The use of legume and grass cover crops induced changes in ion accumulation, growth and physiological performance of young olive trees irrigated with high-salinity water

The impact of intercropping with two different forage crops (legume and grass) on the shoot growth, ion accumulation and some physiological traits of 3-old year olive trees irrigated by high-salinity water (120 mM NaCl) was assessed under greenhouse conditions. Olive plants were subjected to one of the following treatments: TC (control); TG - olive plants intercropped with grass (Oats: Avena sativa L) and TL - olive trees intercropped with legume (Berseem Clover: Trifolium alexandrinum L). Results showed that sodium root:leaf ratio and nitrogen concentration in olive leaves were significantly increased in TL treatment. Olive shoot length and maximum quantum yield of photosystem II (Fv/Fm) were significantly improved by using Berseem Clover as a cover crop. Negative correlation was observed between the total chlorophyll content and the leaf Na+ concentration. On the other hand, polyphenol content was significantly increased in olive leaves when oats were used as cover crops, in relation to the high N-deficiency observed in olive leaves of TG treatment.