The sowing depth on the emergence of wild peanut

Abstract

With the objective of studying the effects of the vertical distribution of seeds upon the emergence of seedlings of wild peanut (Euphorbia heterophylla L.), an experiment was carried out with a Dark-red sandy-phase Latosol taken from the arable layer of the soil. The soil was dried on the shade and passed through a sieve with a 2 mm mesh. The experiment was carried out at the laboratory, on lighted banks, using metallic vases of one liter of capacity. The seeds were sowed at 0 cm, 2 cm, 4 cm, 6 cm, 8 cm and 10 cm deep from the top of the vase. The humidity of the substrate was adjusted periodically to 50% - 60% of the imbibition power of the soil. The seedlings, with the young shoots visible, were daily counted and cut. The emergence period was from the 5^th to the 14^th day after sowing. The highest daily emergence happened to the zero cm and 2 cm depth on the 5^th day; to the 6 cm and 8 cm on the 6^th day, and to the 8 cm and 10 cm on the 7^th day. The sowing depth, except for 0 cm, did not affect the germination of the seeds, which was about 80%; the germination of the 0 cm depth was 21,3% because of the hydric deficiency that occurred more rapidly at the soil surface. This capacity of germinating deeper in the soil profile is an important factor of aggressiveness of the species, of survival in adverse conditions, and as a factor of pre-emergence resistance to herbicide.