The improvement of peanut (Arachis hypogaea L.) oil quality has long been an objective of the Florida breeding program, since it influences the shelf-life and nutritional quality of manufactured products. Fatty acid distribution of the peanut genotypes (228 in 1984 and 298 in 1985) from the Gainesville and Marianna locations was determined by gas-liquid chromatography. A wider range in fatty acid composition, especially in oleic and linoleic acids, was found among these genotypes than that reported previously in the literature for the cultivated peanut. Two closely related experimental lines (435-2--1 and 435-2--2) had 80% oleic and 2% linoleic acid, with iodine values of 74. For the Florida breeding lines, iodine values of the oil ranged from 74 to 107 and the oleic/linoleic (O/ L) ratios from 0.9 to 35:l. Florunner, by comparison, has an iodine value of 95 and an O/L ratio of slightly less than 2. The oleic acid content of the different experimental lines ranged from 37% to 80%, and the linoleic acid content from 2% to 43%. The magnitude of this variability permits the development of peanut cultivars with a range of oil composition for improved nutritional and industrial purposes. All the oil quality factors were highly significantly affected by genotype, and all but three of the factors were significantly affected by season.

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Five peanut (Arachis hypogaea L.) genotypes, Southern Runner, Dixie Runner, Florunner, UF82206, and UF714021, were grown for three years, 1982–1984, near Gainesville, Florida without fungicide applications. Three digging dates, averaging 105 days after planting (DAP), 118 DAP, and 132 DAP, were used each year to determine the effects of early harvest as a management practice for peanut production under leafspot pressure. The different digging dates had no effect on fatty acid composition of the five genotypes, and had only minimal effect on the oil content and iodine value. The largest oil quality differences in this study were due to differences among genotypes and year-to-year variation. The earliest digging date tended to reduce market grade characters, but major pod yield differences were the result of genotype × digging date interactions. Genotypes with little or no resistance to leafspot diseases, such as Florunner and UF 714021, produced nearly 3000 kg/ha without leafspot control up to 118 DAP and then had sharp yield decreases, while resistant genotypes such as Southern Runner and UF 82206 continued to produce pod yields of 3000 kg/ha or higher up to 132 DAP.

The effects of leafspot disease (causal organisms Cercospra arachidicola Hori and Cercosporidium personatum (Berk. Q Curt.) Deighton) on the yield and market quality of peanut (Arachis hypogaea L.) must be understood to more accurately assess genetic potential of breeding lines. Seven peanut genotypes were grown without fungicide application at two locations, Gainesville and Marianna FL, for three years and harvested at three biweekly dates. Consistent pod yields near 5OOO kg ha-' were obtained for leafspot resistant breeding line 94 at Marianna when it was harvested later than 142 days after planting (DAP). Other resistant lines also reached maximum production at late harvests, even though disease incidence increased for all resistant lines. Highest yields of susceptible lines occurred ca. 120 DAP, with the susceptible cultivar Florunner producing over 3400 kg ha' at Marianna. Although disease pressure on the susceptible lines was heavy at 120 DAP, pod yields did not decline until later harvests, indicating that a major effect of the leafspot disease was the loss of pods already produced. Increased disease pressure was poorly correlation with seed size or total sound mature kernels in either resistant or susceptible lines. ~~ ~Key Words: Groundnut, maturity, disease resistance, Arachis hypogaea L., digging date.Worldwide, early and late leafspot (Cercospora arachidicola Hori and Cercosporidium persona turn (Berk. & Curt.) Deighton, respectively) are two of the most serious diseases of peanut. The diseases can cause yield reductions of more than 50% if fungicides are not used (5,lO). Although effective fungicides are available, most notably chlorothalonil, their use increases peanut production costs. The development of peanut cultivars with resistance to early and late leafspot would lower both production risks and costs. Therefore this is an important goal in many breeding programs (6).Correlations have been reported between leafspot resistance and late maturity (2, 4, 7, 11). When leafspot resistant germplasm is used in a crossing program with agronomically acceptable lines, the maturity of segregates varies considerably. Choosing the correct harvest date for breeding lines is a dficult process, because precise methods for determining maturity require destructive sampling techniques and cannot be used on small plots (6). Also, the less resistant material in a test may become so severely affected by the leafspot organisms that yield reductions take place prior to appropriate maturity dates. This research was conducted to accurately assess the effects of harvest dates on disease pressure, agronomic performance, and market grade quality for seven breeding lines with various levels of resistance to leafspot diseases, especially late leafspot (C. personaturn). ' (1981, 1982, and 1983) were spaced at two-week intervals, with the first digging date at Gainesville 106, 106, and 104 days after planting (DAP), and 122, 114, and 117 DAP for the Marianna test. The Grst harvest at each location was made when leaf...