Standardization of grafting technique in Annona atemoya L. (Hanumanphal)

Introduction

The atemoya is a member of the Annonaceae. The atemoya is a hybrid of the sugar apple (Annona squamosa) and cherimoya (Annona cherimoya), two members of the Annona family. The first cross was made by the horticulturist, P.J. Wester, at the United States Department of Agriculture's subtropical laboratory, Miami, in 1908. Seedlings were planted out in 1910. Hanuman phal is widely cultivated across the world. In Brazil, the atemoya became popular and in 2011, around 1,200 hectares of atemoya were cultivated in Brazil. In Taiwan, the cultivating area of atemoya was 2,856.46 hectares in 2020, and Taitung County was the major place for cultivation having about 2,815.19 hectares. The tree closely resembles that of the cherimoya; is fast-growing; may reach 25 to 30 ft (7.5-9 m) and is short-bunked, the branches typically drooping and the lowest touching the ground. The leaves are deciduous, alternate, elliptical, leathery, less hairy than those of the cherimoya; and up to 6 in (15 cm) in length. The flowers are long-stalked, triangular, yellow, 2 3/8 in (6 cm) long and 1 1/2 to 2 in (4 -5 cm) wide. The fruit is conical or heart-shaped, generally to 4 in (10 cm) long and to 3 3/4 in (9.5 cm) wide; some weighing as much as 5 lbs (2.25 kg); pale bluish-green or pea-green, and slightly yellowish between the areoles. The rind, 1/8 in (3 mm) thick, is composed off used areoles more prominent and angular than those of the sugar apple, with tips that are rounded or slightly upturned; firm, pliable, and indehiscent. The fragrant flesh is snowy-white, of fine texture, almost solid, not conspicuously divided into segments, with fewer seeds than the sugar apple; sweet and sub acid at the same time and resembling the cherimoya in flavor. The seeds are cylindrical, 3/4 in (2 cm) long and 5/16 in (8 mm) wide; so dark a brown as to appear black; hard and smooth. The atemoya and bear hermaphroditic protogynous flowers and self -pollination is rare. The flower, in its female stage, opens between 2 and 4 o'clock in the afternoon. Between 3 and 5 o'clock on the following afternoon, the flower converts to its male stage. In cold and humid climates, it releases pollen even though it is sticky. Where the climate is hot and the humidity low at the blooming season, the carpels are short lived and the stigmatic surface soon dries up and insects are necessary to transfer the pollen. Atemoya are adapted to a wide range of temperatures, from lowland tropical to cool subtropical climates. In south Florida during January 1977, young trees were killed or severely injured by prolonged temperatures between -6.7° to -3.9 °C whereas mature trees withstood those temperatures with slight to moderate damage. Constant winds during late winter and spring may cause young atemoya trees to either lean in the leeward direction and to develop canopy and limbs only on the leeward side giving trees an unbalanced canopy. The tree thrives in various types of soil, from sandy loam to red basalt or heavy clay, but best growth and productivity occur in deep, rich loam of medium texture, with good organic content and a moderate amount of moisture. Good drainage is essential; waterlogging is fatal. Micronutrient deficiencies appear to be less of a problem in soils with a neutral to moderately acid ph. 5 to 7. According to analyses made in Florida, the Philippines and at the University of New South Wales, Annona atemoya contains Calories-94, Moisture-71.48 -78.7g, Protein-1.07-1.4g, Fat-0.4-0.6g, Carbohydrates-24g, Fiber-0.05-2.5g, Iron-0.3 mg, Calcium-17 mg, Magnesium-32 mg, α-carotene-10 µg, β-carotene-10 µg, Cryptoxanthin-10 µg, Ascorbic Acid-50 mg. Atemoyas may be propagated by seed, grafting, and budding. However, fruit quality and production of seedlings is extremely variable. Trees may be veneer, cleft or whip grafted (Morton, 1987) [1] and pre-graft preparation of budwood increases success. Grafted trees begin to produce fruit in 3 to 4 years. Grafting is done in the spring, using the whip or tongue graft. In India, the atemoya is usually grafted onto the custard apple or sugar apple. Cherimoya is used as a rootstock in Israel. Little research has been conducted to determine the optimum fertilizer recommendations for atemoya. Current recommendations for mature trees an 8:1.3:7.5Kg NPK/tree or similar material should be applied 3 to 4 times per year at the rate of 450 g per tree per 2.5 cm of trunk diameter per application. To prevent micronutrient deficiencies, foliar application of magnesium, manganese, and zinc and soil drenches of chelated iron are typically made 2 to 4 times per year. The atemoya, preferably chilled, is one of the most delicious of fruits. It needs no seasoning. It may be simply cut in half or quartered and the flesh eaten from the "shell" with a spoon. Slices or cubes of the pulp may be added to fruit cups or salads or various dessert recipes. Some people blend the pulp with orange juice, lime juice and cream and freeze as ice cream. The seeds contain toxins which have been associated with neurological degeneration, they should be removed before consuming, and care should be taken to avoid breaking or otherwise damaging them as the toxins may leach out into the fruit. Some groups have found the crushed seeds of related species useful as a pesticide and for other similar applications. It is rich in vitamins C and B6, essential for immune function and brain health. The fruit also provides dietary fiber, promoting healthy digestion. Additionally, atemoya contains potassium, magnesium, and antioxidants, which contribute to overall heart health and help combat oxidative stress. The fruit and leaves have remedies for digestive issues and respiratory ailments. As the demand for Hanumanphal in local markets is ever increasing, the systematic efforts for its crop improvement, propagation and planting needs to be attempted. As seedlings are heterozygous, do not show true to type characteristics, hence vegetative propagated planting material is necessary for commercial plantations. Taking into consideration above facts, the present investigation entitled "Standardization of Grafting Technique in Annona atemoya L. (Hanumanphal).

