Kraig L. Roozeboom

Performance of wheat variety blends in Kansas

This report is brought to you for free and open access by New Prairie Press. It has been accepted for inclusion in Kansas Agricultural Experiment Station Research Reports by an authorized administrator of New Prairie Press. Copyright 1980 Kansas State University Agricultural Experiment Station and Cooperative Extension Service.

Genomic prediction contributing to a promising global strategy to turbocharge gene banks

The 7.4 million plant accessions in gene banks are largely underutilized due to various resource constraints, but current genomic and analytic technologies are enabling us to mine this natural heritage. Here we report a proof-of-concept study to integrate genomic prediction into a broad germplasm evaluation process. First, a set of 962 biomass sorghum accessions were chosen as a reference set by germplasm curators. With high throughput genotyping-by-sequencing (GBS), we genetically characterized this reference set with 340,496 single nucleotide polymorphisms (SNPs). A set of 299 accessions was selected as the training set to represent the overall diversity of the reference set, and we phenotypically characterized the training set for biomass yield and other related traits. Cross-validation with multiple analytical methods using the data of this training set indicated high prediction accuracy for biomass yield. Empirical experiments with a 200-accession validation set chosen from the reference set confirmed high prediction accuracy. The potential to apply the prediction model to broader genetic contexts was also examined with an independent population. Detailed analyses on prediction reliability provided new insights into strategy optimization. The success of this project illustrates that a global, cost-effective strategy may be designed to assess the vast amount of valuable germplasm archived in 1,750 gene banks.

Seed Treatment Effects on Early-Season Pests of Corn and on Corn Growth and Yield in the Absence of Insect Pests

Abstract Second-generation neonicotinoid insecticides are being used to protect seeds and seedlings against injury by early season insects on a wide variety of crops. Seed-applied insecticides have recently been commercialized in the USA for early season insect control in corn. The systemic insecticides clothianidin (Poncho®) and thiamethoxam (Cruiser®) applied as seed treatments were evaluated for their effect on corn yield in the absence of noticeable insect attack over a three year period at a number of locations representing diverse growing environments in Kansas. No consistent effect on yield was detected for either compound at either high or low rates in locations where insects were not observed at damaging populations. Controlled-environment studies detected no differences in early season growth in the absence of insect pests in response to the same two rates of both insecticides. Both compounds were evaluated for their effect on early season corn pests and were found to be effective at high and low rates on wireworm, white grub, flea beetles and chinch bugs. Higher rates of both compounds were needed to reduce feeding damage caused by black cutworm. Seed treatments with either compound would be useful where early season pests are chronic problems.

Risk Analysis of Tillage and Crop Rotation Alternatives with Winter Wheat

The economic feasibility of soybeans, grain sorghum, and corn in annual rotation with winter wheat using reduced tillage and no-tillage systems in the Central Great Plains was evaluated, with continuous wheat and grain sorghum also analyzed. Net returns were calculated using simulated yield and price distributions based on historical yields, two historical annual price series, and 2011 costs. Stochastic Efficiency with Respect to a Function was used to determine the preferred strategies under various risk preferences. The no-till wheat-soybean and reduced-till wheatsoybean systems are the first and second most preferred, regardless of the level of risk aversion.

Drought-Tolerant Corn Hybrids Yield More in Drought-Stressed Environments with No Penalty in Non-stressed Environments

The potential benefit of drought-tolerant (DT) corn (Zea mays L.) hybrids may depend on drought intensity, duration, crop growth stage (timing), and the array of drought tolerance mechanisms present in selected hybrids. We hypothesized that corn hybrids containing DT traits would produce more consistent yields compared to non-DT hybrids in the presence of drought stress. The objective of this study was to define types of production environments where DT hybrids have a yield advantage compared to non-DT hybrids. Drought tolerant and non-DT hybrid pairs of similar maturity were planted in six site-years with different soil types, seasonal evapotranspiration (ET), and vapor pressure deficit (VPD), representing a range of macro-environments. Irrigation regimes and seeding rates were used to create several micro-environments within each macro-environment. Hybrid response to the range of macro and micro-environmental stresses were characterized in terms of water use efficiency, grain yield, and environmental index. Yield advantage of DT hybrids was positively correlated with environment ET and VPD. Drought tolerant hybrids yielded 5 to 7% more than non-DT hybrids in high and medium ET environments (>430 mm ET), corresponding to seasonal VPD greater than 1200 Pa. Environmental index analysis confirmed that DT hybrids were superior in stressful environments. Yield advantage for DT hybrids appeared as yield dropped below 10.8 Mg ha-1 and averaged as much as 0.6–1 Mg ha-1 at the low yield range. Hybrids with DT technology can offer a degree of buffering against drought stress by minimizing yield reduction, but also maintaining a comparable yield potential in high yielding environments. Further studies should focus on the physiological mechanisms presented in the commercially available corn drought tolerant hybrids.

