Severe postharvest summer pruning of mature 'Forelle' pear trees influences canopy light distribution, and fruit and spur leaf characteristics in the following season.
Dussi, M. C.; Huysamer, M.;
Journal of the Southern African Society for Horticultural Sciences Year: 1995 Vol: 5 Issue: 2 Pages: 57-60 Ref: 26 ref.
1995
บทคัดย่อ
Good light distribution within the orchard canopy is very important for the development of sufficient red skin colour in Forelle pears. A study was conducted in the Elgin area, South Africa (Mediterranean climate, latitude 34 deg S.) in which mature Forelle trees were heavily summer-pruned after harvest (Mar.) or left unpruned in 1994 (in conjunction with standard winter pruning) to evaluate the effect on the 1995 fruit crop. In 1995, light distribution (as photosynthetically active radiation, PAR) was determined at 3 heights in the canopy, on both the northeast and southwest sides of the hedgerow. Fruiting spurs were collected in the same regions of the canopy, and fruit colour characteristics, specific leaf weight (SLW) and total leaf N content were determined. Severely pruned trees tended to have higher canopy PAR levels and a more uniform light distribution through the canopy in both horizontal (northeast to southwest) and vertical (bottom to top) directions. Fruits from pruned trees tended
to be redder (lower hue angle), less intense in colour, darker and more blushed than fruits from unpruned trees. These variables and SLW were significantly correlated with light intensities in the corresponding canopy zones. Spur leaf N content was higher in the unpruned trees, but no differences were found between canopy positions or between opposite sides of the hedgerow. Non-statistical economic evaluation suggested that severe pruning of this cultivar may be a viable option, since the increased percentage of class one fruits more than compensated for the reduction in total yield. The determining factor, however, appeared to be the price obtained for Forelle on the local market.