Seeding Rate and Genotype Effect on Agronomic Performance and End-Use Quality of Winter Wheat

Abstract

Few experiments have studied how seeding rates affect agronomic performance and end-use quality of modern wheat (Triticum aestivum L.) genotypes in the Great Plains. Higher grain yield and better quality grain production requires the use of appropriate seeding rates. During the 1997 and 1998 crop seasons, 20 winter wheat genotypes and experimental lines were evaluated at two locations (four environments) to assess seeding rate and genotype effects on agronomic performance and end-use quality of wheat. Significant differences among environments, seeding rates, and genotypes, and some of their interactions were identified. Lower seeding rates decreased plant population (by 62.3%), grain yield (by 0.8 Mg ha-1), kernel weight (by 1.3 mg kernel-1), flour yield (by 0.8 g/100 g grain), mixing time (by 0.7 min), caused later flowering (by 2 d), and increased flour protein content (by 15 mg g-1) and mixing tolerance (1 unit). Environment X genotype interactions were significant for all the traits except plant population and mixing tolerance. On the basis of the four environments, the seeding rate X genotype interactions were nonsignificant for all traits except plant height. These results provide evidence that agronomic performance and end-use quality traits are greatly influenced by the environmental conditions and less so by seeding rates. Seeding rate affected plant population, days to flowering, plant height, grain yield, kernel weight, flour yield, flour protein, and mixing time and tolerance of wheat; therefore, seeding rate should be considered as a factor in obtaining higher grain yields with good end-use quality.

Full text

Seeding Rate and Genotype Effect on Agronomic Performance and End-Use Quality
of Winter Wheat
B. Geleta, M. Atak, P. S. Baenziger,* L. A. Nelson, D. D. Baltenesperger, K. M. Eskridge, M. J. Shipman,
and D. R. Shelton
ABSTRACT Scheromm et al., 1992; Blue et al., 1990; Johnson et
al., 1988).
Few experiments have studied how seeding rates affect agronomic Seeding rate has long been studied as an integral part
performance and end-use quality of modern wheat (Triticum aestivum of wheat production and productivity. Optimal seeding
L.) genotypes in the Great Plains. Higher grain yield and better quality rate has been shown to be higher in high rainfall and
grain production requires the use of appropriate seeding rates. During irrigated environments (Quisenberry, 1928). Kiessel-
the 1997 and 1998 crop seasons, 20 winter wheat genotypes and experi- bach and Sprague (1926) reported a linear increase in
mental lines were evaluated at two locations (four environments) to
grain yield as seeding rate increased from 34 to 101 kg
assess seeding rate and genotype effects on agronomic performance
and end-use quality of wheat. Significant differences among environ- ha
⫺
1
and concluded that a rate of 84 to 101 kg ha
⫺
1
ments, seeding rates, and genotypes, and some of their interactions was most practical for eastern Nebraska. Johnson et al.
