Effect of Different Nitrogen Fertilizers on Leaf Micronutrients in Apple (Malus domestica Borkh)

Aims: To evaluate the effect of different nitrogen sources on leaf micronutrients of apple in pot culture studies and field studies.

Study Design: The experiment was laid out in a Completely Randomized Design factorial in pot studies and in a Randomized Block Design factorial in field studies.

Place and Duration of Study: The pot culture experiment was carried out at the experimental farm of Department of Soil Science and Water Management, Dr. Y. S. Parmar University of Horticulture and Forestry, Nauni, Solan (H.P.) and field experiment was carried out at Krishi Vigyan Kendra, Rohru, Shimla (H.P.) and Horticultural Research Station, Seobagh, Kullu (H.P.) in 2016 and 2017.

Methodology: Experiments were comprised of fourteen treatments and each treatment was replicated three times, having one plant under each replication. Calculated amount of fertilizers was added in the soil at appropriate time and leaf samples were collected for determination of leaf micronutrients. Copper (Cu), iron (Fe), manganese (Mn), zinc (Zn) contents were determined by using atomic absorption spectrophotometer and boron (B) was estimated by using Azomethine- H method.

Results: In pot culture studies, Cu was 14.96 and 15.05 ppm, Fe was 188.71 and 194.48 ppm, Zn was 31.52 and 32.51 ppm and 64.83 and 65.09 ppm in 2016 and 2017, respectively. The highest B content was recorded under urea alone application (35.64 and 35.48 ppm in 2016 and 2017, respectively). In field studies, Mn was 76.48 and 78.16 ppm at Seobagh and 83.23 and 85.15 ppm at Rohru, Fe was 218.25 and 225.15 ppm at Seobagh and 235.64 and 247.18 ppm at Rohru, Cu was 16.83 and 17.02 ppm at Seobagh and 17.87 and 18.03 ppm at Rohru, Zn was 39.40 and 40.84 ppm at Seobagh and 39.28 and 41.16 ppm at Rohru in 2016 and 2017, respectively. At Seobagh the highest B content in leaves was recorded under urea alone application (37.87 ppm) in 2016 and under the treatment 12:32:16 + calcium nitrate (38.14 ppm) in 2017, while at Rohru highest B content was under urea alone application (33.56 ppm) in 2016 and under calcium nitrate treatment (30.36 ppm) in 2017.

Conclusion: Leaf micronutrients (Fe, Cu, Mn, Zn and B) were significantly affected on application of nitrogen fertilizers and were the highest under urea alone application and were found to have a direct relation with the reduction in pH of the soils.