Seeding Rate Treatments Research Articles

Effect of sowing dates, mulching and seed rates on nutrient uptake and productivity of soybean in sub - humid Punjab, India

A field experiment was conducted for three years to study the effect of sowing dates, mulching and seed rates on nutrient uptake and productivity of soybean under irrigated conditions in sub-humid Punjab on a silty clay loam soil which was low in available N, medium in available P and available K. The experiment was conducted in a split plot design with the combination of three sowing dates and mulch in main plots and three seed rates in sub-plots with three replications on fixed site. The results revealed that sowing on June 30 and mulching recorded the highest number of pods plant-1.There was no significant influence of seed rates on yield attributes. Seed yield also remained at par under different sowing dates, mulching and seed rate treatments. Stover yield however, was significantly higher under the earlier sowing dates and mulching. Highest total N uptake was observed under June 30 sowing date whereas total P and K uptake was highest in May 20 sowing date. No significant effect of mulching was observed on total N and K uptake. Among seed rates maximum total N uptake was observed under 75 kg seed ha-1. The results suggest that soybean performed better when sown with 60 kg seed rate ha-1 on June 30 and mulched with wheat straw.

Yield and yield components of coriander under different sowing dates and seed rates in tropical environment

Coriander makes use of favorable environmental conditions when it is sown at optimum time and rate. However, this information is very limited in the southeastern mid-highlands of Ethiopia. Field experiments were, therefore, conducted between 2011 and 2014 at three different research stations to determine optimum sowing dates and rates. The experiment had split plot design in randomized complete block with three replications, in which sowing dates and seed rates were the main and sub-plot treatments, respectively. The four sowing date treatments were June 20, July 10, July 30 and August 20 while the four seeding rate treatments were 30, 40, 50 and 60 kg ha -1 . Coriander sowed in the third decade of July at Arsi Robe and from the first to the third decades of July at Kulumsa and Sagure gave the highest fruit and biomass yields. Earlier sowing in the second decade of June, and delayed sowing in the second decade of August brought fruit yield reductions of 37-66 and 37% at Arsi Robe, 27-45 and 58-66% at Kulumsa, and 24-40 and 26% at Sagure, respectively. However, coriander did not respond to seed rates. Owing to the enhanced yields of coriander, intermediate cultivation at a seed rate of 30 kg ha -1 was found optimum.

Grain yield and associated photosynthesis characteristics during dryland winter wheat cultivar replacement since 1940 on the Loess Plateau as affected by seeding rate

An experiment was conducted to verify how the grain yield and associated photosynthesis characteristics of wheat respond to seeding rate with cultivar replacement. Seven wheat cultivars released from 1940 to 2004 that were once widely grown on the Loess Plateau were grown in field experiments during the 2011-2012 growing season at the Changwu experiment station in China using three seeding rates (100, 250, and 350 seeds m-2), using a randomized complete block with a split-plot design and three blocks. The grain yield increased linearly with cultivar development in all seeding rate treatments, with annual genetic gains ranging from 0.65% to 1.29%. The cultivars released after the 1980s were less sensitive to seeding rate and had better population regulation. The improvements in the harvest index and thousand grain weights of the modern cultivars were significantly and positively correlated with the grain yield. The photosynthetic rate of the flag leaf and the leaf area index at anthesis consistently increased with cultivar replacement, contributing more to the thousand-grain weight and resulting in grain yield increases. Diffuse non-interceptance at anthesis resulted in opposite, stable trends with time. One reason to adapt modern cultivars for modern cultivation is their lower sensitivity to seeding rate. Thus, larger sinks for the grains and the optimization of plant types for light interception should be given greater consideration in dryland wheat breeding on the Loess Plateau.

