Long-term agronomical performance and iron chlorosis susceptibility of several Prunus rootstocks grown under loamy and calcareous soil conditions

The objective of this work was to evaluate the agronomic performance (vigor, yield, yield efficiency, number of root suckers), fruit quality (fruit weight, fruit size, flesh firmness, soluble solids content, and titratable acidity), leaf and fruit mineral nutrition (macro and micro elements), leaf chlorophyll concentration and iron chlorosis susceptibility of 'Big Top' nectarine cultivar grafted on 20 Prunus rootstocks and grown in loamy and calcareous soil under the hot climate conditions of the Ebro river basin (Spain). After the 10 years of the study (at 11th leaf), statistical analysis showed significant differences among rootstocks for most of the traits evaluated. Based on vigor and cumulative yield, 'Big Top' trees from Padac 04-03 rootstock were found to be the most vigorous and productive, followed by Castore, GF-677, Ishtara (R), PS and Rootpac (R) 70. However, the most efficient rootstocks were Controller 5, Adesoto (R) 101, Rootpac (R) 40, Krymsk (R) 1, Ishtara (R), Penta, IRTA-1, Polluce, and Padac-150. 'Big Top' fruits from Rootpac (R) 40 had the highest fruit weight and fruit size (>70 mm), with good soluble solids content and titratable acidity, but less firmness than the other 'Big Top' fruits. After 3 months with no application of chelate, chlorosis symptoms were visible in most of the trees, with those from Krymsk (R) 1 and PS showing the highest susceptibility. In contrast, AD-105, Adesoto (R) 101, Cadaman (R), GF-677, Padac-150, Rootpace (R) 40 and Tetra were the least susceptible rootstocks. Controller 5, IRTA-1, Padac-04.03 and Penta had moderate susceptibility. In conclusion, Rootpace (R) 40, Ishtara (R), IRTA-1 and Padac-150 may represent a good compromise between canopy size control, yield, yield efficiency, fruit size, and susceptibility to iron chlorosis.