Seed Protein and Oil Concentration of Soybean Cultivars Released in Argentina Between 1984 and 2000.

We compared the seed protein and oil concentration of soybean cultivars released in Argentina between 1984 and 2000 in 15 field trials at Balcarce (37º 45’ S) and Paraná (31º 50’ S).  Cultivars belonged to maturity group (MG) IV at Balcarce and groups IV, VI and VII at Paraná. Major sources of variation included seasonal conditions (both locations), and water supply and fungicide treatment (Balcarce). The rates of change in oil and protein concentration were calculated as the slopes of these variables against year of release (% yr^-1).
Protein concentration declined with year of cultivar release. The average rate of decline in protein was -0.13 % y^-1 (P < 0.001) at Balcarce, and -0.15 % y^-1 (P < 0.001, MG IV), -0.12 % y^-1 (P < 0.001, MG VI) and -0.03 % y^-1 (P < 0.05, MG VII) at Paraná. Water supply did not affect the rate of decline in protein concentration at Balcarce. At Paraná, there was an inverse relationship between rate of change of protein concentration and water supply for MG IV (P < 0.05) and VI (P < 0.01), but not for MG VII cultivars.
Oil concentration generally increased with year of cultivar release. The average rate was 0.11 % y^-1 (P < 0.001) at Balcarce. At Parana rates were significant (P < 0.001) for MG IV (0.14 % y^-1) and VI (0.11 % y^-1) but not for MG VII. Water supply did not affect the rate of increase in oil concentration at Balcarce. As for protein, at Parana there was an inverse relationship between rate of change of oil concentration and water supply for MG IV (P = 0.07), and VI (P < 0.001) but not for MG VII cultivars.