Seeding Rate Recommendations Research Articles

Seeding rate effect on winter malting barley yield and quality

AbstractGrowth in the craft brewing industry has increased the demand for locally sourced malting barley (Hordeum vulgare L.) grain in the Eastern United States. However, most malting barley seeding rate recommendations are from the Northern Great Plains, the Pacific Northwest, and Western Canada. Therefore, seeding rate research was needed in the humid growing environment of the Eastern United States. The objective of this research was to identify the agronomic optimum seeding rate (AOSR) where grain yield is maximized, and identify the seeding rate that met or exceeded grain quality parameters. An experiment with five seeding rate treatments ranging from 1.9 to 6.2 million seeds ha–1 was established at eight site‐years in Ohio. Under normal growing conditions, the AOSR was 3.8–6.2 million seeds ha–1 (average 4.5 million seeds ha–1). When plants experienced winter injury, the AOSR was greater at 5.3–5.4 million seeds ha–1. Grain quality parameters of protein, germination, and deoxynivalenol all tended to improve with increasing seeding rate. Seeding rates of 4.5–4.7 million seeds ha–1 should maximize yield most years while meeting grain quality parameters. However, regions that experience winter temperatures <15°C without snow coverage should increase seeding rates due to increased chance of winter injury reducing plant stand.

Winter Pea, Crimson Clover, and Hairy Vetch Planted in Mixture with Small Grains in the Southeast United States

Core IdeasLegume and small grain cover crops are combined in mixture to provide N fertility and weed suppression for the following cash crop.In environments where winter pea growth is not restricted by cold, winter pea can produce as much biomass in mixture with small grains as crimson clover and hairy vetch.Hairy vetch was the most competitive legume with the small grains across environments and restricted small grain biomass production.The variability in total biomass composition across environments in this study demonstrates the importance of site specific cover crop species selection and mixture seeding rate recommendations.Legume and small grain cover crop mixtures may simultaneously fix N and suppress weeds. Studies were conducted from 2015 to 2017 in Maryland and North Carolina to compare winter pea (Pisum sativumL.) to crimson clover (Trifolium incarnatum) and hairy vetch (Vicia villosaRoth) for cover crop use in mixture with small grains. Five winter pea genotypes, one crimson clover cultivar, and one hairy vetch cultivar were screened in mixture with barley (Hordeum vulgare), oats (Avena sativa), and wheat (Triticum aestivum). Cold injury of the pea genotypes in Maryland severely impacted pea biomass. Peas were able to recover from cold injury in North Carolina. A robustly growing small grain aided in legume cold tolerance in some environments. In the Coastal Plain environments, all legume genotypes generally contributed to at least 50% of mixture biomass production. In the Maryland and Piedmont environments, the small grain dominated the cover crop mixture. Oats were generally more competitive with the legume species than barley or wheat. In the North Carolina Coastal Plain and Piedmont, several winter pea genotypes produced as much biomass in mixture as crimson clover and hairy vetch. Hairy vetch was the most competitive legume with the small grains across environments. The variability in total biomass composition across environments in this study demonstrates the importance of site specific cover crop species selection and mixture seeding rate recommendations.

Dormant‐Season Planting and Seed‐Dormancy Impacts on Switchgrass Establishment and Yield

ABSTRACTEstablishment failures linked to seed dormancy are a challenge to wide‐scale use of switchgrass (Panicum virgatum L.) for biomass feedstock and forage production. One prospective strategy for breaking dormancy is dormant‐season planting. The objectives of this study were to evaluate (i) three switchgrass dormant‐season planting dates (1 December, 1 February, and 15 March) vs. a growing‐season (1 May) control; (ii) two seeding rates (6.7 and 10.1 kg pure live seed [PLS] ha−1); and (iii) high‐ and low‐dormancy seed lots. Treatments were assigned in a split‐plot design with three replications at two locations in Tennessee in 2008 and 2009. Neither seeding rate nor seed‐dormancy level affected plant density or yield (P > 0.05). However, a seeding date × year interaction impacted first‐year density at both locations. Although patterns differed by year for the two locations, density of March plantings equaled or exceeded (P < 0.05) those at other dates for both locations and years. These variations in density did not carry over to impact yield in year two. A sigmoidal regression of seedling density vs. yield was significant (P < 0.001) albeit not strong (R2 = 0.13); yield response approached an asymptote above ∼8 plants m−2. Results suggest March planting dates, using standard seeding rate recommendations (6.7 kg PLS ha−1) irrespective of seed‐dormancy rates, may be more reliable than planting in May. Thus, a broader establishment window than traditionally used may be practical. However, results should be validated over a broader range of soils and climatic conditions, especially over a winter severity gradient.

