Potassium Research and Agricultural Production - The International ...

Nitrogen cOlltent of leaves
According to the literature the N content of adequately nourished leaves of peach
lies between 2.79 and 3.55% {I, 4, 5, 6J. In 1971 there was no observable difference
in N content between healthy and unhealthy leaves (fig. 2). The N contents, 2.84% in
control leaves and 2.83% in unhealthy leaves, lay between the limits quoted in the
literature for optimal nutrition.
The N content of healthy leaves was near enough the same on 10 September 1970
and 8 September 1971. That of leaves showing symptoms was however lower in 1970
(2.22%) than in 1971 (2.83%).
Potassium cOlllellt of leaves
The optimum K content of peach leaves is quoted at from 1.81 to 2.88% {I, 4, 5, 6J.
The K content of leaves in our healthy trees on 10 September 1970 was higher than
the lower of the above limits (fig. 3). Between 2 June and 8 September 1971 K content
did not reach this value but was only slightly less.
Leaves showing symptoms had less than half the K content of healthy leaves. The
mean value for 1971 was only 1.03% i.e. 56% less than the middle value quoted for