59 J. Hortl. Sci. Vol. 12(1) : 59-64, 2017 Effect of GA3 and fungicide at colour-break stage for extension of bearing period and shelf-life in Khasi mandarin (Citrus reticulata Blanco.) S. R. Singh*, A. K. Phurailatpam and Siddhartha Singh College of Horticulture & Forestry, Central Agricultural University, Pasighat - 791 102 Arunachal Pradesh, India * E-mail: romensenjam@yahoo.com ABSTRACT The effect of GA3 of different concentrations along with fungicide was investigated on ten year old trees of Khasi mandarin to study the extension of bearing period and its post harvest shelf life the year, 2014-2015. Fruits on the tree at colour break stage were sprayed with seven concentrations of 10, 15, 25, 30, 35, 40 and 45 ppm of GA3 each along with the fungicide (Carbendazim 1g/L of water) and the control (no GA3 and fungicide). Among the different treatments, optimum fruit retention (237 fruits/tree) was observed in T5 (GA3@30ppm + fungicide i.e Carbendazim 1g/L of water) as compared to control (162 fruits/tree) and also extended the harvesting period for about 18.3 days in T 7 (GA3@45ppm + fungicide i.e Carbendazim 1g/L of water) which is at par with T5 and T6 (18 days). Besides, imposition of GA3 and fungicide at colour break stage also minimized the physiological loss in weight, spoilage loss, shriveling and thus, extended the post harvest shelf life of the fruits of about one week as compared to control under the room temperature. Key words : Khasi mandarin, GA3, fungicide, fruit retention INTRODUCTION Citrus is an important fruit crop which ranks third in production and occupies 12.5% of the total fruit crops production in India. Among the citrus group, mandarin orange (Citrus reticulata Blanco.) is one among the most common among citrus fruits grown in India. It occupies nearly 50% of the total citrus area in India (Anon, 2014). In the North East region of India (Assam, Arunachal Pradesh, Manipur, Tripura and Meghalaya), an ecotype of mandarin called Khasi mandarin occupied an important place among the other varieties of mandarin orange. In Arunachal Pradesh, which is known for its organic Khasi mandarin production it is facing problems. Further, fruits mature and ripe during the period of Nov-Dec months (peak period for Khasi mandarin under Pasighat condition). Due to the harvesting of all the fruits at one peak period and relatively short harvest period, there is low price of the crop value resulting low income to the Khasi mandarin growers. Besides, improper storage facilities, after the harvesting of it result in a glut in the market. However, such post ha r vest loss ca n be minimized through storing for a longer period at temperature of 5-70C with relative humidity 85-90% for about 4-8 weeks in the cold storage or with the application of growth regulator (GA3), its bearing per iod ca n be ex tended s o tha t ther e will be minimization of glut in the market. Therefore, the pr esent r esea r ch wa s init ia ted to ex plor e the potential of growth regulators in extension of its bea r ing p er iod a nd imp r oving the ha r vesting management in Khasi mandarin under the Pasighat condition. Information regarding application of plant growth regulators like GA3 are still lacking in East Siang district of Arunachal Pradesh. Keeping the view and considering the need of fruit retention during the bearing period and to increase the profit among the mandarin growers, the present research was initiated to explore the potential of growth regulators for extension of bearing period and better shelf life of Khasi mandarin under the Pasighat condition of Arunachal Pradesh, India. Original Research Paper 60 J. Hortl. Sci. Vol. 12(1) : 59-64, 2017 Singh et al MATERIAL AND METHODS The present investigations were carried out at the at Bodak village under East Siang district of Arunachal Pradesh (Fig.1.a) during the year 2014- treated plant was supplemented with 450:450:900g N: P: K/plant/year in