CONICET | Buscador de Institutos y Recursos Humanos

Genetic progress is assessed to estimate the genetic contribution of past on-farm yield increases and to identify selected yield-increase traits. Although Argentina is a major soybean producer, there is limited information about genetic progress in its production system. Soybean cultivars farmed in Argentina were developed from U.S. commercial cultivars released throughout the 1970s and 1980s. Because the genetic base on U.S. cultivars is very narrow, we hypothesize that genetic progress in Argentina should have been slower than in the U.S. The objective of this study was to evaluate the genetic gain in cultivars released in Argentina from 1980 to 2015. One hundred and eighty one cultivars belonging to maturity groups (MGs) III, IV, and V were evaluated in three environments under field conditions. Results showed an average genetic gain of 43 kg ha-1 y-1, which was not different across MGs. The genetic gain relative to the oldest expected yield was 1.1 % yr-1. This relative estimate allows comparison with other systems, and showed no substantial differences with reports from U.S. or Brazil. The observed genetic progress was associated with changes in days to maturity and this association was different depending on the maturity group. Cultivars from MGs III and IV showed increased number of days to maturity with increasing year of release, while the cultivars from maturity group V had the opposite trend. The vegetative period was also reduced in the most modern cultivars, especially in those from MGs IV and V. Seed protein concentration was reduced over the years, but the increase in seed yield over-compensated this decline. Therefore, increases in seed protein yield were observed with increasing year of release. When comparing the increase in on-farm yield over the same period of time and location, the genetic gain explained 50 % of the total on-farm yield increase, while the remainder was associated with crop management improvements. Results from this experiment showed that breeding programs in Argentina were able to attain a similar genetic progress to the U.S. even though the starting parents were only a few U.S. cultivars selected from an already narrowed genetic base.