Application of tissue culture on quince rootstock in iron‐limiting conditions1

Two quince rootstocks for pear, clones “MA”; and “Ct.S.212”;, were screened under iron (Fe)‐limiting conditions in in vitro culture. The most important objectives of this work were: first, to develop use of the tissue culture technique as a rapid screening methodology for evaluation of Fe efficiency in quince, and second, to identify morphophysiological characters associated with variation in response. Iron content of the MS medium (200 meq FeEDTA) was reduced to 80%, 65%, 50%, 25%, and 15% of standard content in order to induce chlorosis symptoms. Results showed that “Ct.S.212”; presented a higher proliferation rate and greater growth than clone “MA”; in the 15 and 25% Fe treatments, but clear symptoms of chlorosis were observed in both clones at the two lowest Fe concentrations. Parameters of vegetative development commonly used in in vitro culture proved to be difficult to interpret for this 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.