two split doses. First split dose of the recommended dose of fertilizer of total P and K fertilizers along with half of nitrogen fertilizer was applied in one time at March-April along with a light irrigation after fruit setting and the remaining half of the recommended dose of nitrogen was applied during June-July. Before the fruit drop was anticipated to begin, all the fruits on the ground under the trees were removed. At the time of counting, dropped fruits were classified as sound or unsound. Sound fruit had no visible signs of injury or infection and unsound fruit had visible injury or pathological infection which we assumed induced by abscission. The statistical analysis of the data on the mean values of individual characters was analyzed using M Stat software. RESULTS AND DISCUSSION The effect of different concentrations of GA3 along with fungicide showed significant influence in the extension of bearing period and better shelf life as compared to control without effecting its fruit quality (Tables 1, 2 and 3). It was observed that the maximum extension of bearing period (18 days) was observed in T5 and T6 (18 days) and T7 (18.3 days) whereas the earliest fruit ripening was recorded in control (T9) (50.6 days) after the initiation of colour break stage. Stewart and Hield (1950) reported that the fall of mature fruit was characterized mainly by alterations in the cellular walls in the zone abscission, localized at the peduncle and that the main action of plant growth regulators in the fall of ripe fruit was that of reducing the weakening of the cellular wall material in this region, reducing the fall of fruit (Fig.1.b). Besides, Monselise and Goren Fig.1. (a) Experiment site, Bodak village, A.P. 2015 to evaluate the different concentration of GA3 for the extension of bearing period in the tree. The average altitude of the sites of the experiment are about 155 m MSL and represent a subtropical, hot and humid climate; in the lower valleys, summer temperatures in June, July, and August typically rise to a b ou t 3 0 o C, while winter t emper a t ur es in December, January, and February usually drops to 13°C. Annual rainfall in the state averages about 130 inches (3,300 mm), mostly between April and September. The details of the eight treatments are T1: GA3@10ppm + Carbendazim 1g/L, T2: GA3@ 15ppm + Carbendazim 1g/L, T 3:GA3@25ppm + Carbendazim 1g/L, T4:GA3@30ppm + Carbendazim 1g/L, T 5: GA3 @35ppm + Car benda zim 1g/L, T 6:G A 3 @ 4 0 p p m + C a r b enda z im 1 g/ L , T 7:GA3@45ppm + Ca r benda zim 1g/L a nd T 8 : Control. The PGR GA3 sprayed at colour break stage during September months and the extension of bearing period was evaluated by counting the average fruit retention / branche before spraying a t Sep tember mont h a s initia l r ea ding (equa l average fruit number/tree) and counted average fruits/br anche at November to observ the fr uit retention and its extension of bearing period. Finally, the number of fruits/tree at harvesting stage (last week of Nov) was counted for each treatment for the evaluation for better fruit retention/tree and also evaluated for its fruit quality parameters. Every Fig.1. (b) Fruits drop in control plant 61 J. Hortl. Sci. Vol. 12(1) : 59-64, 2017 Extension of bearing period and shelf-life in Khasi mandarin Ta bl e 1: F ru it re te nt io n of K ha si m an da ri n fo r di ff er en t G A 3 co m bi na tio n tr ea tm en ts Ta bl e 2: P hy si ca l p ar am et er s o f K ha si m an da ri n fo r di ff er en t G A 3 co m bi na tio n tr ea tm en ts 62 Singh et al J. Hortl. Sci. Vol. 12(1) : 59-64, 2017 (1978) also reported that the spraying of auxins and GA3 prevented the dropping of fruit by maintaining the cells at the zone of abscission, preventing the synthesis of hydrolitic enzymes, such as cellulose, which decomposed the cell walls. The trees which are treated with GA3 and fungicide were better in the retention of the green chlorophyll pigment of