[Rooting trials of hardwood cuttings of apple trees]

anglais. In a first screening trial, apical, medium and basal cuttings from 1 year old shoots of 250 apple cultivars were treated with IBA(2500 ppm) and inserted in peat or in perlite substrate on heated benches, in glasshouse and in the open air. Different temperatures of the substrate were tried (from 24 to 28 C). In spite of the very high mortality it was seen that callus formation was higher with lower temperature and in basal cuttings as compared to medium and apical ones. Remarkable differences were shown among cultivars as regards callus formation. In the next two trials, hardwood cuttings from 15 cultivars and 4 root stocks were used. Cuttings were treated with IBA 2500 ppm and inserted in perlite substrate on heated benches under mist in the open air. The temperature of the substrate was kept at 20 C. One trial was carried out in November, the second one in the next February. Best results were obtained with rootstocks as expected: more than 60% of M 26 cuttings rooted while M 9 rooted in a very low proportion. For apple cultivars the percentage of rooted cuttings ranged from 0 to more than 30%. There is a clear difference between cultivars as far as rooting is concerned: some of them rooted in rather good percentage (about 30%) in both trials while the others did not root in any of the two trials.

italien. Nel corso di tre anni di prove si ! cercato di individuare, dapprima attraverso un'ampia sperimentazione a carattere orientativo su circa 250 cultivar l'esistenza di attitudini varietali all'emissione di radici da parte di talee legnose di melo e successivamente, operando su un numero limitato di cultivar e di portainnesti, l'epoca ottimale di prelievo del materiale e le condizioni piu idonee per la radicazione. La sperimentazione condotta, pur confermando la notevole difficolta di ottenere piante autoradicate nella maggior parte delle cultivar ha dimostrato la esistenza di forti differenze varietali nella attitudine alla radicazione e la possibilita di raggiungere percentuali di radicazione anche superiori al 30% soprattutto nell'ambito delle cv. spur. Sui portainnesti clonali sperimentali si sono ottenute percentuali di radicazione variabili da un massimo del 64% (M 26) a un minimo dell'8,5% (M 9).