Soybean seed is highly in demand in Vietnam but seed production is a challenge especially
during the wet season. Organic production could add value to the enterprise but has not
been established as a viable option. The experiments was laid out in a split plot design with
three replications at the CLRRI farm during the 2005 wet season. Main plots consisted of
four production practices i.e. “organic” (cow manure at 40-105-10 NPK and botanicals);
“biodynamic” (biodynamic preparations); “chemical” (synthetic fertilizers at 40-60-30
NPK and insecticides) and control (no inputs). Subplots consisted of two soybean varieties.
The results of study showed that “Nam vang” which had smaller seeds had higher seed
yield, better seed quality (germination and vigor at harvest and storability), and generally
higher protein content than “OMDN111” especially under “organic”. Variety differences
were consistent for most measurements across the different production
practices.“Biodynamic” was not significant in general performance relative to “organic”
and “chemical” (control was generally lowest) in number of filled pods, leaf area index
(highest) and root nodule fresh weight.
The circular paper chromatography pattern of the seed, which may indicate biological
complexity and enzyme activity, revealed differences between varieties and among
production practices. “Organic” and “biodynamic” especially of “Nam vang” which was
more storable than “OMDN111”, tended to have stronger and more complex
chromatographic pattern than the rest of the treatments. The study established that organic
is more effective than chemical approach in soybean seed production but the trend for
biodynamic (in many cases the source of significant interaction between production practice
and variety) merits follow-up studies.