TREE EFFICIENCY AND FRUIT QUALITY IN HIGH-DENSITY APPLE ORCHARDS

S. Sansavini, D. Bassi, L. Giunchi
The yield efficiency of high-density plantings (h.d.p.) of dwarf apple trees on M.26 (5 000 per ha in 'bed systems' with cvs. 'Cooper 4 spur Red Delicious' and 'Yellow-spur Golden Delicious'), trained as free central-leader trees until the fifth year, was evaluated by comparing bearing capacity and fruit quality with those of medium-density plantings (m.d.p.) with 1 666 trees/ha, with palmette hedgerow training, of the same cultivars and rootstock, at the Experimental Farm 'M. Neri', Imola, near Bologna.

The main differences between the two densities of planting were:

  • Accumulated crop per tree was always greater in the medium density plots. Per hectare, it was around 50% greater in the high-density 'Yellowspur' bed system whereas it was only slightly higher for bed systems of cv. 'Cooper 4', which showed alternate bearing.
  • Yield efficiency of the tree was always greater in the m.d.p., as was fruit size even though there were fewer apples per tree in the h.d.p. plots. More encouraging results were obtained with 'Yellowspur' than with 'Cooper 4'.
  • Fruit colour (Hunterlab parameters 'a', 'b' and '1' was also better for apples from m.d.p. plots as regards both the red and yellow components as well as skin brightness. In addition, in the 'Yellowspur' h.d.p., the apples from the lower halves of the trees appeared to be greener than those from the upper halves.
  • Fruit quality was reduced by the excessive density of h.d.p.; ripening began earlier and was more uniform on m.d.p., as revealed by skin brightness, lower acidity and firmness (in 'Cooper 4') and greater sugar content (in 'Yellowspur').
  • Light intensity at noon-time in the lower and upper halves of the canopy of 'Cooper 4' trees ranged, on the average, from 18% to 52% of full daylight in h.d.p. and from 33% to 75% in m.d.p.
Sansavini, S., Bassi, D. and Giunchi, L. (1981). TREE EFFICIENCY AND FRUIT QUALITY IN HIGH-DENSITY APPLE ORCHARDS. Acta Hortic. 114, 114-136
DOI: 10.17660/ActaHortic.1981.114.13
https://doi.org/10.17660/ActaHortic.1981.114.13

Acta Horticulturae