In the 1980s, DNA‐based molecular markers were identified as having the potential to enhance corn (Zea mays L.) breeding. Research has demonstrated the advantage of using molecular markers for selection of simply inherited traits, however only a few studies have evaluated the potential to enhance genetic gain for quantitative traits. In the late 1990s, Monsanto decided to implement marker assisted selection for quantitative traits in our global plant breeding programs. We built genotyping systems and information tools and developed marker assisted methodologies that increased the mean performance in elite breeding populations.
No abstract
Index selection was developed to help breeders practice simultaneous selection for several traits. Our objective was to compare selection differentials, expected gains, and relative index efficiencies of several indexes constructed to improve cold tolerance of two maize (lea mays L.) populations. Cold tolerance traits were percentage emergence, emergence index (i.e., rate of emergence), and seedling dry weight.Best predicted results for all traits were given by a rank summation index, a multiplicative, weight-free index, and a base index (index weights were reciprocals of phenotypic standard deviations). These indexes were not seriously affected by unequal variances among traits and combined 1) simplicity of use, 2) freedom from need to estimate genetic parameters, and 3) good selection differentials and predicted gains in each trait and in the aggregate genotype. Our results also showed that selection for dry weight/plot identified lines with excellent percentage emergence and seedling dry weight.
Plant breeders and plant physiologists would like to know which plant traits have changed to permit new varieties to produce higher yields than older varieties. We studied crosses of improved and unimproved cycles from three recurrent selection programs conducted to increase grain yield in maize (Zea mays L.). Our research was conducted to study changes in several physiological traits that could be important to increased grain production.Results suggested that an extended grain filling period and later plant senescence rather than an increased rate of grain filling was associated with grain yield increases in BS10(FR) x BS11(FR). Testcrosses of the improved Lancaster population produced more dry matter and translocated dry matter to developing kernels at a faster rate and for a longer period of time than did testcrosses of the unimproved population. Crosses of improved cycles of BSSS(R) and BSCBl(R) generally displayed more rapid filling periods and later plant senescence than did crosses of their unimproved cycles. Crosses of improved cycles generally produced more dry matter and translocated a larger percentage of dry matter to the grain.
Conservation-tillage systems produce different soil environments for corn (Zw mays L.) growth and development than do intensive tillage systems. Development of com hybrids specifically adapted to conservation-tillage environments may be one way to increase and stabilize grain yield. A 2-yr field study on a Typic Haplaquolls near Ames, lA, with four hybrids and three tillage systems (no-till, disk, and moldboard plow) was conducted to examine the effects of tillage systems, hybrids, and their interactions on shoot and root dry weights, leaf development, mature-plant height, final plant stand, and grain yield. Moldboard plowing or disking increased vegetative growth relative to no-till. Hybrids responded differently to the three tillage systems only during vegetative growth. Hybrids 2 and 3 had greater increases in shoot growth in response to moldboard plowing than to disking. Hybrid 3 also bad a greater increase in root dry weight and leaf stage With moldboard ploWing than With disking. Response to tillage for mature-plant measurements differed between years but not between hybrids. No-till plots had shorter mature plant heights (1.87 m) and lower grain yields (6.98 Mg ba-1 ) than moldboardplowed plots (1.96 m; 8.34 Mg ba-1 ) only in 1982. Grain moistures of no-till plots averaged over years were 28 g kg-• greater than those of moldboard-plowed plots. Results of this study indicate that during vegetative growth, corn hybrids respond differently to tillage systems. Further evidence of hybrid X tillage interactions, however, is needed to justify development of corn hybrids adapted to specific tillage systems.
scite is a Brooklyn-based organization that helps researchers better discover and understand research articles through Smart Citations–citations that display the context of the citation and describe whether the article provides supporting or contrasting evidence. scite is used by students and researchers from around the world and is funded in part by the National Science Foundation and the National Institute on Drug Abuse of the National Institutes of Health.
customersupport@researchsolutions.com
10624 S. Eastern Ave., Ste. A-614
Henderson, NV 89052, USA
This site is protected by reCAPTCHA and the Google Privacy Policy and Terms of Service apply.
Copyright © 2024 scite LLC. All rights reserved.
Made with 💙 for researchers
Part of the Research Solutions Family.