Physiology

Abstract

The relationships between the critical nutrient level (CNL) of growth and physiological processes were studied for Mn, Zn, and Al on photosynthesis (P_N), chlorophyll (Chl), carbonic anhydrase (CA), and nitrate reductase (NR) in wheat (Triticum aestivum L.), soybean [Glycine max (L.) Merr.], and cotton (Gossypium hirsutum L.). The Mn critical deficiency levels (CDLs) for soybean growth, PS, Chi and NR were 0.18, 0.20, 0.18 and 0.12 mmol/kg, respectively. In wheat, the Mn CDLs for growth, P_N and Chi were 0.23, 0.30, and 0.14 mmol/kg, respectively. The Zn CDLs for soybean growth, P_N, and carbonic anhydrase were 0.18, 0.15, and 0.23 mmol/kg, respectively. In cotton, the CDLs for growth, P_N, and Chl were 0.23, 0.20, and 0.21 mmol/kg. The Mn critical toxicity levels (CTLs) for soybean growth, P_N, Chi and transpiration were 7, 19, 19, and 24 mmol/kg, respectively. The Al CTLs for wheat growth, P_N and Chi were 0.12, 0.15, 0.13 mmol/kg, respectively. The CNLs for growth and physiological processes were similar and distinguished nutrient stress from non‐stress in most cases.

Key words:

• Critical deficiency level
• critical toxicity level
• cotton
• soybean
• wheat
• Al
• Mn
• Zn