ISHS Acta Horticulturae 705: V International Walnut Symposium
‘CHANDLER’ WALNUT TREES TRAINED IN THREE KINDS OF CENTRAL LEADER: STRUCTURED, SEMI-STRUCTURED AND FREE - RESULTS AT THE AGE OF SIX |
| Authors: | N. Aletà, M. Rovira, A. Ninot, A. Vilanova |
| Keywords: | Persian walnut, training system, early bearing |
| Abstract:
In 1998 a ‘Chandler’ orchard was planted in the northern of Spain to compare three different training systems: 1) Structured Central Leader (SCL), 2) Semi-structured Central Leader (SSCL) and 3) Free Leader (FL). SCL corresponds to the Californian central leader: main leader shoot was cut every year and one or two scaffold branches were selected; SSCL was very similar to SCL but the main shoot was only cut in winter if growth was <80 cm. All trees were cut after planting and FL trained trees were not cut anymore. In summer and in winter main leader dominance was kept on the tree top clearing the last 60 cm. Lateral branches were conserved while the canopy was not crowded enough. Systems studied looked for sufficient illumination below canopy, measures of lightening (PAR) were made in 2003. Results at the 7th leaf showed that there were no significant differences in trunk section but there was a difference in total height, being SC trained trees the smallest. Considering pruning for training, removed wood weight (winter + summer) from 1999 to 2004 was 40% more in SCL and 30% more in SSCL than in FL. In 2001, FL trees had more than 300 nuts per tree, while SSCL yielded this nut quantity in 2002 and SCL trees in 2003. In 2004, there was no difference in production anymore (2500 kg/ha, 2400 kg/ha and 1850 kg/ha in FL, SSCL and SCL trained trees, respectively); however, in cumulated production from 2002 to 2004 the rate has been 100-83-62 for FL-SSCL-SCL, respectively. Nut weight and calibre were not significantly different within trainings and calibre over 32 mm was present in more than 90% of nuts. Preliminary data of intercepted light below canopy did not allow establishing significant differences between training systems. | |
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