BIODIVERSITAS ISSN: 1412-033X Volume 18, Number 1, January 2017 E-ISSN: 2085-4722 Pages: 378-382 DOI: 10.13057/biodiv/d180149 Genetic variability and heritability of acid-adaptive soybean promising lines HERU KUSWANTORO Indonesian Legume and Tuber Crops Research Institute, Indonesian Agency for Agricultural Research and Development. Jl. Raya Kendalpayak Km. 8 Malang 65101, East Java, Indonesia. Tel./Fax.: +62-341-801468/801496, ♥ email: herukusw@gmail.com Manuscript received: 15 April 2016. Revision accepted: 23 January 2016. Abstract. Kuswantoro H. 2017. Genetic variability and heritability of acid-adaptive soybean promising lines. Biodiversitas 18: 378-382. Genetic variability and heritability are very important in a variety improvement. The high genetic diversity can increase the probability on obtaining a new superior variety, while heritability can accelerate the selection process. In acidic dry land, genetic variability is also needed in order to increase such probability. The objective of this study was to estimate the genetic variability of acid-adaptive soybean promising lines. Ten advanced soybean-promising-lines derived from Tanggamus × Anjasmoro varieties crossing were used as the materials. Results showed that the characters of days to flowering, the number of branches plant -1 , the number of reproductive nodes plant -1 , 100 grains weight and grain yield had broad genetic variability, while days to maturity, plant height and the number of filled pods plant -1 had narrow genetic variability. Characters of days to flowering, days to maturity, the number of filled pods plant -1 and 100- grain weight showed high broad sense heritability; characters of a number of branches plant -1 , and the number of reproductive nodes plant -1 had moderate broad sense heritability; and plant height and grain yield had low broad sense heritability. Characters with broad genetic variability and high heritability can be used as sources in soybean variety improvement. The positive correlation between number of branches plant -1 with number of reproductive nodes plant -1 and number of filled pods plant -1 were significant. Significant positive correlations were also found between number of reproductive nodes plant -1 with number of filled pods plant -1 . Negative correlations were found between weight of 100 grains with number of reproductive nodes plant -1 and number of filled pods plant -1 . Similarly, negative correlations were also found between days to flowering with grain yield. Negative correlation between days to flowering and grain yield suggests to develop variety with early days to flowering. Keywords: Acid soil, genetic variability, heritability, soybean INTRODUCTION Soybean is one of the important crops after rice and corn in Indonesia. The demand of soybean has not been fulfilled from domestic production. Most of the demand is for food ingredient likes tempeh, tofu, and soy sauce. Indonesian government urges to grown soybean in various agroecology such as in paddy field after rice, dry land, acid soil and tidal swamp land. Acid soil occupies about 69% of total dry land in Indonesia (Mulyani 2006). Developing acid-adaptive soybean variety in this area will increase domestic soybean production. Therefore, many efforts have been being conducted in developing acid-adaptive soybean variety through various agricultural practices including germplasm screening, artificial crossing and mutation, selection of segregated population, potential yield trial, and genetic × environment interaction. In plant breeding program, genetic variability is the primary factor in developing a superior variety. Broad genetic variability allows superior variety can be developed faster. Plant breeders attempt to make their genetic material broader through many programs such as landraces exploration, artificial mutation, and germplasm introduction from other countries. Landraces exploration is very useful to find out genetic material for specific purposes, especially for adaptation in a specific agroecology. Artificial mutation can be served as a technique to broaden genetic variability by damaging plant DNA. The damaged DNA will constitute new DNA sequence that can express the different performance of a character or whole characters in a plant. Germplasm introduction from other countries can broaden genetic variability. There is a geographical correlation that can be detected in a population (Wang and Li 2012). Usually, germplasm introduction express different response to the new environment. Therefore, pretreatment such as acclimation should be performed to find out the genetic value of the introduced germplasm before they are used as new genetic material in a breeding program. Similar to genetic variability, heritability is also the main factor in plant breeding program. Heritability has main role in estimating inheritance ability (Omoigui et al. 2006), by expressing phenotypic value as breeding value. The magnitude of heritability determines the similarity of the parents to the offspring. A trait with high heritability is not relatively affected by the environment, where its performance is most influenced by the genes constitution. Therefore, heritability can also indicate the easiness of a trait to be improved through selection (Bekele et al. 2012).