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Soybean in Indonesia mostly planted during late dry season after rice harvested in rainfed land resulting in crop failure due to drought. The effect of drought in some areas becomes more severe due to climate change. This paper discusses the breeding and development of soybean varieties tolerant to drought to anticipate the effect of climate change in Indonesia. Breeding program at ILETRI has released three drought tolerant soybean varieties during the reproductive phase. Dering 1 variety was derived from a promising line DV/2984-330 which was cross between Davros variety and MLG 2984; Dering 2 variety was derived from a promising line AB-157-41-22 which was a single cross between Baluran variety with Arg/GCP-335 line; and Dering 3 variety was derived from a promising line DM-122-357-17 which a single cross between Dering 1 and Malabar varieties. Dering 1, Dering 2, and Dering 3 varieties showed average grain yield of 2.12, 2.49, and 2.42 t / ha, respectively which was 1.9 - 19.7%, higher than Grobogan variety. These three varieties having a tolerant response to drought could be developed in drought prone areas for sustainable soybean production in Indonesia. [ABSTRACT FROM AUTHOR]

In Indonesia, soybean (Glycine max [L.] Merrill) is planted after rice in dry season II which usually faces yield loss due to drought. The objective of this research was to determine the seed yield stability and adaptability of soybean lines tolerant to drought during the reproductive stage. A total of 15 soybean genotypes consisted of 13 promising lines and 2 check varieties were evaluated in eight locations for seed yield trait and their adaptability during dry season II of 2017. Dering 1 and Grobogan varieties were used as check for drought tolerance and large seed size, respectively. Results of the study showed that 2 out of 13 soybean lines, AB-157-41-22 and DM-122-35-17, had the highest seed yield potential of 3.32 and of 2.99 t/ha, respectively. Average seed yield per ha of the two lines were 2.49 and 2.42 t/ha, respectively, which were higher than Dering 1 as check variety for drought tolerance (each 17.5 and 25.2%). Of the two selected lines, DM-122-35-17 showed stable adaptation across eight environments, while AB-157-41-22 was unstable adaptation. The two check varieties, Dering 1 and Grobogan, were both unstable across eight location with lower seed yield than AB-157-41-22 and DM-122-35-17. Therefore, soybean line DM-122-35-17 could be recommended as new variety possessing drought tolerance, high seed yield, large seed size, and stable in field performance. [ABSTRACT FROM AUTHOR]

Soybean (Glycine max [L.] Merrill) planted in rainfed land during dry season often experiences crop failure due to drought. The objective of this study was to estimate the tolerant level and genetic advance values of 36 soybean genotypes on agronomic traits tested in drought and optimal irrigated conditions. The field research was conducted in Malang, East Java, Indonesia during late dry season of 2016. The soybean genotypes were tested in two environments, namely optimal condition (irrigation was applied until pods ripening) and drought condition (irrigation was applied until flowering). Results of the study showed that based on the genetic advance value, the number of branches per plant and the number of fertile pods per plant could be used as soybean selection criteria in normal irrigation and drought condition, respectively. In general, the mean of all traits in drought condition were lower than those in normal irrigation condition. Seed yield (t/ha) showed the lowest drought stress tolerant index (STI) (0.72). Based on the drought STI, four soybean lines (TGm-161-25-10, AB-142-40-21, AB-157-41-22, and ARG/GCP) had STI values of 1.0 and above 1.0 which are equivalent to the check drought tolerance variety Dering 1. These soybean lines could be grown in drought-stressed conditions. [ABSTRACT FROM AUTHOR]