SEEDS WEEDS. 983 



SEEDS WEEDS. 



The development of single-germ beet seed (C. < >. Townsend and E. C. Rittue 

 ( U. S. Dept. Agr., Bureau of Plant Industry Bui. 78, pp. 23, pis. 8, figs. 6).— This 

 bulletin gives an account of preliminary experiments conducted for the purpose of 

 attempting to develop a race of sugar beets which would produce single-germ seed. 

 These are considered desirable for cultural reasons, principally the lessening of the 

 expense of thinning and the probability of securing a stronger growtli from a single 

 seed ball than where a number of plants come from a multiple-germ seed cluster. 

 The work lias been carried on for 2 years, and some progress is noted. 



The relative germination of single-germ seeds and multiple-germ seeds was tested, 

 in which the percentage of germination of the single-germ seeds was considerably 

 higher than the average of multiple-germ seeds. Further tests showed that the 

 single-germ seeds sprouted in a shorter time than the multiple-germ seeds, the per- 

 centage of germination was higher, and the plants produced from single-germ seeds 

 possessed greater vitality than the others. 



A description is given of the greenhouse and field experiments which have been 

 carried on under the authors' supervision, from which it appears that by cross 

 pollination and selection there is an increased production of single germ seeds. 



The seed characters of Pisum sativum, R. P. Gregory {New PhytoL, 2 {1903), 

 p. 226, fig. 1; abs. in Bot. Cental, 96 {1904), No. 43, p. 424).— In studying the 

 histological nature of the difference between round and wrinkled peas used in 

 Mendel's experiments the author found that round peas, which include the indented 

 sugar peas, have the central tissues of the cotyledons filled with very large starch 

 grains, often reaching 0.2 mm. in length. In the same region the starch grains of 

 wrinkled peas are of a decidedly different type, frequently being compound. Such 

 grains rarely attain a size of 0.2 mm., but the component starch grains never exceed 

 0.1 mm. Seeds of intermediate appearance as well as types which are known to 

 contain seeds of doubtful affinities all proved on microscopical examination to have 

 the starch grains of the round peas. 



The effect of carbon bisulphid on the germination of peas, G. Staes 

 {Tijdschr. Plantenziekten, 9(1903), pp. 119-124).— -The effect of carbon bisulphid 

 on the germination of peas is shown. This chemical is commonly used to destroy 

 the pea weevil i Bruchus pisi), and the author conducted experiments with several 

 lots of peas which were exposed for 10 or 11 minutes to from 50 to 250 cc. of carbon 

 bisulphid to each hectoliter of space. After treating the seed they were divided into 

 several groups and tested. The results of the germination tests are shown in tabu- 

 lar form, from which it appears that the treatment retarded the germination to some 

 extent, but the effect as shown in the total germinations was inappreciable. 



The influence of temperature on the germination of seed, F. Todaro {Staz. 

 Sper. Agv. Jt<i!.. 81 {1904), No. 6, />/'. 458-46%). — Investigations are reported on the 

 germination of Italian rye grass, red and white clover, bird's foot clover, alfalfa, 

 sainfoin, and sulla when subjected to the conditions of the thermostat, laboratory, 

 and open field. The maximum and minimum temperatures in each experiment are 

 given, as well as the total temperatures during the time of the tests. The germina- 

 tions under each experiment are reported by short intervals, indicating the influence 

 of high temperatures in hastening germination. 



In general it was found that a strong fluctuation in temperature or a temporary 

 lowering of the temperature in the field to below the minimum considered desirable 

 for a given kind of seed does not permanently retard germination. The tests made 

 in the laboratory at a somewhat higher temperature and with slight fluctuation 

 gave in nearly every case a lower percentage of hard seed among the leguminous 



