Effect of Salinity on the Development of Gummosis Caused by Phytophthora Citrophthora on Six Rootstocks Commonly Used in Citrus Orchards

Abstract

In Morocco, Sour orange is practically the only rootstock used due to its adaptation to the majority of soils and climatic conditions and its acceptable resistance to Phytophthora spp. Additionally, the resistance of sour orange to the attacks of Phytophthora spp. is affected by the salinity of the soil or irrigation water. The objective of this study is to detect the existence of a specific effect of Cl-ions on the development of gummosis caused by Phytophthora citrophthora on six rootstocks commonly used in citrus orchards. After 12 days of inoculation of six different rootstocks treated with NaCl solutions, the first symptoms of the disease appeared in the form of gummy flow, especially on Lime rang pure and citrimelo winter. There is a highly significant correlation between leaf Cl-ion content and the surface of necrosis at the stem. This made it possible to conclude that the alteration of disease resistance is due to a specific effect of these ions, probably by breaking the defense mechanisms of the host plant and/or by stimulating the growth of the pathogen itself.