This is an open access article d istributed under the terms of Creative Commons Attribution-NonCommer cial-ShareAl ike 4.0 International License, which permits unrestricted non-commercial use, d istribution, and reproduction in any med ium, provide d the original author and source are credited. Original Research Paper INTRODUCTION Papaya (Carica papaya L.) is a common fruit crop grown in the Southern region of India. The crop is being cultivated in an area of 1,49,000 ha with a production of 57,44,000 MT (Anonymous, 2022). Fertigation combines the application of water and nutrient required for plant growth and development and allows an accurate and uniform application of nutrients to the wetted area in the root zone. Through fertigation, it is possible to supply an adequate quantity and concentration of nutrients to meet the demand of the crop throughout growing season. Further, fertigation is the most efficient method of fertilizers application, as it ensures application of the fertilizers directly to the plant roots (Rajput and Patel, 2002). The scheduling of fertigation for crops will benefit the farmers to increase the yield and improve the quality of produce through efficient use of water and fertilizers. Use of fertigation in fruit crops was reported to save 30-50% of fertilizer doses as well as ir r iga tion (Shirgur e et al. , 2001; Shirgur e and Srivastava 2014). Further, it is imperative to a chieve the high nutr ient use efficiency a nd reducing the requirement of bulk fertilizers to 25% (Malhotra, 2016). Fertigation has been substantiated for many crops t hr ou ghout wor ld. I t ha s b een r ep or t ed t ha t efficiency of nitrogenous fertilizers is 95% under drip-fertigation compared to 30-50% under soil application. When a fertilizer is applied to a soil, nearby water begins to move very gradually toward the a rea wher e the fer tilizer has been applied. Fertilizer salts begin to diffuse, or move away from the place where they were applied. This dilutes the fertilizer and distributes it throughout a much larger area. If tender plant roots are close to the placement of a fertilizer, water is drawn from these roots, as well as from surrounding soil (Rajput and Patel, 2002). Further, Sathya et al. (2008) observed that the availability of N, P and K nutrient was found to be higher in root zone area of drip fertigated plot, while nitrogen and potassium moved laterally from point source up to 15 cm a nd vertica lly up to 15-25 cm and P moved 5 cm both laterally and vertically and thereafter dwindled. Nitrogen promotes vegetative growth, flower and fruit set. High level of phosphorus throughout root zone is essential for ra pid root development and good utilization of water and other nutrients by plant. Phosphorous has pronounced effect on the flowering, J. Hortic. Sci. Vol. 18(1) : 104-112, 2023 https://doi.org/10.24154/jhs.v18i1.2133 Standardisation of fertigation in papaya for higher productivity and profitability Manjunath B.L.1*, Gutam S.2 and Raghupathi H.B.3 1Division of Fruit Crops, 2Division of Basic Sciences, 3Division of Natural Resources ICAR-Indian Institute of Horticultural Research, Bengaluru - 560089, Karnataka, India *Corresponding author Email: manjunath.bl@icar.gov.in ABSTRACT A field experiment conducted to standardize the fertigation in papaya (Carica papaya L.) variety Arka Prabhat with 12 treatments in split plot design, indicated that fertigation with 75% recommended fertilizers (250:250:500 g NPK/plant/year) through water soluble fertilizers recorded significantly higher fruit yield (47.34 t/ha), fertilizer use efficiency (20.45 kg fruit yield/kg of nutrient applied) and increase in 31% higher yield over soil application. The TSS of papaya fruit was although not significantly influenced by both doses and sources of fertigation, significantly lower cavity index (3.12%) was observed when RDF was supplied with organics to the soil. Fertigation with 100% RDF through water soluble fertilizers recorded