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La valorizzazione del sorbo da legno
No full textLe specie Sorbus domestica e S. torminalis, vengono collocate tra le essenze impiegabili per la valorizzazione delle zone marginali e per la riforestazione di quelle che, in passato, sono state oggetto di poco razionali interventi di disboscamento. Il sorbo è inoltre apprezzato per il suo legno che viene impiegato per lavori di ebanisteria e, quello di particolare pregio.
Per entrambe le specie la mancanza di impianti specializzati per la produzione del legno rende molto arduo il reperimento di materiale di alta qualità e spesso le piante disponibili sono caratterizzate da accrescimenti diametrici assai ridotti e fusti contorti. Inoltre mancano ancora cloni selezionati per la produzione del legno ma sono in corso da alcuni anni studi dai quali sembra emergere che queste specie, caratterizzate da un accrescimento piuttosto lento quando vegetano in bosco in concorrenza con altre specie o in condizione pedoclimatiche non adeguate, siano invece in grado di svilupparsi a ritmi elevati se allevate in impianti specializzati e su terreni di buona fertilità.
Presso il DIPROVE della Facoltà di Agraria dell'Università degli Studi di Milano è in corso un progetto di ricerca e sperimentazione che ha come obiettivo la selezione di individui di pregio
Physiological Responses Of Grapevine (Vitis Spp.) Callus Cultures To Iron-Deficiency
No full textGrapevine is considered a 'Strategy I' plant because it performs some peculiar biochemical and physiological responses when grown under iron (Fe) deficiency stress conditions. Callus cultures were started from leaf and internode cuts of micropropagated plantlets of two grapevine genotypes well known for their Fe-chlorosis characteristic: Vitis riparia a very susceptible genotype and Vitis berlandieri a resistant one. Modification of NADH: ferric (Fe3+) reductase activity was spectrophotometrically evaluated by following the formation of the complex ferrous (Fe2+)-(BPDS)3, while the malic and citric acid production were determined in callus cultures grown both in the presence (+Fe) and absence (-Fe) of Fe. Moreover, a microsomal fraction was isolated from the calli to evaluate the H+-ATPase and the Fe3+-EDTA reductase activities. As expected, calli of the Fe-efficient genotype (V. berlandieri) was able to enhance Fe3+-EDTA reductase activity when growing under Fe deficiency while the Fe-chlorosis susceptible V. riparia could not or did it with lower efficiency. Therefore, the H+-ATPase assay showed a higher enzymatic activity in the microsomal fraction isolated from Vitis berlandieri grown without Fe with respect to its control (+Fe). Organic acid determination gave quite contradictory results, especially regarding malic acid which, under our study conditions, seemed not to be linked with the strategies of response to Fe deficienc
In vitro shoot regeneration from leaf discs of Betula pendula "Dalecarlica" EM 85
Full text linkThe aim of this work was to evaluate the use of leaf discs as source material for regeneration studies and to test the effects of various organic additions to the medium. Zeatin has already been shown to be effective in inducing regeneration in birch whilst putrescine and cefotaxime can aid regeneration from leaf discs in other tree species such as apple and pea
Impiego della coltura dei tessuti nella selezione precoce di genotipi di Vitis spp. resistenti alla clorosi ferrica
No full textIn vitro culture of Cimicifuga racemosa
No full textThe paper reports the first results of a study on in vitro culture of Cimificuga racemosa. In particular, some experiments were conducted to set up axenic proliferation of shoots from which it could be possible to produce microrhizomes, while in other experiments it was studied the ability of different kinds of explant to develop callus that is needed to initiate a cell suspension culture system. Leaf lamina showed higher competence than petioles in terms of both callus induction and morphogenetic ability. The 2,4-D inductive effect was more remarkable in the dark. Root differentiation of callus occurred only in the dark. Callus growth was generally quite slow and this was likely related to the brownish appearance of the cultures
Influence of Ca2+ and 6-benzyladenine on chestnut (Castanea sativa Mill.) in vitro shoot-tip necrosis
No full textShoot apex necrosis affects in vitro chestnut cultures particularly during the rooting stage. Lack of cytokinins or Ca2+ deficiency in the culture medium have been reported to be responsible for occurrence of tip necrosis. In the present research the effects of three Ca2+ levels (3, 9 and 18 mmol l-1) were tested on C. sativa 'Garrone rosso' and 'Clone 46' shoots treated for rooting. Tissue Ca2+ content of the apical, middle and basal portion of both brown and healthy shoots was determined. In a second trial the tip necrosis related effect of the local (tip) application of CaCl2 (3 mmol l-1), BA (5 μmol l-1) and CaCl2 + BA (3 mmol l-1 and 5 μmol l-1) was tested on Clone 46 shoots, during rooting. With regard to Ca2+ concentration in the rooting medium, no significant difference could be detected from the three tested Ca2+ levels on tip necrosis but the highest one caused a drop in rooting ability. Regardless of Ca2+ concentration, Garrone rosso showed a lower percentage of the disorder and a higher affinity for calcium in terms both of uptake and ion translocation. The data of the second trial showed that the local application of 5 μmol l-1 BA completely eliminated tip necrosis while the application of CaCl2 + BA delayed the appearance of the disorder. Apex calcium content of shoots treated locally revealed that the most the healthy tissue contained higher calcium levels than the necrotic one. BA treated shoots contained the lowest ion levels, independently from their status
Growth and ultrastructural modifications to chestnut calli induced by culture filtrates of virulent and hypovirulent Cryphonectria parasitica strains
No full textCallus cultures of two susceptible Castanea sativa cultivars, 'Garrone rosso' and 'Clone 71' were grown on culture medium supplemented to 50% with culture filtrates (CFs) from E4 virulent (E4-V) or E13 hypovirulent (E13-H) Cryphonectria parasitica strain, respectively. E13-H CFs caused a reduction in fresh weight and an increase in dry weight on calli of both genotypes. E4-V CFs did not induced any modification of these parameters compared with the control, but fresh weight of 'Clone 71' was reduced. Light and electron microscopy observation showed the presence of large osmiophilic aggregates in che vacuoles and, sometimes, the ruptured tonoplast in the E4-V treated calli. Calli grown on E13-H CFs had a meristematic-like appearance, with small, scarcely vacuolated cells containing altered mitochondria and plasmalemma proliferations
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