were identified. Lower seeding rates decreased plant population (by (1965) reported that thinly seeded plots (10, 20, and 40
62.3%), grain yield (by 0.8 Mg ha
⫺
1
), kernel weight (by 1.3 mg ker- kg ha
⫺
1
), when compared with 81 kg ha
⫺
1
at 30-cm-row
nel
⫺
1
), flour yield (by 0.8 g/100 g grain), mixing time (by 0.7 min), spacing, led to later maturity and more winter killing
caused later flowering (by 2 d), and increased flour protein content in NE. Johnson et al. (1966) with a similar trial grown
(by 15 mg g
⫺
1
) and mixing tolerance (1 unit). Environment ⫻genotype under drought conditions at North Platte found a
interactions were significant for all the traits except plant population genotype ⫻seeding rate interaction and the 40 kg ha
⫺
1
and mixing tolerance. On the basis of the four environments, the seeding rate producing the highest yields. Stoltenberg
seeding rate ⫻genotype interactions were nonsignificant for all traits (1968), in a 2-yr study using genotypes grown in 30-cm
except plant height. These results provide evidence that agronomic rows, recommended seeding rates of 17 to 22 kg ha
⫺
1
performance and end-use quality traits are greatly influenced by the for winter wheat in western NE, 34 to 39 kg ha
⫺
1
rates
environmental conditions and less so by seeding rates. Seeding rate in central NE, and no less than 67 kg ha
⫺
1
for eastern
affected plant population, days to flowering, plant height, grain yield,
NE. Koycu (1968) at Lincoln, NE, reported that 60 kg
kernel weight, flour yield, flour protein, and mixing time and tolerance
of wheat; therefore, seeding rate should be considered as a factor in ha
⫺
1
produced approximately 600 kg ha
⫺
1
more grain
obtaining higher grain yields with good end-use quality. than did 30 kg ha
⫺
1
. Blue et al. (1990), in a 3-yr study
on the influence of planting date, seeding rate, and phos-
phorus rate on ‘Brule’ wheat in southeastern NE, found
that an increase in the seeding rate from 34 to 101 kg
Wheat is grown in a wide range of environments ha
⫺
1
increased grain yield by 350 kg ha
⫺
1
. The results
that affect overall performance, particularly grain obtained in NE were similar to those found by Wilson
yield and end-use quality. Wheat yield and end-use qual- and Swanson (1962) and Stickler et al. (1964) at Hays
ity depend upon the environment, genotype, and their and Manhattan, KS.
interaction (Peterson et al., 1998; Eskridge et al., 1994; Although the effect of seeding rate on agronomic
Baenziger et al., 1985). Environmental factors that may performance of genotypes has been studied since 1926,
limit productivity and quality of wheat include climatic little has been published on the effect of seeding rate
factors over which producers have little control (such on end-use quality. The effect of seeding rate on the
as precipitation, temperature, day length), soil types, overall performance of recently released, high-yielding
and management practices (such as fertilizer, herbicides, genotypes is also unknown. Thus, it is important to
fungicides, irrigation, time of sowing, and seeding rate) evaluate the effect of seeding rate on agronomic perfor-
some of which may partially mitigate other environmen- mance and end-use quality of modern genotypes.
tal factors. The objectives of this study were to evaluate the influ-
Management practices play an important role in de- ence of seeding rate on agronomic performance of mod-
termining the yield and end-use quality of wheat. Nu- ern hard red winter wheat genotypes and to investigate
merous studies have documented how N fertilization, the effect of seeding rates on milling and baking proper-
seeding rate, planting date, row spacing, and seeding ties of hard red winter wheat genotypes grown in differ-
depth affect yield and yield components of wheat (e.g., ent environments.
B. Geleta, M. Atak, P.S. Baenziger, and L.A. Nelson, Dep. of Agron- MATERIALS AND METHODS
omy, Univ. of Nebraska, Lincoln, NE 68583; D. Baltenesperger, Dep. Genotypes and Experimental Sites
of Agronomy, Univ. of Nebraska, Panhandle Research and Extension
Center, Scottsbluff, NE 69361; K. Eskridge, Dep. of Biometry, Univ. Fourteen commonly grown winter wheat genotypes from
of Nebraska, Lincoln, NE 68583. Nebraska Agric. Res. Division, J. NE and six advanced lines with diverse genetic backgrounds
Series No. 13200. Received 17 Jan. 2001. *Corresponding author (Table 1) were grown at Lincoln and Mead, NE, in 1997 and
(pbaenziger1@unl.edu). 1998. Though some of the genotypes were originally released
three to seven decades ago, they have been used again in
Published in Crop Sci. 42:827–832 (2002).
827

828 CROP SCIENCE, VOL. 42, MAY–JUNE 2002
Table 1. Pedigree, origin and year of release of the genotypes
row). In 1998, the winter was mild and winter killing of the
used in the experiment.
plant population could not be detected visually. Days to flow-
ering, defined as 50% of the spikes in a plot having extruded
Genotype or
anthers, was measured as the number of days after 30 April.
