Growth and Physiological Characterisation of In Vitro Rooted Citrus macrophylla Explants as Affected by NaCl Stress and Different Concentrations of NO3-, K+ and Ca2+

There are considerable increases in the complexity of the mineral nutrition of plants when saline ions are in the medium since salinity produces a nutritional imbalance in the plant. Additionally, saline ions interact with essential nutrients such as NO3-, K+ and Ca2+. In this study, we analyzed the behaviour of in vitro rooted Citrus macrophylla explants in saline conditions of 0 or 150 mM NaCl and with three levels of NO3-, K+ and Ca2+, Low, Control and High (50, 100 and 150%, respectively, of the complete nutrient concentration in the medium). The salinity decreased the length of roots and shoots but it had no effect on the number of roots. Visibly damaged or fallen leaves were observed in the saline media. The Low level of Ca2+ in the saline medium decreased the length of roots and shoots and produced the highest number of damaged leaves. In the non-saline medium, the Ca2+ level had no effect on the growth parameters. The level of K+ only affected the length of shoots in the saline medium; the longest shoots were obtained with the High K+ level. The lowest number of damaged leaves was observed at the Low K+ level. The Low NO3- level produced the longest shoots in the non-saline media and the longest roots in the saline media. This NO3- level produced the lowest number of damaged leaves. In general, high levels of tested nutrients did not restore the growth parameters decreased with the salinity.