Corn (Zea mays L.) seeding rate optimization in Iowa, USA

Collecting soil, topography, and yield information has become more feasible and reliable with advancements in precision technologies. Combined with the accessibility of precision technologies and services to farmers, there has been increased interest and ability to make site-specific crop management decisions. The objective of this research was to develop procedures to optimize corn seeding rates and maximize yield using soil and topographic parameters. Experimental treatments included five seeding rates (61 750; 74 100; 86 450; 98 800; and 111 150 seeds ha−1) in a randomized complete block design in three central Iowa fields from 2012 to 2014 (nine site-years). Soil samples were analyzed for available phosphorus (Olsen method), exchangeable potassium (ammonium-acetate method), pH, soil organic matter (SOM), cation exchange capacity (CEC), and texture. Topographic data (in-field elevation, slope, aspect, and curvature) were determined from publically available light detection and ranging data. In four site-years, no interaction occurred between seeding rate and the descriptive variables. Three of the site-years resulted in a negative linear seeding rate response which made it impossible to determine an optimum seeding rate above the lowest seeding rate treatment. The seeding rate optimization process in five site-years resulted in seeding rate by variable interactions; four site-years had a single seeding rate by variable interaction (pH, in-field elevation, or curvature) and one site-year had three seeding rate by variable interactions (pH, CEC, and SOM). Meaningful seeding rate optimizations occurred in only three of nine site-years. There was not a consistent descriptive variable interaction with seeding rate as a result of weather variability.

Efficacy of Selected Insecticides Applied to Hybrid Rice Seed.

Hybrid rice and insecticide seed treatments targeting rice water weevil, Lissorhoptrus oryzophilus Kuschel, have altered the landscape of rice production. The effect of reduced seeding rates on seed treatment efficacy in hybrid rice has not been studied. During 2011 and 2012, an experiment was conducted at seven locations to determine the relationship between low seeding rates used in hybrid rice and efficacy of selected insecticidal seed treatments as measured by rice water weevil densities and yield. Labeled rates of thiamethoxam, chlorantraniliprole, and clothianidin were compared with higher rates of these products to determine if labeled rates provide an acceptable level of control of the rice water weevil. Study locations were divided into low, moderate, and high groups based on rice water weevil larval densities. All seed treatments and seed treatment rates reduced rice water weevil densities. However, there was no observed yield or economic benefit from the use of an insecticidal seed treatment in areas of low pressure. Differences in yield were observed among seed treatments and seed treatment rates in moderate and high pressure locations, and all seed treatments yielded better than the untreated plots, but these differences were not always economical. All seed treatments showed an economic advantage in areas of high weevil pressure, and there were no differences among seed treatment products or rates, suggesting that currently labeled seed treatment rates in hybrid rice are effective for rice water weevil management.

Effects of Planter Type and Seeding Rate in No-tillage Systems on Wheat Yield in Pol- e Dokhtar

In the cropping year 2013-2014, a split plot experiment using the randomized complete block design with three replications was conducted in a field in Pol-e Dokhtar in Lorestan Province to study the effects of planter type and seeding rates used in direct and customary planting practices. Results showed there were significant differences between planters with respect to percentage of broken seeds at the 1% level. Comparison of the means indicated the highest percentage of broken seeds (5.1%) belonged to the Barzagar-e Hamadani planter and the lowest to the Gaspardo and Sfoggia direct planters. Type of planter also influenced precision in longitudinal distance at the 5% level. Moreover, comparison of the means revealed that the best uniformity in appropriate longitudinal distance between seeds in planted rows was that of the Gaspardo and Sfoggia direct planters and the worst that of the Barzegar-e Hamadani planter and that the effects of various planters were significant at the 5% level. The Gaspardo and Sfoggia direct planters, with 88.26 and 86.49%, respectively, had the maximum uniformity in depth of planting, and the Barzegar-e Hamadani with 79.03% the minimum. ANOVA suggested the various planters were not significantly different in wheat yield, while the effects of seeding rate treatments on wheat seed yield were significant at the 5% level. Nevertheless, comparison of the means showed that the Gaspardo direct planter raised seed yield by 1.32 and 11.13% compared to the Sfoggia direct planter and the Barzegar-e Hamadani planter, respectively, and that it enjoyed relative superiority over them. Moreover, comparison of the means related to seeding rates indicated the 200 kg/ha rate increased seed yield by 11.05 and 24.36%, respectively, compared to the 160 and 240 kg/ha rates. Results of this research suggested direct planting with the Gaspardo planter at the seeding rate of 200 kg/ha achieved maximum seed yield. Therefore, this combination was recommended for the region.

