Abstract |
- Growth, yield components and leaf area were evaluated on
'Starkspur Supreme Delicious' apple on nine rootstocks: MAC 24, EMLA
7, EMLA 26, OAR 1, MAC 9, 0.3, EMLA 9, M 9, and EMLA 27. Estimates of
planting density based on growth, estimates of leaf area based on
four independent variables and the relationships among yield
components, fruit quality, growth and leaf area were investigated
during 1985.
Tree height, tree spread and trunk cross sectional area were
highest for trees on MAC 24 followed for EMLA 7 while trees on EMLA
26, OAR 1, MAC 9, 0.3, EMLA 9 and M 9 were less in these values in
descending order, with the most dwarfing on EMLA 27. Estimates of
planting densities indicated higher densities with tree canopy spread
than TCSA based on standard trees of the age except on EMLA 27.
The densities for trees on MAC 24 and EMLA 7 were estimated 426 and
496 trees/ha. respectively, while for the rootstocks with
intermediate size ranged from 700 to 1000 trees/ha. The highest
density was for EMLA 27 with 1824 trees/ha.
Flower cluster, fruit number, yield and leaf area were highest
in the least size controlling rootstocks MAC 24 and EMLA 7, and
in general these were a function of tree size. MAC 9 had the highest
flowering density, crop density and yield efficiency followed by 0.3,
EMLA 26 and EMLA 9. Potential yields based on the estimated planting
density were also highest for MAC 9.
Fruit on OAR 1 had greatest soluble solids, firmest at harvest,
but were the smallest. Fruit on EMLA 7 which had the lowest soluble
solids were largest. A negative correlation between flowering
density and fruit set among the rootstocks was found. Crop density
influenced fruit size and weight. Fruit on EMLA 7, MAC 24 and EMLA 9
were the largest but these trees had the lowest crop density. There
was a high correlation of fruit number with yield indicating this was
the main component of yield. The leaf-fruit ratio was negatively
correlated with flowering density, crop density and yield efficiency
and the ratio was lowest on the more efficient rootstocks MAC 9, 0.3
and M 9 while those of MAC 24 and EMLA 7 were highest.
No differences were seen among the regression lines of leaf area
and 4 independent variables obtained from trees on various rootstocks
and within rootstock. Fresh weight was the best estimate of leaf area
but because of greater speed and simplicity, branch cross sectional
area was chosen to predict leaf area. Total leaf area per tree decreased from the least size controlling rootstocks to the most
dwarfing rootstocks. Tree leaf area index ranged from 1.69 in MAC 24
to 0.87 in 0.3, but it did not always increase proportionately to
tree size. Orchard leaf area index from estimated planting densities
showed low values in all rootstocks but a slight increase with the
tree size. This indicated that trees at the estimated densities are
not intercepting the maximum quantity of light.
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