Influence of Pre-harvest spray of Calcium nitrate , Boric acid and Zinc sulphate on Quality and Storage life of Nagpur mandarin ( Citrus reticulata Blanco )

In India citrus fruits have a prominent place among popular and extensively grown tropical and subtropical fruits after mango and banana. Mandarin (Citrus reticulata Blanco) is considered to be one of the most important cultivated species among citrus and is being commercially grown in certain specific region of the country like Nagpur mandarin in Central India; this crop occupies the first position among the citrus in India with respect to area and production. Mandarin juice is refreshing and nutritious due to its ascorbic acid content, sweet acid taste and appealing colour. Nagpur mandarin is being commercially grown in specific region of the country like Nagpur mandarin in Central India, Khasi mandarin in North Eastern regions and Coorg mandarin in Southern regions. The total production of mandarin in India is 34.31 lakh tonnes from an area of 330.0 thousand hectares with the productivity of 10.4 MT/ha (Anonymous, 2015). In Rajasthan mandarin covers 11.20 thousand hectares area producing 229.90 thousand MT with the productivity of 20.5 MT/ha. In the state, In Jhalawar district mandarin where it is grown over 37,251 ha area, 11,323 ha of which are in the fruit bearing stage and the production is 2.5 Lac tonnes [1]. Nutrition is one of the most important aspects of fruit production and accounts for thirty per cent of the total cost of cultivation. The nutrient plays an important role in the development and growth of new cells in plant meristem. The Calcium salts are known to be involved in a number of physiological processes concerning membrane structure, function and enzymatic activity. The exact role of calcium, like that of all minerals, is still obscure, but it is important for cell wall development [2]. Zinc (Zn) is an essential micro element for plants, being involved in many enzymatic reactions and is necessary for their good growth and development. Zinc improves the auxins content and it also acts as catalyst in oxidation-reduction processes [3]. Boron is also a heavy metal micronutrient. It is absorbed by plant in the form of boric acid (H3BO3). It is essential for translocation of sugar; involved in reproduction of plants and germination of pollen grains [4]. Abstract A field experiment was conducted during winter season of 2014 -2015 to study the Influence of Pre-harvest spray of Calcium nitrate, Boric acid and Zinc sulphate on quality and storage life of Nagpur mandarin (Citrus reticulata Blanco) at Department of Fruit Science at College of Horticulture and Forestry, Jhalawar. Various doses of Calcium nitrate (1.0%, 2.0% and 3.0 %), Boric acid (0.2 %, 0.4 % and 0.6 %) and Zinc sulphate (0.2 %, 0.4 % and 0.6 %) were sprayed before harvesting and compared with untreated ones. The results obtained indicated that the trees sprayed with T27 i.e. (Calcium nitrate @ 3.0 % + Boric acid @ 0.6 % + Zinc sulphate @ 0.6 %) showed maximum increase non reducing sugar (2.58%), total sugar (9.02%), Juice per cent (46.89%), Sensory score (9.23/10.0) over control. Further, T24 treatment combination (calcium nitrate @ 3.0 % + boric acid @ 0.4 % + Zinc sulphate @ 0.6 %) has also significantly increased TSS (12.05 0 B), TSS: Acid ratio (15.97), ascorbic acid (50.61 mg) and reduced acidity (0.73%) of fruits. Besides, T27 treatment combination also significantly recorded minimum physiological loss in weight (2.23%), (5.13%) and (10.09 %), decay percent (2.22 %), (5.13 %) and (11.34 %) and higher retention of juice percent (46.31 %), (44.31 %), (41.77%) and (39.12 and sensory score (8.83/ 10), (8.63/ 10) and (8.28/ 10) storage at 5 th , 10 th and 15 th day of storage at ambient temperature.