REMOBILIZATION OF WATER SOLUBLE CARBOHYDRATES IN NON-LEAF ORGANS AND CONTRIBUTION TO GRAIN YIELD IN WINTER WHEAT UNDER REDUCED IRRIGATION

The remobilization of water soluble carbohydrates (WSC) has an important role for grain yield. This study investigated the accumulation and remobilization of WSC in non-leaf organs (chaff, upper stem, and lower stem) and their contribution to grain yield, under different irrigation levels (rainfed, reduced irrigation, and full irrigation) and seeding rate treatments (450, 600 and 750 plants m -2 ) using two winter wheat cultivars, Shijiazhuang 8 (SJZ-8) and Lumai 21 (LM-21), in two field experiments. Results showed that decreasing irrigation and increasing seeding rates increased WSC accumulation and remobilization, remobilization efficiency, and contribution to grain yield in non-leaf organs. When the organs are ranked from highest to lowest in terms of the WSC accumulation amount, remobilization amount, remobilization efficiency, and contribution to grain yield, they are: the lower stem, the upper stem, and then the chaff. And between cultivars, these amounts were higher in SJZ-8 than in LM-21. The total contribution, pre-anthesis contribution, and post-anthesis contribution of WSC remobilization from all non-leaf organs to grain yield ranged from 11.7 to 21.5%, 4.8 to 9.4%, and 6.9 to 12.1%, respectively. This increase in WSC accumulation, remobilization, and contribution to grain yield in non-leaf organs is an important reason high grain yields can be maintained in water-saving and optimal high density management systems.

Effect of seeding rate on growth and nutrient accumulation of Chinese milk vetch

大田试验条件下研究了不同播种量对紫云英(<em>Astragalus sinicus</em> L.)生长及物质养分积累的影响。试验设7 个处理, 播种量为7.5~52.5 kg·hm^-2。试验结果表明, 随播种量增加, 紫云英出苗数显著增加, 单株分枝数、单株复叶数和单株重均呈下降趋势。紫云英鲜草产量随播种量增加而增加, 播种量为7.5~30.0 kg·hm^-2 范围内增产幅度较大, 而播种量>30.0 kg·hm^-2 时, 若继续增加播种量则增产幅度减小。紫云英种子产量随播种量的增加呈先升高后降低的趋势, 播种量为15.0 kg·hm^-2 时种子产量最高。播种量对紫云英养分含量影响较小,但显著影响养分积累量, C、N、P、K、Ca、Mg、Fe、Mn、Cu、Zn 积累量均随播种量增加而增加。紫云英翻压做绿肥的适宜播种量为30.0 kg·hm^-2, 而若以收获种子为目的则播种量以15.0 kg·hm^-2 为宜。

Persistence of Overseeded Cool-Season Grasses in Bermudagrass Turf

Cool-season grass species are commonly overseeded into bermudagrass turf for winter color. When the overseeded grass persists beyond the spring; however, it becomes a weed. The ability of perennial ryegrass, Italian (annual) ryegrass, intermediate ryegrass, and hybrid bluegrass to persist in bermudagrass one year after seeding was determined. Perennial ryegrass, intermediate ryegrass, and Italian ryegrass produced acceptable ground cover in the spring after fall seeding. Hybrid bluegrass did not establish well, resulting in unacceptable cover. Perennial ryegrass generally persisted the most one year after seeding, either because of summer survival of plants or because of new germination the following fall. Plant counts one year after seeding were greater in the higher seeding rate treatment compared to the lower seeding treatment rate of perennial ryegrass, suggesting new germination had occurred. Plant counts one year after seeding plots with intermediate ryegrass or Italian ryegrass were attributed primarily to latent germination and not summer survival. Applications of foramsulfuron generally did not prevent overseeded species stand one year after seeding, supporting the conclusion of new germination. Although quality is less with intermediate ryegrass compared to perennial ryegrass, it transitions out easier than perennial ryegrass, resulting in fewer surviving plants one year later.