Soybean Seed Quality: An Empirical Analysis on Clayey Soils in Arkansas

Soybean [Glycine max (L.) Merr.] seed quality is an important factor for seeding rate recommendations. Which seed quality measure to use for seeding rate recommendations and how seed treatment and planting date affect returns are assessed within. Results suggest that adding seed vigor information to seed labels would be beneficial in providing seeding rate recommendations. Seed treatment is profitable and more so at lower seeding rates. Seed survival impacts yields, but seed quality effects do not affect yield potential post–plant establishment. Planting season is an important determinant of seed survival and yield potential.

Agronomic Optimum Seeding Rate for Irrigated Maize in Texas is Concomitant to Growing Season Mean Daily Minimum Temperature

Our study was conducted to determine agronomic optimum seeding rates (AOSR) for irrigated maize under a range of agroecological conditions in Texas. Environmental factors that affect irrigated maize production vary considerably across Texas. This variability imposes region-specific limitations on statewide maize seeding rate recommendations. Our research examined the efficiency of varying seeding rates on irrigated maize grain yields in five USEPA Level IV Ecoregions that comprise most of the irrigated maize-producing area of Texas. The selected sites span a distance of 1200 km from south to north Texas and elevations from 20 to 1218 m above mean sea level. We conducted the study over three growing seasons from 2005 through 2007 in two Level IV Ecoregions of the High Plains of North Texas (N), one in the East Central Plains (E), one in the Southern Plains and one in Western Gulf Coastal Plains of South Texas (S). We observed that maximum grain yields and AOSR to achieve maximum maize grain yields vary considerably among ecoregions. In South Texas, we observed grain yield response rates of 125–129, 151 kg 1000 seeds−1 in E and 163–199 kg 1000 seeds−1 in N. We show that growing season average daily minimum air temperature (TMIN) explains most of this variation (r2 = 0.98, P-value < 0.01) and conclude that seeding rate efficiency is concomitant to TMIN. Maximum grain yields (GYMAX) determined with seeding rate response analysis also varied among ecoregions and with TMIN from south to north Texas, from a low of 8.3 Mg ha−1 in S to a high of 18.4 Mg ha−1 in N (r2 = 0.59, P-value < 0.01). We conclude that development of agronomic management models by Level IV Ecoregions of Texas combined with site-specific TMIN climatological data serve as a valid template for delivering robust and agroecozone-specific irrigated maize seeding rate recommendations in Texas.

INVESTIGATING COMPONENT SPECIES PROPORTIONS IN A CEREAL-LEGUME COVER CROP MIXTURE UNDER ORGANIC MANAGEMENT

ISHS XXVIII International Horticultural Congress on Science and Horticulture for People (IHC2010): International Symposium on Organic Horticulture: Productivity and Sustainability INVESTIGATING COMPONENT SPECIES PROPORTIONS IN A CEREAL-LEGUME COVER CROP MIXTURE UNDER ORGANIC MANAGEMENT