Materials and Methods

At the Custard Apple Research Station in Ambajogai, the experiment was carried out in a green shed net house. Geographically, it is located in latitude 18°44° North, longitude 76°23°, and an elevation of 1500 feet above mean sea level. A part of the Marathwada region and the district, which is located in the center west of Sambhajinagar, are often more than 1500 feet above mean sea level. Eight months of the year usually dry, but the southwest monsoon season bringing rain. The warmest month has a maximum temperature of 40 °C. Beginning in mid-November, the low temperature drops to 12 °C. The region typically receives 950-1000 mm of rain annually between June and September. The experiment was laid out in Factorial Randomized Block Design with twenty treatment combination and each treatment was replicated four times. Treatment involved date of grafting (15 th December, 1 st January, 15 th January, 1 st February and 15 th February) were combined with length of scion (6, 8, 10 and 12 cm). Observations were recorded on various growth and grafting parameters including Days required for sprouting, Days for first leaf opening, Number of sprouts recorded at initial days, Leaf area (cm 2 ) recorded at 30, 60 and 90 DAG. Success rate (%) and Mortality (%) at 30 and 90 DAG. Fresh weight of shoot (g), Dry weight of shoot (g), Length of root (cm), Fresh weight of root (g), Dry weight of shoot (g) at 90 DAG.

Growth Character

Days required for sprouting Effect of time

The data on the number of days required for sprouting of grafts as influenced by different times of grafting were presented in Table 2. The results showed that the time of grafting had a significant effect on the number of days required for sprouting. The grafts prepared on 15 th February (G 5 ) took the minimum time to sprout (12.81 days), followed by G 3 (12.94 days), G 4 (14.06 days) and G 2 (14.25 days). Grafts prepared on 1st December (G 1 ) took the maximum time (15.06 days) to sprout. The differences in sprouting time might have been due to variations in the physiological condition of the scions and the environmental conditions prevailing during grafting. Similar findings were reported by Kudmulwar et al. (2008) [2] in custard apple. Khopade et al. (2013) [3] also reported considerable variation in the number of days required for sprouting of custard apple grafts, ranging from 12.66 to 22.40 days, which supported the findings of the present study.

