Jákli Bálint, Tavakol Ershad, Tränkner Merle, Senbayram Mehmet, Dittert Klaus
Institute of Applied Plant Nutrition, University of Göttingen, Carl-Sprengel-Weg 1, 37075 Göttingen, Germany.
Institute of Applied Plant Nutrition, University of Göttingen, Carl-Sprengel-Weg 1, 37075 Göttingen, Germany.
J Plant Physiol. 2017 Feb;209:20-30. doi: 10.1016/j.jplph.2016.11.010. Epub 2016 Dec 5.
Potassium (K) is crucial for crop growth and is strongly related to stress tolerance and water-use efficiency (WUE). A major physiological effect of K deficiency is the inhibition of net CO assimilation (A) during photosynthesis. Whether this reduction originates from limitations either to photochemical energy conversion or biochemical CO fixation or from a limitation to CO diffusion through stomata and the leaf mesophyll is debated. In this study, limitations to photosynthetic carbon gain of sunflower (Helianthus annuus L.) under K deficiency and PEG- induced water deficit were quantified and their implications on plant- and leaf-scale WUE (WUE, WUE) were evaluated. Results show that neither maximum quantum use efficiency (F/F) nor in-vivo RubisCo activity were directly affected by K deficiency and that the observed impairment of A was primarily due to decreased CO mesophyll conductance (g). K deficiency additionally impaired leaf area development which, together with reduced A, resulted in inhibition of plant growth and a reduction of WUE. Contrastingly, WUE was not affected by K supply which indicated no inhibition of stomatal control. PEG-stress further impeded A by stomatal closure and resulted in enhanced WUE and high oxidative stress. It can be concluded from this study that reduction of g is a major response of leaves to K deficiency, possibly due to changes in leaf anatomy, which negatively affects A and contributes to the typical symptoms like oxidative stress, growth inhibition and reduced WUE.
钾（K）对作物生长至关重要，且与胁迫耐受性和水分利用效率（WUE）密切相关。缺钾的一个主要生理效应是抑制光合作用期间的净二氧化碳同化（A）。这种降低是源于光化学能量转换或生化二氧化碳固定的限制，还是源于二氧化碳通过气孔和叶肉扩散的限制，目前仍存在争议。在本研究中，对缺钾和聚乙二醇（PEG）诱导水分亏缺条件下向日葵（Helianthus annuus L.）光合碳获取的限制进行了量化，并评估了其对植株和叶片尺度水分利用效率（WUE、WUE）的影响。结果表明，缺钾并未直接影响最大量子利用效率（F/F）或体内核酮糖-1,5-二磷酸羧化酶（RubisCo）活性，观察到的A值降低主要是由于叶肉二氧化碳传导率（g）下降所致。缺钾还损害了叶面积发育，这与A值降低一起，导致植株生长受到抑制和WUE降低。相反，WUE不受钾供应的影响，这表明气孔控制未受抑制。PEG胁迫通过气孔关闭进一步阻碍了A值，并导致WUE提高和高氧化应激。从本研究可以得出结论，g值降低是叶片对缺钾的主要反应，可能是由于叶片解剖结构的变化，这对A值产生负面影响，并导致氧化应激、生长抑制和WUE降低等典型症状。
