THE GERMINATION OF WEED SEEDS AS INFLUENCED BY ENVIRONMENTAL FACTORS

The problem involved in this investigation was that of determining the effect of environmental factors upon the germination of twelve species of weed seeds. The seeds were harvested, divided into three groups designated as Groups I, II and III, and stored under different environmental conditions. Group I, a temperature control group, was stored under conditions of normal temperature, Group II under continued cold and Group III was subjected to intermittent freezing and thawing. A small fourth group, consisting of seeds of species which failed to germinate or showed low percentages of germination in earlier tests was subjected to scarification. These seeds were taken from Group I. Plantings of seeds of Groups I, II and III were made monthly from September to June, exclusive of December, in specially prepared sterile soil. Irregular plantings of Group IV were made in April, May, and June. Upon germinating it was found that the per cent of combined germinations of all seeds in Groups I, II, and III was 6.7, 9.7, and 11.5 per cent, respectively. Indications were that the increased germination percentage of Groups II and III was not due to greater germinations in one of two species alone, for it was found that 75 per cent of all species had the greatest number of seeds germinating in Groups II and III. The per cent of germination in Groups I, II, and III was very low in October, immediately following harvest. The per cent of germination was greatest in Groups I, II and III during the fall and spring months. Scarification of the seed coats seemed to hasten the germination of some seeds while it had but little effect on others