Nutrient Passage in Different Grafted Lemon Trees

Spain is one of the most important productor of lemon fruits in the world. Also, about 80 % of the Spanish production of lemons is located in the arid southeast, where the fertirrigation is important to ensure the highest productivity. The aim of the present study was to determine the content of nutrients present in two different grafted lemon tree (Citrus x limon) of the Verna variety, located in a drip irrigation farm in Librilla (Region of Murcia, Spain). The first one grafted in a Sweet orange (Citrus x sinensis) rootstock, and the second one in a Bitter orange (Citrus x aurantium). Both in a 40 year old trees grown in a conventional agricultural practices. The Bitter orange rootstock (Citrus x aurantium) favoured the appearance of the "Miriñaque" or protuberance of the trunk at the union of the graft. While in Sweet orange rootstock (Citrus x sinensis) did not appeared. For the analysis, fresh samples of old leaf, young leaf and root were collected from 5 different trees for each rootstock. Once processed after having been weighed, dried and ground, they were analysed by inductively coupled plasma (ICP) analysis (Optima 3000, PerkinElmer). The result showed that the growth was higher in the aereal biomass was higher in Verna grafted on Sweet orange rootstock. The root samples of the lemon tree with Bitter orange rootstock contained a higher amount of Fe, Mn and Zn than the samples of the lemon tree Sweet orange rootstock. The rest of the nutrients did not show significant differences. The new and old leaves of Verna on Sweet orange rootstock showed higher amount of Fe, Mn and Zn than the new and old leaves of Verna on Bitter orange rootstock. Also, the rest of the nutrients did not showed significant differences. The study revealed that this protuberance in the trunk prevents the passage of these elements from the root to the aerial part of the trunk. This is probably related to the cell to cell passage.