ANALYSIS OF GROWTH AND YIELD OF MAIZE, SUNFLOWER AND SOYBEAN GROWN ATBALCARCE, ARGENTINA

The objectives of this study are: (1) to analyze the capacity of maize , sunflower and soybean to produce dry matter and seed yield, includin g the responses to shading during flowering, and shading and thinning during seed filling; and (2) to evaluate effects of plant density and sowing date on growth and yield. This report integrates data obtained during seven years of research at Balcarce Experimental Station, Argen tina. In these experiments, nutrients and water were not limiting to g rowth. Maize produced the most biomass because of sustained ground cov er and high light conversion efficiency. It also had the largest harve st index on a dry weight basis. When dry matter was expressed in gluco se equivalents, differences among harvest indices for the three crops were smaller. Flowering in maize, seed filling in soybean and flowerin g and seed filling in sunflower were critical periods in determination of grain yield. Sunflower had more capacity than maize to compensate for fewer grains through greater grain weight. Maize and sunflower had low stability in grain number at Less than optimal plant densities. F inally, delays in sowing date significantly reduced grain yields of th e three crops. These reductions were due to decreases in number of gra ins per m(2) and in grain weight.