Growth, yield and iron deficiency tolerance level of six peach rootstocks grown on calcareous soil

Iron deficiency is a major problem that affects many fruit crops grown on calcareous soils. A four-year study was conducted to evaluate the effect of calcareous soils on the vegetative growth and productivity of six peach rootstocks (Nemaguard, Atlas, MRS 2/5, Cadaman, GF 677 and GxN15) grafted with 'Ruby Diamond' nectarines. Trees were planted in 100 L containers filled with a sandy loam textured, calcareous soil (6.3% active calcium carbonate) with a pH of 8.0 and an intermediate level of available iron (5 mg kg(-1) of Fe+2). The trunk diameter during the 4th growing season was larger in GF 677, GN 15, Cadaman and Atlas, whereas Nemaguard and MRS 2/5 showed smaller average values. Cadaman and Atlas presented the highest pruning weight (a measure of vegetative growth), GxN 15 and GF 677 were intermediate, and Nemaguard and MRS 2/5 exhibited the lowest weight. In the fourth year, yield per tree was higher in Atlas and Cadaman, while Nemaguard had the lowest yield. MRS 2/5 and GxN 15 had the highest individual fruit weights, particularly when compared with Cadaman. Regarding leaf chlorosis, the most severe symptoms were exhibited by Nemaguard (12.3 mg kg(-1) of active iron), with mild symptoms in Atlas and slight to no symptoms in Cadaman, MRS 2/5 and GxN 15. Leaf chlorosis was not observed in OF 677 (26.4 mg kg(-1) of active iron). All rootstocks, especially GF 677, showed better performance than Nemaguard with respect to chlorophyll measurements of the leaves obtained through the SPAD technique.