Mango is an important fruit crop of India, being the ‘king of fruits’. India is the global leader in mango production, with 104.1 million tonnes from an area of 12.02 million ha (NHB, 2009). Our national average productivity is estimated at 6.42 t/ha. Reasons for the low productivity are many, an important one being that most of our commercial varieties are alternate or irregular bearers. To combat the alternate bearing habit in mango, many investigations have been made. Use of chemicals and pruning is one of them. However, results on effect of pruning and chemicals vary depending on the variety, location, dose of the chemical and time of application (Maas, 1989; Rao and Ravishankar, 1992; Srihari and Rao, 1996, 1996a; Rao et al, 1997; Joganande et al, 2003; Jayavalli, 2006) In varieties like ‘Alphonso’, not much work has been done on pruning or on use of chemicals. Hence, the present investigation was carried out on mango flowering and fruit yield. A field trial was conducted from 2005 to 2009 on 16- year old Alphonso mango crop raised on the polyembryonic rootstock ‘Peach’. Trees were spaced at 10m × 5m under rain-fed condition on red loamy soil of pH 7.21 and available N - 249 kg/ha, available P - 14 kg/ha and available K - 149.4 kg/ha. Seven treatments were applied as follows: T 1 : Pruning + 1% K 2 HPO 4 T 2 : Pruning + 1% KH 2 PO 4 Short communication Effect of pruning and chemicals on flowering and fruit yield in mango cv. Alphonso Y.T.N. Reddy and Reju M. Kurian Division of Fruit Crops Indian Institute of Horticultural Research Hessaraghatta Lake Post, Bangalore-560089, India E-mail : nreddy@iihr.ernet.in ABSTRACT A field trial was conducted from 2005 to 2009 on pruning and spray of various chemicals to study their effects on flowering and fruit yield in ‘Alphonso’ mango, at Indian Institute of Horticultural Research, Bangalore. Seven treatments were imposed, with pruning of fruited shoots as a common treatment, followed by chemical sprays and a control. Over the five years, flowering parameters (% vegetative, dormant or flowering shoots) were found to be non- significant among different treatments. Treatments increased fruit yield compared to control. The best treatment was T 3 (Pruning + 1% K 2 HPO 4 + 1% KNO 3 spray) which recorded mean fruit yield of 63.9 kg / plant, compared to a fruit yield of 33.0 kg / plant in control. Key words: Fruit quality, pruning, mango, chemicals, fruit yield T 3 : Pruning + 1% K 2 HPO 4 + 1% KNO 3 T 4 : Pruning + 1% KH 2 PO 4 + 1% KNO 3 T 5 : Pruning + 1% K 2 HPO 4 + 1% Thiourea T 6 : Pruning + 1% KH 2 PO 4 + 1% Thiourea T 7 : Control (No pruning or chemical spray) Pruning treatments were imposed after fruit harvest during August by pruning 15-20 cm of fruited shoots, followed by spray of 1% K 2 HPO 4 or 1% KH 2 PO 4 during October (T 1 and T 2 ); Treatments T 3 to T 6 at the time of bud-break (December). Spray solution @ 4 litres / tree was used along with a wetting agent. The trial was laid out in RBD design with 4 replications and a single tree as a unit / treatment. Regular and uniform cultural practices were followed. Flowering parameters were recorded in January-February and fruit yield parameters during the fruiting seasons 2006- 2009. Data were statistically analyzed as per standard procedure of Panse and Sukhatme (1986). Type of shoots: Percentage of vegetative, dormant and flowering shoots were found to be non significant among various treatments during the different years of observation. However in general, pruning along with chemical sprays reduced percentage of vegetative shoots and increased percentage of flowering shoots compared to control. Similar results were reported by Maas (1989); but, on the contrary, J. Hortl. Sci. Vol. 7(1):85-87, 2012 86 Reddy and Reju beneficial effects of pruning + chemicals spray were reported in mango by Joganande et al (2003) and Chadha and Pal (1993). The difference in response to pruning and chemicals was due to the varieties studied under varying environmental and growth conditions. Panicle length, shoot length and number of days to 50% flowering during different years were found to be non- significant among treatments. Similar results were earlier reported (Maas, 1989; Chadha and Pal, 1993). These attributes were not influenced by pruning or chemical sprays. Fruit yield: Fruit yield as affected by pruning and spray of chemicals is presented in Table 1. Number of fruits/plant and fruit yield/plant was found to be significant between