significantly higher soil organic carbon (1.16%). However, fertigation of 75% RDF with inorganic fertilizers was found more economical with higher gross returns (Rs.7.10 lakh/ha), net returns (Rs.4.7 lakh/ha) and benefit cost ratio (2.96). Keywords : Benefit cost ratio, fertigation, papaya, productivity, profitability 105 Standardisation of fertigation in papaya J. Hortic. Sci. Vol. 18(1) : 104-112, 2023 in combination with N and K improves peel colour, taste, hardiness and vitamin C content and hastens maturity. Potassium tends to increase fruit size, fruit quality and rectifies many disorders. It also helps in decreasing incidence of irregular shaped fruits. However, sta nda r disa tion of the schedules of fertigation is crucial to decide both the doses and in coinciding the crop nutrient requirement with different stages of the crop. Keeping this in view, a field exper iment wa s ca rr ied out to standa rdize the fertigation in papaya. MATERIALS AND METHODS The experiment was conducted during 2020-21 at ICAR-Indian Institute of Horticultural Research, Bengaluru, Karnataka, which is located at an altitude of 890 m above mean sea level and lies between coordinates of 13° 8' N latitude and 77° 29' E longitude. Soil of experimental field was sandy loam with 6.27 pH, 0.16 dS m-1 EC, and 0.78% organic carbon. The soil had an initial nutrient content of 283 kg available N/ha, 42.0 kg available phosphorus/ ha and 246.4 kg available potassium/ha. Uniform and well-developed 45 days old seedlings of papaya var. Arka Prabhat were planted at a spacing of 1.8 m x 1.8 m on raised beds during July 2020 and the tr ea tments wer e imposed with the cr op esta blishment. T he cr op wa s ma na ged with r ecommended pa cka ge of pra ctices except for irrigation. The experiment was carried out in split plot design with 12 treatment combinations consisting of three doses of fertilizers, viz., M0: 100% RDF (250 g N + 250 g P2O5 + 500 g K2O per plant/year), M1: 125% RDF, and M2: 75% RDF as main plot and four sources of nutrients, viz., S0: fertigation through inorganic sources (urea, MKP and SOP) S1: fertigation through organic sources (humic acid and vermiwash), S2: soil application of only organic sources (FYM, vermicompost, neem cake, Sesbania and Glyricidia loppings), and S3: soil application of FYM+ RDF (ur ea , SSP a nd MOP) a s contr ol a s sub-plot treatments. Each treatment was replicated four times and each replication had five plants. Observations were recorded on various parameters of plant growth and physiology, root growth, soil fertility, yield, and TSS and fruit cavity index after 240 days after planting. The physiological parameters were measured using IRGA portable photosynthesis system. The horizontal and vertical root growth was measured for the longest spread, and the root volume was ca lcula ted ba sed on the displacement of water technique at the end of the crop season on a destructive mode. The dry weight of roots was calculated by carefully uprooting the roots with soil, washing with water and drying with hot air oven. Soil samples were collected at the end of the crop from 0-30 cm at 30-40 cm away from the base of the plant. Soil chemical and fertility parameters such as pH, organic carbon, available phosphorus (P) and potassium (K) were analysed as per standard procedures described by Jackson (1973). The fruit cavity index (%) was calculated by fruit cavity volume divided by fruit volume and multiplied by 100. Plant canopy volume was calculated using the formula 2/3πH (A/2 x B/2)], where H stands for plant height, A and B stands for EW and NS plant canopy spread (Thome et al., 2002). Fertilizer use efficiency was calculated based on the fruit yield obtained and the fertilizer nutrient used in each of the treatment. All the experimental data were statistically analysed as per Panse and Sukhatme (1985), and the differences in means were compared at 5% level of significance. RESULTS AND DISCUSSION Plant growth parameters T he