DATA - Self-thinning principle in reduced light and suboptimal nitrogen nutrition in miniature Brachiaria swards
Description
This dataset contains the experimental data underlying the study Self-Thinning Principle in Reduced Light and Suboptimal Nitrogen Nutrition in Miniature Brachiaria Swards. The data quantify how light limitation (45% shade) and nitrogen deficiency (50 kg N ha⁻¹) alter the size–density compensation (SDC) mechanism, the leaf area index (LAI), orthogonal distance to the −3/2 self-thinning line, and dry-matter production of Brachiaria brizantha cv. Marandu maintained under constant canopy heights. The dataset supports the evaluation of allometric shifts, morphological plasticity, productivity responses, and deviations from the theoretical Yoda’s −3/2 rule under controlled resource constraints. Experimental design The experiment followed a randomized block design with three replicates. Factors: Environmental condition (3 levels): MA – Optimal: full light + adequate N (300 kg N ha⁻¹) MA-N – Nitrogen deficit: full light + 50 kg N ha⁻¹ MA-L – Reduced light: 45% shade + 300 kg N ha⁻¹ Management height (4 levels): 12 cm, 24 cm, 36 cm, 48 cm Sampling lasted 50 days (January–March 2023), with weekly cuts to maintain height and periodic destructive measurements of morphology and leaf area. File YODAIA.xlsx – Main analysis dataset Contains all variables used for: Log–log size/density regressions LAI and morphological analyses Orthogonal distance to the −3/2 line Dry-matter production calculations Nitrogen Nutrition Index (NNI) Sheets and Variables Sheet “Data” – Primary dataset (one row per environment × height × block) Variable Description Env Environmental treatment (MA, MA-N, MA-L) Height Target sward height (12, 24, 36, 48 cm) Block Experimental block (1–3) TPD Tiller population density (tillers m⁻²) TS (g) Mean tiller size (g tiller⁻¹) LogTPD Base-10 log of TPD LogTS Base-10 log of TS LAI Leaf area index SLA Specific leaf area (cm² g⁻¹) R Leaf area:volume ratio per tiller DM Cumulative dry-matter production (g DM m⁻² day⁻¹) NNI Nitrogen Nutrition Index Distance Orthogonal deviation from the theoretical −3/2 self-thinning line Prod_rate Daily production rate (if included) Units and data quality Units are included in each column header. All continuous variables were screened for completeness, consistency and outliers. Logarithmic variables were computed only from positive values. Shading structures were monitored for constant 45% light reduction; nitrogen applications were verified by mass balance. Keywords Self-thinning rule; Yoda’s law; allometry; size–density compensation; forage productivity; nitrogen limitation; light limitation; Brachiaria; functional traits; canopy structure. Funding & acknowledgments This dataset was generated within the doctoral research conducted at Santa Catarina State University (UDESC/CAV). Funding was provided by FAPESC (projects TR 1417, TR 813, TR 543).
Files
Steps to reproduce
The dataset was generated from a controlled field experiment designed to quantify size–density compensation under contrasting light and nitrogen availability in Brachiaria brizantha cv. Marandu. Miniature swards were established plots and maintained at fixed target heights (12, 24, 36 and 48 cm) using twice-weekly clippings. Three environmental treatments were applied: (1) optimal conditions (full light, 300 kg N ha⁻¹), (2) nitrogen deficit (full light, 50 kg N ha⁻¹), and (3) reduced light (45% shade, 300 kg N ha⁻¹). Nitrogen was applied as urea; shading was imposed with black polypropylene mesh calibrated with a ceptometer (AccuPAR LP-80). Tiller population density (TPD) was counted in fixed quadrats. Mean tiller size (TS) was determined from destructive sampling, followed by oven-drying at 65°C. Leaf area was measured with a LI-3100C area meter; specific leaf area (SLA) was calculated as leaf area per gram of leaf dry mass. Leaf area index (LAI) was obtained from the product of leaf dry mass and SLA. The nitrogen nutrition index (NNI) was derived from critical N-dilution curves. Daily dry-matter production was computed from sequential harvests and corrected for regrowth interval. For allometric analyses, log₁₀-transformed TPD and TS were regressed to evaluate the size–density slope; orthogonal distances to the theoretical −3/2 line were calculated using trigonometric projection. Raw variables, transformed variables and derived metrics are included in the dataset. All steps can be reproduced using standard agronomic, morphological and allometric procedures described in the manuscript and supplementary methods. For more information, please refer to:
Institutions
- Universidade do Estado de Santa Catarina