the fruit and extended the bearing period on the tree. Besides, fungicide spray during the colour break stage helped in reducing the fungal infection of the mature fruits, resulting in more fruits retention as compared to control. Babu et al. (1984) in acid lime and Greenburg et al., (1986) in Clementine mandarin also reported that application of GA3 at colour break stage increase fruit yield as well a s delay in ha r vest. T his might be due to the enhancement of vegetative growth and preventing the degreening process of the fruit by the GA3 spray which in turn direct improvement in carbohydrate metabolism resulting in better size of the fruit. The application of GA3 and fungicide at the colour break stage also increased the fruit retention and minimized the fruit drop resulting in more number of fruits/tree of 63% at T5 (237 fruits/tree) which are at par with 61% of fruit retention in T6, T7 & T8 showing 215 fruits/tree in T8, 209 fruits/tree in T7 and 202 fruits/tree in T8 respectively. Moreover, a study conducted by Lakshmi et al., 2014 revealed that increase in yield and yield components of acid lime by GA3 spray was attributed to synthesis of chlorophyll from source to sink. The physical parameters like fruit length, fruit breadth, fruit weight, peel weight, pulp weight juice content, number of seeds/fruit were significantly improved by the application of GA3, however non- significant improvement was found in peel thickness (Table 2). This can be attributed to nature of gibberellins in cell elongation which makes better size of fruits, correspondingly it increases fruit weight which certainly affect the fruit juice content. The results are in line with the findings of many workers Ratnababu et al., (1984) in Pant lemon-1, Lakshmi et al., (2014) in acid lime a s well a s Reddy a nd Pr a sa d (2012) in pomegranate with the application of GA3. Analytical investigation with different treatments of GA3 along with fungicide at colour break stage (Fig. 1.c) revealed that the parameters like TSS, reducing sugar, vitamin C, chlorophyll content were significantly but improved there was non-significant improvement Ta bl e 3. Q ua lit y pa ra m et er s o f K ha si m an da ri n fo r di ff er en t G A 3 c om bi na tio n tr ea tm en t 63 Extension of bearing period and shelf-life in Khasi mandarin J. Hortl. Sci. Vol. 12(1) : 59-64, 2017 Fig.1. (c) Application of GA3 and fungicide Fig.1. (d) Colour break stage in acidity and total sugar content of the fruit after the imposition of GA3 and fungicide application at colour break stage (Fig. 1.d). Besides, shelf-life was also found to improve significantly under the average room temperature of 20.50C and average relative humidity of 72 % after the imposition of treatment without affecting the fruit quality (Table 3). The results are in line with the findings of Parthiban et al., (2010); Debaje et al., (2011) and (Lakshmi et al., 2014) who reported GA3 increased quality of acid lime fruits by stimulating the functioning of enzymes involved in physiological processes moreover it might be due to more chlorophyll content resulting extension of bearing period of the tree with GA3 (Fig.1.e) resulting in higher accumulation of metabolites synthesis which makes improvement of the fruit quality parameters after the imposition of the treatment. Besides, the normal harvesting period of the Khasi mandarin was winter period hence, they could kept under the room temperature for a long period (Fig.1.f) however, there was fungal infection after 5th Fig.1. (e) Extension of bearing in the tree day onwards (Table 3). It was also reported that fungicide spray of carbendazim one month before harvest prolong the storage period under the room condition by minimizing the fungal infection of the fruits resulting in the prolonged in shelf-life of the fruit (Ladaniya, 1997). From the investigation, it is concluded that the combination GA3 and fungicide i.e. carbendazim@ 