Effects of Wyoming Big Sagebrush Seeding Rate and Grass Competition on Long-Term Density and Canopy Volume of Big Sagebrush and Wildlife Habitat

This research was initiated in 1997 to evaluate the effects of seeding rates of grass and Wyoming big sagebrush on the establishment of big sagebrush. The research was accomplished at the Belle Ayr West mine, south of Gillette, WY using a randomized complete block with three big sagebrush seeding rates (1, 2, and 4 kg PLS /ha) and seven grass seeding rates (0, 2, 4, 6, 8, 10, and 14 kg PLS /ha ) experimental design. Field data were collected from 1997-2004 and re- sampled in 2010 to evaluate the long-term effects of these seeding rate treatments on big sagebrush density and plant canopy volume. Wyoming big sagebrush average density decreased by 25-33 % from 2004 to 2010 but the density remained above the 1 plant/m 2 level required by regulatory standards. Wyoming big sagebrush average canopy volume in 2010 (per plant) was 15 times greater than observed in 2004. Shrub density, cover, and height met or exceeded the levels recommended for sage grouse and antelope habitat, two primary users of these lands that are a concern to wildlife management agencies and mine regulatory agencies in WY. General sage grouse requirements are 1.5 plants/m 2 , a shrub height of 18 to 26.6 cm, and shrub cover of 5.5 %. General antelope shrub height requirements are 22 to 46 cm, and cover requirements are 5 to 30 %. This emphasizes the importance of grass and sagebrush seeding rates necessary to achieve these desire goals.

Wildlife Impacts to Big Sagebrush on Reclaimed Mined Lands

Wildlife browsing of Artemisia tridentata ssp. wyomingensis (big sagebrush) on reclaimed coal mined land threatens long-term, sustainable reclamation success. A wildlife-proof exclosure was constructed in 2001 on a 10-year old A. tridentata ssp. wyomingensis reestablishment research site at North Antelope Coal mine in northeastern Wyoming to assess wildlife browsing impacts. Artemisia tridentata ssp. wyomingensis survival, growth, and plant community attributes (species richness, canopy cover, and diversity) were evaluated inside and outside the exclosure, across the original grass seeding rate treatments (0, 16, 32 kg PLS ha−1). Long-term A. tridentata ssp. wyomingensis density decreased across all seeding rates from 1994 to 2002. Higher A. tridentata density, leader (shoot) growth, and canopy cover, along with lower mortality, occurred inside the exclosure across all seeding rates. Lower winter use, higher survival, and lower mortality of A. tridentata ssp. wyomingensis in the 32 compared to the 0 and 16 kg PLS ha−1 seeding rates suggest a beneficial relationship between A. tridentata ssp. wyomingensis survival and higher grass seeding rate. Approximately 33% mortality of marked A. tridentata ssp. wyomingensis plants occurred outside the exclosure. Lepus townsendii campanius (white-tailed jackrabbit), L. californicus melanotis (black-tailed jackrabbit), and Sylvilagus audubonii baileyi (cottontail rabbit) were identified as primary browsers of A. tridentata. Plant species richness, cover, and diversity decreased from 2001 to 2002, probably due to below average precipitation during the study. Defoliation of A. tridentata ssp. wyomingensis was severe, indicating the magnitude of impact from browsing wildlife. Post mining wildlife management and habitat manipulation on adjacent rangeland is suggested to ensure successful reclamation of coal mined lands.

Influence of Seeding Rate and Herbicide Treatments on Weed Control, Yield, and Quality of Spring‐Seeded Glyphosate‐Resistant Alfalfa

Field trials were conducted in 2005 and 2006 in central and southwest Missouri to investigate the effect of seeding rate and herbicide programs on weed control, forage quality, and yield within the year of establishment in spring seeded glyphosate‐resistant (GR) alfalfa (Medicago sativa L.). In all experiments, EPTC (4.4 kg ha−1), 2,4‐DB plus sethoxydim (1.1 plus 0.21 kg ha−1), imazamox (0.043 kg ha−1) and glyphosate (0.86 kg ae ha−1) were applied to GR alfalfa that was seeded at 4.5, 8.9, 13.5, and 18 kg ha−1 Across all locations, the glyphosate application provided good control of weeds regardless of alfalfa seeding rate. When applied at the same timing, imazamox provided similar levels of annual broadleaf weed control as glyphosate, while 2, 4‐DB plus sethoxydim provided similar levels of annual grass and broadleaf weed control as glyphosate. Neither glyphosate nor the conventional herbicide treatments reduced alfalfa stem density between the first and last annual harvests, but 2, 4‐DB plus sethoxydim resulted in the most visual injury to seedling alfalfa stands and lowered initial yields at all locations. In addition, alfalfa annual yields were similar or higher in the glyphosate treatment compared to the other herbicide programs. Harvested forage in the herbicide treatments generally had greater crude protein (CP) content than the untreated control forage. Application of glyphosate resulted in similar or higher forage CP content compared to conventional herbicide treatments. In vitro true digestibility of the harvested GR alfalfa ranged from 750 to 860 g kg−1 DM at all locations with few differences across herbicide treatments.