treatments in the years 2007 to 2009. Cumulative fruit yield was also significantly different in treatments compared to control. All the treatments increased fruit yield, and, the most pronounced effect was seen in the treatment Pruning + 1% K 2 HPO 4 + 1% KNO 3 . Hence, mean fruit yield was almost twice (63.9 kg / plant) that in the control (33.0 kg / plant). Similar results have been reported by several workers (Jaganande et al, 2003; Chadha and Pal, 1993). Increased fruit yield owing to pruning and chemicals was due to increased number of flowering shoots and reduced vegetative / dormant shoots, in general, compared to the control. Phosphoric acid and potassium nitrate may have acted synergistically to increase the number of flowering shoots, thereby increasing fruit yield. Cost-benefit ratio: Mean cumulative fruit yield for four years and cost:benefit ratio were worked out and are presented in Table 2. Maximum cost:benefit ratio (1:3.8) was obtained with the treatment Pruning + 1% K 2 HPO 4 + 1% KNO 3 , whereas, control treatment recorded the least cost:benefit ratio (1:1.54) indicating superiority of the treatment. REFERENCES Chadha, K.L. and Pal, R.N. 1993. Biennial bearing in mango. In: Advances in Horticulture, Vol. 4. Fruit Crops, Malhotra Publishing House, New Delhi, pp 2025-2045 Jognande, N.D., Dalal, S.R., Gonge, V.S., Panchbhai, D.M. and Anuje, A.A. 2003. Possibility of induction of flowering in mango variety Pairi through chemical spray. National Seminar on Mango, GAU, Junagadh, June, 14-15, p. 30 Jayavalli, R. 2006. Studies on canopy management and induction of off season bearing under high density planting in mango cv. Neelum. M.Sc. (Hort.) Thesis submitted to HCRI, Periyakulam, Tamil Nadu Mass, E.F. 1989. Potassium nitrate foliar spray induces bloom in mango orchards. Better Crops Int’l. 5:4-5 Table 2. Effect of pruning and chemicals on cost:benefit ratio in mango cv. Alphonso Treatment Gross Net Cost: returns returns benefit (Rs.) (Rs.) ratio Pruning + 1% K 2 HPO 4 102750 75250 1:2.25 Pruning + 1% KH 2 PO 4 110250 82750 1:2.50 Pruning + 1% K 2 HPO 4 + 1% KNO 3 159750 129500 1:3.80 Pruning + 1% KH 2 PO 4 + 1% KNO 3 129750 98750 1:2.65 Pruning + 1% K 2 HPO 4 + 1% Thiourea 124250 93250 1:2.45 Pruning + 1% KH 2 PO 4 + 1% Thiourea 127500 96500 1:2.60 Control (No pruning 82500 54250 1:1.54 or chemical spray) Table 1. Fruit yield in mango cv. Alphonso as influenced by pruning and chemical sprays Treatment No. of fruits / plant Fruit yield (kg / plant) 2006 2007 2008 2009 Cumulative Mean 2006 2007 2008 2009 Cumulative Mean Pruning+1% K 2 HPO 4 200.1 183.7 27.7 388.5 800.0 200.0 42.8 43.5 7.1 71.0 164.4 41.1 Pruning+1% KH 2 PO 4 210.2 156.0 58.2 438.0 862.4 215.6 44.9 38.7 14.2 78.7 176.5 44.1 Pruning+1% K 2 HPO 4 + 198.5 299.7 91.7 647.5 1237.4 309.3 40.0 79.5 21.9 114.5 255.9 63.9 1% KNO 3 Pruning+1% KH 2 PO 4 + 178.5 247.5 68.0 481.7 975.7 243.9 39.5 62.0 17.0 89.2 207.7 51.9 1% KNO 3 Pruning+1% K 2 HPO 4 + 195.6 235.0 85.7 465.0 981.3 245.3 40.6 56.5 19.3 83.2 199.6 49.9 1% Thiourea Pruning+1% KH 2 PO 4 + 189.1 210.0 67.5 486.2 952.7 238.1 42.1 52.7 17.0 92.5 204.3 51.0 1% Thiourea Control (No pruning 141.5 121.2 24.0 348.2 634.9 158.7 30.4 28.4 6.1 67.2 132.1 33.0 or chemical spray) F-test NS * NS * * NS * * * * S. Em ± 8.1 23.9 18.7 29.4 42.3 5.9 6.6 3.7 10.5 18.3 C.D. (P= 0.05) - 72.0 - 90.5 127.6 - 20.1 10.9 30.9 54.7 *Significant at 5% NS: Non-Significant J. Hortl. Sci. Vol. 7(1):85-87, 2012 87 National Horticultural Board. 2009. Database of Horticultural Crops, 2009, New Delhi Panse, Y.G. and Sukhatme, P.V. 1985. Statistical methods for agricultural workers. Fourth edition, ICAR, New Delhi, pp. 201-215 Rao, M.M. and Ravishankar, H. 1992. Chemical induction of flowering on fruited shoots in “off” phase Alphonso mango trees. Karnataka J. Agril. Sci., 5:180-193 Rao, M.M., Srihari, D., Patil, V.S. and Madalageri, M.B. (MS Received 08 March 2011, Revised 16 June 2012) Pruning and chemicals in flowering and fruit yield in mango 1997. Further studies on chemical induction of flowering on fruited shoots in “off” phase Alphonso mango trees. Karnataka J. Agril. Sci., 10:598-601 Srihari, D. and Rao, M.M. 1996. Induction of flowering in off phase mango trees by soil application of Paclobutrazol. Acta Hort., 455:491-495 Srihari, D. and Rao, M.M. 1996a. Induction of flowering directly on de-blossomed shoots in the “off” phase of Alphonso mango trees. J. Res. ANGRAU, 25:48-50 J. Hortl. Sci. Vol. 7(1):85-87, 2012