Effects of sowing dates on performance of dryland rice cultivars under sprinkler irrigation, in Selviria, MS, Brazil

This study was carried out to evaluate the effects of sowing periods on the performance of dryland rice (Oryza saliva L.)(IAC 201,Carajas, Guarani, IA C 202, CNA 7800, CNA 7801, Caiapo, Rio Paranaiba and Araguaia cultivars) un der sprinkler irrigation. The seeds were sowed at the beginning of the seco nd fortnight of September, October, November, December, January and Februar y. The experiments were conducted in Selviria, MS, Brazil, during the agric ultural years of 1995/96 and 1996/97. The experimental design used in each sowing was in randomized blocks, with four replications. The irrigation con trol was done through tensiometer and the water supply was established when the matric potential reached -0.033 MPa, during the reproductive phase and -0.058 MPa, in the other phases. The results showed that CNA 7801, Carajas , IAC 201, CNA 7800, and IAC 202 presented better performance; November sow ing reached higher productivity; earlier servings (September-October) or de layed (February) caused smaller laying indexes; IAC 202, CNA 7800, and CNA 7801 presented absence or lower laying index, in the different sowing times and, in delayed sowing (February) larger whole grain rate was obtained.