干旱区生态环境知识资源中心

Understanding the effect of boron (B) on plant physiology will help to refine the diagnosis of B deficiency and improvement in B fertilizer recommendations for cotton (Gossypium hirsutum L.) growing areas. This study shows the testing of hypotheses "that application of B-fertilizer improves net photosynthetic rate (P-N) and water use efficiency (WUE) for cotton plant on a B-deficient soil [< 0.50 mg B kg(-1) hydrochloric acid (HCl)-extractable] in an arid environment". Thus, a permanent layout [two-year field experiment (2004 and 2005)] was conducted to study the impact of B fertilizer at 0, 1.0, 1.5, 2.0, 2.5, and 3.0 kg ha(-1) on gas exchange and electrolyte leakage (EL) characteristics of cotton crop (cv. ’CIM-473’). The soil at experimental site was alkaline (pH 8.1), calcareous [calcium carbonate (CaCO3 5.6%)], and silt loam (Typic Haplocambid). Boron use decreased EL of plant membrane (P <= 0.05), and increased PN, transpiration rate (E) and stomatal conductance (g(s)), while intercellular concentration of carbon dioxide (CO2; C-i) significantly decreased (P <= 0.05) during both experimental years. There was a positive, but non-significant effect of B concentration on chlorophyll content in plant leaves. Application of 3.0 kg B ha(-1) improved WUE up to 9.7% [4.62 mu mol (CO2) mmol(-1) water (H2O)] compared to control plants (4.21 [mu mol (CO2) mmol(-1) (H2O)]. Principal component analysis (PCA) of data indicates positive correlations between leaf B concentration and P-N, E, gs, and WUE, while a negative relationship existed between leaf B concentration and intercellular CO2 (C-i). This study showed that addition of B fertilizer in the B-deficient calcareous soil proved beneficial for growth and development for cotton crop by enhancing its WUE and gas exchange characteristics.