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Production Papers

Management and Production Potential of Value-Added Soybean Cultivars in South Central USA

Department of Plant and Soil Sciences, Univ. of Kentucky, 1405 Veterans Drive, Lexington, KY 40546-0312

^* Corresponding author (s.kumudini{at}uky.edu)

Received for publication June 22, 2004.

	ABSTRACT

TOP NOTES ABSTRACT INTRODUCTION MATERIALS AND METHODS RESULTS AND DISCUSSION SUMMARY REFERENCES

 
Growth of value-added commodities, especially high-protein and tofu soybean [Glycine max (L.) Merr.], may offer a profitable option for growers faced with the decline in traditional crops in the south central region of the USA. There is limited information on the production potential and management options necessary for optimal production of value-added soybean crops in this region. The objectives of this study were (i) to determine the production potential of value-added soybean cultivars in the south central region, and (ii) to evaluate various management options for optimal production in this area. Three tofu-type and three high-protein soybean cultivars were compared with commodity-type (check) soybean cultivars under various N and plant density treatments over 4 location/years. Yield and yield component data were collected including seed protein and oil concentrations. Both high protein and tofu-type soybean cultivars had comparable yields and generally greater protein concentrations and larger seed size (tofu-type soybean) than an equivalent check cultivar. The exceptions were cultivars that had, on average, a greater than 10% higher protein concentration than the check cultivar. These higher protein cultivars generally yielded less than other value-added soybean cultivars or the standard check cultivar. The value-added soybean cultivars responded well to management practices currently being used to grow standard commodity cultivars. Neither change in plant population density nor late-season fertilizer applications was necessary to maintain total yield and yield components at a level equivalent to the check cultivar. There is good production potential of value-added soybean cultivars in the south central region, even when grown with current equipment and management practices utilized for commodity soybean crop production.

	INTRODUCTION

TOP NOTES ABSTRACT INTRODUCTION MATERIALS AND METHODS RESULTS AND DISCUSSION SUMMARY REFERENCES

 
THE SOUTH CENTRAL USA region has been particularly affected by the decline in tobacco (Nicotiana tabaccum L.) production. With this loss of a critical crop, there is a need to explore alternatives. Of particular interest are commodities that are familiar to growers and can be grown with farm equipment readily available to farm operators in the region. High-protein and tofu soybean cultivars both have high protein concentrations and are considered value-added crops. These specialty soybean cultivars may offer better economic returns than growing commodity soybean, depending on production potential and cost of crop management of these value-added crops in this region.

Soybean is unique in having high concentrations of both oil and protein, it has the highest protein concentration of all edible legumes (Breene et al., 1988). The large, commodity-based soybean industry in the USA has centered around production of both soybean oil and protein meal (Leffel and Rhodes, 1993). Soybean oil has uses as industrial oil as well as being used for human consumption as edible oil products. Soybean meal is mainly used as a source of protein in livestock and poultry feed. The soybean protein fraction has been growing as an important protein source for poultry, swine, and other animal feeds (Breene et al., 1988).

More recently the protein fraction has been of interest in the manufacturing of certain soybean-based foods for human consumption. Soybean-based foods (soyfoods) have become popular in North American markets moving from health food stores to mainstream supermarkets and are now marketed by large food companies such as Kraft, General Mills, and Unilever (Kaufmann, 2004). The soyfoods market is not as large as the commodity-based oil and protein meal soybean market; however, it has taken on momentum especially since 1999 when the U.S. Food and Drug Administration decided to permit health claims to be placed on edible soybean products. The emerging markets in Asia have further increased the demand for soyfood. The demand for soyfoods has increased annually, and the soyfoods industry was estimated to soon exceed $4 billion (Kaufmann, 2004).

In North America, growers of value-added soybean cultivars are generally contracted by a particular manufacturer of tofu and related products. These growers are generally required to grow specific cultivars with known seed color, protein concentration, and other characteristics. Although soybean production for the food industry accounts for a small fraction of the national soybean market, this market is a highly profitable niche for soybean growers (Silva, 1998). Furthermore, the soyfood industry is growing at a faster rate than the commodity soybean sector (Kaufmann, 2004). The premiums for food-grade soybean are in the range of $74 Mg^–1, although the best prices are available for certified organically grown food-grade soybean (Sullivan, 2003). High protein concentration is an important quality component of many soyfoods. Consequently not only is high-protein soybean likely to increase in importance, but food-grade soybean is also likely to gain as an important niche market (Kaufmann, 2004). Production of high protein and tofu soybean cultivars has the potential to significantly improve farm economic returns.

