Growth, development and yield of five sunflower hybrids

Abstract

Studies were conducted to assess the physiological basis of variation in yield among five genotypes during the summer seasons of 1987 and 1989, using the techniques of growth and yield analysis. The sowing of second-crop sunflowers allowed maximum values of total dry matter to be reached that were quite similar for both years, between 581 and 821 g m −2. Total dry matter yields in 1987 were reached with lower maximum leaf area index (LAI) and lower total leaf area duration (LAD) than in 1989. In both years of testing, the hybrid SH-222, which has a somewhat longer cycle than the other hybrids, stood out not only for its maximum LAI, but also for its higher LAD after flowering, total LAD and maximum crop growth rate (CGR), and for maximum and final total dry matter. The high temperatures and low relative humidities during the two seasons affected pollination and formation of achenes, especially in 1987 and in the cultivars showing low autocompatibility (Arbung-133 and SH-31), which had the greatest dry weight per 1000 fertile achenes. There were positive significant correlations between maximum CGR, total LAD, number of fertile achenes per head and concentration of oil in the achenes, and yield of achenes. However, the correlation with the protein concentration in the achenes was negative. LAD after flowering, head fertility and maximum of total dry matter were also positively correlated with achene yield, but with significant statistics in only one of the two years studied. Their correlations were negative with the dry weight of 1000 fertile achenes.