pla nt height in pa pa ya wa s significa ntly influenced by fertilizer doses and fertigation sources (Table 1). Significantly higher plant height (1.19 m) was recorded with 125 % RDF and among the sources, fertigation with RDF through inorganics recorded higher plant height (1.20 m). Number of leaves were significantly higher with 125% RDF (20.63/plant) as compared to other sources, and further application of water soluble fertilizers recorded significantly higher number of leaves (20.6/plant) differing from other sources. Among the interactions, soil application of organic sources meeting 125 % RDF recorded significantly more number of leaves (21.5/plant). The plant girth in papaya differed significantly both due to doses and sources of nutrients although their interactions were non-significant. Significantly higher plant girth (26.28 cm) was recorded with application of 75 % of RDF, and among the sources, fer tiga tion with inorganic sources recorded more plant girth (26.92 cm). Canopy volume in papaya was not significantly influenced by the fertilizer doses and their interaction with various sources. However, fertigation with water soluble fertilizers recorded significantly higher (1.64 m3) canopy volume differing from rest of the sources. 106 Manjunath et al. Treatment Plant height No. of Stem girth Canopy volume (m) leaves/plant (cm) (m3) Main plot M0 1.00 15.66 20.56 0.95 M1 1.19 20.63 25.78 1.18 M2 1.10 18.63 26.28 1.16 Subplot S0 1.20 20.63 26.92 1.64 S1 1.05 16.67 22.42 1.00 S2 1.03 17.33 22.71 0.81 S3 1.11 18.59 24.79 0.93 Interaction M0S0 1.10 21.00 24.75 1.44 M0S1 0.95 13.75 20.00 0.75 M0S2 0.90 12.00 17.00 0.65 M0S3 1.07 15.88 20.50 0.96 M1S0 1.32 21.00 26.75 1.78 M1S1 1.13 19.00 23.38 1.34 M1S2 1.15 21.50 27.50 0.87 M1S3 1.15 21.00 25.50 0.74 M2S0 1.18 19.88 29.25 1.71 M2 S1 1.06 17.25 23.88 0.92 M2S2 1.05 18.50 23.63 0.91 M2S3 1.12 18.88 28.38 1.10 S Em ± Main 0.02 0.65 0.37 0.07 Sub 0.03 0.66 0.80 0.21 Main x Sub-1 0.05 1.19 1.25 0.32 C.D (P=0.05) Main 0.07 2.31 1.30 NS Sub 0.08 1.93 2.33 0.60 Main x Sub-1 NS 3.69 NS NS Table 1 : Mean plant growth parameters in papaya as influenced by fertilizer doses and fertigation sources Physiological parameters in papaya Although, the fertigation sources found to have non- significa nt impa ct on differ ent physiologica l parameters recorded, the doses of fertilizers influenced the photosynthesis, r espir a tion a nd stoma ta l conductance significantly (Table 2). Application of either 75% or 100% recommended fertilizers recorded significantly higher photosynthetic rate (16.34 µ mol m-2 s-1 and 16.24 mol m-2 s-1, respectively), the former a lso r ecor ded significa ntly higher stoma ta l conductance (0.14 mol H2O m -2 s-1) and transpiration rate (3.07 mol m-2 s-1). Among the interactions, application of recommended fertilizer s through fertigation (M0S0) recorded significantly higher photosynthetic rate (17.53 µ mol m-2 s-1), which was followed by application of 75% RDF with organic sources of fertigation (M2S1), the latter also recording higher transpiration rate (3.14 mol m-2 s-1). Application of 75% RDF through fertigation (M2S0) recorded significantly higher stomatal conductance (0.16 mol H2O m -2 s-1) also. Better physiological parameters in fertigated plants may be attributed to the higher nutritional status (N, P and K content), leaf N and K contents and physiological efficiency (Shirgure et al., 2001), fertigated papaya plants recorded higher physiological efficiency (especially total chlorophyll content), photochemica l efficiency, stoma ta l conducta nce a nd net photosynthesis, water use efficiency and relative water content compared with plants not subjected to fertigation. J. Hortic. Sci. Vol. 18(1) : 104-112, 2023 107 Table 2 : Physiological parameters in papaya as influenced by fertilizer doses and fertigation sources Treatment Photosynthetic Stomatal Transpiration rate conductance rate (µ mol m-2 s-1) (mol m-2 s-1) (mol m-2 s-1) Main plot M0 16.24 0.09 1.94 