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Ames, IA, United States

Sukumaran S.,Kansas State University | Li X.,Kansas State University | Zhu C.,Kansas State University | Bai G.,Kansas State University | And 7 more authors.
Crop Science | Year: 2016

Molecular breeding can complement traditional breeding approaches to achieve genetic gains in a more efficient way. In the present study, genetic mapping was conducted in a sorghum recombinant inbred line (RIL) population developed from Tx436 (a non-stay-green high food quality inbred) × 00MN7645 (a stay-green high yield inbred) and evaluated in eight environments (location and year combination) in a hybrid background of Tx3042 (a non-stay-green A-line). Phenotyping was conducted for agronomic traits (grain yield and flowering time), physiological traits of stay-green (chlorophyll content [SPAD] and chlorophyll fluorescence [Fv/Fm] measured on the leaves), and green leaf area visual score (GLAVS). This population was genotyped with genotyping-by-sequencing (GBS) technology. Data processing resulted in 7144 high quality single nucleotide polymorphisms (SNPs) that were used in a genome-wide single marker scan with physical distance. A selected subset of 1414 SNPs was used for composite interval mapping (CIM) with genetic distance. These complementary methods revealed fifteen QTLs for the traits studied. In addition, QTL mapping for individual environments and year-wise combinations revealed 42 QTLs. A consistent QTL for grain yield under normal and stressed conditions was identified in chromosome 1 that explained 8 to 16% of the phenotypic variation. QTLs for flowering time were identified in chromosomes 2, 6, and 9 that explained 6 to 11% of the phenotypic variation. Stay-green QTLs in chromosomes 3 and 4 explained 8 to 24% of the phenotypic variation. These identified QTLs with flanking SNPs of known genomic positions could be used to improve grain yield, flowering time, and stay-green in sorghum molecular breeding programs. © Crop Science Society of America | 5585 Guilford Rd., Madison, WI 53711 USA All rights reserved.

Sawyer J.E.,Iowa State University | Pedersen P.,Iowa State University | Barker D.W.,Iowa State University | Ruiz Diaz D.A.,Kansas State University | Albrecht K.,Dep. of Agronomy
Agronomy Journal | Year: 2010

Nitrogen fertilizer is an important input for corn (Zea mays L.) production and leaching losses contribute to NO3-N in water systems. This study was conducted to determine whether a kura clover (Trifolium ambiguum M. Bieb.) intercropped corn system could reduce corn N fertilization need and NO3-N in the soil profile, while maintaining corn productivity. Two systems were studied at six sites in Iowa, soybean [Glycine max (L.) Merr.]-corn intercropped with established kura clover and soybean-corn without kura clover. Six N fertilizer rates were applied to corn in each system. Excessive kura clover competition caused reduced corn population, delayed development, and reduced grain yield in 2006. More vigorous kura clover growth suppression in 2007 resulted in similar yield between the kura clover and no-kura clover systems, with greater yield in the intercropped kura clover at a site with coarse-textured soil. The kura clover system did not reduce corn N fertilization requirement, as measured by response in plant N stress and grain yield. The kura clover also did not influence NO3-N in the soil profile before, during, or after the growing season. These results differ from other studies where kura clover intercropping has reduced corn N fertilization need and not reduced corn yield. Intercropping corn with kura clover posed the challenge of sufficiently suppressing the clover to allow successful corn establishment and production, and in addition did not provide potential benefits such as reduced N fertilization requirement or less NO3-N in the soil profile. © 2010 by the American Society of Agronomy.

Mbofung G.C.Y.,95ed Science Center | Susana Goggi A.,95ed Science Center | Leandro L.F.S.,Iowa State University | Mullen R.E.,Dep. of Agronomy
Crop Science | Year: 2013

Seed treatments are applied to soybean [Glycine max (L.) Merr.] seeds to control early season diseases and insects. Unsold, treated soybean seed must be disposed in a different manner than untreated seed. To minimize treated seed disposal costs, it is necessary to improve seed storage. The objective was to determine the best storage environments that would minimize deterioration of treated soybean seed. Twentyfour soybean varieties, different in lipid and protein contents and from four maturity groups, were treated either with fungicide or a mixture of fungicide plus insecticide or were untreated and were stored in three storage environments differing in temperature and relative humidity: a cold storage (CS) (10°C), a warm storage (WS) (25°C), and a warehouse (WH). Seed viability and vigor were evaluated each 4 mo for 20 mo using standard germination and accelerated aging tests. Seed viability remained high throughout the study for seeds stored in CS (>92%) and moderate in the WS (>78%) but decreased to almost 0% after 20 mo in the WH. The seed viability of treated seed was significantly higher than that of untreated seed after 16 mo in the WH while in the CS and WS the positive effects lasted for 20 mo. Seed vigor was affected by only seed lipid content for seeds stored for 12 mo, regardless of storage environment. Treated soybean seeds could be carried over for two seasons if the storage temperature is maintained at 10°C and the relative humidity is below 40%. © Crop Science Society of America.

Stamm M.,Kansas State University | Berrada A.,Yellow Jacket | Buck J.,University of Georgia | Cabot P.,Ford Motor Company | And 20 more authors.
Journal of Plant Registrations | Year: 2012

'Riley' (Reg. No. CV-24, PI 663949), a canola-quality winter oilseed rape (Brassica napus L.), was developed and released by the Kansas Agricultural Experiment Station. Riley is a selection from the cross with pedigree KS3580/'Jetton.' Riley was tested in regional yield trials as the experimental variety KS4158 and was an entry in the National Winter Canola Variety Trial from 2008 through 2010. Riley was released because of its disease tolerance, improved oil content, and superior yield compared with 'Wichita' and other check varieties. The fatty acid profile and glucosinolate content of the meal of Riley are excellent quality. Riley had significantly greater yield than all check cultivars (P < 0.05), yielding 113% of Wichita and 116% of 'DKW46-15'. Through 27 site-years on the southern Great Plains and High Plains, Riley averaged 400 g kg -1 total oil compared with Wichita's average of 388 g kg -1 (P < 0.05). The performance record of Riley suggests an increase in yield and consistency among commercial cultivars. As winter canola is planted on more hectares, demand is growing for improved genotypes. © Crop Science Society of America.

Mardorf J.L.,Dep. of Agronomy | Fehr W.R.,Iowa State University | O'Neal M.E.,Dep. of Agronomy
Crop Science | Year: 2010

Soybean [Glycine max (L.) Merrill] yields can be reduced signifi cantly by infestations of the soybean aphid (Aphis glycines Matsumura). A dominant allele, Rag1, providing resistance to the aphid was identifi ed in PI 548663. The objective of this study was to compare the agronomic and seed traits of 27 lines with the Rag1 allele to those of 27 lines with the rag1 allele that were derived from the same segregating population. The lines were evaluated under aphid-infested conditions at two Iowa locations in 2008 and under aphid-infested and aphid-free conditions at three Iowa locations during 2009. There were signifi cant differences in mean yield between the Rag1 and rag1 lines in all the aphid-infested environments. The difference in yield between the two types reached 47.6% at one location under heavy infestation. Under aphid-free conditions, there was no signifi cant difference in mean yield between the two types. The differences between the two types of lines for maturity, height, lodging, protein content, oil content, and seed weight were either not signifi cant or suffi ciently small to make it possible to develop aphid-resistant cultivars with the Rag1 gene that were comparable to susceptible cultivars. © Crop Science Society of America.

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