Optimal seeding rate for organic production of lentil in the northern Great Plains

Organic lentil (Lens culinaris Medik.) producers must rely upon the recommended rate for conventional production of 130 plants m-2, but this seeding rate may not be suitable, as organic and conventional production systems differ in management and inputs. The objective of this study was to determine an optimal seeding rate for organic production of lentil considering a number of factors, including yield, weed suppression, soil nitrogen and phosphorus concentrations, plant uptake of phosphorus, and economic return. A field experiment was conducted for 4 site-years at locations near Saskatoon, SK. Treatments included seeding rates of 15, 38, 94, 235 and 375 seeds m-2. Seed yield increased with increasing seeding rate up to 1290 kg ha-1. Weed biomass was reduced by 59% at the highest seeding rate as compared with the lowest seeding rate. Post-harvest soil phosphorus and nitrogen levels were similar between seeding rate treatments. Economic return was maximized at $952 ha-1 at the highest density of 229 plants m-2, achieved with a seeding rate of 375 seeds m-2. Organic farmers should increase the seeding rate of lentil to achieve a plant density of 229 plants m-2 to increase profitability and provide better weed suppression.Key words: Lentil, organic, seeding rate, weed suppression, economic return

Blue Fescue Overseeding Improves Performance of Fairway Height Buffalograsses

Buffalograss [Buchloe dactyloides (Nutt.) Engelm.] use as a fairway turfgrass is limited in northern portions of its adaptation zone by its extended winter dormancy and tan coloration in early spring and late fall. Cool-season grasses mixed with buffalograss could enhance turfgrass appearance and performance in fall and early spring. Research was conducted near Mead, NE, with eight buffalograss genotypes maintained under fairway conditions to determine the effect of blue fescue (Festuca ovina L. var. glauca Lam.) overseeding rate on turfgrass performance. Interactions were nonsignificant in most cases so main effects are emphasized. Differences were observed between seeding rates and genotypes for most traits studied. Overseeding blue fescue enhanced spring green-up, fall color retention, stand density, and turfgrass quality. These effects were most pronounced in late fall and early spring, when buffalograss plants were entering or exiting winter dormancy. The 5 g·m−2 blue fescue overseeding rate improved all performance traits studied when compared with the nonoverseeded buffalograss control and was not different from the 10 g·m−2 seeding rate treatment. Thus, the 5 g·m−2 blue fescue overseeding rate appeared to be near optimum for overall turfgrass performance, offering reduced seed cost and decreased potential for species interference. The ‘Legacy’ buffalograss and ‘SR-3200’ blue fescue mixture had the best performance of the genotypes studied as a result of their visual compatibility in terms of color similarity.

Optimal seeding rate for organic production of field pea in the northern Great Plains

Seeding rates have not been established for organic production of field pea in the northern Great Plains and producers must rely upon a recommended target stand of 88 plants m-2 for conventional production of this crop. This seeding rate may not be suitable as the two systems differ in the use of inputs and in pest management. The objective of this study was to determine an optimal seeding rate for organic production of field pea considering a number of agronomic factors and profitability. Field sites were established using a randomized complete block design with increasing seeding rates, summerfallow and green manure treatments. Seed yield increased up to 1725 kg ha-1 with increasing seeding rate. Weed biomass decreased with increasing seeding rate by up to 68%. Post-harvest soil phosphorus levels and soil water storage did not change consistently between treatments. Post-harvest soil inorganic nitrogen (N), however, was higher for the summerfallow and green manure treatments than for the seeding rate treatments. Field pea reached a maximum economic return at a seeding rate of 200 seeds m-2 and an actual plant density of 120 plants m-2. Organic farmers should increase the seeding rate of field pea to increase returns and provide better weed suppression. Key words: Pea (field), organic, seeding rate, weed suppression, profit, soil N