Cover Crop Impacts on Soil Water Status

Water is a primary concern for producers in the Great Plains; as such, research is warranted to quantify how much cover crops affect the amount of soil water available to subsequent cash crops. Cover crop mixes have been marketed as a means to conserve water in no-till cropping systems following winter wheat (Triticum aestivum L.) harvest. The objectives of this study are to quantify changes in soil profile water content in the presence of different cover crops and mixtures of increasing species complexity, to quantify their biomass productivity and quality, and to quantify the impact of cover crops on subsequent corn (Zea mays L.) yields. We hypothesized the change in soil water brought on by the cover crop treatments would be correlated to the quantity of biomass produced and the species composition, rather than mixture complexity. Soil moisture was measured using a neutron probe to a depth of 9 ft. Results from 2013–14 showed no difference in water use between cover crop mixtures and single species. Cover crops depleted the soil profile by a maximum of 3.5 in. during growth, but fallow was able to gain 0.75 in. of water during the same period. At the time of corn planting, soil moisture under all cover crops had replenished to levels at cover crop emergence, except for the brassicas, which had extracted water from deeper in the profile. Corn yields were reduced following the grass cover crops and the six-species mix. Corn yields were more closely related to the carbon:nitrogen (C:N) ratio of the cover crop residue than to profile soil moisture at corn emergence. The fact that yields were similar for corn after fallow and for corn after brassica cover crops implied that water was not the cause of yield reductions after the other cover crops.

Effect of Residue Management, Row Spacing, and Seeding Rate on Winter Canola Establishment, Winter Survival, and Yield

Winter survival of canola (Brassica napus L.) is a challenge for producers using high-residue, no-tillage, or reduced-tillage systems. An innovative residue management system being developed by AGCO Corporation was compared to cooperating canola producers’ residue management and planting methods in wheat stubble. This series of on-farm experiments was conducted in 2014-2015 and 2015-2016 at ten locations in central and south-central Kansas. The AGCO treatments were 20or 30-in. row spacing and three seeding rates (100,000, 150,000, and 200,000 seeds/a) for a total of six treatments. The producer treatment at each location included row spacing, seeding rate, and residue management practices preferred by that producer. Due to winter stand loss, only one of the six experiments planted in the fall of 2014 was harvested for yield in 2015. All four experiments planted in fall 2015 were harvested for yield in 2016. Fall stands usually differed in response to seeding rate and often were greater in 20-in. rows than in 30-in. rows. Spring stands were not as tightly correlated with seeding rate, but were consistently greater in narrow rows, regardless of seeding rate and residue management practices. Winter survival increased with reductions in seeding rate at most locations and was greater in 20-in. rows than in 30-in. rows at three of the five harvested locations. Yields were not affected by residue management, row spacing, or seeding rate at two of the five locations, including the location with yields surpassing 60 bu/a. At the other three locations, yields with the AGCO residue management system equaled or exceeded yields obtained with cooperator practices that typically included much greater seeding rates. Yields seldom responded to seeding rate, but when they did, yields tended to increase as seeding rate decreased.

Impact of Cover Crops and Phosphorus Fertilizer Management on Nutrient Cycling in No-Tillage Corn-Soybean Rotation

The objective of this study was to quantify the effects of cover crops and different fertilizer management techniques on the amount of nutrients being removed and recycled in the soil system. This study was conducted at Ashland Bottoms, KS, from 2014-2016. A 2 × 3 factorial design with three replicates was utilized in this study. The fertilizer management treatments included a control of 0 lb/a P2O5, along with fall broadcast and spring injected applications of P2O5 based on a build and maintain recommendation system. Results show that total uptake of K2O and recycling of P2O5 and K2O are directly influenced by cover cropping. Application of P2O5 fertilizer also statistically impacted the yield of soybeans during the 2016 growing season.

Do Winter Canola Hybrids and Open-Pollinated Varieties Respond Differently to Seeding Rate?

Several producers have turned to planting canola in 30-in. rows as a strategy to take advantage of residue management options (e.g. planter-mounted residue managers and strip tillage) to facilitate planting canola in high-residue cropping systems. Canola hybrids are gaining acres in the southern Great Plains and may require different management than the traditional open-pollinated cultivars. The objective of this study was to determine the effect of seeding rate on winter survival and yield of hybrid and openpollinated winter canola cultivars in 30-in. and 9-in. rows. Experiments were conducted in 2013-2014, 2014-2015, and 2015-2016 at two K-State Research and Extension facilities. Treatments were four locally adapted cultivars (two hybrids and two open-pollinated cultivars) and three or five seeding rates for a total of twelve or twenty treatments in each experiment. Due to nearly complete winter stand loss of hybrids in the experiment planted in 2013, only open-pollinated cultivars were harvested. No experiments were harvested for yield in 2015 because of nearly complete stand loss in all treatments at all locations. In both row spacings, fall stands tended to increase with increasing seeding rates, and hybrids tended to establish more plants than open-pollinated cultivars. Differences in stands due to seeding rate were somewhat less evident in the spring, but stand differences due to cultivars were more evident. Winter survival tended to increase as the number of plants present in the fall decreased, whether that was due to seeding rate or other factors. Bloom occasionally was delayed, and harvested seed moisture tended to be greater when fewer plants were present in the spring, likely due to a greater percentage of buds forming on branches. Seeding rate had a minimal impact on yields in 30-in. rows, with hybrids and open-pollinated cultivars responding similarly in most cases. In 9-in. rows, seeding rate did not affect yields in 2014. In 2016, both hybrids and open-pollinated cultivars maximized yield at 300,000 seeds per acre in 9-in. rows, but hybrids maintained greater yields than open-pollinated cultivars at sub-optimal seeding rates.

Grain Sorghum Response to Water Supply and Environment

This report is brought to you for free and open access by New Prairie Press. It has been accepted for inclusion in Kansas Agricultural Experiment Station Research Reports by an authorized administrator of New Prairie Press. Copyright January 2016 Kansas State University Agricultural Experiment Station and Cooperative Extension Service.