Experimental Year of
line Pedigree Origin Release
Plant height (cm) was measured from the soil surface to the
top of the spike (awns excluded) of three random plants sam-
1. Arapahoe Brule/3/Parker*4/Agent//Belot.198/ NE 1988
pled from the middle rows of each plot. Grain yield was mea-
3/Lancer
2. Niobrara Tam 105*4/Amigo//Brule NE 1994
sured by harvesting the middle two rows of each plot in 1997
3. Pronghorn Centura/Dawn//Colt sib. NE 1996
and all four rows in 1998. Kernel weight (mg kernel
⫺
1
) was
4. Windstar TX79A2729//Caldwell/Brule field NE 1996
calculated for each genotype by counting and weighing 500
sel. #6/3/Siouxland
kernels per plot. Grain volume weight (kg hL
⫺
1
) was measured
5. NE91631 NE82761/Brule sel. NE –
6. NE92628 MV11-85/Redland NE –
in a 200-mL sample.
7. NE92646 NE82413/Colt NE –
To estimate end-use quality, a 35-g sample of grain was
8. NI92662 Redland/NE82419 NE –
taken from each plot and tempered to a moisture basis of
9. Alliance Arkan/Colt//Chisholm Sib NE 1993
152gH
2
Okg
⫺
1
grain for 18 to 20 h prior to milling. The sample
10. Vista NE68513/NE68457//Centurk/3/Brule NE 1992
11. Redland NE851182: Brule sel NE 1985
was then milled in a Quadrumat Jr. mill (C.W. Branbender
12. Tam 107 TAM 105*4/Amigo TX 1984
Instruments Inc., South Hackensack, NJ). Flour was separated
13. Nekota Bennett/TAM 107 NE 1994
from bran with a standard shaker (Strand Shaker Co., Minne-
14. Karl 92 Selection from Karl KS 1992
apolis, MN) at 225 rpm for 90 s with a U.S.A. standard testing
15. Scout 66 Selection from Scout NE 1966
16. Centura Warrior*5/Agent//NE 68457/3/ NE 1983
sieve No. 70 and the flour was weighed. Flour yield was ex-
Centurk78
pressed as grams of flour per 100 g of grain. Flour protein
17. Cheyenne Sel. From Turkey Red NE 1933
content, expressed as milligram protein per gram flour at a
18. Buckskin Scout/4/Quivira/2/Tenmarq/3/ NE 1973
Marquillo/Oro
140gH
2
Okg
⫺
1
flour moisture basis, was determined by the
19. NE93405 NE85707/Thunderbird NE –
Udy dye binding (Udy dye Method 46-14A) and periodically
20. Culver Trapper//CMN/OT/3/CIMMYT/ NE 1998
checked using a Crude Protein-Combustion method (Ameri-
Scout/4/Buckskin sib/Homestead
can Association of Cereal Chemists, 1983).
Mixograph analysis was performed with a National Manu-
production in recent years. The soil type was Sharpsburg facturing Mixograph (Lincoln, NE) and a 10-g sample and
silty clay loam (i.e., a fine montmorillonitic, mesic typic argui- constant water absorption of 620 g H
2
Okg
⫺
1
flour. Mixing
doll) at Lincoln and Mead. The experimental design within time was recorded as the time in minutes to maximum Mixo-
each environment was a randomized complete block design graph curve height. Mixing tolerance was determined on the
(RCBD) with two replications. A factorial treatment design basis of comparisons with standard Mixograph curves in the
was used with four seeding rates of 16, 33, 65, and 130 kg ha
⫺
1
Nebraska Wheat Quality Laboratory and scored by a scale
and 20 genotypes in 1997. Seeding rates were considered as from 0 to 7 with higher scores indicating greater tolerance of
environments influencing agronomic and end-use quality of dough to overmixing (Method 54-40; American Association
wheat. In 1998, kernel weight of each genotype was measured of Cereal Chemists, 1983).
