TOLERANCE OF PRUNUS ROOTSTOCKS TO POTASSIUM CARBONATE-INDUCED CHLOROSIS

A standardized screening procedure for tolerance to bicarbonate-induce d Fe chlorosis using a commercial fertilizer mix (Plantex) as the nutr ient. source, high solution pH (8.5) and 1.5 mM bicarbonate to simulat e a calcareous soil situation was used with a 1 vermiculite : 1 perlit e (v/v) support media, small pots and topping (pinching back the tops of shoots). The tolerance level of peach [Prunus persica (L.) Batsch] rootstocks could be assessed by leaf visual-chtorosis ratings and Spad -502 chlorophyll readings instead of extractable leaf-chlorophyll conc entration or plant Fe concentration. Although most of the tolerant gen otypes had almond [P. amygdalus (Mill.) D.A. Webb] in their parentage, a few peaches ('Swat', NJ672281007) showed high to moderate levels of tolerance.