Effects of Naphthalene Acetic Acid, Carbaryl and Accel on Thinning of Apples

Abstract

Studies were conducted in 1994 and 1995 to investigate the effect of Naphthalene acetic acid (AN), Carbaryl (Naphthylmethyl carbamate) and Accel (N-(phenylmethyl) - (H-purine - 6 - amine (BA)) on fruit set, yield, quality and leaf mineral concentration in ‘Paulo Red\' apples. The treatments consisted of NAA at 5ppm, 10ppm, 15ppm; Carbaryl at 0.05%, 0.1% and 0.2%, and. Accel at 25ppm, 50ppm and 75ppm and unsprayed control. Thinning trials conducted over two years indicated that Accel and Carbaryl consistently thinned the apples as evidenced by the lower number of fruits per limb cross sectional area on the sprayed trees compared to the unsprayed trees. The treatments reduced yield (total fruit weight per tree) but caused increases in pH, total soluble solids content, percent red color, return bloom and mean fruit weight. The treatments did not influence the number of seeds in the fruit. Accel and carbaryl treatments caused increases in fruit length fruit diameter and fruit length to diameter ratio while NAA had no effect on these parameters. Leaf mineral composition was affected differently during the two experimental years. NAA reduced N and Ca contents in 1994 and 1995 but increased K contents during those years. In contrast, carbaryl increased N and Ca contents and reduced K contents in both years but reduced Mg contents in 1994 only. Accel increased K and Mg contents, reduced Ca contents but had no effect on N in 1994 while it increased K and Ca contents in 1995. Both N and Mg contents were not affected by Accel in 1995.

Journal of Agriculture, Science and Technology Vol.3(2) 2001: 45-56