Submitted to: Crop Science
Publication Type: Peer reviewed journal
Publication Acceptance Date: 5/25/2002
Publication Date: 1/1/2003
Citation: FLINT-GARCIA, S.A., MCMULLEN, M.D., DARRAH, L.L. GENETIC RELATIONSHIP OF STALK STRENGTH AND EAR HEIGHT IN MAIZE. CROP SCIENCE. 2003. v. 43. p. 23-31. Interpretive Summary: Stalk lodging in corn is the breakage of the corn stalk at or below the ear which results in the loss of the ear at harvest. The rind penetrometer is an effective tool for measuring stalk strength in an effort to improve corn germplasm for stalk lodging resistance. However, previous studies have demonstrated that plants that have lower ear heights have stronger stalks. If the ear height of the plant solely determines stalk strength, then corn breeders should simply select for low ear heights. However, if rind penetrometer resistance measures the actual stalk strength of the plant, then breeders cannot select plants with strong stalks based on ear height alone. We found that, although ear height has a significant effect on stalk strength, the rind penetrometer can measure the actual stalk strength independent of ear height. This information is important to corn breeders in their attempts to decrease stalk lodging, and to other researchers to study the biochemical basis of stalk strength.
Technical Abstract: The rind penetrometer is an effective tool for measuring stalk strength in an effort to improve maize (Zea mays L.) germplasm for stalk lodging resistance. However, previous studies have indicated a significant negative correlation between rind penetrometer resistance (RPR) and ear height (EH). The correlation between RPR and EH is of interest in understanding response to selection for RPR. Has selection for high RPR resulted primarily in increased stalk strength per se and coincidentally lower ear heights, or has selection for high RPR resulted in lower ear heights and subsequently higher stalk strength? The objective of this study was to determine the genetic relationship between RPR and the correlated trait EH. To accomplish this goal, three F2:3 populations were used to characterize and compare quantitative trait loci (QTL) for RPR, EH, and RPR adjusted for EH (RadjE). The correlation between EH and RPR was highly significant in all three populations. The original QTL analysis of RPR detected a total of 26 QTL across populations. Adjusting RPR for EH caused 11 of the original RPR QTL to lose their significance. However, the majority, 15 of 26, of the original RPR QTL remained significant as QTL for RadjE. These results demonstrate that although EH has a significant effect on RPR as reflected in the negative correlation, QTL analysis can be used to separate genetic effects for RPR per se from genetic effects caused by the correlated trait.