Effect of Row Spacing and Seeding Rate on Soybean Yield

Soybean [Glycine max (L.) Merr.] yield response to narrow row spacing has been consistently positive in the upper Midwest and new split‐row planters have made narrow row soybean production feasible, yet adoption has been slow in Iowa. Wide (76‐cm) and narrow (38‐cm) row spacing and four seeding rates (185,000; 309,000; 432 000; and 556,000 seeds ha−1) were evaluated at three locations during 2004, 2005, and 2006 to determine seed yield in wide and narrow row spacing and four seeding rates and evaluate economic advantages associated with changes in row spacing. Soybean planted in 38‐cm row spacing yielded 248 kg ha−1 greater than soybean planted in 76‐cm rows after adjustment for differences in final plant populations. Maximum yield at all locations was attained at a final harvest population of 462,200 plants ha−1 but &gt;95% of the maximum yield was achieved with final populations as low as 258 600 plants ha−1. Increased production costs associated with greater seeding rates removed the yield benefit from greater harvest plant populations. Farm size of 144 ha with at least 50% of the land base dedicated to soybean production would benefit from conversion from wide to narrow rows. To break even on the investment in a split‐row planter a yield increase of 124 kg ha−1 was necessary for farms with 30% of 288 ha dedicated to soybean production. These data indicate that yield and economic benefits are sufficient to support the production of soybean in narrow rows and at seeding rates below current seeding rate recommendations.

Soybean Yield and Yield Component Response to Plant Density in Narrow Row Systems

Soybean (Glycine max) yield is responsive to changes in plant population and row spacing under dryland conditions. Soybean seeding rate recommendations in many states were developed prior to the release of herbicide tolerant varieties when soybean seed costs were lower. As a result, many recommendations are high, and soybean performance at low plant densities in narrow rows needs to be reevaluated. This study was conducted to evaluate soybean yield response to plant density in narrow row, drilled systems (7.5 and 15 in) and evaluate the effects of plant population on yield components. The study was conducted in six environments with optimum plant populations ranging from 80 000 to 140 000 plants acre. The two yield components responsible for the yield optimization were pods plant and pods acre. As plant population increased, pods plant decreased steadily; however, yield was not reduced either year of the study by the loss of pods plant because pods acre increased as plant population increased. The optimum seeding rates for each year of the study were below the 150 000 to 160 000 plants acre seeding rate normally recommended in the region. The decreased optimum plant populations in both years did not adversely affect yield and might be useful in reducing input costs in dryland soybean production.

Optimizing Seeding Rates for Winter Cereal Grains and Frost‐Seeded Red Clover Intercrops

Growing winter cereal grain/forage legume intercrops can provide multiple benefits to cropping systems in the North Central USA. Intercropping red clover (Trifolium pratense L.) with winter cereal grains can provide forage and a green manure crop. Seeding rate recommendations for sole crops may not optimize intercrop system productivity if interactions exist. This study was conducted during the 2002–2003 and 2003–2004 growing seasons to determine optimum cereal grain and red clover forage seeding rates for maximum returns using partial budget analyses. In March, red clover was frost‐seeded at 0, 300, 600, 900, 1200, and 1500 seeds m−2 into winter wheat (Triticum aestivum L.) and triticale (X Triticosecale Wittmack) seeded at 100, 200, 300, and 400 seeds m−2 the previous October. Triticale and wheat maximized returns at seeding rates of 300 and 400 seeds m−2. No cereal grain by red clover seeding rate interactions were detected for red clover dry matter production (DM). Red clover plant densities after cereal grain harvest were 10 to 22% of the original seeding rates. Red clover DM production and return was maximized at 3.49 Mg ha−1 with 900 seeds m−2 in 2003 and 6.67 Mg ha−1 with 1200 seeds m−2 in 2004. Winter cereal/red clover intercrops in the North Central USA can maximize return using a cereal grain seeding rate between 300 and 400 seeds m−2 and red clover seeding rates between 900 and 1200 seeds m−2

Profit-maximizing seeding rates and replanting thresholds for soybean: Maturity group interactions in the Mid-South

