The experiment was conducted during three successive seasons from
2007 to 2009 on twenty five years old Balady mandarin trees budded on sour
orange rootstock at 5x5 meter apart, planted in an orchard located at private
orchard at El-Kalubia Governorate. The trees was in (ON)year at the first
season (2007), to investigate the effects of soil and foliar application of
potassium on leaf (NPK), yield and some fruit physical properties (weight,
volume, diameter, length, peel thickness, peel weight and some fruit chemical
properties( T.S.S.%, total acidity%, T.S.S./ acid ratio, Reducing sugar, total
sugar% and Ascorbic acid. The experiment was divided into two parts, the first
part was as soil addition and included four treatments (0 – 200 – 400- 800) gm
potassium sulphate 48%K2Oper tree. The amount of potassium was divided
into two equal batches the first dose added to the soil at mid March and the
second added at August. The second part of the experiment was the foliar
addition which included three treatments (0- 150 and 300) ppm potassium
sulphate, sprayed three times in mid March, May and July. All chosen trees
received the usual dose of potassium which used in the orchard studied. Results
revealed that all treatments led to increase leaf N and K contents. Increasing the
rate of potassium was most effective to increasing leaf N&K, yield per tree and
improved both fruit physical properties (fruit weight and volume, diameter
length, peel weight and juice percent) and fruit chemical studied properties
(T.S.S.%, T.S.S./acid ratio, reducing sugar %, total sugar% and Ascorbic acid).
While, leaf P was decreased. Concerning peel thickness, no trend was detected
in the three seasons. So, the highest potassium rate had the highest values in all
studied parameters except leaf P content, peel thickness and acidity. The main
observation was about, K foliar application was most effective in increasing
yield and improving fruit quality than soil addition.