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Book of Abstracts First Legume Society Conference 2013: A Legume Odyssey Novi Sad, Serbia, 9-11 May 2013
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Chilling tolerance in soybeans – pod setting and indirect selection criteria
Christiane Balko
Julius Kühn Institute, OT Groß Lüsewitz, Sanitz, Germany
Soybeans have relatively high demands in temperature and water supply. Especially during
flowering and early pod setting low temperatures may affect yield as well as quality of grains
negatively. Therefore – with respect to extending soybean cultivation to the north, chilling
tolerance is an important trait besides earliness. To compare chilling tolerance of cultivars and
breeding lines, a test under controlled conditions in a growth chamber was used. Plants were
subjected to a 3 weeks-period of cool temperatures (15 °C day/10 °C night) compared to a
control (25 °C day/20 °C night) starting at the beginning of flowering. At the end of the stress
period, free proline, soluble sugars, chlorophyll content (SPAD) and dry matter content of leaves
as well as pod setting per node were determined. Plants were cultivated till harvest and pod
setting, grain number and yield were recorded. Results show a clear variability in chilling tolerance
as well as compensation behavior within the 35 early soybean cultivars investigated. Immediately
after the stress period, pod setting was reduced by the stress treatment compared to the control
by 21.8% – 91.2%. During further cultivation, some genotypes showed compensation behavior
partly resulting in higher pod numbers and yield in stressed plants. This was related to a longer
time till ripening in some genotypes, the delay in ripening ranging from 0 to 49 days. Really
sensitive genotypes could not compensate for the reduced pod setting. Relative yields
(y stress*100/y control) ranged from 12% to 180%. A chilling event during flowering time in the field in
2011 was used to validate tolerance to cool temperatures determined under climate chamber
conditions.
Acknowledgements
The authors thank the Federal Ministry for Food, Agriculture and Consumer Protection (BMELV) and the Federal
Office of Agriculture and Food (BLE) for financial support (2809 OE 113).
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