Effect of scion stick

The results presented in Table 2 indicated that the length of the scion stick influenced the time required for sprouting of the grafts. The grafts prepared with 10 cm long scion sticks (L 3 ) sprouted earlier and took the minimum time of (13.50) days was at par with L 4 (13.70) and L 2 (13.85). In comparison, grafts prepared with 6 cm long scion sticks (L 1 ) required the maximum time of (14.25) days to sprout. Similar results were reported by Purbiati et al. (1991) and Gurudutta et al. (2004) [4] , which were in agreement with the findings of the present study. Interaction effect The data presented in Table 2 showed that the combined effect of time of grafting and length of scion sticks had a significant influence on the time required for sprouting. Among the different treatment combinations, G 5L3 recorded the earliest sprouting, taking only (11.75) days was at par with G 3L4 (12.25), G 3L3 (12.50) and G 5L2 (12.75). In contrast, the grafts made on 15 th December using 12 cm long scion sticks took the longest time (15.75) days required for sprouting.

No. of days for first leaf opening effect of time

The results presented in Table 2 showed that the time of grafting affected the number of days required for the opening of the first leaf.

The grafts prepared on 15 th February (G 5 ) opened their first leaf earliest, taking (13.31) days, was at par with G 4 (13.56 days) and followed by G 3 (14.56 days) and G 2 (14.69 days). Grafts prepared on 15 th December (G 1 ) took the longest time, requiring (15.50 days) for the first leaf to open. The earlier opening of the first leaf in grafts performed on 15th February (G 5 ) may be attributed to the favourable temperature and environmental conditions, which enhanced cambial activity, callus formation and graft union development. Similar results were reported by Usare (2016), which supported the findings of the present study.

Effect of length of scion stick

The results presented in Table 2 showed that the length of the scion stick had a significant effect on the time taken for the opening of the first leaf. The grafts prepared with 10 cm long scion sticks (L 3 ) opened their first leaf earlier, taking (13.80) days was at par with L 2 (13.95), whereas grafts prepared with 6 cm long scion sticks (L 1 ) took the longest time of (14.80) days. The 10 cm scion stick (L 3 ) promoted early leaf opening possibly due to its adequate stored carbohydrate reserves, which supported rapid bud growth. Similar observations were reported by Purbiati et al. (1991) and Gurudutta et al. (2004) [4] , which supported the findings of the present study.

Interaction effect

The results presented in Table 2 indicated that the interaction between the time of grafting and scion stick length significantly affected the time required for the first leaf to open. The grafts under the G 5L3 treatment combination showed the earliest leaf opening, taking only (11.50) days and followed by G 5L2 (13.00). G 4L4 (13.25) and G 4L1 (13.50). In contrast, the G 1L1 treatment combination took the longest time, with (16.50) days required for the first leaf to open. The delayed leaf opening under 15 th December grafting (G 1 ) and 6 cm scion length (L 1 ) may be due to lower temperature and comparatively limited food reserves, respectively.

Number of sprouts effect of time

The results presented in Table 2 showed that the time of grafting had a significant effect on the number of sprouts produced by the grafts. The maximum number of sprouts was observed in grafts prepared on 15 th February (G 5 ), with (3.75) sprouts per graft and followed by G 4 (3.00), G 2 (2.63) and G 3 (2.94). Minimum number of sprouts was recorded in grafts prepared on 15 th December (G 1 ), with (2.44) sprouts per graft.

