Previous PageTable Of ContentsNext Page

Variation in Water-use Efficiency of Peanut Varieties Across Peanut Production Regions

Diane Rowland1, Paul Blankenship1, Naveen Puppala2, John Beasley3, Mark Burow4, Dan Gorbet5, David Jordan6, Hassan Melouk7, Charles Simpson8 and Jim Bostick9

1USDA/ARS, National Peanut Research Laboratory, 1011 Forrester Dr. SE, Dawson, GA 31742
2
New Mexico State University, Las Cruces, NM 88003
3
University of Georgia, Tifton, GA 31793
4
Texas A&M University, Lubbock, TX 79403
5
N Florida Res. & Educ. Center, Marianna, FL 32446
6
NC State University, Raleigh, NC 27695
7
USDA/ARS, Oklahoma State University, Stillwater, OK 74078
8
Texas A&M University, Stephenville, TX 76401
9
Alabama Crop Improvement Assn., PO Box 357, Headland, AL 36345

Abstract

The ability of a peanut variety to use water efficiently can spell the difference between high yields or a failed crop when water is limited. Because of this, high water-use efficiency (WUE), or the ratio of yield to water use, may now become a priority in many peanut breeding programs. To support such a breeding effort effort, we examined the variation in WUE (as measured by carbon isotope composition) as well as two leaf characteristics, specific leaf area and chlorophyll content, of up to 19 varieties in six U.S. peanut producing areas: Georgia, Florida, North Carolina, Texas, Oklahoma, and New Mexico. We found significant variation among sites and among varieties grown at single sites in all three characteristics, indicating these traits were under genetic control but had the potential for genotype by environment interactions.

Media summary

Genetic variation in seasonal water-use efficiency among U.S. grown peanut varieties exists and can be affected by growing environment.

Key Words

δ13C, SLA, SPAD

Introduction

Irrigation can increase peanut yields by up to 19% over dryland production (Lamb et al. 1997) and irrigated peanut acreage now comprises over 50% of all peanut production in the U.S. Yet, due to the often precarious balance between increased yields and the high cost of irrigation equipment, maintenance, and fuel, it becomes necessary for a grower to optimize water use as much as possible.

One area that has the possibility of tipping the scales in favor of growers is maximizing peanut water-use efficiency while maintaining optimum production. Water-use efficiency (WUE), defined as the ratio of photosynthesis to transpiration, can be an important limitation to productivity under drought (Nageswara Rao and Wright 1994). However, increased WUE at the expense of yield has no utility in agricultural systems. Peanut has the potential to have very high photosynthetic capacity accompanied by low stomatal conductance levels, which translates into high WUE without sacrificing carbon assimilation and possibly yield (Wright et al. 1993). This characteristic would allow the successful breeding of highly water-use efficient, high yielding peanut varieties.

However, the existence of genetic variation in WUE among commonly grown U.S. peanut cultivars is not known, nor the role that environment plays in changing the expression of these genetic differences. We conducted this experiment in order to document genetic variation and the effect of environment on peanut WUE for U.S. grown varieties.

Methods

During the growing season of 2001, we determined the local and regional variation in WUE among several commonly grown U.S. peanut varieties. We chose six sites across the major U.S. peanut producing regions to measure WUE, specific leaf area (SLA), and SPAD chlorophyll content. These sites were: 1) Plains, GA; 2) Marianna, FL; 3) Lewiston, NC; 4) Seminole, TX; 5) Clovis, NM; and 6) Ft. Cobb, OK (Figure 1). At each location, breeding trials had been established in which several peanut varieties were grown in replicated trials. WUE (as measured by carbon isotope composition, δ13C), SLA, and SPAD chlorophyll content measurements were made in: 1) those varieties commonly grown within the region where that particular site was located and, 2) those varieties that were grown in several different sites. At each site, varieties were grown under irrigation.