and the same number of kernels were planted per ha as would The data were analyzed by PROC GLM (SAS Institute,
be planted at 16, 33, 65, 130 kg ha
⫺
1
of ‘Arapahoe’. This change 1994). Homogeneiety of variance tests were done before com-
was considered to add precision but had a minor effect because bining across environments in the combined ANOVA. In this
most genotypes had very similar 1000-kernel weight. These study, locations and years were considered random environ-
seeding rates were 0.25, 0.5, 1, and 2 times the normal seeding ments in the combined analysis of variance.
rate for eastern NE. The fields were prepared with standard Environments and replications were considered random
production practices, such as land preparation, fertilizer appli- effects and seeding rates and genotypes were considered fixed
cation, herbicide application, and seed was planted in plots effects. The respective error terms for F-test were estimated
that had four 2.4-m rows with 0.30 m between rows. by meansof the random statement with test option in PROC
GLM to detect significant differences among main effects and
Data Recorded interactions. Means statement was used for calculating treat-
ment means, and Fisher’s least significance difference (P⫽
Plant population was estimated visually in 1997 as the per-
centage of plants in a given plot relative to a full stand (solid 0.05) was used for comparing the mean differences.
Table 2. Combined analysis of variance for agronomic and end-use quality traits of 20 winter wheat genotypes grown at four seeding
rates in four Nebraska environments.
Grain
Plant Days to Plant Grain Kernel Volume Flour Flour Mixing Mixing
Source df population df flowering height yield weight weight protein yield time tolerance
% d cm Mg ha
⫺
1
mg kg hL
⫺
1
mg g
⫺
1
g min 0–7
Mean Squares for the traits under study
Environment ⫽Env 1 4 388.2 3 13 902.8** 50 338.3** 165.8** 472.9* 707.1** 350.33** 17.59 21.11** 10.01**
Error a 2 656.6 4 6.5 184.4 3.6 60.8 11.3 6.73 2.97 5.35 3.88
Seed Rate ⫽SR 3 65 769.4** 3 124.0** 291.9** 21.9** 49.9** 146.9** 87.20** 1.69** 17.14** 40.86**
Genotype ⫽C 19 744.3** 19 119.4** 1 371.3** 3.0** 101.9** 33.9** 10.75** 4.92** 22.62** 4.67**
SR ⫻C 57 118.19 57 2.05 24.0** 0.17 5.0 6.1 0.64 0.17 0.47 0.87
Env ⫻SR 3 481.1* 9 17.1** 247.2 7.3** 36.5** 23.8** 16.92** 0.95** 1.79** 2.19**
Env ⫻C 19 149.9 57 5.13** 44.9** 0.88** 10.2** 8.1** 1.44** 0.66** 1.66** 0.72
Env ⫻SR ⫻C 57 82.71 171 2.1** 27.6 0.19 6.2 5.1 0.85 0.16 0.39 0.61
Error b 158 128.0 316 1.28 26.1 0.19 5.7 4.8 0.90 0.143 0.356 0.69
CV (%) – 16.3 – 3.84 5.9 15.0 7.7 3.0 8.01 1.82 11.4 21.7
* Indicates significance at P⫽0.05.
** Indicates significance at P⫽0.01.

GELETA ET AL.: SEEDING RATES AND THEIR AFFECT ON WINTER WHEAT PERFORMANCE 829
Polynomial regression was used on trait means for each
seeding rate averaged over genotypes to develop equations
on how seeding rates affect the traits. Optimum seeding rate
was determined by inverse polynomial regression for each
trait with the use of orthogonal polynomial contrasts from
the ANOVA to determine the degree of the polynomial for
regression equations (Draper and Smith, 1981).