Effect of length on scion stick

The results presented in Table 2 indicated that the length of the scion stick influenced the number of sprouts produced by the grafts. The maximum number of sprouts was recorded with 10 cm long scion sticks (L 3 ) with (5.00 sprouts) per graft was followed by L 4 (3.35 sprouts) L 2 (2.20 sprouts). In contrast, the minimum number of sprouts (1.25) was recorded with 6 cm long scion sticks (L 1 ). This could be due to attributed to an adequate supply of healthy and matured scion sticks with possibly higher accumulation of carbohydrate and other biochemical. Besides this favourable weather conditions experienced during grafting date could have contributed to the activation of swollen buds. Similar findings were reported by Ghojage et al. (2011) [5] in jamun.

Interaction effect

The data presented in Table 2 showed that the combination of time of grafting and length of scion stick had a significant effect on the number of sprouts produced. Among the different treatment combinations, G 5L3 recorded the highest number of sprouts (7.00) followed by G 4L3 (5.50), G 3L3 (4.50) and G 2L3 (4.00). Whereas the lowest number of sprouts (0.75) was observed in G 1L1 .

At 30 DAG, the data presented in [6] , Alam et al. (2006a) [7] and Ram et al. (2012) in jamun and mango.

Effect of length of scion stick

Leaf area was significantly affected by the length of scion sticks used for grafting. Among the different scion lengths, L 3 recorded maximum leaf area of (40.90), (47.00) and (53.65) at 30, 60 and 90 days after grafting respectively. Minimum leaf area was recorded in L 1 , (37.00), (42.50) and (48.95) at 30, 60 and 90 DAG. The greater leaf area observed in L 3 might have been associated with better leaf growth and development of the grafts. Similar results were also reported by Nalage et al. (2010) [8] .

Interaction effect

The interaction between time of grafting (G) and length of scion stick (L) was non-significant effect on leaf area at 30, 60 and 90 days after grafting. However, at 30 DAG maximum leaf area was recorded in

The data presented in [9] , who recorded 96.4 per cent graft success in custard apple.

Effect of length of scion stick

The results presented in Table 4 showed that scion length had a significant influence on graft success at 30 and 90 DAG. Among the different scion lengths, the highest graft success was recorded with 10 cm long scions (L 3 ), which showed (92.85) and (89.25) success at 30 and 90 DAG, respectively. In contrast, the lowest graft success was observed with 6 cm long scions (L 1 ), recording (85.65) at 30 DAG and (79.40) at 90 DAG. The higher success obtained with 10 cm long scions might have been due to the better availability of stored food reserves, which helped the scion to establish and develop successfully after grafting. Similar findings were reported by Ratan et al. (1987)

Interaction effect

The interaction between time of grafting (G) and length of scion stick (L) was not significant for graft success at 30 and 90 DAG. However, some variation was observed among the different treatment combinations. The highest graft success was recorded in G 5L3 , with (97.50) and (94.75) at 30 and 90 DAG, respectively. In comparison, the lowest success was recorded in G 1L1 , with (78.25) and (71.50) at 30 and 90 DAG respectively. The results indicated that grafting at a suitable time with an appropriate scion length helped in obtaining better graft establishment and higher success. Although the combination G 5L3 performed better, the interaction between the two factors was statistically non-significant.

The data presented in Table 4 revealed that the mortality of Hanumanphal grafts was influenced by the time of grafting. The lowest mortality was recorded in G 5 , with (5.06) and (10.13) at 30 and 90 days after grafting (DAG), respectively. This was followed by G 4 , which recorded (7.88) and (12.38) mortality, while G 3 recorded (10.88) and (16.13) mortality at 30 and 90 DAG respectively. G 2 showed comparatively higher mortality of (14.00) and (18.69) at 30 and 90 DAG, respectively. The highest mortality was observed in G 1 , with (17.63) at 30 DAG and (22.75) at 90 DAG. The lower mortality observed with G 5 might have been associated with more favourable conditions during graft establishment. Similar observations were reported by Mulla et al. (2011) [10] in jamun and Raghvendra et al. (2011) in wood apple, supporting the findings of the present study.

