Wheat Development and Yield as Affected by Era of Variety Release and In-Furrow Fertilizer

Limited information exists on the interaction between historical and modern wheat varieties and in-furrow fertilizer. Our objectives were to estimate grain yield and differences in dynamics of biomass accumulation of historical and modern winter wheat varieties as affected by different fertilization practices. Two field trials were established during the 2017–2018 growing season in Kansas. Eight winter wheat varieties released between 1920 and 2016—Kharkof (1920), Scout 66 (1966), Karl 92 (1988), Jagger (1994), Jagalene (2001), Fuller (2006), KanMark (2014) and Larry (2016)—were sown using one of two different fertilizer treatments: either the university recommendation (control with no in-furrow fertilizer due to high testing soil-P levels) or a treatment where 100 lb/a MESZ were applied in-furrow. Grain yield was greater in semi-dwarf varieties relative to tall varieties. In-furrow fertilizer showed greater grain yield in comparison with no fertilizer treatment. Whole plant biomass accumulation at matu­rity did not change over decades. In-furrow fertilizer presented larger biomass accu­mulation than no fertilizer treatment. Harvest index increased from tall to semi-dwarf varieties. More site-years of this study are needed to determine whether there is a need for re-evaluation of current fertility recommendations for semi-dwarf wheat varieties, considering that no interaction between variety and fertility was observed

Wheat Development and Yield as Affected by Era of Variety Release and In-Furrow Fertilizer

Nutrients play a major role in wheat yield determination; however, limited informa­tion exists on the differential responses of historical and modern varieties to in-furrow fertilizer. Our objectives were to estimate grain yield and differences in agronomic traits of historical and modern winter wheat varieties as affected by different fertilization programs. Two field trials were established during the growing season 2016–2017 (i.e., Ashland Bottoms and Belleville, KS). Seven winter wheat varieties released between 1920 and 2016–Kharkof (1920), Scout 66 (1966), Karl 92 (1988), Jagalene (2001), Fuller (2006), KanMark (2014), and Larry (2016)–were sown using one of two different fertilizer practices: either the university recommendation or a treatment where 100 lb/a MESZ were applied in-furrow. At both locations, historical varieties were taller and had thinner stems than modern ones. In-furrow fertilizer increased yield of modern varieties relative to no fertilizer treatment in a sandier soil in Ashland Bottoms, while historical varieties showed neutral to negative yield response. In the silt loam soil near Belleville, there was only a significant variety effect but no fertilizer effect, likely due to a greater cation exchange capacity of the studied soil. More site-years of this study are needed to determine whether there is a need for re-evaluation of current fertility recommendations for modern wheat varieties

Wheat Variety Response to Seed Cleaning Method and Pesticide Seed Treatment Following a Growing Season with Severe Infestation of Fusarium Head Blight

Fusarium head blight (scab) is a common concern in eastern and central Kansas. Wheat seed quality might be compromised following a growing season with severe infestation of scab. Our objectives were to evaluate the effects of variety, seed cleaning method, and seed treatment, on wheat stand establishment and yield following a growing season where scab was severe. A trial was established during the 2015-16 growing season using seed harvested from the 2014-15 growing season, which was characterized by severe infestation of scab. Three commonly grown wheat varieties with differing levels of scab resistance (Everest, SY Wolf, and WB Grainfield) were submitted to three different seed cleaning methods (unclean, air screened, or top-gravity table) and two different pesticide seed treatments (no seed treatment versus Gaucho XT fungicide and insecticide). Plots were 30 feet long by 5.6 feet wide and sown at 1.2 million seeds per acre. Seed cleaning method affected wheat seed size, with top-gravity table resulting in larger seed size, approximately 3,000 fewer seeds per pound compared to unclean seed. Seed cleaning method also increased stand establishment from 10.4 emerged plants per row foot resulting from the unclean seed to 11.9 emerged plants per row foot resulting from the top-gravity table. Notwithstanding, there was no effect of variety or seed treatment on stand establishment. Grain yield, on the other hand, was increased from 55.6 to 61.3 bushels per acre in response to seed treatment and was significantly different among varieties. The variety WB Grainfield yielded 68.4 bushels per acre, which was statistically greater than the 53 bushels per acre achieved by both Everest and SY Wolf. There was no effect of seed cleaning method on grain yield