RESULTS AND DISCUSSION
Differences among environments, seeding rates, and
genotypes were observed for agronomic performance
Fig. 1. Mean grain yield of 20 winter wheat genotypes grown at Lin-
and end-use quality traits (Table 2) with the exception coln 1997 (L97), Mead 1997 (M97), Lincoln 1998 (L98), and Mead
of plant population and flour yield ⫻environment inter- 1998 (M98) Nebraska environments.
action. This indicates agronomic performance and end-
use quality were significantly affected by the growing grain yield. If the environment is conducive, wheat geno-
conditions (environments and seeding rates) and geno- types have the ability to compensate under relatively
types. No difference due to environment for plant popu- lower seeding rates to establish good stands with many
lation implies that the average stands were similar in tillers, larger heads, or more kernels, resulting in higher
the two environments (in 1997) where this trait was grain yield.
measured. The environment and seeding rate influenced Environment ⫻genotype interactions were found for
all traits. all the traits except plant population and mixing toler-
The seeding rate ⫻cultivar interaction was significant ance (Table 2). This result appeared to be explained
for plant height only (Table 2), indicating that genotypes mainly from changes in relative magnitude, although
responded similarly to seeding rate. The interaction ef- a few change in order were also found. The environ-
fect for plant height was most likely due to the inclusion ment ⫻genotype interaction mean squares for all traits
were greater than for the seeding rate ⫻genotype inter-
of semidwarf and tall genotypes in this study. Semidwarf
action, implying that genotypes were more sensitive to
and tall genotypes are known to respond differently to
environment than to seeding rates. As the ANOVA
the environment (Budak et al., 1995), in this case to results suggest (i.e., from the mean squares of the traits),
seeding rate. This result agreed with the findings of a large portion of the variability was due to main effects,
Johnson et al. (1988), who reported genotype ⫻seeding seeding rates, and genotypes and the two-way interac-
rate interactions were not present for agronomic traits of tions were due mainly to changes in magnitude, rather
five diverse soft red winter wheat genotypes. However, than reversals in order. The three-way interaction was
Freeze and Bacon (1990) found a genotype ⫻seeding significant for days to flowering only. Hence, seeding
rates interaction for grain yield for other soft red winter rate and genotypes will be discussed further.
wheat genotypes.
All traits except plant height had environment ⫻
Seeding Rate Effects on Agronomic
seeding rate interactions (Table 2). The interaction ap- and End-Use Quality of Winter Wheat
peared to be due mainly to changes in magnitude, rather
than to changes in order, except for grain yield. In three An increase in seeding rate was found to increase
of four environments, grain yield increased linearly with plant population (in 1997), plant height, grain yield, and
increasing seeding rate (Fig. 1). However, in the Lincoln grain volume weight averaged over genotypes (Table
1998 environment, there was a mild winter and higher 3). Reducing seeding rates placed a greater reliance on
seeding rates which resulted in lower grain yields. a genotype’s ability to compensate for fewer plants,
‘Mead’ had more winter and frost killing in 1997, and particularly by increasing the number of harvested ker-
nels per square meter through increasing the numbertherefore lower plant populations that resulted in lower
Table 3. Mean agronomic and end-use quality traits for each seeding rate averaged over 20 genotypes grown at four Nebraska environ-
ments and estimated optimum rate for each trait.
Seeding rates, kg ha
⫺
1
Traits 16 33 65 130 Optimum
Plant population (%)‡ 33.9d† 59.7c 88.7b 96.2a 103.9
Days to flowering (days)‡ 30.6a 29.7b 28.9c 28.6d 110.3
Plant height (cm)‡ 84.3c 85.4bc 87.5a 86.3b 87.2
Grain yield (Mg ha
⫺
1
)§ 2.4c 2.9b 3.2a 3.2a 118.3
Kernel weight (mg)‡ 30.7b 31.1ab 31.4a 30.1c 64.4
Grain volume weight (kg hL
⫺
1
)§ 71.6c 72.5b 73.5a 73.5a 96.9
Flour yield (g)‡ 58.9c 59.3b 59.7a 59.5ab 87.8
Flour protein (mg g
⫺
1
)‡ 128a 122b 113c 113c 98.2
Mixing time (min)‡ 4.8c 5.1b 5.5a 5.5a 97.6
Mixing tolerance (0–7)§ 4.5a 3.8b 3.5c 3.5c 58.8
† Values followed by the same letter in a row are not significantly different from each other.