However, little is known of the management practices required or the production potential of novel soybean cultivars in the south central USA. The production potential of tofu and high protein soybean may be lower than standard soybean cultivars since seed protein concentration is usually negatively correlated with seed yields (Leffel and Rhodes, 1993). High protein cultivars are considered to yield considerably less than conventional cultivars of similar maturity.

The relationship between yield and protein concentration has led to speculation that N stress may limit seed yield. There have been conflicting reports on the advantages of late season N application to improve soybean yield and possibly protein concentration (Diebert et al., 1979; Gascho, 1991; Wood et al., 1993; Wesley et al., 1998). Leffel et al. (1992) noted that the high-protein cultivar accumulated more whole plant N than its normal-protein counterpart. More plant N may arise from access to more soil-available N or through increased duration or rate of N₂ fixation. In discussing the relationship between C and N assimilation and yield, Lawlor (2002) concluded that crop productivity is ultimately dependent on adequate N supply and at the appropriate stage of development. Although he did contend that there was a genetic component to yield, he suggested that the large impact of environment on yield was due to N supply. If this is indeed the case, the need for N supply would be even greater in genotypes with high seed protein such as the tofu and the high protein soybean cultivars. The yield of the high-protein and tofu cultivars may be responsive to late season N application by reducing the impact of N stress on soybean yield.

Since the tofu genotypes tested were developed in states to the north and west of the present test sites, it is not known how well these cultivars would be adapted to different regions of central and western Kentucky, which represents the south-central region of the USA. Soil and climatic differences may have implications not only for production potential but also for appropriate management practices. Considering the longer growing season in the south central region, it may be possible to plant at lower densities since we have a longer period over which canopy cover may be established. Lower plant densities could have the added benefit of increasing seed size, a desirable quality for food-grade soybean. Lowering plant density has the added advantage of providing savings on the cost of seed. Late season N fertilizer application may also maintain the higher protein concentration in these cultivars and still allow for high yields.

There is only limited information available on either novel soybean cultivar performance in the south central region, or the optimum management practices required to grow food-grade and high-protein soybean cultivars in this region. The objectives of this research were: (i) to determine the production potential of novel soybean cultivars in the south central region, and (ii) to evaluate management strategies for novel soybean production in this area.

	MATERIALS AND METHODS

TOP NOTES ABSTRACT INTRODUCTION MATERIALS AND METHODS RESULTS AND DISCUSSION SUMMARY REFERENCES

 
Tofu Experiment
The experiment was conducted in Lexington, KY, and Princeton, KY, in 2000 and 2001. The field plots in Lexington were located on the Spindletop research station (38° N lat, 84° W long) and the soil at this location was a Maury silt loam (fine, mixed, semiactive, mesic Typic Paleudalfs). The field plots in Princeton were at the Princeton research station (37° N lat, 87° W long) and the soil at this location was Crider silt loam (fine-silty, mixed, active, mesic Typic Paleudalfs).

