Potassium deficiency impact on the photosynthetic apparatus efficiency of radish

Abstract

Potassium is an essential nutrient for plants and its limited resources impose the improvement of the fertilizer-use efficiency. To address this issue, it is important to understand its roles in the photosynthesis and to provide a quick, noninvasive method for diagnosing its deficiency in plants. The impact of potassium deficiency on the photochemical phase of photosynthesis has not been well understood. In this work, we present the K+-deficiency effect on gas exchange, chlorophyll content, and electron transport chain in two hybrid cultivars of radish. Our results showed that one of the cultivars proved to be tolerant and maintained the net photosynthetic rate at the level of the control plants. In both cultivars, the effect on the photochemical phase of photosynthesis was observed. We suspect that low K+ availability impaired the balance of the H+ influx to thylakoid lumen which increased its acidification and triggered the downregulation mechanism leading to the rearrangement of PSII complexes and an increase in energy dissipation.

Keywords

• chlorophyll a fluorescence
• jip-test
• stomatal conductance
• transpiration rate