NH4+对不同基因型棉花幼苗K+吸收和利用的影响

溶液培养条件下研究了NH4+对棉花不同基因型幼苗干物质积累以及K+吸收和利用的影响。结果表明，NH4+在不同供钾条件下均显著降低了棉花幼苗的干重、钾吸收量和钾利用指数，低钾条件下（K+ 0.03 mmol/L）尤其如此。中等供钾（K+ 0.5 mmol/L）在一定程度上缓解了NH4+对棉花幼苗干物质积累以及K+吸收和利用的抑制； 充分供钾 （K+ 2.5 mmol/L）却未能在中等供钾的基础上进一步减轻NH4+的毒害作用。鲁棉研22苗期的干物质积累在不同供钾条件下受NH4+影响的程度均较153018品系大，这主要与其体内钾利用能力受NH4+影响较153018大有关。

Effects of NH4+ on K+ uptake and utilization of different cotton genotypes at seedling stage

In order to investigate the interaction of NH₄⁺ with K⁺ in cotton seedlings, an hydroponics experiment containing three K⁺ concentrations (0.03, 0.5, 2.5 mmol/L) combined with four NH₄⁺ concentrations (0, 0.5, 2.5, 5.0 mmol/L) was conducted to examine the responses of seedling growth, K⁺ uptake and utilization to NH₄⁺ with two cotton genotypes, Lumianyan 22 and 153018, differed in potassium efficiency in greenhouse. The results indicated that NH₄⁺ significantly inhibited seedling growth, K⁺ uptake and utilization irrespective of K⁺ level in solution. However, K⁺ at 0.5 and 2.5 mmol/L concentration could alleviate the impact of NH₄⁺ similarly, compared to 0.03 mmol/L K⁺. For example, dry matter of Lumianyan 22 was reduced to only 76.5% of control by 0.5 mmol/L NH₄⁺ under 0.03 mmol/L K⁺, and to 88.4% and 89.2% of control under 0.5 and 2.5 mmol/L K⁺ respectively. In addition, the magnitude of the NH₄⁺ effect differed among genotypes. Lumianyan 22, more sensitive to K⁺ deficiency than 153018, was affected by NH₄⁺ to a larger extent than the latter. Further analysis showed that NH₄⁺ had the same effect on K⁺ accumulation of Lumianyan 22 and 153018, but reduced Lumianyan 22 K utilization index more than the latter, which may have contributed to higher sensitivity of Lumianyan 22 to NH₄⁺, compared to 153018. Nevertheless, we can not conclude that there is inevitable correlation between K⁺-sensitivity and NH₄⁺-sensitivity in cotton seedlings based on the results of this study.