The treatments consisted of four cultivars, two plant densities, and two N treatments. The cultivars selected consisted of three tofu-type soybean and one commodity-type soybean. Cultivar ‘FG1’ (Ohio Foundation Seed, Croton, OH) was selected as it had a popular market position in the Japanese market. Cultivar ‘IA3011’ (Iowa State University, Ames, IA) was the highest yielding among the maturity group (MG) III lines from the Iowa State University cultivar release program. Pioneer brand ‘9305’ (Pioneer Hi-Bred International, Johnston, IA) was selected as representative of a private company release. The commodity check soybean cultivar was Pioneer brand ‘93B01’ (Pioneer Hi-Bred International, Johnston, IA). It was selected as a representative of a high yielding commodity soybean cultivar against which the three food-grade cultivars were tested. The two plant density treatments were established by using seeding rates of 288000 and 433000 seeds ha^–1, to represent 67 and 100% of the traditional seeding rate. The N fertilizer treatment consisted of either 0 or 44.8 kg ha^–1 of ammonium nitrate broadcast applied between the soybean rows when 50% of the plants had reached the R2 (Fehr and Caviness, 1977) stage. This corresponded to 19 June, at Spindletop in 2000 and 2001, and 1 July and 20 June at Princeton in 2000 and 2001, respectively. Planting dates in Spindletop were 1 and 7 May for 2000 and 2001, respectively. Seeds were planted in Princeton on 8 and 10 May for 2000 and 2001, respectively. Plots were 6 m long and 6 rows wide, and each row was 0.38 m wide. Harvest for final yield was sampled on a strip 5 m long and 4 rows wide (interior rows). Harvest dates were 18 Sept. 2000 and 2 Oct. 2001 at Spindletop and 20 Sept. 2000 and 18 Sept. 2001 at Princeton.

High-Protein Experiment
This experiment was conducted in 2000 and 2001 and at the same two locations (Spindletop and Princeton) as the previous experiment (see tofu experiment for soil and location details). The precipitation and daily average temperature data were obtained from two near-by weather stations (<1.5 km from each of the field plots).

The treatments consisted of six cultivars and two N treatments. Six genotypes with high and standard protein concentrations in MG II, III, and IV were selected. Data from uniform regional tests were used to select high-protein cultivars that also had good yield potential. The standard commodity cultivars were selected using results of Kentucky Soybean Performance Tests. The high-protein MG II genotype ‘U97-207427’ (University of Nebraska, Lincoln, NE) was paired with the standard protein cultivar ‘Jack’ (Illinois Foundation Seed, Champaign, IL). The high-protein MG III cultivar ‘NE 3396’ (University of Nebraska, Lincoln, NE) was paired with the standard protein cultivar ‘93B11’ (Pioneer Hi-Bred International, Johnston, IA). The high-protein MG IV cultivar ‘KS4103sp’ (Kansas State University, Manhattan, KS) was paired with the standard protein cultivar Caverndale ‘CF461’ (Caverndale Farms, Danville, KY).

The N fertilizer treatment consisted of 0 or 44.8 kg ha^–1 of ammonium nitrate broadcast applied between the soybean rows when 50% of the plants had reached growth stage R5 (Fehr and Caviness, 1977). The cultivars from the three MGs reached R5 on different dates, so the N fertilizer was applied on different days. Planting dates at Spindletop were 1 and 7 May for 2000 and 2001, respectively. Seeds were planted in Princeton on 8 and 10 May for 2000 and 2001, respectively. At the Spindletop research station, the plants were fertilized on 17, 24, and 31 July for MGs II, III, and IV, respectively, in 2000. In 2001 the plants at this location were fertilized on 23 July, 30 July, and 6 August, for the MGs II, III, and IV, respectively. At Princeton, the plants were fertilized on 19 July for MGs II and III, and on 2 August for MG IV in 2000. In 2001 the plants at this location were fertilized on 18, 25, and 31 July for the MGs II, III, and IV, respectively. Plots size and sampling area was identical to that for the tofu experiment. Harvest date was 2 October at Spindletop in both years and all MGs with one exception. In 2001, MG IV cultivars were harvested on 9 October. Harvest dates for Princeton were 28 September in 2000, and 18 September for MG II and 3 October for MGs III and IV cultivars in 2001.

The experimental design and statistical procedures were similar for all experiments reported. The experiments were designed as randomized complete block designs with four replications at each location. The experimental data were analyzed using Proc GLM (SAS ver. 8.0, SAS Institute, Cary, NC), with years, locations, and blocks being random and blocks nested within years and locations. The LSD values were calculated from studentized t values ( = 0.05).