Considerable interest in adopting earlier-maturing soybean [ Glycine max (L.) Merr.] cultivars exists among producers in the Mid-Southern United States, as the potential for irrigation water savings and improved labor and equipment scheduling are attractive. Previous reports suggested that maturity group (MG) selection should depend primarily upon yield and not irrigation requirements, as irrigation savings generally did not offset lower yield of earlier MG. This research, however, did not account for differences in seeding rate recommendations. This report considered results from a conventional soybean (MG 00 to MG VI) population density trial (seeded at 10–100 seeds m −2) conducted at Fayetteville, AR for 3 years. The analysis revealed that planting soybean at the economically optimal seeding rate can lead to substantially different investment in seed (an average of $97 ha −1 for MG 00 vs. $27 ha −1 for MG VI). The results also indicated that later-maturing soybean exhibited greater flexibility in environments with plant establishment uncertainty, as the yield response to plant population density was less pronounced and investment in seed was lower compared to earlier-maturing cultivars. Later-maturing varieties did exhibit larger changes in optimal seeding rates over time than earlier-maturing varieties, however. Based on our results, a producer would be advised to examine yield potential of different MG soybean and to consider planting a range of cultivars within MG II–VI. Finally, while the numeric results of this research were location and cost specific, the analyses provided guiding principles for other regions with similar characteristics for crop establishment and replanting thresholds.

Economic Evaluation of Soybean Fungicide Seed Treatments

The effects of fungicide seed treatments on seeding rate, location, simulated rainfall at emergence, time of planting, and seed quality were analyzed for soybean [Glycine max (L.) Merr.] in this study. Variation in plant emergence allowed estimation of economically optimal seeding rates and partial returns (PR = Gross revenue − Seed cost) across seed treatment options. Study results proved a single seed treatment to be superior across most study conditions. In fact, a comparison of optimally treated to untreated seed revealed that a seemingly insignificant input in terms of cost (&lt;$8.65 ha−1) enhanced profitability by an average of $43.71 ha−1 in this study. Using high rather than low quality treated seed increased producer returns by an average of $64.27 ha−1. Seeding rate recommendations need to be viewed with the precaution that added seed may be low cost insurance against lesser‐than‐expected survival rates. For the cultivar Hutcheson (MG V), planting in May compared with April and June provided better yields using less seed on average. Finally, as the planting season progressed, replanting plant population density thresholds decreased.

Influence of Seeding Variables on ‘Tifton 9’ Bahiagrass Establishment

Abstract‘Tifton 9’ possesses attributes similar to ‘Pensacola’ bahiagrass (Paspalum notatum Flügge var. saurae Parodi) including persistence, wide adaptation, and positive rotation effects for subsequent crops. Seed dormancy has been implicated as a cause of slow establishment of bahiagrass. Our objective was to evaluate dormancy‐reducing seed treatments on multiple seed lots with a range of seeding rates during spring, summer, or fall planting. Tifton 9 seed lots with high or low dormant seed fractions were planted without treatment, after solid matrix priming (SMP), or after accelerated aging (AA) at elevated temperature and humidity. Seed was planted during 2 yr at Tifton, GA (31°26' N, 83°35' W), or Immokalee, FL (26°27' N, 81°26' W), using seeding rates of 5.6, 16.8, or 50.4 kg ha−1. Tiller counts at 1 and 2 mo following planting, stand occupation the year following planting and dry matter harvested were obtained to monitor establishment. Seed lot had no influence on any variable evaluated. Initial stands were improved by SMP, indicating enhanced early emergence; however, SMP did not increase second‐year stands and forage yield compared with other seed treatments. Accelerated aging provided no advantage. Increasing the seeding rate resulted in greater emergence and second‐year stand coverage, but yield advantages were small. Response to planting season varied with year and location. A November freeze damaged October‐planted stands at Tifton in 1993. Stand establishment was hastened with a high seeding rate, but any advantage of high seeding rates was short lived. Seed treatments examined in this research provided little benefit, and it may be possible to reduce standard seeding rate recommendations without impairing long term establishment.

