Effect of chemical fertilizers and Plant Biostimulants in yield and some characteristics of Citrus sinensis, var.Valencia leaves and fruits in the southern Kerman province

This study was conducted to evaluate the application of growth stimulants and chemical fertilizers on yield of Valencia oranges in the south of Kerman province. 

The experiment was performed as a factorial experiment in a randomized complete block design with 21 treatments in three replications. The first factor was chemical fertilizer at three levels and the second factor was growth stimulants at 7 levels. At the end of the experiment, yield, weight and average diameter of fruit and total soluble solids, total acidity, pH and vitamin C in fruit were measured. 

Seaweed showed the greatest effect on fruit diameter and yield, which were 2.9 and 53.3% better than the control, respectively. In chemical fertilizer treatment based on 75% of soil test, humic acid had increased yield (22.6% of a control treatment). Also, regardless of the type of chemical fertilizer treatment, the highest amount of nitrogen, phosphorus and potassium was observed in the seaweed treatment. 

Humic acid and seaweed were the best growth stimulants in increasing yield in the presence or absence of chemical fertilizers. The treatment of Chemical fertilizer based on soil test and foliar application of seaweed with a concentration of 5 per thousand after falling flowers and Hazelnut fruit showed the highest increase in the yield and nutrient uptake in leaves compared to other treatments.