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a Dep. of Crop and Soil Sciences, Univ. of Georgia, Coastal Plain Experiment Station, Tifton, GA 31793-0748
b Dep. of Plant Pathology, respectively at the Univ. of Georgia, Coastal Plain Experiment Station, Tifton, GA 31793-0748
* Corresponding author (wdbranch{at}uga.edu).
ABSTRACT
‘Georgia-07W’ (Reg. No. CV-102, PI 652441) is a high-yielding, large-seeded, runner-type peanut (Arachis hypogaea L. subsp. hypogaea var. hypogaea) cultivar with resistance to tomato spotted wilt virus (TSWV) and white mold (Sclerotium rolfsii Sacc.). It was developed at the University of Georgia, Coastal Plain Experiment Stations at Tifton, GA, and was released by the Georgia Agricultural Experiment Stations in 2007. Georgia-07W originated from a cross made between ‘C-99R’ x ‘Georgia Green’. Pedigree selection was practiced within the early-segregating generations. Performance testing began in the F4:6 generation with the advanced pure-line selection, GA 011514, the experimental designation of Georgia-07W. Averaged over 14 tests conducted at three locations in Georgia during three years (2004–2006), Georgia-07W had significantly less midseason TSWV incidence and late-season total disease (TSWV and soilborne disease) incidence, and significantly higher yield, grade, and dollar value return per hectare compared with the two parental check cultivars, C-99R and Georgia Green, respectively. Georgia-07W has also shown significantly less white mold and significantly higher pod yield compared with the resistant female parent, C-99R, when grown in soil with high disease pressure from S. rolfsii.
Abbreviations: FSIS, federal–state inspection services • SMK, sound mature kernels • TD, total disease • TSMK, total sound mature kernels • TSWV, tomato spotted wilt virus
‘Georgia-07W’ (Reg. No. CV-102, PI 652441) is a high-yielding, large-seeded, runner-type peanut (Arachis hypogaea L. subsp. hypogaea var. hypogaea) cultivar with resistance to tomato spotted wilt virus (TSWV) and white mold (Sclerotium rolfsii Sacc). It was developed at the University of Georgia, Coastal Plain Experiment Station at Tifton, GA, and was released by the Georgia Agricultural Experiment Stations in 2007. Georgia-07W was tested experimentally as GA 011514. Georgia-07W is intended for the same U.S. domestic market as other runner-type peanut cultivars. It was developed by conventional breeding and did not involve any genetically modified organisms.
Georgia-07W was selected from a cross made in 1997 between the two U.S. runner cultivars, C-99R (Gorbet and Shokes, 2002) x Georgia Green (Branch, 1996). Georgia Green (PI 587093) is a regular-seeded, TSWV-resistant, runner market-type peanut cultivar. C-99R (PI 613135) is a large-seeded, runner-type cultivar with resistance to late leafspot caused by Cercosporidium personatum (Berk. & M.A. Curtis) Deighton, white mold or stem rot caused by S. rolfsii, and TSWV.
Methods
Georgia-07W was developed using the pedigree selection method for peanut breeding (Knauft et al., 1987). The seed for F1 plants were space-planted approximately 122 cm apart in one-row plots, 6.1 m long by 1.8 m wide at the University of Georgia, Coastal Plain Experiment Station research farm in 1998. The seed for F2 plants were space-planted the following year approximately 30-cm apart in two-row plots, 24.4 m long by 1.8 m wide. Ten individual F2 plant selections (6% intensity) were made on the basis of pod shape, seed size, testa color, growth habit, maturity, pod yield, and grade characteristics. Because TSWV occurred naturally during these early-segregating generations (F2–F4), individual plants were selected for TSWV resistance.
In 2000 F3 plants were space-planted approximately 30 cm apart in two-row plots, 39.6 m long by 1.8 m wide. Twenty-five individual plant selections (10% intensity) were made using the same selection criteria as in the F2 population.