M1 12.61 0.07 2.32 M2 16.34 0.14 3.07 Sub plot S0 14.70 0.11 2.52 S1 14.25 0.09 2.23 S2 15.82 0.10 2.55 S3 15.48 0.10 2.47 Interaction M0S0 17.53 0.11 2.54 M0S1 15.15 0.08 1.85 M0S2 16.26 0.09 1.58 M0S3 16.00 0.08 1.77 M1S0 9.69 0.05 1.91 M1S1 10.35 0.04 1.71 M1S2 16.10 0.09 3.01 M1S3 14.29 0.09 2.67 M2S0 16.88 0.16 3.11 M2 S1 17.26 0.14 3.14 M2S2 15.09 0.11 3.06 M2S3 16.15 0.13 2.97 S Em ± Main 0.20 0.01 0.15 Sub 0.41 0.01 0.15 Main x Sub-1 0.64 0.01 0.27 C.D (P=0.05) Main 0.80 0.03 0.60 Sub NS NS NS Main x Sub-1 1.98 0.04 0.89 Root growth The impact of fertigation treatments on root growth parameters indicated that both the lateral and vertical root growth in papaya was significantly influenced by the doses and sources of fertigation although the root volume showed non-significant differences (Table 3). The vertical growth of the roots was significantly higher with application of 100 % RDF (84.1 cm) and especially with soil application of organic sources (97.5 cm) both of which differing significantly from other treatments. Although, the horizontal growth of roots was significantly influenced both by the fertilizer doses and the fertigation sources, their interaction was non- significant. In general, application of 75 % of RDF (163. 8 cm) a nd a mong the sour ces, soil a pplica tion of nutr ients (174. 5 cm) showed significantly higher lateral spread of roots. Root dry weight in general was significantly higher with 125 % RDF, and among the sources soil application of RDF shown significantly higher root dry weight (641.2 g plant-1) differing significantly from rest of the fertigation sources. Soil fertility The pH of soil was influenced significantly both by the doses and sources of fertigation under papaya. Lowering the dose of fertilizers to 75 % RDF recorded pH 6.06 as compared to pH 5.96 in 100 % RDF. Among the sources, soil application of FYM and RDF recorded relatively better soil pH (6.11), while, among Standardisation of fertigation in papaya J. Hortic. Sci. Vol. 18(1) : 104-112, 2023 108 Root Root Root Root fresh Root dry Treatment length breadth volume weight weight (cm) (cm) (cm3 plant-1) (g plant-1) (g plant-1) Main plot M0 84.1 109.9 1222.5 1606.9 395.9 M1 65.6 154.8 1530.6 2378.1 594.4 M2 50.0 163.8 1332.5 2556.3 554.8 Subplot S0 69.8 131.5 1260.8 1900.0 496.8 S1 70.0 117.0 1215.8 1920.8 408.5 S2 65.8 148.2 1490.8 2158.3 513.6 S3 60.7 174.5 1480.0 2742.5 641.2 Interaction M0S0 74.5 105.5 1032.5 1187.5 323.0 M0S1 85.0 86.0 765.0 962.5 162.4 M0S2 97.5 109.5 1460.0 1900.0 477.2 M0S3 79.5 138.5 1632.5 2377.5 621.1 M1S0 85.0 114.0 1340.0 1887.5 677.6 M1S1 77.5 140.0 1612.5 2800.0 609.9 M1S2 52.5 180.0 1750.0 2275.0 501.2 M1S3 47.5 185.0 1420.0 2550.0 589.0 M2S0 50.0 175.0 1410.0 2625.0 489.9 M2 S1 47.5 125.0 1270.0 2000.0 453.2 M2S2 47.5 155.0 1262.5 2300.0 562.6 M2S3 55.0 200.0 1387.5 3300.0 713.7 S Em ± Main 0.2 2.7 145.9 37.0 20.4 Sub 2.0 7.5 281.5 155.7 52.7 Main x Sub-1 3.0 11.6 446.7 236.4 81.6 C.D (P=0.05) Main 0.7 9.5 NS 130.5 72.1 Sub 5.8 21.9 NS 454.1 153.7 Main x Sub-1 8.7 NS NS 693.2 NS Table 3 : Root growth in papaya as influenced by fertilizer doses and fertigation the interactions, fertigation through organic sources with 75 % of RDF recorded a soil pH of 6.19. The lower pH of soil with recommended fertilizers may be attributed to the addition of acidic fertilizers and the same was relatively better when applied along with FYM. The organic carbon content in soil was significantly influenced by doses and sources of fertigation. Application of 100 % RDF recorded significantly higher organic carbon (0.93 %) as compared to either 75 % (0.59 %) or 125 % (0.82 %). Among the sources, application through water soluble fertilizers recorded significantly higher organic carbon (0.92 %) as compared to other sources and the control. Among the interactions, 100% RDF through water soluble fertilizers recorded significantly higher organic carbon (1.16%) differing significantly from rest of the tr ea tment combina tions except the tr ea tment application of 125% RDF through soil application of organics (1.05%). The higher organic carbon content with water soluble fertilizers may be attributed to the better availability of plant nutrients in turn favouring the accumulation of organic carbon in the soil. T he nitrogen content in soil wa s significa ntly influenced by doses and sources of fertigation. Application of 100 % RDF recorded significantly higher a va ila ble nitr ogen (150. 