Joel K. Ransom

PAPER PRESENTED AT INTERNATIONAL WORKSHOP ON INCREASING WHEAT YIELD POTENTIAL, CIMMYT, OBREGON, MEXICO, 20–24 MARCH 2006 Sustainable improvement of wheat yield potential: the role of crop management

A significant proportion of wheat (Triticum aestivum L.) yield increases achieved at the farm level in the past can be attributed to improved crop management practices. The important role of crop management practices in increasing the yield potential in wheat sustainably is illustrated with recent research findings from North Dakota. In the dryer regions, no-till and crop rotations significantly improve yield and protect the productivity of the soil. Intensifying management in the wetter regions through increased plant populations and by nitrogen timing did not increase yield in 2005 while fungicide applied at flowering for scab control did. In one study genotype interacted with management, with the most disease-tolerant genotypes producing the highest yield when treated with fungicides. Identifying and exploiting positive genotype by management interactions offers a potential avenue for increasing yield potential in wheat in the future. Identifying or developing crop management practices that hold potential for synergistically improving the yield of genotypes is a significant challenge. Imposing management practices that hold promise for improving yield sustainably on breeding material during the selection process has scope for identifying genotypes with greater yield potential at the farm level when these management practices are employed.

Quality Trait Variation in Major Hard Red Spring Wheat Cultivars Released in North Dakota Since 1968

ABSTRACT Over the last 40 years, grain yield of hard red spring wheat (HRSW) (Triticum aestivum L.) has increased dramatically in North Dakota and neighboring regions. This yield increase has caused some concern that recent higher yielding cultivars might be released at the expense of quality performance. A two-year study was initiated in 2004 to examine the changes in quality performance of HRSW cultivars released by North Dakota State University (NDSU) over the past 40 years. The experiment was conducted in North Dakota at three and two sites in 2004 and 2005, respectively. The study included 33 HRSW genotypes laid out in a randomized complete-block design with four replicates. Grain protein content, flour-extraction yield, mixogram scores, Falling Number, glutograph scores, water absorption, dough character score, and loaf volumes did not vary significantly with year of release. Linear regression of cultivar means on year of release showed an annual increase in crumb color score of 0.4%/yr since 1968. ...

Spring Wheat Breeding

Wheat (various species of the genus Triticum) is a grass originating from the Levant area of the Middle East. However, only hexaploid common wheat (Triticum eastivum), and tetraploid durum wheat (Triticum turgidum ssp. durum) are presently cultivated worldwide. Not only is wheat an important crop today, it may well have influenced human history. Wheat was a key factor enabling the emergence of civilization because it was one of the first crops that could be easily cultivated on a large scale, and had the additional advantage of yielding a harvest that provides long-term storage of food. Today, there are different classes and uses of wheat. Although, it is mainly used as a staple food to make flour for leavened, flat and steamed breads, wheat can also be used as livestock feed, for fermentation to make beer and other alcoholic liquids, and recently, as a source of bio-energy. Global wheat production must increase at about 2% annually to meet future demands. The potential of increasing the global arable land is limited; hence, future increases in wheat production must be achieved by enhancing the wheat productivity to the land already in use. The objectives of most breeding programs include: high and stable yields, superior end-use quality, desirable agronomic characteristics, biotic (mainly, pests) resistance, and abiotic (environmental stresses) tolerance. While it is virtually impossible to combine all these characteristics into a single ‘perfect’ variety, continuous breeding efforts toward achieving these objectives will ensure that new varieties possess as many desirable and economic traits as possible. Details of the different breeding approaches to enhance modern wheat breeding are discussed in this chapter.

Type and placement of zinc fertilizer impacts cadmium content of harvested durum wheat grain

