Sound Splits as Influenced by Seed Size for Runner and Virginia Market Type Peanut Shelled on a Reciprocating Sheller

Abstract

The objective of this study was to examine peanut (Arachis hypogaea L.) kernel percent sound splits as a function of sound mature kernel seed size when shelled on a reciprocating sheller. Data were compiled from a total of 139 field experiments conducted in the Virginia-Carolina region and Georgia from 2005 to 2020. Runner and Virginia peanut market types were graded according to United States Department of Agriculture (USDA) standards using standard sheller screens with upper grid sizes corresponding to the red pan from the pre-sizer of 10.3 × 19.1 mm (26/64 × 3/4 ″) and 13.5 × 25.4 mm (34/64 × 1 ″) with minimum bar grid clearances of 8.7 (11/32 ″) and 12.7 mm (1/2 ″), respectively. A subset of runner market type samples was graded using the Virginia sheller screen. Grade data per market type and sheller screen was analyzed separately. Among runner market types shelled with the standard runner-type screen, percent sound splits increased linearly with increasing seed size at the logit rate of 1.16 per sound mature kernel g (p < 0.001). Sound splits for Virginia and runner market types shelled on the standard Virginia-type screen did not significantly vary by kernel size (p = 0.939 and 0.687, respectively). Extra-large kernels (proportion) for Virginia types linearly increased with seed size at 1.91 per sound mature kernel g (logit scale) (p < 0.001). Runner market types sized 75 to 91 g/100 sound mature kernels (605 to 500 seed/lb) were estimated to have a 50% probability of a 2.3 to 4.5% or greater increase in sound splits when shelled with the standard runner-type screen compared to runner-type seed sized 55 g/100 sound mature kernels (820 seed/lb), respectively, equivalent to a potential deduction increase of 1.8 to 4.4 USD /1000 kg. For both Virginia and runner market types, seed weight linearly increased with pod weight at 0.169 and 0.195 g/g (p < 0.001), respectively. Results from this study may be used as a reference to suggest runner-type seed sizes above which larger reciprocating sheller screen utilization in line with USDA grading practices is warranted to reduce mechanically induced sound splits during grading and subsequent economic deduction penalties for corresponding farmer stock peanut.