DOI: 10.5281/zenodo.17183256
title: Shade avoidance restricts soybean breeding progress and increases herbivore susceptibility

description: High planting densities expose field crops to competition for light, which typically induces shade avoidance responses such as stem elongation. While adaptive in natural environments, these responses can lower yield and increase susceptibility to stress in agricultural systems. We tested whether soybean breeding over the past century has altered shade avoidance and associated trade-offs. Twenty-one Canadian cultivars released between 1922 and 2018 were grown in pots under either control or shade-avoidance-inducing light conditions, achieved by altering reflected light spectrum without reducing photosynthetic radiation. Plants exposed to shade-avoidance inducing light grew taller and suffered greater thrips damage, consistent with expectations of increased stem elongation and reduced defense. More recent cultivars showed higher susceptibility to thrips than older ones. Breeding progress in seed yield was driven largely by greater biomass allocation to seeds and a reduction in branching. However, under shade-inducing light, the yield improvements were smaller, pointing to shade avoidance as a limiting factor. Our results indicate that while soybean breeding has improved yield and shifted morphology towards ideotypes suited for high-density stands, persistent shade avoidance responses constrain breeding progress and increase herbivore susceptibility. Breeding strategies that reduce sensitivity to neighbor cues may therefore improve soybean productivity and resilience.
description: Description of the elements in shade_avoidance_soybean_field_data_2024.csv

The harvest date for the growing stage can be found in the following file harvest_dates_shade_avoidance_soybean_2024.xlsx

pot_numb = each pot in the experiment got a number

height = height of the plant in cm

growth_stages = Growing stages of the soybeans at the moment of data collection

shoot_biomass = above ground biomass in gram

root_biomass = belove ground biomass in gram

shoots = number of side shoots

yield = seed number in gram per plant

genotypes = name of the soybean cultivar

treatments = treatment using the green or transparent filter

reps_numbers = number of the replicate

SW_ID = internal seedbank ID for genotypes

ID = ID of the plant in the experimental setup

YOR = year of release of the cultivar (public release)

shoot_root = ratio of the shoot biomass to the root biomass

biomass = total biomass of shoot and root biomass

sb_h = shoot biomass divided by height

y_sb = yield divided by shoot biomass

y_rb = yield divided by root biomass

y_b = yield divided by total biomass

bio_pro_shoot = biomass divided by numbers of shoots

yield_shoot = yield divided by numbers of shoots

stover = shoot biomass minus the yield
description: Description of the elements in Thrips_damage_shade_avoidance_soybean_2024.csv

The thrips damage data was collected on the 9th of July 2024.

Reihe = position in the row of the pot

Spalte = position in the column of the pot

SW_ID =  internal seedbank ID for genotypes

treatments =  treatment using the green or transparent filter

reps_numbers = number of the replicate

genotypes = name of the soybean cultivar

ID_pot = ID of the plant in the experimental setup

pot_numb = each pot in the experiment got a number

Thripsschaden = damage caused by thrips ranging from 0 (no damage) to 3 (deformed leaves)
description: Description of the elements in harvest_dates_shade_avoidance_soybean_2024.xlsx

genotypes = name of the soybean cultivar

SW_ID = internal seedbank ID for genotypes

sowing = sowing date of the plants

harvest_VC = harvest date at growth stage VC

harvest_R2 = harvest date at growth stage R2

harvest_R6 = harvest date at growth stage R6

harvest_R8 = harvest date at growth stage R8