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United States Department of Agriculture

Agricultural Research Service

Title: Developmental Changes Associated with Divergent Selection for Rind Penetrometer Resistance in the Moscsss Maize Synthetic

Authors
item Abedon, B - RHODES COLLEGE
item Darrah, Larry
item Tracy, W - UNIV OF WISCONSIN

Submitted to: Crop Science
Publication Type: Peer Reviewed Journal
Publication Acceptance Date: April 20, 1998
Publication Date: N/A

Interpretive Summary: Maize stalk lodging has decreased through plant breeder selection of germplasm with improved stalk lodging resistance. Despite this progress, major yield losses continue to occur because of intensive production practices, such as high plant densities and high fertilization rates. Rind penetrometer resistance has been used to indirectly select for stalk lodging resistance. Effective selection for reduced stalk lodging would be facilitated by a better understanding of developmental mechanisms affecting rind penetrometer resistance. Vegetative development can be divided into juvenile-vegetative and adult-vegetative phases. Vegetative phase change occurs when juvenile-vegetative traits are replaced by adult- vegetative traits. This study determined indirect responses to selection in the timing of vegetative phase change and other developmental traits in nine cycles of divergent selection for rind penetrometer resistance in Missouri Second Cycle Stiff Stalk Synthetic (MoSCSSS). In the high direction of selection, vegetative phase change occurred relatively earlier in the vegetative stage of plant growth, with the result that ear leaf number and total leaf number decreased. In the low direction of selection, vegetative phase change was relatively later, and ear leaf number and total leaf number increased. These results implicate the timing of vegetative phase change in development of rind penetrometer resistance and hence, resistance to stalk lodging. The impact of this discovery is that selection for earlier vegetative phase change timing may be used to identify germplasm with stronger stalks, and such selection requires no specialized measuring equipment.

Technical Abstract: Rind penetrometer resistance (RPR) has been used to indirectly select for stalk lodging resistance in maize (Zea mays L.). Breeding for stalk lodging resistance would be facilitated by a better understanding of developmental mechanisms affecting RPR. Vegetative development can be divided into juvenile-vegetative and adult-vegetative phases. Vegetative phase change occurs when juvenile-vegetative traits are replaced by adult-vegetative traits. The objective of this study was to determine indirect responses in the timing of vegetative phase change and other developmental traits in nine cycles of S0 phenotypic, divergent selection for RPR in Missouri Second Cycle Stiff Stalk Synthetic (MoSCSSS). In the high direction of selection, vegetative phase change occurred at lower nodes while ear leaf number and total leaf number decreased. In the low direction of selection, vegetative phase change was delayed to higher nodes while ear leaf number and total leaf number increased. In both directions of selection, plants became shorter and flowered earlier. These results indicate that the timing of vegetative phase change may be a factor in determining the level of RPR and stalk lodging resistance. Alternately, modifiers may exist in MoSCSSS that coordinately regulate vegetative phase change with traits, such as ear leaf number, that are directly affected by selection for RPR.

Last Modified: 7/28/2014
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