Peanut leaf tissue was collected approximately 90 days after planting (ranging from late July to mid August, 2001). Tetrafoliate leaves were excised and chlorophyll content was measured using a Minolta SPAD chlorophyll meter (Minolta Corp., Ramsey, N.J.). Leaf area of the four leaflets was measured with a LI-3000A leaf area meter (LI-COR Inc., Lincoln, NE) and summed to give total leaf area. Leaves were then oven dried at 60 C for 72 hours and weighed. Specific leaf area (SLA) was calculated as the ratio of leaf area to leaf dry weight. Leaves were then fine ground using a Braun (model KSM2) coffee grinder and analyzed for carbon isotope composition, δ13C, at the University of Arkansas Stable Isotope Laboratory.

Figure 1. Six sites located in the major peanut producing regions of the U.S. Several varieties at each site were measured for δ13C, SLA, and SPAD chlorophyll content.

Results

There was significant variation in WUE (δ13C), SLA, and SPAD chlorophyll content among varieties grown within single sites. When varieties were grown simultaneously at different sites, a significant effect of environment was also detected in δ13C.

The significant effect of variety within single sites for δ13C, SLA, and SPAD chlorophyll content showed the existence of genetic variation for peanut WUE and leaf morphological characteristics. Varietal differences in δ13C were most strongly detected at Florida, Texas, and Oklahoma; for SLA, all sites showed significant effects of variety except for those grown in New Mexico. SPAD chlorophyll content showed significant varietal differences at Florida, North Carolina, Texas, and Oklahoma.

For those varieties grown at several different sites simultaneously, a significant effect of environment was detected as well as varietal effects, indicating both environmental and genetic controls over δ13C. For example, the variety Georgia Green was grown simultaneously in five of the six sites and had a significant site difference in δ13C.

Ranking of each variety within a single site illustrated the existence of both genetic and environmental effects as well (Table 1). For example, some varieties, such as Florunner and Tamrun 96, appeared to have strong genetic control over δ13C due to their consistently higher (less negative) δ13C values (and thus higher WUE) than other varieties, even when grown in the disparate environments of Florida, Texas, and Oklahoma. At the other end of the spectrum, Georgia Green appeared to have strong environmental plasticity due to the highly variable values of δ13C in its leaf tissue across the sites of Florida, North Carolina, Oklahoma, and Texas. However, when grown under the similar climate and environmental conditions of Florida and Georgia, its δ13C values were very consistent.

Table 1: Ranking of peanut varieties that were measured for δ13C, SLA, and SPAD chlorophyll content at each of six sites throughout the major U.S. peanut production regions. Varieties are listed in order of δ13C value; therefore, those listed first have higher (less negative) δ13C and thus higher WUE. Different letters in parentheses within a site column refer to varieties that are significantly different from one another.

Site

         

Georgia

Florida

Oklahoma

Texas

New Mexico

North Carolina

AT201 (a)

NCV 11 (a)

FlavRunner 458 (a)

Florunner (a)

GA Valencia (a)

NCV 11 (a)

GA HiOL (a)

Tamrun96 (a)

Florunner (a)

Tamrun 96 (a)

Valencia A (a)

GA Green (a)

C99R (a)

GA HiOL (a)

GA Green (ab)

GA Green (b)

Valencia C (a)

Gregory (a)

GA Green (a)

Florunner (a)

Tamrun 96 (ab)

   

Perry (a)

 

AT201 (ab)

Tamspan 90 (b)

   

NC 12C (a)

 

VAC 92R (ab)

Valencia A (c)

     
 

Gregory (ab)

       
 

VA 98R (ab)

       
 

NC 12C (ab)

       
 

Perry (ab)

       
 

Virugard (ab)

       
 

GA Green (b)

       
 

C99R (b)

       

Conclusion

Our study documented the existence of genetic variation among currently grown peanut cultivars in the U.S. for δ13C (and thus WUE), SLA, and SPAD chlorophyll content, but we also found that environment played a significant role in the genetic expression of these traits. The existence of variation among different varieties when grown in common environments at single sites showed genetic control over WUE in the peanut varieties we measured and supports previous work that documented genotypic variation in δ13C and WUE for peanut in greenhouse (Hubick et al. 1986) and field conditions (Nageswara Rao et al. 1993).