ABSTRACT Due to potential international marketing concerns, North Dakota durum wheat (Triticum turgidum L. Desf.) producers require strategies that limit cadmium (Cd) in harvested grain. These trials were conducted in order to determine the impact of type and placement of zinc (Zn) fertilizer on harvested grain seed Cd levels and to determine the best timing of foliar Zn-ethylenediaminetetraacetic acid (EDTA). Foliar Zn-EDTA applied at Feekes 10 growth stage had the lowest grain Cd of 0.97 mg kg−1 when evaluating different fertilizer sources and application timings. Application of 22.4 kg ha−1 potassium chloride with the seed at planting resulted in the highest grain Cd of 0.151 mg kg−1 and might be a concern when environmental conditions are conducive for Cd uptake from soil. Stepwise linear regression determined that soil pH and chloride explained 96% of the variability of grain Cd. Applying 1.1 kg Zn ha−1 as foliar Zn-EDTA in combination with 33 kg nitrogen ha−1 at Feekes 10.54 growth stage resulted in significantly lower grain Cd, and significantly higher grain Zn, iron, and protein content. Treatments that significantly lowered grain Cd did not decrease grain yield, test weight, or protein content. The treatments that most reduced grain Cd resulted in the most benefits from a production, marketing, and nutritional standpoint and represents an agronomic approach to biofortification of durum wheat.

Transgenic Bt Corn, Soil Insecticide, and Insecticidal Seed Treatment Effects on Corn Rootworm (Coleoptera: Chrysomelidae) Beetle Emergence, Larval Feeding Injury, and Corn Yield in North Dakota

Abstract Northern, Diabrotica barberi Smith & Lawrence (Coleoptera: Chrysomelidae), and western, Diabrotica virgifera virgifera LeConte (Coleoptera: Chrysomelidae), corn rootworms are economic pests of corn, Zea mays L. in North America. We measured the impacts of corn hybrids incorporated with Cry3Bb1, Cry34/35Ab1, and pyramided (Cry3Bb1 + Cry34/35Ab1) Bacillus thuringiensis Berliner (Bt) proteins, tefluthrin soil insecticide, and clothianidin insecticidal seed treatment on beetle emergence, larval feeding injury, and corn yield at five locations from 2013 to 2015 in eastern North Dakota. In most cases, emergence was significantly lower in Bt-protected corn than in non-Bt corn hybrids. Exceptions includedWyndmere, ND (2013), where D. barberiemergence from Cry34/35Ab1 plots was not different from that in the non-Bt hybrid, and Arthur, ND (2013), where D. v. virgifera emergence from Cry3Bb1 plots did not differ from that in the non-Bt hybrid. Bt hybrids generally produced increased grain yield compared with non-Bt corn where rootworm densities were high, and larval root-feeding injury was consistently lower in Bt-protected plots than in non-Bt corn.The lowest overall feeding injury and emergence levels occurred in plots planted with the Cry3Bb1 + Cry34/35Ab1 hybrid.Time to 50% cumulative emergence of both species was 5–7 d later in Bt-protected than in non-Bt hybrids.Tefluthrin and clothianidin were mostly inconsequential in relation to beetle emergence and larval root injury. Our findings could suggest that some North Dakota populations could be in early stages of increased tolerance to some Bt toxins; however, Bt corn hybrids currently provide effective protection against rootworm injury in eastern North Dakota.

Development, evaluation and genetic analysis of sulfosulfuron herbicide resistance in sorghum

Herbicide tolerant varieties in combination with herbicide seed treatments can be used to manage Striga. However, there are no herbicide resistant sorghum varieties in Kenya. The objectives of this study, therefore, were to develop sulfosulfuron resistance in sorghum, to determine the level of resistance in resultant herbicide tolerant mutants, and to determine the genetic inheritance of herbicide tolerance in sorghum. Five ethyl methane sulphonate (EMS)-derived sulfosulfuron tolerant mutants (designated hb6, hb8, hb12, hb56, and hb462) were identified and selfed to M4 generation. Varying rates of sulfosulfuron, either as a spray or seed coat, were applied to determine the level of tolerance of the mutant lines. Mutant lines were also crossed with the wild-type Seredo and among themselves to determine mode of inheritance. Results showed that the susceptible wild-type Seredo was killed at the lowest herbicide rates of 0.5 g ha-1 and 1 g ha-1 sulfosulfuron. Dry matter from the spraying and seed coating experiments showed mutants to be up to 170 times more resistant to sulfosulfuron than the wild-type. The LD50 values indicated a general trend of hb46 > hb12 > hb462 ~ hb56 > hb8 for level of tolerance under both spraying and seed coating experiments. The F2 progeny of mutant X wild-type crosses segregated in a 1:2:1 fashion for resistant, intermediate, and susceptible, indicating semi-dominant inheritance. Intercrosses between mutant lines did not segregate for resistance in the F2 generation indicating the same mutation could be responsible for the tolerance in all five mutants.