to the rule of Hervé Mangon. He also finds 639° C. for the sum total of temperatures between the dates of germination and heading out after rejecting all days below 6° C. On this last hypothesis are calculated the duration of the heading stage and the mean dates of heading for the respective years as given in the columns 6 to 9 of this table. These computed dates of heading out show that the sowing of wheat on October 15 or November 1 or 15 brings it to a head at the end of February or beginning of March, but when the sowing occurs on October 1 it is brought to a head so much earlier in February as to expose it to great chance of injury by the frost; for although the grasses and the green wheat plant resist the action of frost, yet the embryo seed in the ear or head does not do so, and if once destroyed by frost will not be replaced unless the soil is very fertile. The third epoch, or the flowering of the wheat, takes place in France, according to Gasparin, when the mean temperature has risen to 16° C. or when the sum total of daily shade temperatures has amounted to 813° C., counting from the beginning of vegetation in the spring or from the date when the mean daily temperatures is 5° C. in the shade. This figure relates, of course, to an average of many years, and the individual years may vary very considerably. Marié-Davy, as before, adopts the views of Hervé Mangon as to rejecting all mean daily temperatures below 6° C., and thus finds 1,496° as the mean value of the sum of temperatures from the date of sowing to that of flowering. The similar sum from the date of heading to flowering is 860°, or 1,496° less 639°. The fourth epoch, or the ripening of the wheat, occurs when the sum total of the mean daily shade temperatures since the date of flowering, rejecting all below 6° C., amounts to 815° C., and in the climate of Paris this occurs about forty-five or forty-six days after the date of flowering. The range of uncertainty in this last interval is only four or five days, owing largely to the uniformity of the climate at this season. It is the best defined of all the periods and so well ascertained that, knowing any actual date of flowering we can safely predict the date of ripening. In proportion as we approach the latter date the process of ripening seems to concentrate itself more and more within the wheat; water and sunlight become less and less important; rain becomes a source of uneasiness as to the harvest, and the intensity of sunshine has only an indirect influence on the quality and quantity of the grain. The influence of sunlight during the first phase or germination is negligible and probably nothing; it is a maximum at the beginning of the fourth phase, but diminishes rapidly as the fourth phase progresses and in proportion as the wheat becomes more yellow. We shall therefore consider the amount of sunshine, or more properly the total radiation from sun and sky, during the first thirty days after flowering and neglect its amount during the remainder of the period up to maturity. The following table shows the amount of radiation, as expressed by Marié-Davy in actinometric degrees or percentages and computed from actual observations of his actinometer at Montsouris for the various stages of growth, viz, the second or heading stage from germination to heading, the third or flowering stage from heading to flowering, and fourth for the first thirty days of the fourth or ripening stage immediately following the flowering: 1877 1878 1879 1880 842 1,332 1,755 1,848 3,205 2,979 2,870 2,954 1.103 1,199 1,399 1,450 1,320 1,496 1,131 1,184 1,076 1,092 1,321 1,362 733 739 977 1,255 2,096 2,502 2,282, 2, 208 800 1,382 1,476 1,743 2,749 2,634 2,630 2,506 840 1,251 1,582 1,600 3,095 2,580 2,658 2,607 1,000 1,578 1,924 1,991 3,519 3,106 2,849 2,865 1.391 1,433 1,433 1,486 α. b. C. d. a. b. C. d. α. b. C. d. 1,176 1,608 1,548 1.581 1,220 1,171 1,194 1,504 1,526 1.558 Average of 6 years.... 857 1,117 1,497 1,653 2,977 2,808 2,723 2,629 1,268 | 1,363, 1,360 1,363 If we sum up the second, third, and fourth series of figures we finally obtain the sum total of the effective radiation received during the whole interval from germination to ripening, as given in the following table: The relative value of the wheat crops, as observed at two stations, is given in the last column of the preceding table, and the comparison of the figures shows that a deficiency of sunshine has a decided effect in diminishing the relative value of the crop; but the converse is not true, for we may have an excess of sunshine and still get poor crops, owing to a deficiency of rain or irrigating water. In fact, the preceding study only shows the nature of the influence of the solar radiation; the exact quantitative effect on the amount of the crop must vary with the irrigation or rainfall, with the fertilizers applied to the soil, and with the peculiarities of the seed. As to the rainfall, it was in the preceding cases distributed as shown in the following table: From these figures we conclude that the excess of rain in the wheat season of 1878-79, which would have been advantageous with a clear sky, as in Egypt," was at Paris accompanied by too little sunshine, ' and therefore the crop suffered. For a given quantity of sunshine a certain quantity of water is best for the crop; if the sunshine is diminished the plant can not use so much water, and that must be correspondingly diminished. a Or as in the case of irrigation in the arid portions of the United States.-C. A. The influence of the date of sowing and its relation to sunshine and frost is fully shown in the table for Montsouris, which gives the sum total of actinometric degrees from the time of germination to maturity for seeds sown on successive weeks in 1879, 1880, and 1881, and harvested in 1880, 1881, and 1882: Among other conclusions that may be drawn from these figures are the following, most of which are also given by Marié-Davy: 1. The season 1880-81 was characterized by much sunshine and little rain, which hastened the ripening, but delayed the flow of sap, and therefore of nourishment to the grain, so that the crop was rather poor. 2. For the crops of fall wheat the sunshine increased more and more as the seed was sown later from September, 1880, even to the end of December; then it began to diminish, and for the spring wheat, sown in March, 1881, it was too small. 3. By considering other weather records it is evident that the freezing of the ground in January, 1881, not only prevented the sowing of the seed, as noted in our table, but prevented the germination of the seeds sown on December 22 and 29, 1880, which would otherwise have sprouted on February 4 and 19, 1881, respectively. |