During 2001 the F4 was space-planted approximately 30 cm apart in two-row plots, 36.5 m long by 1.8 m wide. Twelve individual plant selections (1% intensity) were made on the basis of the same F2 and F3 selection criteria. Since S. rolfsii is naturally present every year as a soilborne disease pathogen, plants were also selected for white mold resistance as well by not applying any pesticides during the growing season.
In 2002 the F4:5 progeny rows were space-planted approximately 30 cm apart in two-row plots, 6.1 m long by 1.8 m wide. Progeny rows were selected using the same selection criteria as for earlier generations. Individual progeny rows were bulked as pure lines for subsequent preliminary yield tests. Georgia-07W was designated as GA 011514 for further testing.
Yield, grade, and other agronomic traits were determined from 14 replicated field trials conducted in randomized complete block designs over 3 yr (2004–2006) at three locations each year in Georgia. Plots consisted of two-rows 6.1 m long by 1.8 m wide with row spacing of 0.8 m between the rows within a plot and 1.0 m between rows on adjacent plots. Tests were planted between mid-April and mid-May at six seed 30.5 cm–1. Production practices included conventional tillage, fertilization, recommended pesticides and rates, irrigated, and nonirrigated. The field trials were in a 3-yr rotation following cotton (Gossypium L.) and corn (Zea mays L.). Entries were dug near optimum maturity each year on the basis of hull-scrape determination from adjacent border plots (Williams and Drexler, 1981).
Disease incidence of TSWV was first assessed at midseason, when TSWV is usually the only disease evident or at approximately 70 d after planting. Percentages (0–100%) of total disease incidence were scored before digging, which included primarily TSWV but also any soilborne disease present. A disease hit equaled one or more symptomatic plants within a 30.5-cm section of row.
Disease incidence of white mold was assessed in separate field trials conducted at a site with a long-term continuous history of high white mold disease pressure. Each year after peanut plots were dug and inverted, the number of white mold hits were determined as one or more infected plants in a 30.5-cm section of row.
After digging and picking, pods and seed were dried with forced warm air to 6% moisture. Pod samples were then hand-cleaned over a screen table before weighing for yield, shelling, and grading. In the grading process, total sound mature kernels (TSMK) equal the sum of sound mature kernels (SMK) and sound splits. Sound mature kernels equals the percentage of sound mature seed excluding damaged and split seed riding a minimum slotted screen size of 6.35 mm in width. Dollar values were calculated on USDA peanut loan schedules for each crop year and were based on yield and grade factors to obtain a gross dollar value return per hectare.
Data for each variable were subjected to analysis of variance. Waller–Duncan's Baysean t test (k-ratio = 100) was used for mean separation involving three or more entries (Table 1
). For only two entries, an LSD t test was used for mean separations (Tables 2–4
).
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Georgia-07W is a large-seeded runner market type peanut cultivar belonging to subspecies hypogaea botanical variety hypogaea because it has predominantly the following combined characteristics: flowers lacking on the main stem, alternate branching patterns, prostrate or runner growth habit, profuse branching, and two seeds per pod (Hammons, 1973; Krapovickas and Gregory, 2007).
In general, the cultivated peanut has an indeterminate fruiting pattern. Georgia-07W is distinctively different from C-99R in having a medium vs. late maturity profile, respectively. Georgia-07W matures about 2 wk earlier than C-99R in southern Georgia. Georgia-07W is also distinctively different from Georgia Green in having a darker green leaf color (Royal Hort. Soc. 139A vs. 137C) and a tan vs. pink testa color, respectively.