Plant Population Effects on Corn Hybrids Differing in Ear Growth Habit and Prolificacy

Terminology characterizing differences in ear growth habit and prolificacy is commonly used by seed companies to relate corn (Zea mays L.) hybrid yield potential to varying plant populations. Little information is available to document the significance of various ear response types associated with commercially available Corn Belt hybrids. The objective of this study was to assess hybrid x plant population interactions of commercial corn hybrids differing in ear growth habit and prolificacy. Field experiments were conducted in 11 environments in Ohio during 1990 and 1991. Four hybrids (LH119 x LH51, B73 x LH38, LH132 x DM2, and LH123 x LH93) chosen to represent different responses to plant population associated with ear type were compared at three plant populations (16 000, 24 000, and 32 000 plants/acre). Grain yields, ears per plant, and stalk lodging varied with hybrid and plant population in both years. The semiprolific hybrid and the fixed and flex single ear hybrids exhibited similar yield response to plant population across a wide range of environmental conditions. In 1990, grain yields were greatest for the flex (LH51 x LH119) and fixed (B73 x LH38) single ear hybrids and semiprolific (LH123 x LH93) hybrid at 32 000 plants/acre and the prolific (LH132 x DM2) hybrid at 24 000 plants/acre; whereas in 1991, under drier, hotter conditions, yields for all four hybrids were greatest at 24 000 plants/acre. Prolificacy was most pronounced in LH132 x DM2 and at the low plant population; it was least evident in LH119 x LH51 and at the high plant population. Stalk lodging was greatest in the prolific and semiprolific hybrids and at the high plant population; it was negligible in the fixed single ear hybrid and at the low plant population. Although the prolific hybrid exhibited relatively high yields under stress in 1991, its greater predisposition to lodging limits its potential use in Eastern Corn Belt environments where diseases and weather conditions make stalk quality a major factor in hybrid selection. The relatively minor role that hybrid x population interactions played in determining grain yield compared with environment, hybrid, and plant population main effects suggests that hybrid differences in ear growth habit and prolificacy are of limited importance in determining optimum plant populations.

Variations in the Number of Seeds per Unit Weight Among Turfgrass Cultivars1

AbstractKentucky bluegrass (Poa pratensis L.) and the fine fescues (Festuca rubra L., Festuca rubra var. commutata Gaud. and Festuca ovina var. duriuscula L. Koch) are widely used turfgrasses in temperate regions. Seeding rate recommendations for these species are dependent on seed number per unit weight and are based on counts available in the literature. In recent years, however, breeding and selection have produced cultivars of these species with visible differences in seed size, yet variations in seed numbers have not been documented. This study was conducted to determine seed count variations among several cultivars of Kentucky bluegrass, fine fescue, and among individual lots of Kentucky bluegrass cultivars. Counts for the fine fescues were estimated by calculations made from the weight of 100 seeds. Kentucky bluegrass seed numbers were estimated by the above method and by an electric seed counter.Differences in seed count existed among cultivars of both turfgrasses. Fine fescue cultivars varied from 1,272 seeds/g to 618 seeds/g with a mean for all cultivars of 1,020 seeds/g. Kentucky bluegrass cultivars varied from 4,413 seedsjg to 1,847 seeds/g with a mean of 2,744 seeds/g. Significant differences in seed count were also found to exist among lots of individual Kentucky bluegrass cultivars. Differences among lots as large as 805 seeds/g for ‘Merion’ and 373 seeds/g for ‘Pennstar’ were recorded.Six Kentucky bluegrass cultivars with widely varying seed counts were established on a seed count (308 live seed/dm2) and on a weight basis (0.75 kg/are). This part of the investigation was conducted on a Typic Argiaquolls, Fine‐Loamy, mixed mesic soil at the Ohio State Univ. turf plots in Columbus, Ohio.Initially, cultivars with higher seed counts were established more rapidly than were cultivars with fewer seeds/g, when seeded at the 0.75 kg/are rate. After 6 growing months, no differences in percent cover between either seeding rate or cultivars existed. After 1 year, sod strength determinations were essentially the same among all treatments. If the goal of seeding is rapid establishment, there may be an advantage to seeding Kentucky bluegrass cultivars with fewer seeds/g (larger seeds) at a higher weight/unit area than cultivars with greater seed counts.