Date of Graduation

2000

Document Type

Thesis

Degree Type

MS

Committee Chair

Bradford Bearce

Abstract

A field study was conducted on the apple cultivar ‘Nittany’ on M.9 and M.26 rootstocks. Four crop load treatments levels: an unthinned check, 7.5, 5.0, and 2.5 fruit per centimeter trunk cross-sectional area (TCSA) were imposed on replicated trees of each rootstock to determine the effects on shoot growth and fruit size. Average terminal and bourse shoot growth were greater for the M.26 rootstock than the M.9 rootstock. Crop load levels had no significant effect on shoot growth. Thinning fruit to the 2.5 fruit/cm2 TCSA level showed the most consistent results in fruit diameter, length, and weight. Fruit size as determined by fruit weight, diameter, and length increased as crop load decreased. There was no significant difference between rootstocks. All fruit from crop load treatments were significantly larger than fruit from the unthinned check. Average fruit diameter, length, and weight were greater on M.9 rootstock than on M.26 rootstock.

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