Impact of Various Combinations of Organic and Inorganic Fertilizers on Fruit Production and Quality of ‘Kinnow’ Mandarin ( Citrus reticulata Blanco.)

Citrus fruits have a prominent position among the tree fruits and are extensively grown in tropical and subtropical regions of the world. Citrus is a perennial fruit crop that is highly nutrient-responsive and requires appropriate nutrition for optimum growth and development. The transition from conventional chemicals to biofertilizer (organic) sources is gaining popularity these days. This study aimed to assess the effects of different organic and synthetic fertilizer doses on the yield and quality of 10-year-old ‘Kinnow’ mandarin trees (grafted on ‘Rough lemon’) for three consecutive seasons: 2015–2016, 2016–2017, and 2017–2018. Six different formulations of fertilizers were used in this study, i.e., farmyard manure (FYM), humic acid (HA), and inorganic fertilizers (NPK). As a source of nitrogen, we used calcium ammonium nitrate for phosphorous (single superphosphate, SSP) and sulphate of potash (SOP) were used. The recommended dosage of organic and inorganic fertilizers was used during the experiment, namely T1 (50 Kg/plant FYM + 1000:500:500 g/plant NPK); T2 (60 Kg/plant FYM + 750:375:375 g/plant NPK); T3 (70 Kg/plant FYM + 500:250:250 g/plant NPK); T4 (150 g/plant HA + 1000:500:500 g/plant NPK); T5 (200 g/plant HA + 750:375:375 g/plant NPK) and T6 (250 g/plant humic acid + 50% Basic dose of NPK). According to the results, T2 fertilizer significantly enhanced plant growth, canopy volume, and plant spread. Moreover fruit yield (55, 52, 54 g) was improved in T2 treatment for 3 consecutive years compared to the other treatments. The better fruit size (65, 67, 65 mm) and juice percentage (40, 45, 41%) remained substantially higher and increased in T2 compared to other tested treatments. The research findings exhibited that orchard nutrition management notably affected tree growth and productivity. The combination of a large quantity of organic (FYM) with a lower level of inorganic fertilizer showed significantly better plant growth and yield than other combinations. In the future, these doses should be advised for mandarins in the field conditions in order to improve yield and fruit quality.