Effects of genotype and agro-ecological conditions on storability of soybean [Glycine max (L.) Merr.] seed
Chirchir, Grace J.
Nyamongo, Desterio O.
Gweyi-Onyango, Joseph P.
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Soybean seed storability in the tropics is especially important due to rapid deterioration that varies with the environment, genotype and management practices. The objective of this study was to investigate soybean seed quality during storage as influenced by genotype and agroecological conditions in Meru South Sub-County, Kenya. Seeds of two commonly grown soybean genotypes- Gazelle and TGx 1740-2F (SB19) harvested in February 2013 were used to investigate seed storability. Seed samples (2.5 kg) were stored in gunny bags in a completely randomized design with three replications, giving a total of 6 experimental units per site. The storage treatments were set on farm under ambient conditions in two contrasting agro-ecologies: Upper Midlands II (altitude- 1529 m above sea level; temp.- 18.2–20.6 ºC) at Kirege and Lower Midlands IV (altitude- 1129 m above sea level; temp.- 21.0–23.5 ºC) at Igambatuntu. Changes in seed quality were monitored at 0, 123 and 246 days of storage by subjecting them to germination, electrical conductivity and accelerated aging tests. Data were analyzed using SAS 2009. Results revealed that smaller-seeded soybean genotype TGX 1740-2F was a better storer seed than larger seeded Gazelle as shown by a higher vigor at end 246 days (8 months) of storage. In addition, seed storage environmental conditions significantly influenced the degree of seed deterioration. Soybean seed stored at cooler Upper Midlands II had greater vigor than that stored at the warmer Lower Midlands IV agro-ecology. This study concludes that soybean seed deteriorates in storage and that genotype by environment interaction plays an important role in expression of seed storability. It is recommended that soybean be stored in the cooler higher agro-ecologies of the tropics for improved storability.