DOI: 10.5061/dryad.3tx95x6f3
title: Novel digital assessment technique used to describe peanut nodulation life history

description: Biological nitrogen fixation (BNF) in legume root nodules is an important
 source of N globally. Typically, the quantification of BNF is an estimate
 of N fixation through techniques such as an acetylene reduction assay or
 isotopic signatures. However, these methods have large logistical
 limitations, and do not allow for assessments of the nodule morphology or
 the nodulation process itself, knowledge that is important to fully
 understand the BNF process. To provide an updated method of nodulation
 assessments, peanut (Arachis hypogaea L.) nodules were sampled from a
 two-year field trial and quantified using scanned images of excised
 nodules, allowing digital assessment of nodule number and size. Further, a
 digital color analysis method was developed to assess internal nodule
 color (a known proxy for nodule BNF activity and senescence). To apply and
 validate the new method, peanut nodulation trait data was used for an
 exploration of the relationship between nodulation traits, plant
 physiological processes, and nitrogen status in the plant, followed by a
 nodulation life history analysis. The nodulation assessment method was
 validated by strong correlation with measures of peanut tissue N, biomass,
 photosynthetic function, and yield. Nodulation life history data suggest
 novel findings regarding differences in the development of nodules between
 taproots and lateral roots, contrary to the previous understanding of
 peanut nodulation life history. This new nodulation assessment method can
 provide further insight into the BNF process by allowing the collection of
 detailed data in a relatively simplified manner in field conditions. This
 dataset represents the nodulation and other variable data collected for
 this study.
description: Data was collected in a field study in Live Oak, Florida in
 peanut using a novel nodulation assessment technique at 40, 60, 80, 100,
 120, and 140 DAP in 2016 and 2017. This technique used digital imaging
 software to calculate the nodulation density (nodules per cm root), nodule
 size, average internal redness of nodules (activity), and average internal
 greenness of nodules (senescence). Nodule biomass was also measured, as
 was root, shoot, and pod biomass of peanut plants. The N mass in these
 tissue samples was also calculated. In addition,
 chlorophyll <em>a </em>fluorescence data was collected as a
 correlate. Data was collected across three treatment levels in a RCBD,
 with data considered across these three treatment levels for correlation
 purposes. The treatment levels relate to the N application rate to corn in
 the season before the peanut was grown and sampled in the field. These
 nodulation data have been collected using a novel moethod developed for
 this purpose. 
description: Missing values exist where sampling was physiologically
 impossible (i.e., peanut pods in the early season), or occassionally as
 the result of error or damage. Such instances are highlighted in yellow in
 the datasheet. See also "Appendix B" regarding missing values at
 80 DAP in 2016.