Timing and Positioning of Simulated Hail Damage Effects on Wheat Yield in Kansas

Hail events often decrease wheat yields in Kansas; however, estimates of yield loss due to hail event timing and position relative to the flag leaf are only available for old varieties. Our objectives were to quantify wheat yield losses as affected by timing of hail event relative to the crop development and positioning of the damage relative to the flag leaf. A total of 12 hail damage treatments including six different timings during the growing season (boot, anthesis, milk, soft dough, hard dough, and ripe) and two different positionings relative to the flag leaf (above or below) were evaluated in a trial conducted in Manhattan, KS, during the 2015-16 growing season. Hail damage was simulated by bending 100% of the stems within each plot. Wheat yield loss due to stem bending treatment ranged from 5.8 bushels per acre (9.0%) for treatment imposed below the flag leaf during hard dough to as much as 23.7 bushels per acre (36.7%) for treatment imposed during the milk stage, above the flag leaf. The greatest loss in wheat grain test weight was 4.5 pounds per bushel (8.1%) for treatments established during the milk stage. More years of research are needed to achieve robust estimates of wheat yield loss due to hail damage, but these preliminary data indicate that the milk stage of development is more sensitive to hail damage than other studied stages

Wheat Variety Response to Seeding Rate in Kansas During the 2015–2016 and 2016– 2017 Growing Seasons

Plant density is among the major factors determining a crop’s ability to capture resources such as water, nutrients, and solar radiation; therefore, different wheat varieties might require different seeding densities to maximize yield. The objective of this project was to better understand the response of different wheat varieties to seeding rate. Two field experiments were conducted during 2015–2016 and repeated during 2016–2017, evaluating seven wheat varieties subjected to five different seeding rates (0.6, 0.95, 1.3, 1.65, and 2.0 million seeds/a). Crop was managed for a 70 bu/a yield goal and pests were controlled using commercially available pesticides. Final stand and grain yield were measured, and all statistical analyses were performed for relating emerged plants per acre to grain yield. At each individual environment and across varieties, grain yield usually was maximized at approximately 0.9 million emerged plants per acre. There were significant differences among varieties in grain yield, with Joe and Tatanka usually outperforming the remaining tested varieties. Across environments, grain yield usually was maximized at populations between 0.6 and 0.7 million plants per acre for less responsive varieties (1863, Everest, and Tatanka), at approximately 0.9 million plants per acre for average responsive varieties (Joe, Bob Dole, KanMark, and Zenda), and more than 1.05 million emerged plants per acre for more responsive varieties (Larry and AG Icon). These preliminary data suggests that there is the potential to manage each wheat variety according to its individual tillering potential; however, more data are needed to make definite conclusions about each variety’s optimum seeding rate. Thus, this experiment is currently being conducted at five sites during the 2017–18 growing season

Timing and Positioning of Simulated Hail Damage Effects on Wheat Yield in Kansas: 2015–2016 and 2016–2017 Growing Seasons

Hail events often decrease wheat yields in Kansas; however, estimates of yield loss due to hail event timing and position relative to the flag leaf are only available for older varieties. Our objectives were to quantify wheat yield losses as affected by timing of hail event relative to the crop development and positioning of the damage relative to the flag leaf. A total of 14 hail damage treatments including seven different timings during the growing season (boot, anthesis, watery ripe, milk, soft dough, hard dough, and ripe) and two different positioning relative to the flag leaf (above or below) were evaluated in a trial conducted in Manhattan, KS, during the 2015–2016 and 2016–2017 growing seasons. Hail damage was simulated by bending 100% of the stems within each plot, which averaged approximately 15 bu/a both growing seasons across treatments, ranging from non-significant to 20.4 bu/a. The lowest grain yield (or highest grain yield loss) due to simulated hail occurred when treatments were imposed during milk stage or anthesis (above and below flag leaf) and during soft dough stage below flag leaf in 2015–2016. Delaying treatment to hard dough, when most of the photosynthates have already been translocated to the grain, also decreased grain yields when compared to the control both years, especially when stem bending occurred below the flag leaf. More years of research are needed to achieve robust estimates of wheat yield loss due to hail damage, but these preliminary data indicate that wheat grain yield is more sensitive to hail damage during the interval between anthesis and the milk stage of grain development

Does transcranial direct current stimulation to prefrontal cortex affect mood and emotional memory retrieval in healthy individuals?

Studies using transcranial direct current stimulation (tDCS) of prefrontal cortex to improve symptoms of depression have had mixed results. We examined whether using tDCS to change the balance of activity between left and right dorsolateral prefrontal cortex (DLPFC) can alter mood and memory retrieval of emotional material in healthy volunteers. Participants memorised emotional images, then tDCS was applied bilaterally to DLPFC while they performed a stimulus-response compatibility task. Participants were then presented with a set of images for memory retrieval. Questionnaires to examine mood and motivational state were administered at the beginning and end of each session. Exploratory data analyses showed that the polarity of tDCS to DLPFC influenced performance on a stimulus-response compatibility task and this effect was dependent on participants' prior motivational state. However, tDCS polarity had no effect on the speed or accuracy of memory retrieval of emotional images and did not influence positive or negative affect. These findings suggest that the balance of activity between left and right DLPFC does not play a critical role in the mood state of healthy individuals. We suggest that the efficacy of prefrontal tDCS depends on the initial activation state of neurons and future work should take this into account. © 2014 Morgan et al