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<p>This study investigated how elevated potassium (K) supply influenced the physiological and biochemical responses of <i>Pinus caribaea</i> var. <i>hondurensis</i> and <i>Pinus taeda</i> seedlings under two contrasting water availability conditions. The research aimed to determine whether higher K levels would affect the acclimation mechanisms to drought stress. A 90-day greenhouse experiment was conducted, involving two water conditions (well-watered and water deficit) and two soil K levels (low and high). Key parameters analyzed included plant biomass, leaf water potential, carbon (C), and nitrogen (N) isotopic leaf composition (δ<sup>13</sup>C and δ<sup>15</sup>N ‰), chlorophyll fluorescence parameters, and chlorophyll-<i>a</i> and anthocyanin indexes. High potassium supply was associated with reduced nutrient use efficiency (K, Ca, Mg, P) in well-watered <i>Pinus</i> spp. seedlings. The analysis indicated impaired photosynthetic activity under elevated potassium levels, as evidenced by reductions in maximum fluorescence (F<sub>m</sub>), quantum efficiency of photosystem II (F<sub>v</sub>/Fₘ), normalized difference vegetation index (NDVI), and chlorophyll and anthocyanin levels. Regardless of the K-fertilization regime, water deficit conditions were linked to a significant decrease in leaf water potential (Ψ<sub>w</sub>) and an increase in leaf δ<sup>13</sup>C. Higher K supply did not alleviate drought sensitivity and negatively affected plant photochemistry in both <i>Pinus</i> species. This research underscores the importance of maintaining optimal nutritional balance to enhance the effectiveness of management strategies, particularly those aimed at improving tolerance to drought stress.</p>

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High Potassium Supply Detrimentally affects Nutrient use Efficiency and Photochemistry in Pinus spp. Seedlings

  • 期刊论文

  • 发表日期：

    2025年2月14日

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  • Deborah Rodrigues de Souza Santos,
  • Nikolas de Souza Mateus,
  • Cecilia Pereira Theodoro Chotti,
  • Clíssia Barboza Mastrangelo,
  • Mario Tomazello Filho,
  • José Lavres

摘要

This study investigated how elevated potassium (K) supply influenced the physiological and biochemical responses of Pinus caribaea var. hondurensis and Pinus taeda seedlings under two contrasting water availability conditions. The research aimed to determine whether higher K levels would affect the acclimation mechanisms to drought stress. A 90-day greenhouse experiment was conducted, involving two water conditions (well-watered and water deficit) and two soil K levels (low and high). Key parameters analyzed included plant biomass, leaf water potential, carbon (C), and nitrogen (N) isotopic leaf composition (δ13C and δ15N ‰), chlorophyll fluorescence parameters, and chlorophyll-a and anthocyanin indexes. High potassium supply was associated with reduced nutrient use efficiency (K, Ca, Mg, P) in well-watered Pinus spp. seedlings. The analysis indicated impaired photosynthetic activity under elevated potassium levels, as evidenced by reductions in maximum fluorescence (Fm), quantum efficiency of photosystem II (Fv/Fₘ), normalized difference vegetation index (NDVI), and chlorophyll and anthocyanin levels. Regardless of the K-fertilization regime, water deficit conditions were linked to a significant decrease in leaf water potential (Ψw) and an increase in leaf δ13C. Higher K supply did not alleviate drought sensitivity and negatively affected plant photochemistry in both Pinus species. This research underscores the importance of maintaining optimal nutritional balance to enhance the effectiveness of management strategies, particularly those aimed at improving tolerance to drought stress.