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ARS Home » Pacific West Area » Pendleton, Oregon » Columbia Plateau Conservation Research Center » Research » Publications at this Location » Publication #269845
Title: Soil water potential requirement for germination of winter wheat

Author
item Wuest, Stewart
item LUTCHER, L. - Oregon State University

Submitted to: Soil Science Society of America Journal
Publication Type: Peer Reviewed Journal
Publication Acceptance Date: 11/12/2012
Publication Date: 1/8/2013
Citation: Wuest, S.B., Lutcher, L.K. 2013. Soil water potential requirement for germination of winter wheat. Soil Science Society of America Journal. 77: 279-283. doi: 10.2136/sssaj2012.0110.

Interpretive Summary: In dry climates crops are often sown into soil with inadequate moisture for germination. We performed this study to determine how dry a soil can be and still germinate winter wheat. We also tested different varieties of wheat and different seed lots of each variety to learn if some are capable of germinating in drier soil than others. We found that germination was rapid (3 to 4 days) when water potentials were wetter than 1.1 MPa, and germination was slightly slower (4 to 5 days) when water potentials were between 1.1 and 1.6 MPa. In soils drier than 1.6 MPa germination was incomplete. Field measurements confirmed that germination and emergence can occur when seed is planted into soils with water potential wetter than 1.6 MPa. The two seed lots of each cultivar varied in time to germination by an average of 0.20 days, and the six cultivars tested varied by an average of 0.34 days. This means variation between seed lots is as important as variation between cultivars when looking for seed with superior germination under marginal soil water contents.

Technical Abstract: In semi-arid climates seed is often sown into soil with inadequate water for rapid germination. This study was designed to measure the soil water potential limits for rapid, adequate, and marginal germination of winter wheat (Triticum aestivum L.). We also tested for differences between cultivars and seed lots. A laboratory experiment at 15 and 20°C using three silt loam soils revealed that germination was rapid (3 to 4 days) at water potentials above 1.1 MPa, and slightly slower (4 to 5 days) at water potentials from 1.1 down to 1.6 MPa. Below 1.6 MPa less than half of the experimental units achieved the cut-off criteria of 75% germination and 5 mm radical length within 25 days. Field measurements confirmed that germination and emergence can occur when seed is planted into soils with water potential greater than 1.6 MPa. The two seed lots of each cultivar varied in time to germination by an average of 0.20 days, and the six cultivars tested varied by an average of 0.34 days. We conclude that variation between seed lots may be as important as variation between cultivars when looking for seed with superior germination under marginal soil water contents.