Hard Red Spring Wheat Response to Row Spacing, Seeding Rate, and Nitrogen

Row spacing, plant density, and N application timing can be manipulated to optimize plant growth and spatial distribution, therefore maximizing sunlight, nutrients, soil water use efficiency and grain yield. A 2‐yr field study to evaluate the effects of four seeding rates (108, 215, 323, and 430 seeds m−2), two row spacings (15 and 30 cm), and three N treatments (FA1, 100% at seeding; FA2, 50% at seeding and 50% at tiller formation; and FA3, 50% at seeding and 50% at shoot elongation) on grain yield of McNeal hard red spring wheat (Triticum aestivum L.) was conducted in central Montana. Spring wheat accumulated greater biomass at a faster rate under the 15‐cm row spacing than the 30‐cm row spacing. Grain yield was 410 and 412 kg ha−1 greater at 15‐cm than at 30‐cm row spacings in 2004 and 2005, and the yield increase was primarily attributed to 44 and 40 more spikes m−2 at 15‐cm than at 30‐cm row spacing in 2004 and 2005, respectively. Grain yield was not significantly affected by the N treatments, thus all N should be applied at seeding. The optimum seeding rate was 215 seeds m−2. Tillers at higher seeding rates had larger phyllochrons and greater mortalities. Low protein content was found in FA3 and high seeding rate treatments in 2005. Narrow row spacing is recommended for high spring wheat yield in the northern Great Plains. This yield increase cannot be achieved by increasing seeding rate at wide row spacing.

Iron Deficiency Chlorosis in Soybean: Soybean Seeding Rate and Companion Crop Effects

Iron deficiency chlorosis (IDC) is an important production problem in soybean [Glycine max (L.) Merr.] grown in the upper Midwest. Although IDC‐tolerant varieties are available to producers, even tolerant cultivars suffer from IDC‐related stresses. Several cultural methods have been utilized in an attempt to reduce IDC losses. Interplant competition from increased soybean seeding rates or companion crops appears to reduce IDC symptoms. Two related studies were established to examine increased seeding rates and the planting of companion crops to reduce IDC of soybean in eight IDC‐prone environments. In one study, soybean was planted at five seeding rates from 432 000 to 926 000 seeds ha−1. In a second study, a glyphosate‐resistant soybean variety was planted as a sole crop or with companion crops of glyphosate‐susceptible soybean or oat (Avena sativa L.). Seeding rate treatments affected IDC scores and yield, but these effects were confounded by environmental interactions. Overall, yield increases from higher seeding rates tended to be small and inconsistent, but among seven environments exhibiting mild to moderate IDC symptoms, increasing seeding rates from 432 000 to 926 000 seeds ha−1 increased yields by 281 kg ha−1 (16%). Blending of a glyphosate‐susceptible with a glyphosate‐resistant variety seemed to have little positive effect on yield of soybean (yield gains varied from −333 to + 566 kg ha−1). Likewise, using oat interseeded with soybean to reduce IDC symptoms and increase soybean yields is unlikely to be a profitable practice for soybean producers.

Effect of Seeding Rate and Seed Treatment Fungicides on Agronomic Performance, Fusarium Head Blight Symptoms, and DON Accumulation in Two Winter Wheats.

Fusarium head blight (FHB), caused by Fusarium graminearum, is an important disease of wheat (Triticum aestivum). FHB reduces yield and quality, and the pathogen produces several toxins in the grain, the most important being deoxynivalenol (DON). In North America, the foliar fungicide tebuconazole is used to reduce FHB symptoms and DON accumulation. Because of the narrow window required for its application, uniform flowering of wheat is important. The objective of this study was to investigate the influence of variety, seeding rate, and seed treatment fungicides on the flowering period of winter wheat and their effect on FHB symptoms and DON accumulation. The seed of two winter wheat varieties (Pioneer 25W60 and Pioneer 25R57) was treated with Dividend XL (difeconazole+metalaxyl), Vitaflo 280 (thiram+carbathiin), Raxil (tebuconazole), and Baytan 30 (triadimenol) and planted at 320, 480, and 640 seeds per m2 for each treatment at Ridgetown, ON, Canada in 2000 and 2001. The plots were sprayed with tebuconazole at 50% anthesis and inoculated with F. graminearum 3 days later. Increased seeding rate increased the number of emerged plants, tillers, spikes per m2, and yield. All seed treatments, compared to nontreated controls, increased plant emergence and number of spikes per m2, and all except tebuconazole increased tillering and yield. Increased seeding rate decreased the length of flowering period. As flowering period increased, FHB index and DON level decreased, suggesting that greater infection was linked to more uniform flowering.