	RESULTS AND DISCUSSION

TOP NOTES ABSTRACT INTRODUCTION MATERIALS AND METHODS RESULTS AND DISCUSSION SUMMARY REFERENCES

 
Tofu Test
The yield of tofu and conventional soybean cultivars was affected by year, location, and cultivar (P < 0.0001). Across cultivars and years, the mean yield was higher at Spindletop than at Princeton (Table 1). More precipitation was received in Princeton and in 2001 than in the year 2000 (Fig. 1) . No relationship was apparent between the precipitation received and the yield levels at the four location/years. There was, however, a relationship between temperature and yield at the two locations. Princeton is in a more southern location and the average growing season temperatures are several degrees above that for Spindletop (Fig. 1). It was postulated that the warmer growing temperatures accelerated the rate of development of the plants grown at Princeton. The consequent shorter growing period, and therefore, the shorter period of assimilate accumulation at Princeton may well have led to the lower observed yields. Considering that these tofu cultivars were developed in more northern regions and are MG III cultivars, their sensitivity to warmer temperatures is not unexpected. Cultivars better adapted to the warmer temperatures found in this region could potentially yield more.

View larger version (32K): [in this window] [in a new window]   Fig. 1. Monthly average temperature and cumulative precipitation for Princeton and Spindletop in (a) 2000 and (b) 2001.

View larger version (29K): [in this window] [in a new window]   Fig. 2. Soybean seed size when grown at normal (100%) and reduced (67%) plant density (relative to standard commodity soybean plant density). Averages over two locations in 2000 and 2001. Bars represent standard error bars.

The one tofu-cultivar that yielded lower than the check in some location/years, was IA3011 (Table 1). Cultivar IA3011 also had the highest protein concentration among those tested. Food-grade soybean generally had higher protein concentrations than their nonfood-grade counterpart (93B01), but IA3011 had as much as a 15% higher protein concentration than the check cultivar (Table 1). Although IA3011 may not have as high yields as the other tofu soybean cultivars tested, its higher protein concentration may well compensate for its lower yield if premiums were available for the higher protein concentration.

There is no reported consistent effect of fertilizer N on nodulated soybean yield or protein concentration (Diebert et al., 1979; Gascho, 1991; Wood et al., 1993; Wesley et al., 1998). Brevedan et al. (1978) was the only exception in that they reported repeated yield advantage to fertilizer N application during the reproductive period. Others reported that fertilizer N application resulted in increased yield or protein concentration in only some years/locations or cultivars of nodulated soybean (Diebert et al., 1979; Gascho, 1991; Wood et al., 1993; Wesley et al., 1998). Consistent with previous reports, in the current study, application of fertilizer N had no significant impact on yield or protein concentration. Also there was no significant interaction of planting density and N fertilizer treatment on seed yield or protein concentration (data not shown). The results of the current study support the contention that management strategies, specifically the plant density and fertility management currently used in commodity soybean production, is satisfactory to obtain comparable seed yield, and comparable or higher protein concentrations in tofu soybean.

High Protein Test
Yield and yield components (seed size and seed number) of the six genotypes tested were affected by location, year, and genotype (Table 2). The plots at Spindletop had higher yields than those at Princeton (Table 2) in both years of the test. The warmer temperatures in Princeton may have accelerated the rate of development, and thus hastened maturity and resulted in reduced yield potential (Fig. 1). The fact that even the later maturity group (MG IV) cultivars from both high protein and standard cultivars maintained higher yields at Spindletop may be an indication that the yield potential of even later maturing cultivars were limited by the warmer temperatures in Princeton. Consistent with the current data, the data from multi-year, state-wide, variety tests also indicated that the yield potential in Princeton is lower than that at Spindletop for MG III and IV cultivars (Lacefield et al., 1999, 2000; Lacefield and Pfeiffer, 2002).

Although in the high-protein test there was no significant genotype main effect on yield, there was a significant genotype main effect on seed quality (P < 0.001 and P < 0.01 for protein and oil concentrations, respectively). Consistent with previous studies that contend that seed protein and oil concentrations are genotype-dependent, the genotypes in this study also showed consistency in protein and oil concentrations across years and environments (Table 2). The high protein genotypes generally had significantly higher protein concentrations and lower oil concentrations than the normal protein cultivars against which they were compared (Table 2).

It is generally considered difficult to produce high yielding, high-protein cultivars due to the negative relationship between seed protein concentration and seed yield. Wilcox and Cavins (1995), in summarizing a number of breeding tests, reported a moderate to strong inverse relationship between seed yield and protein concentration. Leffel et al. (1992), however, identified a high-protein cultivar that was as high or higher yielding than a regular protein cultivar. Cober and Voldeng (2000) developed soybean populations that had no or low association between seed protein concentration and seed yield, supporting the idea that yield and protein concentrations are not necessarily negatively correlated.

