ISHS Acta Horticulturae 227: International Symposium on Vegetative Propagation of Woody Species
THE EFFECT OF HEATING OF WALNUT GRAFT UNIONS ON GRAFTING SUCCESS. |
| Authors: | D. Avanzato, G. Tamponi |
| Abstract:
In Italy, the propagation of walnut by grafting has not been successful, thus most orchards are composed of seedling trees. This study was initiated to investigate the effect of heating of the graft union on increasing the percent success of walnut grafts. Two heat generating methods were utilized; the hot callusing pipe as described by Lagerstedt and a modification of this method utilizing heating cables (the hot callusing cable). The hot callusing cable is a device utilizing a variable voltage potential cable (BTV -Raychem), which is a thermostatically controlled cable that can be maintained at 27°C. The trials were conducted during 1986 and 1987 in Rome, Italy. One year old seedlings of Juglans regia L. were cleft-grafted at the end of January and February with 'Hartley' scions in 1986 and with 'Hartley', 'Sorrento', and 'Mayette' scions in 1987. The graft union area was wrapped with aluminum foil in order to maintain uniform temperature and high humidity and was heated for 24 days. During this period, the graft union and air temperatures were maintained at 27°C. Heating of the graft union significantly improved grafting success. Seventy three percent of the heated unions were successful while only 6% of the unheated unions produced successful grafts. Grafting in February produced a higher percentage of success than grafting in January. | |
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