Potential Link Between Contents of Fatty Acids and Soybean Seed Germination Rate Under Early Production System.

Soybean seed that produced from the early soybean production system (ESPS) in the Midsouth has a low germination rate with poor seed quality. The mechanism of this phenomenon is not clear. Study was conducted in 2008 and 2009 to investigate the role of certain fatty acids on seed quality and germination ability. Experiment was conducted on a silt-loam soil at the Delta Research and Extension Center, Stoneville MS. Two maturity group (MG) IV soybean varieties, AG4403 (relative maturity, RM is 4.4) and AG4903 (RM 4.9), were planted in late April and mid-May. Plants matured from late August to late September. Seeds were harvested at the three (3) and six (6) weeks after maturity (WAM), respectively. Preliminary results from 2008 indicated that soybean yield was reduced with delayed harvest (at 6 WAM); however, seed germination rates were not significantly affected. Meanwhile, planting dates (or seed maturity dates) had affected soybean seed compositions and germination rates. Regression analysis has indicated a significant positive correlation between seed germination rate and content of linoleic acid in two tested cultivars (R² = 0.72, P<0.05). Early planting of early maturity variety (AG4403) had the lowest linoleic acid content while late planting of late maturity variety (AG4903) had the highest linoleic acid content. Meanwhile, the content of oleic acid in the seeds had an opposite pattern compared with that of linoleic. Results from this study indicated that the content level of certain seed composition components such as linoleic and oleic percentages in seed may be involved in the germination ability of soybean seeds. The temperature, especially at seed maturity period, may be an essential factor in altering the contents of the fatty acid (s), which further determines the seed germination ability.