Effects of Foliar KNO3 Application on Nutrient Concentration, Fruit Set and Fruit Quality in Pummelo (Citrus grandis Obs.)

Abstract

Effects of foliar KNO3 application on leaf nutrient concentration, fruit set and fruit quality in
pummelo (Citrus grandis Obs.) were studied. Thong Dee cultivar grown in pummelo production area in
Nakhon Pathom province was used for the experiment. KNO3 at the concentrations of 0 (control), 2, 4 and
6 % were applied to pummelo leaf and inflorescence at anthesis stage, 1 month after fruit set and 2 months
after fruit set. The randomized complete block design was employed for the experimental design.
The results indicated that KNO3 did not affect to fruit set, fruit diameter, fruit quality, leaf carbohydrate
concentration and leaf P concentration. However, KNO3 applied to the pummelo leaf and inflorescence
statistically increased leaf N and K concentrations (P ≤ .05). At 3 months after fruit set, 6 % KNO3 gave

the highest leaf N and K concentrations (3.55 and 3.38 % respectively) followed by 4 % KNO3 (3.25 and
2.89 %), 2 % KNO3 (3.20 and 2.62 %) and 0 % KNO3 (control) (2.75 and 2.35 %). While, at 7 months after
fruit set, the 6 % KNO3 gave also the highest leaf N and K concentrations (3.45 and 3.85 %) followed by 4
% KNO3 (3.25 and 3.52 %), 2 % KNO3 (2.88 and 3.30 %) and 0 % KNO3 (2.72 and 2.68 %).