THE INFLUENCE OF NITROGEN AND POTASSIUM ON PEACH TREE GROWTH, PRODUCTIVITY, AND COLD HARDINESS.

The influence of nitrogen (N) and potassium (K) on 3-year-old peach tree growth, productivity, and cold hardiness was investigated at the Fruit Research Laboratory, Biglerville, in southcentral PA. Factorial treatments were imposed involving fertilizer application rates in an effort to attain 2.5, 3.5, and 4.5% N in combination with 1, 2, and 3% K. In 1987, the actual leaf N levels attained were 2.91, 3.36, and 3.74% while the K values were 1.47, 1.90, and 2.17%. Trunk cross-sectional area was influenced by N (P = .01) and K (P = .10). Tree height and width were more influenced by N than by K. On the other hand, fruit yield was more dramatically influenced by K (P = .01) than by N (P = .06). Fruit maturity was delayed by the higher N levels.

Cold hardiness was determined by measuring the electrical conductivity of solutions surrounding 5 gm samples of 1-year-old frozen shoots.
In December 1987, only small differences in hardiness between treatments were detected at -24 and -30° C. In February 1988, at both -24 and -32° C, there were suggestions that higher K resulted in less hardiness.
In March 1988, at -24 and -30° C, higher K appeared to result in larger losses in hardiness than were evident in February.
The trees attained maximal cold hardiness in February followed by December and March.

II International Peach Symposium

G.M. Greene II, C.B. Smith

https://doi.org/10.17660/ActaHortic.1989.254.38