EFFECTS OF FRUIT THINNING SPRAYS OF NAA AND BA ON CROPPING OF ‘ELSTAR’ AND ‘GLOSTER’ APPLES

The effects of high volume sprays of naphthaleneacetic acid (NAA, 15 mg/L) and benzyladenine (BA as Accel or Paturyl, 50 mg/L a.i.) applied at about 7 mm king fruit diameter were evaluated for cropping and fruit growth of ‘Elstar’ and ‘Gloster’ on M.9. For ‘Elstar’, NAA decreased yield significantly (-11%) and increased fruit size (+20%) and percentage fruit 70–80 mm diameter.
BA did not decrease yield, had no significant effect on mean fruit size, but increased percentage large fruit.
Combinations of NAA and BA decreased yield (-16%), increased mean fruit size (+30%) and percentage large fruit.
Fruit firmness and soluble solids were not altered.
Color formation was less with BA than NAA or NAA + BA. Mean seed number/fruit was not related to treatment (range 6.7–7.3). There were no significant differences between the two BA formulations (Accel, Paturyl). In ‘Gloster’, there was no treatment effect on yield, but mean fruit weight and percentage large (75–90 mm diam.) fruit were greater in the NAA + BA treatments.
Mean seed number/fruit was decreased from 5.9 (nonthinned) to 4.2 (NAA + BA). BA had no pronounced effect on fruit form in ‘Elstar’, but increased unequal carpel development leading to lopsided fruit in ‘Gloster’.

XXV International Horticultural Congress, Part 4: Culture Techniques with Special Emphasis on Environmental Implications

M.J. Bukovac, M. Schroeder, G. Noga

Apple, benzyladenine, fruit thinning, Malus domestica, Naphthaleneacetic acid

https://doi.org/10.17660/ActaHortic.2000.514.10