DOI: 10.5061/dryad.crjdfn3cz
title: Neighbor-detection causes shifts in allocation across multiple organs to prepare plants for light competition

description: To maximize their fitness, plants have to adjust their allocation strategy
 according to their abiotic and biotic environments. Plants can use the
 ratio of red to far-red light (R:FR) to sense neighbors, allowing them to
 modify their growth in response to aboveground competition. In this study,
 we used supplemental FR light to artificially lower the R:FR of the lower
 leaves of common sunflowers (Helianthus annuus) to examine how plants
 change their growth in response to the threat of neighbors. We combined
 this treatment with a nitrogen fertilization treatment to investigate how
 responses to neighbor-detection interact with nitrogen limitation. Plants
 grown in low R:FR increased in height at the expense of root growth,
 resulting in nitrogen limitation that restricted leaf growth. However, we
 found that plants reduced their nitrogen investment into leaves in low
 R:FR. By weakening the nitrogen sink strength of these lower leaves before
 they experienced low photosynthetically active radiation, plants were able
 to preemptively allocate nitrogen to leaves higher in the canopy. Plants
 responded to the perception of neighbors by simultaneously diverting
 resources from root growth to stem elongation and from leaves threatened
 by neighbors to leaves that would pose a threat to neighbors. This
 whole-plant response to neighbor-detection enables plants to change their
 allocation in a way that simultaneously manages their limited nitrogen and
 prepares them for future light competition.
description: # Neighbor-detection causes shifts in allocation across multiple organs to
 prepare plants for light competition
 [https://doi.org/10.5061/dryad.crjdfn3cz](https://doi.org/10.5061/dryad.crjdfn3cz) This dataset tracks the dimensions, height, and SPAD of every leaf on common sunflower plants (Helianthus annuus var. Solara F1) over a five week experimental period. In this experiment, plants were in one of four treatment groups: no nitrogen fertilization and no supplemental far-red light, no nitrogen fertilization and supplemental far-red light, nitrogen fertilization and supplemental far-red light, or nitrogen fertilization and no supplemental far-red light. This is complemented with the dry mass of the leaves, roots, stem, and flower buds for each individual at the end of the experiment and a validation dataset used to convert SPAD measurements into leaf nitrogen per area. ## Description of the data and file structure Plant IDs are given by the row (A-H) and a numerical ID (1-15). Plants in rows A, B, G, and H were in the supplemental far-red treatment groups. Plant IDs with an odd number were fertilized with nitrogen in rows A, C, E, and G, while Plant IDs with an even number were fertilized with nitrogen in rows B, D, F, and H. Leaf IDs are consistent for each plant over the five measurements. Lengths, widths, and heights are measured in centimeters. Leaf area was calculated using an equation that converts leaf dimensions into area, with units of square centimeters. There are three csv files: **Uyehara_FE-2024-00303_Leaves.csv** contains the timeseries of leaf data for each plant. The columns and their descriptions are as follows: Index = row index Week = the week of measurement Plant_ID = unique identifier for individual plants Leaf_ID = unique identifier for individual leaves on a plant) Length = length of leaf in cm Width = width of leaf in cm Height = height of petiole insertion of leaf in cm SPAD = average of five SPAD readings distributed over the leaf blade Proportion_Dead = the estimated proportion of the leaf area that was dead Nitrogen = indicator of whether the plant received nitrogen fertilizer (1 for yes, 0 for no) Far-Red = indicator of whether the plant received supplemental far-red light (1 for yes, 0 for no) Area = area of leaf using an equation to transform leaf dimensions into area in cm^2 **Uyehara_FE-2024-00303_Final_Mass.csv** contains the final dry mass of each plant, divided by organ type. The columns and their descriptions are as follows: Plant_ID = unique identifier for individual plants Stem = mass of stem, including petioles in grams Flower = mass of all floral buds in grams Leaves = mass of leaves in grams Roots = mass of roots in grams Nitrogen = indicator of whether the plant received nitrogen fertilizer (1 for yes, 0 for no) Far-Red = indicator of whether the plant received supplemental far-red light (1 for yes, 0 for no) Total_Mass = sum of stem, flower, leaf, and root mass in grams **Uyehara_FE-2024-00303_SPAD_Validation.csv** contains data for 36 leaves grown in different light conditions and then measured and analyzed for their nitrogen concentration to validate the relationship between SPAD and leaf nitrogen per area. The leaves were measured when living then dried and weighed. For chemical analysis, the leaves were ground into a powder and a small amount was used to find the nitrogen concentration. The columns and their descriptions are as follows: Sample Name = name of leaf sample Light = the light environment the plant was grown in (low, high, or greenhouse) Length (cm) = length of leaf in cm Width (cm) = width of leaf in cm Weight (g) = dry weight of leaf in g SPAD = average of five SPAD measurements Sample Weight (ug) = mass of sample used to calculate nitrogen concentration in ug Nitrogen Concentration = concentration of nitrogen in the analyzed sample as a percent