In the current study only one of the three high protein cultivars tested showed a negative correlation between seed yield and seed protein concentration. The cultivar KS4103SP (a high-protein MG IV cultivar) had at least 20% greater protein concentration than its check, the highest protein concentration of any of the cultivars tested, and yielded consistently lower than its regular protein counterpart. The yields of the other two high protein cultivars tested were not consistently lower, and in some cases were even higher than the yield of the regular protein cultivars against which they were tested (Table 2). With the small subset of lines tested, it appears that moderate advances in protein concentration can be achieved without a negative impact on yield, but in cases where high-protein cultivars and checks had a large difference in protein concentration, a negative association with yield was apparent.

As was observed in the tofu-grade soybean test, in the high-protein test, there was no consistent relationship between late season N fertilizer application and yield or protein concentration (data not shown). Earlier reports on N fertilizer application on nodulated soybean cultivars also found no consistent relationship between fertilizer N application and yield and protein concentration (Diebert et al., 1979; Gascho, 1991; Wood et al., 1993; Wesley et al., 1998). The high-protein genotypes in the current study were able to accumulate more N than the standard commodity soybean cultivars. Furthermore, the greater protein concentration was apparent whether or not they received late-season N fertilizer application. It is therefore concluded that late-season fertilizer N application is not necessary to maintain high protein concentrations or to improve seed yield of high protein soybean genotypes.

	SUMMARY

TOP NOTES ABSTRACT INTRODUCTION MATERIALS AND METHODS RESULTS AND DISCUSSION SUMMARY REFERENCES

 
It was apparent from this multi-location/year study that there was good production potential for value-added soybean cultivars in the south central region of the USA. Both high protein and tofu-grade soybean had comparable yields and generally greater protein concentrations and frequently larger seed size (tofu-grade soybean) than an equivalent standard commodity soybean. The value-added soybean cultivars responded well to management practices currently being used to grow regular commodity soybean cultivars. Neither change in plant population density nor in late-season fertilizer applications was necessary to maintain good yield and quality in these value-added crops. Therefore, production of value-added soybean cultivars in this region appears to be a valid option for producers interested in alternative crops for which they could negotiate a higher price.

	ACKNOWLEDGMENTS

 
We thank the following people for their suggestions regarding the manuscript: Walter R. Fehr, Iowa State University; Steven St. Martin, Ohio State University; Bill Schapaugh, Kansas State University; and Steve Schnebly and Bob Kennedy, Pioneer Hi-Bred International. We also gratefully acknowledge the following people and/or organizations for providing seed: George Graef, University of Nebraska; Bill Schapaugh, Kansas State University; and Caverndale Farms, Illinois Foundation Seed, Iowa State University, Ohio Foundation Seeds, and Pioneer Hi-Bred International. The inclusion of brands/varieties/lines does not indicate endorsement on our part.

	NOTES

TOP NOTES ABSTRACT INTRODUCTION MATERIALS AND METHODS RESULTS AND DISCUSSION SUMMARY REFERENCES

 
This manuscript is published with the approval of the Director of the Kentucky Agric. Exp. Stn. as paper no. 05-06-010. This study was made possible by the generous support of the New Crop Opportunities Center (funded by a USDA Special Research Grant), Univ. of Kentucky, College of Agriculture.

	REFERENCES

TOP NOTES ABSTRACT INTRODUCTION MATERIALS AND METHODS RESULTS AND DISCUSSION SUMMARY REFERENCES

 

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This Article Abstract Figures Only Full Text (PDF) Free Alert me when this article is cited Alert me if a correction is posted Services Similar articles in this journal Similar articles in ISI Web of Science Alert me to new issues of the journal Download to citation manager Citing Articles Citing Articles via Google Scholar Google Scholar Articles by Kumudini, S. Articles by Steele, C. C. Search for Related Content PubMed Articles by Kumudini, S. Articles by Steele, C. C. Agricola Articles by Kumudini, S. Articles by Steele, C. C. Related Collections Soybean Production Agriculture