‡ Quadratic significant.
§ Cubic significant.

830 CROP SCIENCE, VOL. 42, MAY–JUNE 2002
of spikes per square meter or kernels per spike. Mean have been caused by the presence of additional second-
ary tillers that delayed maturity and reduced kerneldays to flowering decreased as seeding rate increased,
although this effect varied with the genotype. An in- uniformity at lower seeding rates. The later tillers pro-
duce smaller grains that result in low grain volumecrease in seeding rate resulted in proportionally more
main culms, which normally flower earlier than do the weight. Samuel (1990) also found that grain volume
weights increased as the seeding rates were raised fromsecondary tillers. The greater the proportion of main
culms in the plot, the earlier the plot appeared to be. approximately 90 to 270 kg ha
⫺
1
, but the effects were
slight.This result was in agreement with the findings of Wilson
and Swanson (1962) and Johnson et al. (1965), who Flour yield increased with increased seeding rates up
to 65 kg ha
⫺
1
, which was similar to flour yield at thefound later maturity in thinly seeded plots. Prodigious
tillering resulting from reduced seeding rates may also 130 kg ha
⫺
1
seeding rate (Table 3). Flour protein content
decreased with increased seeding rate up to 130 kg ha
⫺
1
.be the cause of variable and delayed maturation (Thomp-
son et al., 1993) which in term resulted in the crop being This result confirms the findings of Samuel (1990), who
stated that protein concentration declined as seedinguneven and more difficult to manage and harvest.
There were differences in plant height among the rates and yields increased. However, Campbell et al.
(1991) reported that seeding rate has no effect on grainseeding rates. The height was not significantly changed
between 16 and 33 kg ha
⫺
1
seeding rates, but increased protein concentration. The higher protein content at
lower seeding rate could be explained by less competi-between 33 and 65 kg ha
⫺
1
and decreased between 65
and 130 kg ha
⫺
1
. The differences in plant height resulting tion among plants for nitrogen. In contrast, at higher
seeding rates, there would have been strong competitionfrom increasing the seeding rate from 16 kg ha
⫺
1
to 65
kg ha
⫺
1
was 3.2 cm averaged over genotypes. These among plants for nitrogen since no extra fertilizer was
applied in this experiment at higher seeding rates. Theheight increases reflect fewer secondary tillers, which
tend to be shorter, at the higher seeding rates. Increased higher grain yields obtained at relatively higher seeding
competition (which also shortened tillers) affected plant rates imply that more carbohydrate was produced and
height at the highest seeding rate. Except for a very few stored in the grain.
genotypes, the tallest height for most genotypes was Mixing time of wheat increased with increased seed-
obtained at 65 kg ha
⫺
1
. Our results contrast with those ing rate up to 65 kg ha
⫺
1
, with no significant increase
of Stapper and Fischer (1990) in New South Wales, at the 130 kg ha
⫺
1
rate. The lower seeding rate resulted
Australia. In that report, interplant competition may in higher protein content and shorter mixing time. Mix-
have led to weaker, taller stems and increased lodging ing tolerance significantly decreased as seeding rate in-
as seeding rate was increased from 50 to 200 kg ha
⫺
1
. Our creased up to 65 kg ha
⫺
1
. The mixing time and tolerance
results also contrast with those of Wilson and Swanson result may be explained by the protein content of the
(1962) at Hays, KS, where moisture may have been seeding rate treatments.
