The critical period of arvenses competition with the crop of corn (Zea mays L.) in Huambo, Angola

Abstract

The investigation was directed to the determination of the critical period of competition among the weeds and the corn (Zea mays L.), a crop of economic interest and main food of the nutritious diet of the population of the county of Huambo. The sowing of two experiments was carried out on a Ferralitic soil with a variety of long cycle, in an agricultural ecosystem severely affected by the limitless use of herbicides, what has generated very aggressive, dominant species and the difficult handling. A design of blocks settled down at random, with eighteen treatments and four replication for two circumstance "with weed until" and "without weed until" at the 7, 14, 21, 28, 35, 42, 49, 56 days after the germination and a control with and without weed the whole cycle of the cultivation of corn, for each circumstance respectively and in a later experiment, just by three treatments (with and without weed during the whole cycle and without weed only in the critical opposing period). Among the dominant species they were: Cyperus rotundus L., Bidens pilosa L., Cynodon dactylon (L.) Pers. and Chloris polydatyla (L.) Swartz. the results showed that the critical period of competition of the weed with the corn crop is located between 21 to 49 days to the germination, imperative moment to carry out works of weed handling. Before and after this period, doesn't benefit to the crop and the production costs were increased. The relationship between the height and number of leaf of the plant with the yield and number of days with and without weed, showed positive for R2 superior to 0,95 for both variable vs yields and similar answer regarding the days "with and without weed until", but with better adjustment.