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Effects of Nitrogen Level on Growth, Nutrient Uptake, and Nitrogen Use Efficiency in Cotton Seedlings

Dandan Chen , Zhao Zhang , Honghong Wu , Guozheng Yang

Abstract

Cotton, as a globally important economic crop, has high nitrogen (N) demand but low N uptake and utilization efficiency (NUE). optimizing N input by improving NUE represents a critical challenge for sustainable cotton production. In this study, six N levels (0, 0.04, 0.4, 1, 4, 8 mM Ca(NO3)2, designated as N0, N0.04, N0.4, N1, N4, and N8, respectively) were applied to examine their effects on morphology, biomass, nutrients absorption, and NUE at four treatment duration. The results showed that seedling growth and nutrient accumulation first increased and then decreased with increasing N levels. The optimal N ranges for seedling growth at 7, 14, 21 and 28 d were 0.4, 0.4-1, 1-4 and 4-8 mM Ca(NO3)2, respectively. Under optimal N, seedlings achieved maximum accumulations of N, P, K, and Ca (55.8, 8.8, 64.9, and 26.2 mg/plant at 28 d, respectively), while maintaining consistent N:P:K:Ca ratios of approximately 1:0.2:1.2:0.5 across seedling stage. Under low N, nutrients were preferentially allocated to roots, promoting root growth. NUE exhibited positive correlations with root traits and nutrient proportion, whereas shoot traits showed positive associations with nutrient accumulation and shoot nutrient proportion. These findings provide a theoretical basis for scientific fertilization, and establish a theoretical foundation for understanding the physiological mechanisms of efficient N use in cotton

FP25145  Accepted 15 August 2025

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