Evaluation of soybean cultivars in macro plots in northwestern Argentina

DEVANI, M; LEDESMA, F; GANDUR, M; LENIS, J; PLOPER, L.D.; GARCÍA, M B; GAMBOA, D

Foz do Iguassú

Conferencia; VII World Soybean Research Conference (VII WSRC).; 2004

Embrapa SOJA y WSRC Continuing Committee

The area with soybean in northwestern Argentina (NWA) is of approximately 700,000 hectares, which are distributed in the provinces of Tucumán, Salta, west of Santiago del Estero and southeast of Catamarca.  A wide range of environments and soil types characterizes this extense territory.  Management of the soybean crops is also variable within this region.  Sustainable soybean production in NWA requires the use of cultivars adapted to those conditions, with high yield potential and good performance against prevalent pests and diseases.  The last decade was marked by a continuous replacement of soybean cultivars, caused by disease epidemics, environment changes, the appearance of transgenic soybeans and the availability of a great number of cultivars offered by breeding companies.  From the 1997/98 to the 2002/03 growing seasons, regional testing of commercial soybean cultivars in macro plots was carried out annually al different locations of NWA.  The objective of this set of experiments was to evaluate adaptation and yield potential of commercial soybean cultivars in large-scale plots.  Collaborators in these tests included technical consultants and researchers from privates companies and public institutions.  In each experiment, cultivars of late maturity groups (MG) (VII, VIII and IX) were planted apart from those of early MG (IV, V and VI).  Each plot consisted of 1,000 m2 with rows spaced 0.5 m apart.  Control plots, consisting of the most widely used cultivar in the region, were located at each side of the test plots.  Yield data was corrected by a normalization index to minimize the differences by soil variations.  Finally, the calculated normalized yield was used to carry out a descriptive analysis about the performance of the different cultivars.  Results obtained during the 2000/01, 2001/02, and 2002/03 growing seasons, at 13 representative locations of the NWA soybean area, indicated that late maturity cultivars (MG VII and VIII) had the best performance due to yield potential and adaptation to environmental conditions.  A very good performance of indeterminate, early maturity cultivars (IV and V) was also observed.  It is important to mention that for these early maturity varieties it is necessary to take into consideration aspects such as planting date, population density, and row spacing.  The cultivar A 8000 RG showed the highest average yield for the 3 growing seasons.  Nevertheless, other cultivars had average yields that did not differ significantly from that of A 8000 RG, such as A 7636 RG, A 4910 RG, A 8100 RG, and Munasqa RR. The information obtained from this set of experiments has been widely used by farmers and consultants in NWA as a tool in the selection of new cultivars to be planted.