While our ability to detect genotypic and environmental effects was somewhat limited due to the small number of varieties grown simultaneously at several sites across geographical regions, it appears that for several runner, Virginia, and high oleic peanut varieties, both genetics and environment play a strong role in the expression of δ13C and thus WUE. Very few previous studies in peanut have documented that variation in δ13C was influenced by both location and genotype (Hubick 1990; Nageswara Rao and Wright 1994; Brown and Byrd 1996). In contrast, Wright et al. (1988) demonstrated a very strong genetic control over δ13C with little effect of the environment for Virginia and Spanish varieties when grown either in open or closed canopies. That makes our positive G X E interaction for the varieties we measured across regions somewhat surprising. However, our survey is across such diverse environments that an expression of G X E may be made more apparent under these conditions. This assumption is supported by the results for the variety Georgia Green. Georgia Green consistently showed a very large G X E interaction for δ13C when compared across eastern and western U.S. production regions, but no G X E interaction when grown in the very similar environments of Georgia and Florida.

The utility of using δ13C and SLA in breeding programs depends on the consistency of the ranking of genotypes in a wide range of environments (Nageswara Rao et al. 1995), as we have done in this study. There is a need for breeders and physiologists to collaborate more extensively in order to provide better knowledge of the physiological basis behind the performance of genotypes in different environments and speed up the development of superior genotypes (Wright et al. 1996). Currently grown peanut varieties and developing cultivars need to be assessed for WUE not only across different growing regions, but also different growing conditions. This may allow us to tailor varieties for production management methods and environmental conditions and to make better-informed varietal recommendations to growers for improved WUE without sacrificing yield.

Acknowledgements

We thank the staff at the National Peanut Research Laboratory and specifically Kathy Gray, Larry Powell, William Pearce, Eva Whitehead, Latoya Rucker, and Kip Balkcom who provided invaluable field collection, sample processing, and general assistance.

References

Brown RH and Byrd GT (1996). Transpiration efficiency, specific leaf weight, and mineral concentration in peanut and pearl millet. Crop Science 36: 475-480.

Hubick KT (1990). Effects of nitrogen source and water limiation on growth, transpiration efficiency and carbon-isotope discrimination in peanut cultivars. Aust. J. Plant physiol. 17: 413-430.

Hubick KT, Farquhar GD and Shorter R (1986). Correlation between water-use efficiency and carbon isotope discrimination in diverse peanut (Arachis) germplasm. Australian Journal of Plant Physiology 13: 803-816.

Lamb MC, Davidson Jr. JI, Childre JW, and Martin Jr. NR (1997). Comparison of peanut yield, quality, and net returns between nonirrigated and irrigated production. Peanut Science 24: 97-101.

Nageswara Rao RC, Udaykumar M, Farquhar GD, Talwar HS and Prasad TG (1995). Variation in carbon isotope discrimination and its relationship to specific leaf area and ribulose-1,5-bisphosphate carboxylase content in groundnut genotypes. Australian Journal of Plant Physiology 22: 545-551.

Nageswara Rao RC, Williams JH, Wadia KDR, Hubick KT and Farquhar GD (1993). Crop growth, water-use efficiency and carbon isotope discrimination in groundnut (Arachis hypogaea L.) genotypes under end-of season drought conditions. Ann. appl. Biol. 122: 357-367.

Nageswara Rao RC and Wright GC (1994). Stability of the relationship between specific leaf area and carbon isotope discrimination across environments in peanut. Crop Science 34:98-103.

Wright GC, Hubick KT and Farquhar GD (1988). Discrimination in carbon isotopes of leaves correlates with water-use efficiency of field-grown peanut cultivars. Aust. J. Plant Physiol. 15:815-825.

Wright GC, Hubick KT, Farquhar GD and Nageswara Rao RC (1993). Genetic and environmental variation in transpiration efficiency and its correlation with carbon isotope discrimination and specific leaf area in peanut. In ‘Stable Isotopes and Plant Carbon-Water Relations’. (Eds. JR Ehleringer, AE Hall and GD Farquhar) pp. 247-267. (Academic Press, Inc., San Diego, CA, USA).

Wright GC, Nageswara Rao RC and Basu MS (1996). A physiological approach to the understanding of genotype by environment interactions – a case study on improvement of drought adaptation in groundnut. In ‘Plant Adaptation and Crop Improvement’. (Eds. M Cooper and GL Hammer). (CAB International).

Previous PageTop Of PageNext Page