No‐Tillage Corn and Grain Sorghum Response to Cover Crop and Nitrogen Fertilization

No‐tillage cropping systems may benefit from the addition of winter annual cover crops through decreased soil erosion, accumulation of biologically fixed N, or increased crop yield. The objectives of this research were to assess the amount of cover provided by winter annual legumes and oat (Avena sativa L.) to quantify the fertilizer N equivalent value of each cover crop system and the effect of cover crop and N rate on corn (Zea mays L.) and grain sorghum [Sorghum bicolor (L.) Moench] grain yield. Two experiments, one in corn and one in sorghum, were conducted in 1997, 1998, and 1999. In each experiment, the main‐plot effect was cover crop treatment while the subplot effect was spring N rates of 0, 56, 112, and 168 kg ha−1. The addition of oat to the legume cover crop treatments increased fall ground cover but decreased total spring dry matter yield. Maximum spring dry matter yield was greatest in the hairy vetch (Vicia villosa Roth)‐alone treatment. Hairy vetch alone also produced the greatest mean fertilizer N equivalent value in the corn and sorghum experiments, 43.6 and 56.9 kg N ha−1, respectfully. These values, however, were variable among years. Corn and sorghum grain yield were greatest in the Austrian winter pea (Pisum sativum L.) and hairy vetch full seeding rate treatments, 5.19 and 7.06 Mg ha−1, respectfully. Our results indicate that winter annual cover crops provide several distinct benefits to no‐tillage corn and sorghum production systems and that cover crops should be selected based on specific grower needs.

Influence of Fall-applied Treatments on Spring Transition of an Overseeded Bermudagrass Green

Bermudagrass [Cynodon dactylon (L.) Pers × C. transvaalensis Burtt-Davy] greens across the southern United States are normally overseeded in the fall to provide a uniform green playing surface and tolerance to wear during winter bermudagrass dormancy. The spring transition from overseed grass back to bermudagrass is a major problem associated with overseeding because there can be a decline in putting green quality and playability. There have been recommendations, but relatively few published reports, on the effect of treatments associated with seedbed preparation and overseeding on bermudagrass spring transition. The objective of this 2-year study was to determine if spring transition of an overseeded `Tifgreen' bermudagrass green was influenced by fall-applied scalping level, chemical, and seed rate treatments. Treatment factors and levels were designed to reflect the range of practices used by golf course superintendents in the region at the time of the study. The green was located in the Palm Springs, Calif. area, which has relatively mild winters and a low desert, southern Calif. climate. The first year of the study was from September 1996 to July 1997 and the second year was from September1997 to July 1998. Scalping level treatments included a moderate and severe verticut and scalp; chemical treatments included a check, trinexapac-ethyl at two rates, and diquat; and seed rate treatments included a high and low rate of a mixture of `Seville' perennial ryegrass (Lolium perenne L.) and `Sabre' rough bluegrass (Poa trivialis L.). The plot was maintained under golf course conditions and a traffic simulator was used to simulate golfer traffic. Visual ratings of percent green bermudagrass coverage were taken every 3 weeks from 20 Feb. 1997 to 29 July 1997 and from 11 Nov. 1997 to 22 July 1998. Visual turfgrass quality ratings were taken during the second year of the study. Results showed that spring transition was not influenced by fall-applied treatments during both years. Also, visual turfgrass quality was not influenced during the second year. Chemical names used [4(cyclopropyl-_hydroxy-methylene)-3,5-dioxocyclohexanecarboxylic acid ethyl ester (trinexapac-ethyl); 9,10-dihydro-8a-, 10a-diazoniaphenanthrene (diquat).