7 kg ha -1) a s compared to either 75 % (96 kg ha-1) or 125 % RDF Manjunath et al. J. Hortic. Sci. Vol. 18(1) : 104-112, 2023 109 (133 kg ha-1). Among the sources, application through water soluble fertilizers recorded significantly higher available nitrogen (148.2 kg ha-1) as compared to other sources and the control. Among the interactions, 100 % RDF through water soluble fertilizers recorded significantly higher N (187.1 kg ha -1) differing significantly from rest of the treatment combinations. The available phosphorous content in soil was significantly influenced both by the doses and sources of fertigation. Application of 125 % RDF recorded significa ntly higher a va ila ble phosphor ous (40.92 kg ha-1). Among the sources, soil application nutr ients thr ough orga nic sour ces r ecor ded significantly higher available phosphorous (47.31 kg ha-1) as compared to other sources and the control. Among the interactions, 75 % RDF through organic sources recorded higher available phosphorous content (58.46 kg ha-1) differing significantly from rest of the treatment combinations except application of 125 % RDF through soil application of organic sources (55.91 kg ha-1) and application of 100 % RDF through water soluble fertilizers (54.19 kg ha-1). T he a va ila ble pota ssium content in soil wa s significantly influenced by doses and sources of fertigation. Application of 125 % RDF recorded significantly higher soil available potassium (281.3 kg ha-1). Among the sources, application through water soluble fertilizers recorded significantly higher available potassium (284.2 kg ha-1) as compared to other sources and the control. Among the interactions, 100 % RDF through water soluble fertilizers recorded significantly higher potassium (353.8 kg ha-1) differing Treatment pH EC (dSm-1) O.C. (%) N (kg ha-1) P (kg ha-1) K (kg ha-1) Main plot M0 5.93 0.20 0.93 150.7 34.12 256.3 M1 5.96 0.16 0.82 133.0 40.92 281.3 M2 6.06 0.17 0.59 96.0 39.20 243.1 Subplot S0 5.96 0.22 0.92 148.2 40.59 284.2 S1 5.99 0.15 0.76 122.3 32.16 251.3 S2 5.88 0.21 0.76 123.1 47.31 252.1 S3 6.11 0.13 0.70 112.6 32.26 253.4 Interaction M0S0 5.71 0.35 1.16 187.1 54.19 353.8 M0S1 6.03 0.16 0.95 153.1 26.20 261.3 M0S2 5.92 0.15 0.80 128.8 27.56 152.5 M0S3 6.09 0.15 0.83 133.7 28.53 257.5 M1S0 6.08 0.16 0.75 121.5 35.82 243.8 M1S1 5.76 0.13 0.68 109.4 38.46 258.8 M1S2 5.80 0.22 1.05 170.1 55.91 351.3 M1S3 6.19 0.13 0.81 131.2 33.50 271.3 M2S0 6.10 0.14 0.84 136.1 31.77 255.0 M2 S1 6.19 0.17 0.65 104.5 31.83 233.8 M2S2 5.92 0.26 0.44 70.5 58.46 252.5 M2S3 6.04 0.12 0.45 72.9 34.76 231.3 S Em ± Main 0.06 0.02 0.03 4.5 5.15 NS Sub NS 0.05 0.07 11.5 NS NS Main x Sub-1 NS 0.08 0.11 17.7 NS 71.3 C.D (P=0.05) Main 0.02 0.01 0.01 1.3 1.46 12.1 Sub 0.08 0.02 0.02 3.9 4.51 13.1 Main x Sub-1 0.12 0.03 0.04 6.0 6.92 23.1 Table 4 : Soil fertility and major nutrients of soil in papaya as influenced by fertigation treatments Standardisation of fertigation in papaya J. Hortic. Sci. Vol. 18(1) : 104-112, 2023 110 significantly from rest of the treatment combinations except application of 125 % RDF through soil application of organic sources (351.3 kg ha-1). These differences in NPK may be attributed to the movement of applied nutrients in the soil both horizontally and vertically as well as concentration of immobile elements (Sathya et al., 2008). The easy availability of water-soluble nutrients right at the root zone of the crop through fertigation in a balanced form through RDF might have favoured better availability of plant