ChileanJAR

This paper analyses the behaviour of wheat in different dates of sowing Iram 1970 to 1989. Information published belore is used. This information is complemented with unpublished results that were obtained in 1984, 1988 and 1989. The behaviour of five bread wheat cultivars, in five sowing dates using 160 kg/ha, was studied at La Platina Exp. Sta. (INIA, Santiago), in 1984. In 1988 and 1989 bread and durum cultivars were studied in five dates of sowing and using two rates al seeding (350 and 500 grains/m²). In 1984, the average yields for the dates al sowing were: 65.3 quintals/ha, May 18; 67.6, June 14; 60.0, July 13; 49.5, August 10; and 28.9, September 12. In 1988, 71.3, May 25; 78.1, June 15; 72.8, July 7; 66.6, July 27; and 46.2, August 26. In 1989, 77.4, May 29; 80.8, June 19; 79.4, July 18; 72.0, August 14 and 47.7, September 1. In the three years the differences between the dates al sowing were statistically significant (P < 0.05). The differences in yield between the rates al seeding were statistically significant in 1988 but not in 1989. The results al 12 years of dates al sowing trials indicate that the yields obtained in the second fortnight of August show a daily loss al 0.5% as compared with the yield obtained in the second fortnigth of June. There was no interaction between dates of seeding and rates of seed. This shows thatthere are no advantages in increasing the rates of seeding in late sowings.