1g/ L of water helped in the extension of the bearing period in the tree and also extended the post harvest shelf - life of the fruits under the room condition for a week more than the control which will help in the controlling of glut in the market during the peak harvest season of Khasi mandarin. Therefore, application of GA3 @ 30 ppm along with fungicide (Carbendazim 1g/L of water) can be recommended to the citrus grower which will help in minimizing the spoilage of the fruit in the peak harvest season and increases the profit to the citrus growing farmers. Fig.1. (f) Better shelf life after treatment 64 REFERENCES Anonymous 2014. All India area and production of fruits and vegetables. Indian Horticulture Database, National Horticulture Board, Ministry of Agriculture, Govt. of India. pp. 50. (http.//www.nhb.gov.in). Babu, R.S.H., Rajput, C.B.S. and Rath, S. 1984. Effect of Zinc, 2,4-D and GA3 on fruiting of Kagzi lime (Citrus aurant if ol ia Swi n gl e). Indi an Journal of Horticulture, 41(3/4): 216-220. Debaje, P., Ekta, P., Shine, D. and Ingle, H.V. 2011. Effect of plant growth regulators and nutrients on quality of acid lime (Citrus aurantifolia Swingle). The Asian Journal of Horticulture. 6(1): 253-255. Greenburg, J., Monselise, S.P. and Goldschmidt, E.E. 1986. Effect of ingestion of GA3 and CCC into citrus trees. Acta Horticulture, 179 (I): 283-286. Ladaniya, M.S. 1999. Response of Nagpur mandarin fruit to pre-harvest spray of gibberellic acid and carbendazim. Indian Journal of Horticulture, 54 (3): 205-212. Lakshmi, L.M., Ramana, K.T.V., Krishna, V.N.P.S., Yuvaraj, K.M., Lakshmi, T.N., Sarada, G.T., Sankar, T.G., Gopi, V. and Gopal, K. 2014. Effect of growth regulators and chemicals on fruit yield and quality of hasta bahar flowering in acid lime (Citrus aurantifolia Swingle) cv. Balaji. Journal of Agriculture and Allied Sciences, 3(3): 11-13. Monselise SP and Goren R 1978. The role of internal factors and exogenous control in flowering, peel growth, and abscission in citrus. Hortscience, 13, 134-139. Parthiban, S., Saraswathy, S., Indra, N., Samundeeswari, A.V., Rani, B.U. and Selvarajan, M. 2010. Problems and prospectus of citrus production in India with special reference to acid lime (Citrus aurantifolia Swingle) cultivation in Karnataka. Proceeding of National Seminar on “Citrus Biodiversity for livelihood and Nutritional Security” October 4-5, 2010, NRC, Citrus, Nagpur, Maharastra. pp. 344-349 Ratnababu, G.H.V. Lavaniya, M.L. and Misra, K.K. 1984. Effect of plant growth regulator on yield and physiochemical composition of Pant lemon-1 (Citrus limon Burm .) fruits in the off season flush. Progressive Horticulture, 16(3-4): 191-198. Reddy, P.A. and Prasad, D.M. 2012. Effect of plant growth r egul a tor s on fr ui t ch a ra ct er s an d yi el d of pomegranate (Punica granatum L.) cv. Ganesh. International Journal of Plant, Animal and Environmental Science, 2(2): 91-93. Stewart, W.S. and Hield, H.Z. 1950. Effects of 2,4- Dich l or ophen oxya cet i c a ci d a n d 2, 4, 5- Trichlorophenoxyacetic acid on fruit drop, fruit production, and leaf drop of lemon trees. Proceeding American Society Horticulture Science, 55, 163-171. (MS Received 16 September 2016, Revised 13 April 2017, Accepted 04 May 2017) Singh et al J. Hortl. Sci. Vol. 12(1) : 59-64, 2017 ACKNOWLEDGEMENT The authors like to render gratefulness to the College of Horticulture & Forestry, Central Agricultural University for funding the research work under the IRP project scheme. 00 Content JH June 2017.pdf 00 SPH-Journal November new 12.pdf 01 SPH-Journal November new 01.pdf 02 SPH-Journal November new 04.pdf 03 SPH-Journal November new 05.pdf 04 SPH-Journal November new 07.pdf 05 SPH-Journal November new 09.pdf 06 SPH-Journal November new 10.pdf 07 SPH-Journal November new 11.pdf 08 SPH-Journal November new 13.pdf 09 SPH-Journal November new 03.pdf 10 SPH-Journal November new 06.pdf 11 SPH-Journal November new 08.pdf