nutrients favouring their accumulation in the soil. Fruit yield The fruit yield in papaya was significantly influenced by fertilizer doses and fertigation sources (Table 5). Application of 75 % RDF through fertigation recorded significantly higher fruit yield (47.34 t ha-1), which was followed by application of organic sources 125 % RDF (44.37 t ha-1). The increase in yield of papaya was over 31 % with fertigation clearly indicating the relative advantage, which may be attributed to higher nutrient use efficiency resulting in more number of fruits, fruit weight, TSS and lower fruit cavity index. Jeyakumar et al. (2010) reported that, application of 100 % recommended dose of N and K2O through drip resulted in more number of fruits, fruit weight, TSS and low fruit cavity index with soil application of P2O5. Although significantly lower cavity index was observed when RDF was supplied with organics to the soil (3.12%), among the fertilizer dosages, relatively lower cavity index (10.51%) was observed with 125% RDF, while, among the sources of nutrients, soil application of only orga nic sources r esulted in marginally lower cavity index (10.44%). No. of Individual Fruit Fruit TSS Cavity Treatment fruits fruit weight yield yield (oB) Index plant-1 (kg) (kg plant-1) (t ha-1) (%) Main plot M0 9.50 0.87 6.12 21.18 10.28 13.97 M1 21.09 0.69 10.49 32.39 9.61 10.51 M2 20.91 1.14 10.58 32.66 9.86 12.77 Subplot S0 21.17 0.66 11.95 36.87 9.66 13.74 S1 13.38 0.92 6.82 21.07 10.44 12.75 S2 15.94 0.75 9.11 28.91 10.57 10.44 S3 18.18 1.27 8.38 28.13 9.00 12.75 Interaction M0S0 19.25 0.70 12.73 39.27 10.10 19.06 M0S1 7.88 1.53 5.03 15.53 11.28 21.63 M0S2 3.25 0.71 1.73 7.70 11.30 3.12 M0S3 7.63 0.56 5.00 22.22 8.45 12.08 M1S0 23.50 0.54 7.78 24.00 9.30 11.60 M1S1 17.88 0.52 7.61 23.50 9.80 5.21 M1S2 21.75 0.89 14.38 44.37 9.38 11.23 M1S3 21.25 0.79 12.21 37.69 9.98 14.00 M2S0 20.75 0.73 15.34 47.34 9.58 10.55 M2 S1 14.38 0.72 7.83 24.17 10.25 11.42 M2S2 22.83 0.66 11.23 34.67 11.03 16.96 M2S3 25.67 2.47 7.93 24.48 8.58 12.18 S Em ± Main 1.33 NS 0.89 2.75 0.37 2.45 Sub 1.33 NS 1.17 3.62 0.47 2.19 Main x Sub-1 2.39 NS 1.97 6.09 0.79 4.10 C.D (P=0.05) Main 4.69 0.248 3.14 9.72 NS NS Sub 3.87 0.276 3.41 10.57 NS NS Main x Sub-1 7.44 0.483 5.98 18.53 NS 12.85 Table 5 : Fruit yield and quality in papaya with different fertilizer doses and fertigation sources Manjunath et al. J. Hortic. Sci. Vol. 18(1) : 104-112, 2023 111 T he tr ea t ment combina t ion M 2S 0 (75 % RD F) recorded maximum fertilizer use efficiency (20.45 kg of yield /kg of nutrient applied) (Fig. 1). This may be due to the application of nutrients directly to the root zone through fertigation coupled with complete solubility of water soluble fer tilizers increasing the efficiency of the applied nutrients. Similar results of 75% N and K when applied through drip recorded on par papaya yield with 100% RDF (Sadaraunnisa, 2010). It was attributed to the better yield components like number of fruits/ plant, fruit weight in the treatments where fertilizers wer e a pp lied t hr ou gh dr ip comp a r ed t o soil application of fertilizers. It was also concluded that since there was no significant difference between 100% and 75% N and K treatments through drip regarding yield and yield attributes, the later dosage is economical over the former. T he T SS in pa pa ya fr uits wa s not influenced significantly either by fertilizer doses and the sources of fertigation or their interaction (Table 5). However, relatively higher TSS was observed when RDF was supplied with organics either through soil (11.30 oBrix) or through fertigation (11.28 oBrix). T he ca vity index in papa ya wa s significa ntly influenced by the interaction of fertilizer doses and fertigation sources. Significantly, lower cavity index was observed when RDF was supplied with organics to the soil (3.12) and it was followed by application Fig. 1 : Fertilizer use efficiency in papaya as influenced by fertilizer doses and methods Table 