Effects of Brown Midrib-3 on Yields and Yield Components of Maize1
- Myoung Hoon Lee and
- J. L. Brewbaker2
The brown midrib-3 (bm3) gene associated with low lignin in corn (Zea mays L.) was evaluated for its effects on yield and yield components in Hawaii. Fifteen bm3 hybrids representing a sixparent diallel and their 15 isogenic normal counterpart hybrids were planted as paired rows in two trials. Yields of the bm3 hybrids were significantly lower than normals in both trials, with average reductions of 20% (range 7 to 29%) for grain and 17% (range 8 to 25%) for stover. Traits also affected negatively by bm3 included kernel number per row (−;12%), filled ear length (−10%), ear height (−7%), plant height (−5%), and five other measured traits. Correlation matrices of yields and all measured traits revealed few consistent differences among normal and bm3 hybrids. Grain yields correlated highly with leaf area index for normal hybrids, but not for the isogenic bm3 hybrids. Mean square values for general and specific combining ability (GCA, SCA) were significant for grain and stover yields and plant height, and GCA effects were significant for kernel number per row and ear length. The GCA/SCA ratios were higher for bm3 hybrids than for normals for grain and stover yield. The gains in stover digestibility of bm3 through lowered lignin content did not offset yield losses enough to justify separate breeding programs with bm3. Linkage of the bm3 gene with yield-reducing genes was virtually excluded in this study as a cause for the yield reduction, and a role of colored lignins in reducing photosynthates is postulated.Please view the pdf by using the Full Text (PDF) link under 'View' to the left.
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