RESPONSE OF SUNFLOWER CULTIVARS TO PLANT- DENSITY IN 2 PLANTING DATES.2. CHARACTERISTICS ASSOCIATED WITH HARVESTING

This experiment was done in Eldorado do Sul, Rio Grande do Sul, Brazil , in order to evaluate the effects of plant density in two dates of th ree cultivars of sunflower, on the percent of lodging and/or breaking of plants and other agronomic characteristics associated with mechaniz ed harvest. It also sought to verify the efficiency of the planting da te and plant density as management practices to ancicipate harvest dat e. To do this, the cultivars Contisol 711, Dekalb 180 and GR-10, plant ed on July 28th and September 18th, 1989, in densities of 30, 50, 70 a nd 90 thousand plants per ha were used. The increase in plant density reduced the stalk and capitulum diameters. On the other hand, plant he ight increased with an increased plant density. Independent of plant d ensity, the cultivar of higher stature (GR-10) showed greater lodging than the others. An increase in plant density resulted in earlier flow ering, diminished the duration of the subperiod physiological maturati on-harvest, as well as speeded up the loss of humidity both in grains and receptacle, independent of the cultivar and of the time of plantin g. This aspect, associated with precocious seeding (end of July), resu lted in an earlier harvest.