Field Evaluation of Early Maturing Soybean Genotypes for Differential Adaptation to Low Night Temperatures
- Majid Seddigh ,
- Gary D. Jolliff and
- James H. Orf
Night temperature has a strong effect on soybean [Glycine max (L.) Merr.] productivity. Successful development of soybean genotypes tolerant to low night temperatures depends on the identification of genetic variation for this trait. Field experiments were conducted at Oregon State University and the University of Minnesota in 1984, 1985, and 1986 to assess genetic variation for adaptation to low night temperature within twenty soybean genotypes of maturity groups (MG) 000,00, and 0 of different origins. All genotypes were grown at Corvallis, OR, and St. Paul, MN, which have mean minimum night temperatures of approximately 10 and 16°C, respectively, during the summer months. Mean maximum temperatures for the same period of the year are similar for the two locations. Both locations are also at about the same latitude (ca. 45° N). Indices for adaptation to cool nights were calculated for seed yield, above ground dry matter (excluding leaves), apparent harvest index, seed weight, and days to maturity. These indices were calculated based on the performance of each genotype for a given trait in Corvallis relative to the mean performance of all genotypes within the same maturity group in Corvallis, as compared to the same value calculated for St. Paul. Genetic variations for adaptation to cool nights were identified for all the traits under investigation. In terms of seed yield, ‘Fiskeby V’ (MG 000), ‘Caloria’ and ‘McCall’ (MG 00), and ‘Dawson’ and ‘Evans’ (MG 0) appeared to be most adapted to low night temperatures, while ‘Maple Presto’ (MG 000), ‘Heike 3’ and ‘Maple Arrow’ (MG 00), and PI 290119 and ‘Ozzie’ (MG 0) seemed to be least adapted to cool nights. It also appeared that different characteristics contributed to the differential adaptation of genotypes to cool nights for seed yield. This information should be useful in breeding programs to develop soybean cultivars less sensitive to variations in night temperature.
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