6 : The economics of papaya cultivation under different fertilizer doses and sources of fertigation Fruit Gross Total Net B:C Treatment yield returns cost returns ratio (t ha-1) (Rs. ha-1) (Rs. ha-1) (Rs. ha-1) Main plot M0 21.18 3,17,734 2,46,228 71,506 1.28 M1 32.39 4,85,820 2,58,475 2,27,345 1.87 M2 32.67 4,89,975 2,34,119 2,55,856 2.08 Subplot S0 36.87 5,53,050 2,54,147 2,98,903 2.21 S1 21.07 3,15,990 2,26,582 89,408 1.40 S2 28.91 4,33,675 2,52,532 1,81,143 1.70 S3 28.13 4,21,990 2,51,833 1,70,157 1.67 Interaction M0S0 39.27 5,89,125 2,54,148 3,34,977 2.32 M0S1 15.53 2,32,980 2,26,582 6,398 1.03 M0S2 7.70 1,15,500 2,50,032 -1,34,532 0.46 M0S3 22.22 3,33,330 2,54,148 79,182 1.31 M1S0 24.00 3,59,955 2,68,238 91,717 1.34 M1S1 23.50 3,52,425 2,33,782 1,18,643 1.51 M1S2 44.37 6,65,505 2,70,595 3,94,910 2.46 M1S3 37.69 5,65,395 2,61,284 3,04,111 2.16 M2S0 47.34 7,10,070 2,40,055 4,70,015 2.96 M2 S1 24.17 3,62,565 2,19,382 1,43,183 1.65 M2S2 34.67 5,20,020 2,36,970 2,83,050 2.19 M2S3 24.48 3,67,245 2,40,068 1,27,177 1.53 Standardisation of fertigation in papaya J. Hortic. Sci. Vol. 18(1) : 104-112, 2023 112 of 125 % RDF through fertigation using organic sources (5.21). The lower cavity index recorded may be attributed to the production of more photosynthates due to more number of leaves and leaf area which might have resulted in better transfer to the sink, the developing fruit with thicker pulp and low cavity index. Jeyakumar et al. (2010) also observed that application of 100% recommended dose of N and K2O through drip resulted in lower cavity index in papaya. The economics Fertigation of 75% RDF with inorganic fertilizers was found more economical with higher gross returns (Rs. 7.10 lakh ha-1), net returns (Rs. 4.7 lakh ha-1) and benefit cost ratio (2.96) (Table 6). The higher net returns with the treatment (M2S0) may be attributed to the moderately higher papaya yield (47.34 t ha-1). It was followed by soil application of 125 % RDF through organic sources with better gross returns (Rs. 6.65 lakh ha-1), net returns (Rs.3.94 lakh ha-1) and benefit cost ratio (2.46). In a similar study, Jeyakumar et al. (2010) also reported that the increase in number of fruits and fruit weight were attributed for higher fruit yield per tree and the resultant total fruit yield per hectare with high B:C ratio in plants treated with 100 % recommended dose of N & K2O per plant through drip (50 g N and 50 g K2O), in addition to soil application of 50 g P2O5. CONCLUSION The results of field experiment on fertigation in papaya indicated that application of 75% RDF through drip using water soluble fertilizers is beneficial to get higher fruit yield (47.34 t ha-1) with higher nutrient use efficiency and was found economical with higher net returns (Rs.4.7 lakh ha-1) and benefit cost ratio (2.96). ACKNOWLEDGEMENT The authors gratefully acknowledge the financial help rendered by project on Consortia Research Platform on Water, coordinated by ICAR-Indian Institute of Water Management Research, Bhubaneshwar. REFERENCES Anonymous, 2022. Area and production of horticulture crops for 2021-22 (Advance Estima tes), Na tiona l Hor ticultur a l Boa r d. India , www.nhb.gov.in Jackson, M.L. 1973. Soil Chemical Analysis. Prentice Hall of India Pvt. Ltd., New Delhi, p. 498. Jeyakumar, P.R., Amutha, T.N., Balamohan, J., Auxcilia. and Nalina, L. 2010. Fertigation improves fruit yield and quality of papaya. Acta Hortic., 851: 369-376. Malhotra, S.K. 2016. Water soluble fertilizers in horticultural crops-An appraisal. Ind. J. Agric. Sci., 86(10):1245-1256. Panse, V.G. and Sukhatme, P.V. 1985. Statistical methods for agr icultura l wor kers. Indian Council of Agricultural Research, New Delhi pp. 87-89. Rajput, T. B. S. and Patel, N. 2002. Water soluble fertilizers –opportunities and challenges. 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(Received : 04.01.2023; Revised : 21.06.2023; Accepted 23.06.2023) Manjunath et al. J. Hortic. Sci. Vol. 18(1) : 104-112, 2023