FIELD CROPS. 335 



is definitely stated. The fall in growtli rate here brought out is similar to the 

 decrease in rate of certain other physiological processes under the influence of 

 high temperatures during prolonged periods. 



"At temperatures near the minimum (12-14°) for the growth of shoots of 

 maize seedlings under the conditions here employed, no decrease iu the growth 

 rate is shown, even with rather prolonged periods of exposure. 



"The growth rate at medium temperatures accords with the van't Hoff law, 

 showing a doubling of the rate for each rise of 9 or 10° C." 



Fertilizers for potatoes, W. P. Brooks (Massachuftctts Sta. Circ. 42 (1914), 

 pp. //). — A revision of Circular 2^^, previously noted (E. S. R.. 23, p. 731). 



On the "dead grains" of rice, G. Silvestri (Ann. Chim. Appl. [Rome], 

 1 (1914), No. 5-6, pp. 212, 2i3).— This article discusses the appearance and 

 methods of separating the so-called "dead" or immature grains found in rice, 

 which it is stated often reach 25 per cent of the harvest. An analysis of this 

 inferior rice is given as moisture 15.01, ash 1.74, protein 7.18, starch 66.4, and 

 fat, cellulose, and undetei-niined matter 9.67 per cent. 



Perennial rye grass seed, A. H. Cockayne (Jour. Agr. [New Zeal.], S 

 (1914), No. 6, pp. 619-639, figs. 70).— This is a profusely illustrated article 

 giving results of a study of the perennial rye-grass seed industry of New Zea- 

 land, including data as to bushel weight, purity, presence of ergot, germination, 

 and adulteration. An illustrated list of 63 adulterating seeds is given. 



It is noted that " the average yield is about 500 lbs. per acre of undressed 

 seed, but in seasons when bad weather is exijerienced the average may not 

 exceed 400 lbs., while in exceptionally favorable years the yield may be as high 

 as 650 lbs. In individual cases over 1,200 lbs. per acre may be harvested, but 

 these are really exceptional, and are mainly restricted to crops from young 

 pasture." 



The grain sorghums, O. O. Churchill and A. H. Wright (Oklahoma Sta. 

 Bui. 102 (1914), PP- 70, figs. 31). — This bulletin discusses grain sorghums with 

 special reference to Oklahoma conditions and treats of their history, distribu- 

 tion, classification, seed and seed selection, standard of perfection, soils and 

 soil management, methods of cultivation, harvest, rotation, storing, handling, 

 and uses, including composition of the grain, insect enemies, and diseases. 



In discussing moisture requirements the results of pot experiments are given 

 that show the influence of 5, 10, 15, 20, 25, 30, and 40 per cent water content of 

 soil on Kafir corn, milo maize, corn, broom corn, and oats. Practically no 

 growth with broom corn or oats occurred in the pots containing 5 or 10 per 

 cent of moisture. 



" In all series the amount of water required to produce a pound of dry matter 

 decreased as the water content approached 25 per cent. This is approxi- 

 mately 55 per cent of the total water-holding capacity of the soil. The amount 

 of water required to produce a pound of dry matter increased above this per 

 cent. This indicates that plants make the most economical use of water in this 

 soil when the moisture content is about 20 per cent. . . . 



" From 15 to 30 per cent moisture the growth increased nearly in proportion 

 to the increase in moisture present. The plants grown in soil containing 40 

 per cent moisture did not show any decided increase in dry matter over those 

 grown in 30 per cent. . . . 



" The sorghums grew and produced well with 15 per cent of water in the soil. 



" This test indicates that Kafir and milo will grow and produce fair crops 

 when the water content of the soil is too low for the production of com." 



In a series of pot tests run to determine the wilting coefficient of corn, oats, 

 Kafir corn, milo maize, and cowpeas, the recorded results show that it requires 

 a longer period of time for the grain sorghums to reach the wilting point than 