more limiting. They found that reduced stands at lower Achieving higher agronomic performance and better
seeding rates below 50 kg ha
⫺
1
were shown to be greater end-use quality requires management practices such as
in height. seeding rates to be carefully optimized and periodically
The highest grain yield averaged over environments reviewed. Seeding rate is a predictable environmental
and genotypes was obtained at the higher seeding rates variable that affects many agronomic and end-use qual-
(65 and 130 kg ha
⫺
1
), with the exception of the Lin- ity traits of wheat. Therefore, to obtain high grain yields
coln—1998 (L98) environment, where the highest grain with good end-use quality, seeding rate must be under-
yield was obtained at 33 kg ha
⫺
1
(Fig. 1). Mean grain stood. On the basis of the shape of the response curve,
yield increased up to 65 kg ha
⫺
1
, which was not signifi- the optimum-seeding rate for each trait averaged over
cantly different from the yield at 130 kg ha
⫺
1
seeding genotypes varied (Table 3). Seeding rate significantly
rate (Table 3). These seeding rates produced 33% more affected some of the traits.
grain yield than those seeded at 16 kg ha
⫺
1
(Table 3).
Similarly, Sahs (1970) over a 2-yr period, found 37% Genotype Performance
more grain yield from wheat seeded at 67.2 kg ha
⫺
1
Predominantly modern genotypes and a few historical
compared with the 22.4 kg ha
⫺
1
seeding rate. Sharma
genotypes were used in the study to ensure that the
and Smith (1987) at Stillwater and Lahoma, OK, and
genotypes had diverse genetic backgrounds and that the
Stickler et al. (1964) at Manhattan KS, also reported
that higher seeding rates (i.e., 67.2 and 123 kg ha
⫺
1
, modern and older genotypes varied greatly for the traits
measured. The estimated plant population of the geno-respectively) resulted in higher grain yields and earlier
maturity of wheat. types ranged from 51% for Arapahoe to 78% for ‘Prong-
horn’ (Table 4). Both genotypes were among intermedi-In general, kernel weight increased with increasing
seeding rates up to 65 kg ha
⫺
1
, although this increase ate groups in their yield performance across the seeding
rates and environments. The genotypes had a 1-wk in-is not significantly different from the average weight
obtained at 33 kg ha
⫺
1
(Table 3). Grain volume weights terval for days to flowering. The average height of the
genotypes ranged from 75 to almost 99 cm. Mean grainwere least when planting rate was 16 kg ha
⫺
1
but in-
creased at higher seeding rates (i.e., 65 and 130 kg ha
⫺
1
, yield of the genotypes across seeding rates ranged from
2.3 to 3.3 Mg ha
⫺
1
(Table 4). ‘NE92662’, ‘Niobrara’,Table 3). This result agreed with those of Wilson and
Swanson (1962) and Sahs (1970), and this result may ‘NE92628’, ‘NE92646’, ‘NE93405’, and ‘Windstar’ were

GELETA ET AL.: SEEDING RATES AND THEIR AFFECT ON WINTER WHEAT PERFORMANCE 831
Table 4. Mean agronomic and end-use quality traits of 20 winter wheat genotypes grown at four seeding rates in four Nebraska envi-
ronments.
Grain
Plant Days to Plant Grain Kernel Volume Flour Flour Mixing Mixing
Genotype population Flowering height Yield Weight Weight yield Protein time tolerance
% d cm Mg ha
⫺
1
mg kg hL
⫺
1
gmgg
⫺
1
min 0-7
1. Arapahoe 50.9 30.5 84.1 3.0 30.1 72.8 59.7 121 5.08 3.47
2. Niobrara 65.0 29.3 86.3 3.3 31.4 71.8 60.4 112 5.92 3.5
3. Pronghorn 78.1 28.2 89.3 2.9 31.1 74.2 59.2 120 6.38 4.37
4. Windstar 65.6 30.6 85.0 3.2 29.8 72.7 58.5 113 6.44 4.41
5. NE91631 72.8 31.9 91.3 2.9 26.4 71.2 58.9 113 6.63 4.28
