Effect of Micronutrients and Plant Growth Regulators on Fruit Set , Fruit Retention , Yield and Quality Attributes in Litchi Cultivar Dehradun

The litchi (Litchi chinensis Sonn.) recognized as “Queen of the fruits” is the most important sub-tropical evergreen fruit tree, belongs to family Sapindaceae [1]. It is indigenous to south eastern China from where it is considered to have reached eastern India through Myanmar by the end of 17 th century or shortly thereafter [2]. In India, 585.30 thousand metric tonnes of litchi is produced annually from 84.20 thousand hectares area [3]. It is highly specific to climatic requirements, as it required cool dry winters and warm wet summers and due to this reason its cultivation is restricted to few states in our country. Litchi is grown mainly in the states of Bihar, West Bengal and Uttar Pradesh. It is also grown in limited scale in Tripura, Orissa, Punjab, Himachal Pradesh, Assam and Nilgiri hills in the south. In Punjab, its cultivation recommended to sub-mountainous tracts of Gurdaspur, Hoshiarpur, Roopnagar, SAS Nagar Mohali and Patiala districts. In Punjab, litchi is growing in an area of 2152 hactares with the production of 35239 metric tonnes [4]. Litchi is an arillate and nut type fruit botanically which is known for its excellent quality, juicy, slightly sour and sweet taste, characteristic pleasant flavour, attractive colour and nutritional value. The fruit is rich in sugars, minerals and vitamins [5] and can be processed into juice, wine, pickles, jam, jelly, ice cream and yoghurt [6]. It comes to the market in the months of May-June when the market is full of other fresh fruits. But, inspite of the availability of different types of fruit in the market, the demand for fresh litchi is always very high due to its unique taste, flavour and colour [7]. The problems responsible for low economic potential of litchi cultivation in various litchi growing regions include poor fruit set [8], heavy fruit drop [9], fruit cracking [10] and inferior fruit quality [11]. Therefore, plant growth regulators have been used for many years to alter the fruit plant behaviour for the economic benefits such as to control the vegetative growth, increase in flowering and fruit set, stimulation of maturity and ripening and improving fruit quality. It is also reported that growth substances like gibberellic acid(GA3), borax, naphthaleneacetic acid(NAA) and 2, 4-D have great influence on litchi and proved beneficial in reducing the cracking and dropping of fruits and enhancing the quality of fruits along with delay in harvest. GA3 has been found to offer suitable means of controlling ripening process in litchi and improving fruit quality [12] and other fruit crops [13]. Micronutrients plays specific role in improving the growth, yield and quality of litchi even though these elements are needed in small quantities. Zinc element is essentially required for growth, development and also involved in diverse range of enzyme system in litchi. The functional role of zinc includes auxin metabolism, influence on activating Abstract The present investigation entitled “Effect of micronutrients and plant growth regulators on fruit set, fruit retention, yield and quality attributes in litchi cultivar Dehradun. ” was carried out in the Punjab Agricultural University, Regional Research Station, Gurdaspur during the year 2014-15 and 2015-16. The experiment was laid out in Randomized Block Design with eleven treatments and replicated thrice with a unit of one plant in each replication of a treatment. Different doses of zinc sulphate (ZnSO4) @ 0.4%, 0.6%, and 0.8%; Borax @ 0.2%, 0.4% and 0.6% along with control were sprayed on new growth flushes before initiation of inflorescence, whereas 2, 4-D @ 10 ppm, 20 ppm and 30ppm; GA3 @25 ppm, 50 ppm and 75 ppm were sprayed after fruit setting in Dehradun litchi. Results shows that the maximum fruit set (78.15%), fruit retention (60.17%), fruit length (5.6cm), breadth (5.0cm), fruit weight (25.90gm), fruit yield(158.73kg/tree), pulp weight(22.19gm), pulp stone ratio(9.44), TSS(22.96°Brix) and sugars (18.52%) with minimum fruit cracking(2%), stone weight(2.35gm), peel weight(1.36gm) and acidity(0.4%) were recorded with 0.4% borax application followed by 50ppm GA3.