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Title:Experimental Production and Performance of Hybrid Soybean Varieties
Author(s):Nelson, Randall Lee
Department / Program:Agronomy
Degree Granting Institution:University of Illinois at Urbana-Champaign
Subject(s):Agriculture, Agronomy
Abstract:The inability to produce large quantities of seed and/or to achieve economic levels of heterosis are major problems in most self-pollinated crops, including soybeans {Glycine max (L.) Merr.}. However, very little work has been done on hybrid soybeans. In all previous reports on hybrid soybeans, the hybrid seed was produced by hand pollination. This greatly limited the amount of hybrid seed available so almost all observations have been recorded from single, spaced plants. Since the discovery of genetic male sterility in soybeans, no studies have been published on hybrid soybeans which have used male sterility to produce the hybrid seed.
The objectives of this research were: (1) to test the feasibility of using genetic male sterility to produce hybrid soybean seed, (2) to compare the yield of the resulting hybrids with the parents of those hybrids, and (3) to identify other characteristics in hybrids which differ from those in the parents.
The most significant variable in the production of hybrid soybean seed was the location. Pollen movement in intensely-cultivated east central Illinois was very low. As high as 75% of the male-sterile plants were barren and those plants with seed averaged less than 4 seeds/plant. The addition of bees to the production plots provided some increase in seed set. The most successful location was in southwestern Illinois. Male-sterile plants averaged over 40 seeds/plant in that environment. This area is less intensely cultivated and is a more conducive habitat for insects. No census of the insect population was taken so it is not known what insect or insects were responsible for the pollen movement. Also it could not be determined from this study what effect the differences in temperature and humidity have on cross pollination. Although small quantities of hybrid seed can be successfully produced in this manner, these methods are not feasible for large-scale hybrid seed production.
Data was collected on 37 soybean hybrids from 15 parents. The tests were grown in two locations for two years. Because of the difficulty in consistently producing hybrid seed not all hybrids were grown in all environments. Many traits were measured in both the hybrids and the parents and few examples of heterosis over the better parent were observed. The greatest expression of heterosis for seed yield at a single location was 29% over the higher yielding parent. When the data was averaged over two locations the best hybrid yielded only 19% more than the better parent. Although several hybrids exceeded the higher parent only one hybrid was significantly higher yielding than the best pure-line variety in any one or combination of environments.
Parents were selected both for their yielding capacity and their diverse genetic origin. Based on the known pedigrees of the parents, it was not possible to predict the expression of heterosis in the hybrids.
This research demonstrated that heterosis for seed yield can be expressed in hybrid soybeans; however, crossing of previously developed pure-line varieties will not result in economically exploitable heterosis. Given the major mechanical barriers to hybrid seed production, the lack of combining ability in current improved soybean cultivars, and the continual yield increases still being achieved through the breeding of new pure-line varieties, the development of commercial hybrid varieties does not seem to be a very promising approach for increasing the yield of soybeans.
Issue Date:1980
Description:105 p.
Thesis (Ph.D.)--University of Illinois at Urbana-Champaign, 1980.
Other Identifier(s):(UMI)AAI8108614
Date Available in IDEALS:2014-12-14
Date Deposited:1980

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