Georgia-07W is similar to C-99R and larger than Georgia Green in pod and seed size (Table 1). However, it is similar to Georgia Green in medium maturity (approximately 140 d), whole and partial blanchability (99 vs. 99%, not significant), oil content (50 vs. 50%, not significant), and excellent roasted peanut flavor intensity units (5 vs. 5, not significant). From 1986 to 2000 across multiple locations in the United States (Pattee et al., 2003), Georgia Green was found to have a similar sensory roasted peanut flavor attribute as the all-time peanut industry standard runner-type cultivar, Florunner (Norden et al., 1969). In the same study, Georgia Green was also found to be among the highest in breeding value as a parent for roasted peanut and sweet attributes as determined by the Best Linear Unbiased Prediction model.
Averaged over 14 tests conducted at three locations in Georgia during the past 3 yr (2004–2006), Georgia-07W was found to be significantly (P 
0.05) lower in TSWV incidence and total disease (TD) incidence and significantly (P 0.05) higher in pod yield, TSMK grade, and dollar value return per hectare compared with Georgia Green and C-99R (Table 1). During 2005 and 2006 at two locations in Georgia when planted early (mid-April) to increase TSWV disease pressure, Georgia-07W was found to be among the lowest in TSWV incidence and TD incidence, and highest in pod yield, TSMK grade, and dollar value return per hectare compared with 17 runner genotypes in 2005 and 21 runner genotypes in 2006.
During 2005 Georgia-07W was included in the Uniform Peanut Performance Tests conducted in Alabama, Florida, Georgia, North Carolina, Oklahoma, Texas, South Carolina, and Virginia. When averaged across all 10 U.S. test locations, Georgia-07W was found to be among the highest in yield and grade (Branch et al., 2006). Thus, Georgia-07W has a wide range of adaptability among these eight peanut-producing states.
Averaged across 13 field tests conducted at multiple locations in Georgia during 4 yr (2003–2006), Georgia-07W was found to have greater (P 0.05) percentage of U.S. large fancy grade pods than Georgia Green (Table 2). Georgia-07W had a higher percentage of pods than Georgia Green in the 
15.08-mm U.S. jumbo grade and 13.49-mm U.S. fancy grade but lower percentage in the <13.49-mm size distribution using federal–state inspection services (FSIS) pod presizer.
After pod presizing, the same pod samples were shelled according to FSIS standard procedures (USDA-Agricultural Marketing Service, 1998) to determine shelling outturn. Georgia-07W was also found to have greater (P 0.05) percentage of U.S. jumbo kernels but lower percentage of U.S. medium and U.S. No. 1 kernels than Georgia Green (Table 3). However, Georgia-07W was found to be similar to Georgia Green in percentage of SMK, other kernels, damage kernels, total meat, and total hull content.
During 4 yr (2004–2007) in field trials conducted at a site with a long-term history of high white mold disease pressure, Georgia-07W was found to be lower (P 0.05) in white mold incidence and higher in pod yield than the resistant female parent, C-99R (Table 4). Georgia-07W was purposely dug later in 2006 but still was found to be similar to C-99R in disease incidence and higher in yield. Across multiple years, Georgia-07W exhibited a high level of resistance to white mold caused by the soilborne pathogen S. rolfsii. These results agree with previous reports (Branch and Csinos, 1987; Branch and Brenneman, 1993) for using both low disease incidence and high yield performance for evaluation of white mold resistance.
Availability
U.S. Plant Variety Protection is pending for Georgia-07W. Breeder seed of Georgia-07W will be maintained by the University of Georgia, Coastal Plain Experiment Station at Tifton, GA. Foundation seed stock will be available from the Georgia Seed Development Commission, 2420 S. Milledge Ave., Athens, GA 30605. Small quantities of seed may be obtained from the corresponding author for at least 5 yr for research purposes only. Recipients of seed are asked to make appropriate recognition of the source if Georgia-07W is used in the development of a new cultivar or germplasm line.
Footnotes
All rights reserved. No part of this periodical may be reproduced or transmitted in any form or by any means, electronic or mechanical, including photocopying, recording, or any information storage and retrieval system, without permission in writing from the publisher. Permission for printing and for reprinting the material contained herein has been obtained by the publisher.
Received for publication December 4, 2007.
References
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