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Association of Quality Characters in Flowers of Male Hops 1
Author(s) -
Brooks S. N.
Publication year - 1962
Publication title -
crop science
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 0.76
H-Index - 147
eISSN - 1435-0653
pISSN - 0011-183X
DOI - 10.2135/cropsci1962.0011183x000200030004x
Subject(s) - criticism , citation , quality (philosophy) , library science , agricultural experiment station , association (psychology) , crop , agriculture , agricultural science , biology , political science , computer science , psychology , law , agronomy , philosophy , epistemology , ecology , psychotherapist
A KNOWLEDGE of the interrelations of traits within **• a species is necessary if selection for the simultaneous improvement of these traits is to be most effective. Phenotypic associations between variables may be genetically controlled or they may be brought about by environmental influences. They may be brought about by the direct influence of one variable on another or by correlated common causes. A positive genotypic correlation between two variables can be counteracted by a negative environmental correlation, thus making it impossible to select for any two variables at the same time because of the cancelling-out effects of environment. The reverse may also be true. Furthermore, selection for a trait in one direction may cause an undesired diminution of another trait by direct or indirect effect via a third variable. Therefore, it becomes necessary for a plant breeder to look more closely at the nature of the associations among traits in which he is trying to make progress. Dewey and Lu (2) recently demonstrated the utility of path coefficient analysis in plant selection. This type of analysis, described first by Wright (6) as a tool in animal breeding, furnishes a means of measuring the direct and indirect effects of one variable on another. It starts with the assumption that the direct influence along a given path can be measured by the standard deviation remaining in the effect after all other possible paths of influence are eliminated. At the same time, variation of the causes back of the given path is kept as great as ever, regardless of the relations of these causes to the other variables which have been held constant. A path coefficient, which is defined as a standardized partial regression coefficient, allows the separation of a correlation coefficient into direct and indirect components. Detailed discussions of the theory and application of path coefficient analysis are given by Wright (6) and Li (4) . The purpose of this paper was to determine the interrelations of quality characters in male hops (Humulus lupulus L.). For a detailed description of these characters and their significance to hop breeding, the reader is referred to an earlier paper (1).