6. NE92628 63.1 30.6 87.1 3.3 32.1 72.4 61.9 118 4.81 3.44
7. NE92646 69.4 30.1 80.4 3.2 29.8 72.8 59.5 122 4.74 4.06
8. NE92662 63.4 30.8 85.9 3.3 31.9 72.3 60.4 119 5.34 4.06
9. Alliance 78.1 29.0 83.1 2.9 28.6 70.9 60.0 109 4.83 3.34
10. Vista 72.5 30.0 74.6 2.7 30.6 72.3 59.8 121 5.28 3.47
11. Redland 75.3 30.0 86.2 3.0 29.6 71.2 60.2 111 5.73 3.69
12. TAM107 62.5 25.7 79.3 2.8 32.0 71.8 57.6 113 4.76 3.5
13. Nekota 71.6 29.2 78.4 2.9 32.3 73.6 59.1 116 4.01 3.28
14. Karl 92 75.6 25.2 75.3 2.8 32.0 73.3 59.1 123 6.00 4.47
15. Scout 66 69.7 29.2 95.0 2.3 32.5 74.1 59.6 121 3.48 3.59
16. Centura 78.1 29.5 88.4 2.6 29.0 73.3 58.3 123 5.27 4.09
17. Cheyenne 70.9 33.0 97.1 2.3 29.6 73.3 60.7 128 4.26 3.81
18. Buckskin 64.4 30.1 98.7 2.6 30.6 73.9 58.5 121 5.26 3.72
19. NE93405 74.4 26.1 88.6 3.2 34.7 74.4 57.4 132 6.09 4.12
20. NE93545 66.9 30.3 83.6 3.1 32.0 72.1 58.0 121 4.69 3.72
Mean 69.4 29.5 85.9 2.9 30.8 72.3 59.4 119 5.3 3.8
LSD 0.05 7.9 0.56 2.51 0.2 1.60 1.43 0.54 4.7 0.29 0.41
among the top yielding genotypes with an average yield could be required for better grain yield and end-use
quality of wheat. Higher seeding rates decreased theof over 3.1 Mg ha
⫺
1
across all environments and treat-
ments including seeding rates. In contrast, ‘Scout 66’, proportion of secondary tillers. Seeding rate is a predict-
able environmental factor that affects some agronomic‘Cheyenne’, ‘Buckskin’, ‘Centura’, ‘Vista’, and ‘Karl 92’
were genotypes with relatively, lower yields. Thousand- and end-use quality traits of wheat; therefore, it should
be studied carefully to obtain higher grain yields withkernel weight and grain-volume weight ranged from
26.4 to 34.7 g and 70.9 to 74.4 kg hL
⫺
1
, respectively. relatively better end-use quality. The non-significant
mean values of some traits at higher seeding rates (65NE93405 was the highest in performance for both of
the traits while ‘NE91631’ was among the lowest. and 130 kg ha
⫺
1
) indicate the optimum seeding rate is
between those two seeding rates. Further study isThe overall flour protein and flour yield ranged be-
tween 109 to 132 mg g
⫺
1
and 57.4 to 61.9 g (Table needed at rates between 65 and 130 kg ha
⫺
1
.Onthe
basis of the response curves, optimum seeding rate for4). Cheyenne, an older genotype, was one of the best
performers genotypes for flour protein and yield but grain yield was about 118 kg ha
⫺
1
; for plant height it
was 87 kg ha
⫺
1
; for grain volume weight, flour protein,had lower grain yield. NE91631, Pronghorn, Windstar,
and Karl 92 exhibited good mixing time and mixing and mixing time it was about 97.5 kg ha
⫺
1
; and for mixing
tolerance and 1000-kernel weight it was 59 and 64 kgtolerance. Most of the highest grain yielding genotypes
had relatively lower mixing time and mixing tolerance. ha
⫺
1
respectively. At present, the recommended seeding
rate is 65 kg ha
⫺
1
for eastern NE is still appropriate.Grain yield was positively correlated with mixing time
(r⫽0.22**), and it was correlated negatively with mix- Optimum seeding rate was environment-specific be-
cause of fluctuations in moisture and winter survival.ing tolerance (r⫽⫺0.22**). This result might be be-
cause genotypes with higher grain yield potential had
lower flour protein content. REFERENCES
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date, seeding rate, and phosphorus rate on wheat yield. Agron.performance and end-use quality of wheat than did envi-
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65 kg ha
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