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Abstract
The objectives were to: (1) determine light and temperature effects on chlorophyll concentration and ascertain if this effect could be detected with a chlorophyll meter, (2) evaluate cold tolerant traits using a diallel mating design, (3) evaluate inbred lines for cold tolerance and yielding potential, (4) and compare results from controlled environments with field trials. Inbreds developed at the University of Nebraska-Lincoln were evaluated in field, greenhouse, and growth chamber trials. Inbreds were categorized and evaluated in four groups: Group 1, high yielding; Group 2, freeze tolerant; Group 3, B population; and Group 4, 100% germination. Greater quantities of chlorophyll were found in plants grown in the light warm than in the light cool growth chamber. A linear relationship existed between the chlorophyll meter and total chlorophyll. Therefore, the chlorophyll meter was found to be useful in predicting changes in chlorophyll concentration. Reciprocal differences in diallel hybrids were found for emergence index, leaf greenness (measured with the chlorophyll meter), dry weight, and total plants emerged. Additive effects were predominant for inheritance of emergence index, leaf greenness, and dry weight since GCA and SCA ratios (GCA/(GCA + SCA)) were large. Crosses having cold tolerant maternal parents emerged sooner, had greater leaf greenness, dry weight, and grain yield than crosses having susceptible maternal parents when grown in cool environments. Checks emerged in less time in late field plantings but later in growth chambers than groups. Groups 1 and 4 had greater dry weights in inbred and hybrid trials than checks. All groups had a higher percentage of emerged plants than checks. Groups 3 and 4 had nonsignificantly greater means for grain yield than checks. Positive and significant rank correlations were obtained between early field planting and growth chamber for dry weight and total plants emerged and greenhouse and growth chamber for dry weight. Rankings of groups grown as inbreds and testcrosses were significantly positive for emergence index, leaf greenness, dry weight, and total plants emerged.
