Effect of Planting Density on Flower Bud Formation of 'Starking Delicious' Apple Trees Grafted on Dwarfing and Semi-dwarfing Rootstocks.
Year: 2000
Type: article
Abstract: The effect of planting density on the flower bud formation on 'Starking Delicious' apple trees (Malus domestica Borkh.) grafted on dwarfing M.9 and M.26 and semidwarfing M.7 and MM.106 rootstocks and trained to a central leader was studied. 1. As planting density increased, the number of flower buds per tree and the percent of flower bud formation decreased, but the number of flower buds per hectare tended to increase. 2. The relationship between the number of flower buds per tree (Z) and the planting density (ρ) could be represented by the following reciprocal equation. 1/Z=(1.46ρ+82.7)10-6 (1) Also, the relationship between the number of flower buds per hectare (δ) and the planting density (ρ) could be represented by the following reciprocal equation. 1/δ=1.46·10-6+82.7·10-6/ρ (3) 3. The number of flower buds per tree and the percent of flower buds formed were negatively correlated to the tree height/spread ratio, indicating that the decrease of flower bud formation with an increased planting density was closely related to the upright form of the trees. 4. The vertical distribution of flower buds was closely related to the attenuation pattern of relative solar radiation along the canopy profile, indicating that the decrease of flower bud formation with an increased planting density was caused by decreasing of relative solar radiation. 5. In the 5th leaf of trees on M.9, an inhibition of 5% and more in flower buds formation occurred at higher density. As the trees aged, the inhibition shifted to the lower density plot. This shifting rate was accelerated in trees on M.26, M.7, and MM.106, compared with trees on M.9. The relationship between the percent of flower buds formed (φ) and the planting density (ρ) could be represented by the following reciprocal equation from the age of 6 years for trees/M.9 and 5 years for trees on other rootstocks, 1/φ=Aφρ+Bφ (4) where φ is 0≤φ≤100, and Aφ and Bφ depend on the tree age and rootstocks. 6. The φ remains constant at a lower LAI (F), whereas it decreased abruptly at a certain LAI. The relationship between the F and the φ could be approximated with the following two equations, In case of 0<F≤-b/2a, φ=-(b2/4a)+c (5) In case of F≥-b/2a, φ=aF2+bF+c (6) where a, b and c depend on the tree age and rootstocks. 7. LAI at which φ begins to decrease is defined as the critical LAI (Fφcri); Fφcri is expressed by the following equation. Fφcri=-b/2a (7) The Fφcri estimated by Eq. (7) had values of 1.9a2.1, regardless of tree age and rootstocks. 8. The relationship between the planting density (ρcri) and the number of flower buds per tree (ucri) at Fφcri, regardless of tree age and rootstocks, could be expressed as follows : ρcri=1.5×104·ucri-0.92 (10)
DOI: 10.2503/jjshs.69.298
Authors: Haruyuki Kuroda, Kazuhiko Chiba
Language: English
Subfield: Plant Science
Domain: Life Sciences
SDG: Zero hunger
Open Access status: diamond
OpenAlex ID: W1994544141