One foliar spray in “Valencia” and “Shamouti” orange was conducted respectively 6 and 8 weeks after flowering. Spraying 20 ppm 2,4-D (auxin) + 5% KNO3 increased fruit size by 8-20% for “Shamouti” and 8-25% for “Valencia” compared to the control. Potassium nitrate also increased significantly the juice acid level in “Shamouti” orange by 15%. Spraying with KNO3 was more efficient than spraying K2SO4 in increasing fruit size per 1000 distributed fruits (Figure 1).
Figure 1. Effect of foliar sprays on % extra packed boxes (untreated control=0%).
Erner, Y., Y. Kaplan, B. Artzi, and M. Hamou. 1993. Increasing citrus fruit size using Auxins and potassium. Acta Horticulturae 329: 112-119.