A method of classification based on color and morphological differences of the mesocarp is described for determining the developmental stages of fresh peanut [Arachis hypogaea (L) ‘Flo-runner’] pods. Developmental stages are designated as Classes 1-7, with each subsequently numbered class representing progressively greater degrees of maturity. For illustration each class is subdivided into one-quarter increments which are represented pictorially by beginning points. Because various combinations of classes and/or subclasses can be used, the system has inherent flexibility to accomodate the degree of refinement dictated by classification needs. Maturity determination by this method requires removal of a portion of the exocarp or epidermis to expose the pod mesocarp. The exocarp can be removed by sand blasting, gentle abrasion, or lightly scraping with a knife. Because removal of the exocarp is non-destructive to the remaining pod structure and enclosed seeds, the method has inherent advantages for use in commercial culture and in biological investigations requiring intact pods and/or seed.

A nondestructive peanut pod maturity classification method, Pod Maturity Profile (PMP), based on visual examination of the color and structural characteristics of pod mesocarp after partial removal of pod exocarp, was used to separate freshly harvested peanut pods into maturity classes. The separations made nondestructively were compared with those made by a method involving the examination of internal pericarp and testa characteristics. The groups separated by the two methods were closely related. In oil from the PMP classes, color decreased, free fatty acid content decreased, iodine value remained approximately constant, and oven stability of the extracted oil increased with increasing maturity. Total oil contents and fatty acid profiles had consistent but more complex relationships with maturity. The data indicate that the PMP method allows consistent and reproducible classification of peanut fruit maturity.

Florunner peanut pods (Arachis hypogaea L.) were sampled at nine weekly intervals from 92 to 148 days after planting (DAP) in crop year 1979. The fresh pods-were divided into six maturity categories according to the color and structure of the mesocarp. After drying, individual pods and seed for each maturity class and date were sized over a series of screen slots conforming to official grade standards. The cumulative distribution function (CDF) for the logistic distribution was used to quantlfy the cumulative percentage by weight of pods and seed which rode a designated screen. The parameters of the logistic CDF were regressed separately by maturity class as functions of plant age. These relationships provide a mathematical approach for a better understanding of the influence of pod maturity and plant age on pod and seed sizes.

The differential response of peanut (Arachis hypogaea L.) cultivars to soil applications of Ca has been established for many years. Recent research reports, however, have indicated that peanut cultivars respond similarly to Ca application. This may result in part from new peanut cultivars differing in their response to Ca. Experiments were therefore conducted on a low Ca soil to measure responses of three commonly grown peanut cultivars to soil‐applied Ca. Gypsum was applied at 0 and 1,121 kg/ha in a split‐plot design using ‘Florunner,’ ‘Florigiant,’ and ‘NC‐Fla 14’ peanut cultivars. Other nutrients were applied uniformly. Yield, sound mature kernels (SMK), extra large kernels (ELK), and % N and oil in the seed were measured. Results from this experiment show that gypsum had no effect on yield or sound mature kernels of Florunner peanuts. Florunner peanuts produced higher yields and grades than Florigiant or NC‐Fla 14, regardless of treatments. Gypsum application to Florigiant and NC‐Fla 14 peanuts increased yields, sound mature kernels, and extra large kernels. In general, gypsum increased the % oil in all cultivars. Florigiant contained less oil than the other cultivars. Nitrogen content of the seed of all cultivars was reduced by gypsum application. These data indicate that on low Ca soils Florunner peanuts can produce higher yields and quality with or without gypsum, while Florigiant and NC‐Fla 14 need gypsum fertilization to increase yield and improve quality.