Study on grafting of different pummelo (Citrus grandis L. Obseck) varieties on Cv. Konkan Lemon

Introduction

Pummelo (Citrus grandis L. Osbeck) is belong to the Rutaceae family, is the largest citrus fruit and a primary ancestor of grapefruit. Native to Southeast Asia and Malaysia, it is cultivated across tropical and subtropical regions for its large, juicy and mildly sweet fruits. Known by various regional names such as Papanas, Batabilebu and Chakkota, pummelo is valued for its high vitamin C content, antioxidants and bioactive compounds. Despite its nutritional and economic importance, the crop remains underutilized due to poor root adaptability, susceptibility to soilborne diseases and delayed bearing (Kate et al., 2014). Grafting has emerged as a sustainable technique to overcome these constraints by combining desirable scion and rootstock traits. Cultivar Konkan Lemon, a vigorous and drought-tolerant rootstock well adapted to the Konkan region of Maharashtra, offers strong compatibility with several citrus cultivars, including pummelo. Understanding the graft compatibility and growth response of different pummelo varieties on Konkan Lemon is essential for improving propagation success, orchard performance and long-term sustainability under coastal agro-climatic conditions.

Materials and Methods

The present investigation entitled "Study on grafting of different pummelo (Citrus grandis L. Osbeck) varieties on Cv. Konkan Lemon" was carried out during the academic year 2024-2025 at the College of Horticulture, Dr. Balasaheb Sawant Konkan Krishi Vidyapeeth (DBSKKV), Dapoli, District Ratnagiri (M.S.), India. The experiment was conducted at Fruit Crop Nursery No.10. Geographically, Dapoli is situated at 17°45′ N latitude and 73°12′ E longitude with an altitude of 280 m above MSL. The region represents a humid tropical climate with high relative humidity, warm temperatures and an average annual rainfall of about 2,700 mm. mainly received from June to September. The experiment was laid out in a Factorial Randomized Block Design (FRBD) with three replications, comprising two factors -Month (M) and Variety (V) -resulting in 18 treatment combinations. The months of grafting were April (M1), May (M2), June (M3), October (M4), -November (M5) and December (M6), while the pummelo varieties included Anjarle White Fleshed (V1), Anjarle Red Fleshed (V2) and Dapoli-2 (DPLP-2) (V3). Each treatment had 30 grafts per replication, totaling 1620 grafts, raised in 8 cm × 20 cm polybags filled with a mixture of soil, sand and farmyard manure in the ratio of 2:1:1. Healthy 1 year old Konkan Lemon seedlings were used as rootstocks and disease-free scion sticks of uniform thickness and 25 days before grafting defoliated scion sticks were collected from elite mother plants maintained at the 4 No. Nursery, Department of Horticulture, DBSKKV, Dapoli. The rootstock was decapitated about 8 cm above the collar and a V-shaped slit (3 cm) was made for inserting the wedge-shaped scion. The graft joint was bound with a transparent polyethylene strip (1.5 cm × 45 cm; 200 gauge) to ensure proper cambial contact. The grafts were maintained under shade with regular irrigation and removal of rootstock sprouts. Observations were recorded on sprouting percentage, survival percentage, union height and rootstock girth, number of leaves, leaf area, root length, root volume. Statistical analysis was carried out using FRBD as per the method of Panse and Sukhatme (1985) and treatment means were compared using the F-test and C.D. at 5% probability level.

Result and Discussion

Effect of Season and varieties and their interaction days required for sprouting, sprouting (%) and survival (%) on cv.

Konkan lemon of pummelo grafts

The interaction effect of season and variety was found to be significant for days required for sprouting, sprouting percentage and survival percentage of pummelo grafts. The earliest sprouting (22.13 days) was recorded in treatment M5V2 (November + ARF), followed by M6V2 (December + ARF) with 22.53 days, whereas the longest period for sprouting (36.08 days) was observed in M3V3 (June + DPLP-2). The maximum sprouting percentage (94.67%) was also recorded in M5V2 (November + ARF), followed by M6V2 (December + ARF) with 90.67%, while the minimum sprouting percentage (8.00%) was observed in M2V1 (May + ARF). The highest survival percentage (100.00%) was recorded in M5V2 (November + ARF), followed by M6V2 (December + ARF) with 98.67%, whereas the lowest survival percentage (18.67%) was recorded in M2V3 (May + DPLP-2). This interaction indicates that genetically responsive varieties express their maximum sprouting potential when grafted under favourable environmental conditions. Optimal temperature and humidity during November enhanced hormonal activity, carbohydrate mobilization and physiological compatibility at the graft union, resulting in rapid bud break and higher sprouting success.

Conclusion

Based on the overall performance of growth and survival parameters, Konkan Lemon (Citrus limon L.) proved to be a compatible and suitable rootstock for pummelo grafting across seasons and varieties, with no incompatibility observed. Grafting during November and December significantly enhanced graft success with the Anjarle Red Flesh (ARF) variety showing superior response. that enhanced cambial activity and graft union, indicating November and December as the most suitable months for softwood grafting of pummelo on Konkan lemon under Konkan conditions. The superior performance during November (M5) and December (M6) was attributed to maximum temperature (33.17-32.92 °C), minimum temperature (15.09-15.83 °C), high morning relative humidity (88.89-88.91%), moderate evening relative humidity (55.11-57.56%), low wind speed (3.60-3.68 kmph), low rainfall (21.64-33.77 mm), fewer rainy days (0.26-0.66), higher bright sunshine hours (8.71-8.28 hrs) and moderate evaporation (3.65-3.56 mm), which provided favourable conditions for callus formation, graft union establishment, sprouting and survival of pummelo grafts. The treatment combination M5V2 (November + ARF) consistently resulted in early sprouting, higher survival and sprouting percentages and improved vegetative growth at 180 days after grafting. Thus, grafting pummelo on Konkan Lemon rootstock during November-December is recommended for achieving higher graft success.

Acknowledgment

I would like to thank Dean of College of Horticulture for their administrative support and resources made available for this research. I am deeply grateful to my guide [Dr.M.M. Kulkarni] for their intellectual mentorship. Additionally, I acknowledge the support of all faculty members who contributed to the successful completion of this research. Also thank researchers whose research and methods helped to conduct and conclude research findings.

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