Effect of Cultivation and Nitrogen Levels on Storage Quality, Yield and Color Grade of Starking ‘Red Delicious’ Apple Grown Under Grass Sod1

Abstract

Abstract ‘Starking Red Delicious’ trees 15 years old on seedling rootstocks were fertilized with 5 levels of N as ammonium nitrate from 0.165 to 3.0 lb. per tree applied in a narrow band from 1961 to 1966 and cultivated at a shallow depth with a rotavator each year in March and May, March alone, or not at all. Evaluation of fruit quality at harvest time showed that there was no significant effect of N level or cultivation treatments on fruit color. Pressure test was reduced by the higher N treatments but soluble solids concentration was highest at the medium N applications. Titratable acidity was reduced by the higher N treatments but cultivation treatments had no effect. Flesh color of the fruit was the most sensitive of several tests made, higher N and more cultivation causing greener flesh. In tests at the end of storage life, pressure test and titratable acidity were still reduced by the higher N treatments. There was little effect on soluble solids, per cent rots or storage scald. Again, cultivation treatments had no effect. There was very little difference in yield among the N treatments except at the lowest levels of 0.5 and 0.165 lb. This effect was most marked with no cultivation. The N content of the leaves was increased by the N treatments from approximately 2.1% at the lowest level to approximately 2.4% at the highest level. There was no effect on terminal length or trunk circumference. It was shown that grass sod with or without moderate cultivation could largely override the effect of a very wide range of N levels. There was a deleterious effect only at very low N levels combined with no cultivation.