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Several deciduous fruit tree species are affected by iron chlorosis when grown in calcareous soils and worldwide research on rootstock breeding and screening in relation to iron deficiency is carried out. For many years the goal of our department has been to investigate morphological and physiological aspects related to lime‐induced chlorosis, and to identify markers usable as tools for tolerance screening of clonal rootstocks. Experimental strategies using pot, hydroponic and in vitro culture have been used to understand if they are able to originate suitable indicators on developmental and biochemical changes resulting from iron deficiency. Results risen up from in vitro trials suggest that iron deficiency sensitive system should work in a divergent way from that of bicarbonate system. Physiological and morphological data highlight diverse syndromes and behaviors among the genotypes, probably reflecting properly perception, regulation, and activation of biological answer system to iron deficien...

SummaryThe morphogenic effect of different light qualities was investigated on in vitro shoot proliferation of Prunus cerasifera (clone Mr.S. 2/5) in relation to apical dominance and node formation. In intact microcuttings, leader stem length was not affected by light quality but blue and white light produced a higher number of nodes, with shorter internodes than red or far-red light or darkness. The proportion of nodes producing outgrowing lateral shoots was higher in red and far-red light than in white, blue or darkness. In decapitated microcuttings apical dominance was fully released in all the light treatments but not in darkness. Taken together the data show that the proliferation rate is a product of bud induction and release from apical dominance which are differentially affected by light quality. The much lower percentage outgrowth in white and blue light as compared with red light indicates a specific effect of blue light acting in the opposite direction to active (far-red light absorbing) form o...

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 we...

SummaryA method for obtaining whole plants from immature cotyledons via somatic embryogenesis is described. Cultures were initiated by placing cotyledonary tissues at different developmental stages on SH medium supplemented with NAA and 2iP at different concentrations as an embryo induction medium (EIM). Proliferating masses of adventitious embryos were produced by cvs Frangivento, Picholine and Frantoio when transferred to the embryo expression medium (EEM) characterized by the exclusion of growth regulators. ‘Frangivento’ was maintained on EEM for three years without showing any loss of embryogenic potential while cvs Picholine and Frantoio retained their embryogenic capacity for only three subcultures. Optimum conversion into plantlets for ‘Frangivento’ was observed. Plants established in the greenhouse showed normal growth without change in performance. The protocol described makes it possible to maintain long-term embryogenic capacity; this may be particularly advantageous for propagation and biotech...