APPLICATION OF TISSUE-CULTURE ON QUINCE ROOTSTOCK IN IRON-LIMITING CONDITIONS

Two quince rootstocks for pear, clones ''MA'' and ''Ct.S.212'', were s creened under iron (Fe)-limiting conditions in in vitro culture. The m ost important objectives of this work were: first, to develop use of t he tissue culture technique as a rapid screening methodology for evalu ation of Fe efficiency in quince, and second, to identify morphophysio logical characters associated with variation in response. Iron content of the MS medium (200 meg FeEDTA) was reduced to 80%, 65%, 50%, 25%, and 15% of standard content in order to induce chlorosis symptoms. Res ults showed that ''Ct.S.212'' presented a higher proliferation rate an d greater growth than clone ''MA'' in the 15 and 25% Fe treatments, bu t clear symptoms of chlorosis were observed in both clones at the two lowest Fe concentrations. Parameters of vegetative development commonl y used in in vitro culture proved to be difficult to interpret for thi s type of screening, and further tests will be necessary. In contrast, type and content of chlorophyll were shown to be an indicative test, although not completely reliable.