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Title:Adaptability of Soybeans to Late-Planted Environments (Isolines, Gxe, Double Cropping)
Author(s):Raymer, Paul Lindell
Department / Program:Agronomy
Degree Granting Institution:University of Illinois at Urbana-Champaign
Subject(s):Agriculture, Agronomy
Abstract:Soybeans {Glycine max (L.) Merr.} are grown in the Midwest primarily as a full-season crop and only to a limited extent as a double crop. Development of cultivars specifically adapted to double cropping has been suggested as a means to expand double-crop acreage in this area. Before initiating a separate breeding program for the development of Midwestern double-crop cultivars, information is needed concerning genotype by cropping system interactions, plant traits associated with high yield in double-crop environments, and sources of breeding lines possessing these adaptive traits.
Three studies were conducted in an attempt to obtain this information. Performance in conventional early environments was compared with performance in double-crop environments. Douple-cropping was simulated by late planting in a conventionally prepared seedbed.
In the first study, 16 cultivars currently in use in the Midwest were evaluated. No significant cultivar by planting date interactions were found for yield. All cultivars suffered substantial yield reductions when planted late and the extent of yield reduction was similar among all cultivars. The relationship of yield with various plant traits varied greatly among years and no differences in these relationships were observed between the planting dates.
In the second study, near-isogenic lines in 'Harosoy' and 'Clark' genetic backgrounds which possess genes controlling maturity, stem morphology, and resistance to downy mildew (Peronospora manshuria) were evaluated. The lines tested provided a very wide range of maturities and stem lengths, and produced wide differences in yield at both planting dates. Maturities of 96-101 days and medium plant size were found to be optimum in both planting dates.
The objective of the third study was to identify breeding lines for use in a Midwestern double-crop breeding program. Soybean introductions were screened for low yield reduction or high yield when planted late. A number of lines were identified which experienced slightly less yield reduction than the best cultivars did when planted late, but these lines were usually inferior in terms of actual yield when planted late.
Issue Date:1984
Description:79 p.
Thesis (Ph.D.)--University of Illinois at Urbana-Champaign, 1984.
Other Identifier(s):(UMI)AAI8502279
Date Available in IDEALS:2014-12-16
Date Deposited:1984

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