Effect of winter foliar application of urea on flowering, yield and changes of mineral elements in shoots of Kinnow Mandarin

Nitrogen plays an important role in managing the nutrition of the citrus. An experiment was set  as  factorial in a randomized complete block design with three replications to investigate the effect of different levels of urea (0, 0.75%, 1.5%), and different times of urea foliar application (Dec 22, Jan 5, Jan 20) on nitrogen, phosphorus, potassium contents to evaluate flower characteristics and yield in Kinnow mandarin plant. Samples were taken from leaves and nodes at 1, 3 and 5 wks after spraying. Results showed that, 3 wks after foliar application, the plants which receiving 1.5% urea had the high leaves nitrogen content (2.5%) on Dec 22., whereas the highest nitrogen content (1.73%) of the nodes was obtained in plants treated with 1.5% urea concentration on Dec 22. The highest amounts of potassium and phosphorus of leaves were reported under 1.5% urea concentration on the 30th of January. It also indicated that different concentrations of urea are capable of enhancing the number of flowers, promoting ovarian growth and boosting yield of the crop. The most effective promotion on plant characters had been appeared on the rate of 1.5% urea concentrations.