Evaluation of Elite Exotic Maize Inbreds for Use in Temperate Breeding

Abstract

While maize (Zea mays L.) is a highly diverse species, this diversity is not well represented in U.S. maize production acreage. Increased genetic diversity can be obtained through breeding with exotic germplasm, especially tropical‐exotic sources. However, the pool of available tropical germplasm is large and diverse, making choices of tropical parents difficult. The maize breeding program at North Carolina State University has initiated a large‐scale screening effort to evaluate elite exotic maize inbreds, most of which are tropical‐exotic in origin. Here we report screening results for 88 inbreds obtained from various international breeding programs. These lines were tested in replicated yield trials in North Carolina as 50% exotic topcrosses by crossing them to a single‐cross U.S. tester of stiff‐stalk (SS) by non‐stiff‐stalk (NSS) origin. The more promising lines additionally entered 25% tropical topcrosses with SS and NSS testers and were further evaluated in yield‐trials. A handful of tropical inbred lines—CML10, CML108, CML157Q, CML274, CML341, CML343, and CML373—performed well overall. It was further determined that topcrossing to a single SS by NSS tester will suffice for initial screening purposes, allowing for elimination of the poorest performing lines. Topcrossing to additional SS and NSS testers may be of value when determining where, in terms of heterotic patterns, the better‐performing lines will fit into a breeding program.

Combining Ability of Adapted and Exotic Drought-tolerant Maize Inbred Lines Under Full Irrigation and Rainfed Conditions in Nigeria

“…These authors suggest that un-adapted tropical germplasm or temperate materials may be regarded as "exotic" in another tropical environment, and vice versa, depending on their adaptation status. Tropical germplasm regarded as exotic materials have gainfully been used in the U.S. temperate hybrid maize-breeding programs for developing superior genotypes that exhibited improved performance (Tarter et al 2003;Nelson and Goodman 2008) because of increased genetic variability and enhanced response to selection (Fan et al 2004). In the same vein, genetic materials, mostly elite inbred lines, are being exchanged among breeders at CIMMYT and IITA for the purpose of accessing useful genes from such exchanged germplasm for maize yield improvement (Dhliwayo et al 2009) in a target environment.…”

Conservation of Rice Genetic Resources for Food Security

“…One of the major reasons why germplasm may be under-utilized is a lack of evaluation data that breeders can use for their parental choices. 29,30 This is a common challenge in most gene banks around the world, and it has become a major priority activity for the Global Plan of Action on the Conservation and Sustainable Use of Plant Genetic Resources for Food and Agriculture.…”

Construction of a crop—wild hybrid population for broadening genetic diversity in cultivated sunflower and first evaluation of its combining ability: the concept of neodomestication

“…Introgression from the wild compartment for genetic base broadening has been performed for many crops: sugar cane (Kennedy 2001), maize (Nelson et al 2006), oil palm (Soh et al 2003), rice (Xu et al 2004), bean (Singh 2001) tomato (Saavena et al 2001) and wheat (Reif et al 2005), with different strategies, aiming to enhance the genetic diversity without loosing the yield and the quality of the crop (Hodgkin 2001;Hajjar and Hodjkin 2007). The study of the potential adaptative variability in the wild germplasm for genes and traits of agricultural relevance is of special interest for breeders to develop the best strategy for the further releasing of the adaptative novelties of hybrids for crop improvement.…”