Alterations in plant architecture and physiology allow maize to sustain yield after early defoliation

Maize (Zea mays L.) responses to early defoliation are shaped by
genotype-specific physiological and morphological traits, and
understanding these responses is essential for improving both breeding
strategies and agronomic management. We evaluated the effects of complete
canopy defoliation at the V4 vegetative stage on shoot growth, root
morphology, chlorophyll fluorescence, and yield stability in four maize
genotypes. The dataset comprises individual experimental-unit measurements
of growth traits, root characteristics, chlorophyll fluorescence
parameters, and yield components collected under defoliated and
non-defoliated conditions. Early defoliation consistently reduced total
leaf area, plant height, and root biomass, while increasing root tissue
density and harvest index across genotypes. Despite these structural
adjustments, key yield components, including grain yield, were largely
maintained. Chlorophyll fluorescence measurements revealed clear
genotype-specific physiological responses over time. Under defoliation,
the hybrid KWS9606 VIP3 showed enhanced photochemical efficiency at 9 days
after defoliation (DAD) and increased photochemical quenching (qP) at 17
and 24 DAD, whereas BRS1010 exhibited consistently higher qP under
defoliation across all sampling dates, indicating greater openness of PSII
reaction centers. In contrast, NPQ responses varied among genotypes
without a consistent pattern, reflecting distinct energy dissipation
strategies, while NS90 PRO2 displayed limited physiological sensitivity to
defoliation. Multivariate analysis further highlighted trade-offs between
morphological and physiological traits, with root-related variables
contributing most strongly to the first principal component and
chlorophyll fluorescence parameters influencing the second. Overall, these
data document contrasting response strategies among maize genotypes
exposed to early defoliation and provide a robust basis for investigating
mechanisms underlying tolerance to foliar loss while maintaining yield
stability.