Effect of length on scion stick

The results presented in Table 4 showed that the length of the scion stick significantly influenced graft mortality at 30 and 90 DAG. The lowest mortality was recorded when 10 cm long scions (L 3 ) were used, (7.60) and ( 11.20) at 30 and 90 DAG, respectively. In contrast, the highest mortality was observed with 6 cm long scions (L 1 ), which recorded (14.75) and (21.10) mortality at 30 and 90 DAG respectively. The lower mortality with longer scions might have been due to their better physiological condition and greater availability of stored food reserves, which helped in maintaining the graft until successful union was established. Similar results were reported by Ratan et al.

Interaction effect

The data presented in Table 4 showed that the interaction between time of grafting (G) and length of scion stick (L) did not significantly affect graft mortality at 30 or 90 DAG. However, differences were observed among the various treatment combinations. The lowest mortality was recorded in G 5L3 , with (2.00) and ( 5.75) at 30 and 90 DAG, respectively.

The data showed in Table 5 in regards to time of grafting revealed that maximum fresh weight of shoot (26.38) was recorded in the G 5 which was at par with G 4 (24.81) and followed by G 3 (24.56) and G 2 (24.50) respectively. Minimum fresh weight of shoot (22.19) was recorded in G 1 .

Effect of length of scion stick

Interaction effect

Interaction effect between time of grafting (G) and length of scion stick (L) with regards to fresh weight of root was non-significant. Maximum fresh weight of shoot (28.25) was recorded in G 5L3 , was at par with G 4L3 (27.50), G 2L3 (27.00), G 1L3 (26.75), and G 5L4 (26.25). However minimum fresh weight of root (18.00) was recorded in G 1L1 . The higher fresh shoot weight recorded in G 5L3 may be attributed to better graft establishment and stronger vegetative growth, which promoted greater photosynthetic activity and accumulation of assimilates in the developing shoots. Similar observations were reported by Pawar et al. (2018) in custard apple.

The results presented in Table 5 indicated that the time of grafting influenced the dry weight of the shoot. The highest shoot dry weight was recorded in G 5 (9.25) was at par with G 4 (8.71) and followed by G 3 (8.62) and G 2 (8.60). The lowest shoot dry weight was observed in G 1 (7.75).

Effect of length of scion stick

Interaction effect

Interaction effect between time of grafting (G) and length of scion stick (L) with regards to dry weight of shoot was non-significant.

B) Root character

Effect of length of scion

The data showed in Table 4.27 in regards to different length of scion revealed that maximum length of root (23.60) was recorded in the L 3 which was followed by L 4 (22.90) and L 2 (22.70) respectively. Minimum length of root (21.10) was recorded in L 1 . The better performance of L 3 may be attributed to sufficient food reserves and vigorous scion growth, which provided more assimilates for root development. Similar result was reported by Amrita et al. (2019) [11] .

Interaction effect

Interaction effect between time of grafting (G) and length of scion stick (L) with regards to length of root was non-significant.

The data showed in Table 6 in regards to time of grafting revealed that maximum fresh weight of root (24.81) was recorded in the G 5 which was followed by G 4 (24.13), G 3 (23.41) and G 2 (22.94) respectively. Minimum fresh weight of root (22.09) was recorded in G 1 . The higher fresh root weight in G 5 may be due to favourable growing conditions that encouraged better root growth and biomass accumulation. Hussain et al. (1997) [12] observed significant difference in fresh weight of roots in sapota grafts. Roshan et al. (2013) also observed such difference in sapota grafts, which confirms present finding.

Effect of scion stick

The data showed in Table 6 in regards to different length of scion revealed that maximum fresh weight of root (24.65) was recorded in L 3 which was followed by L 4 (23.40) and L 2 (23.18) respectively. Minimum fresh weight of root (22.68) was recorded in L 1 . The greater value with L 3 may be attributed to better graft establishment and healthy plant growth, which supported stronger root development. Similar result was reported by Amrita et al. (2019) [11] and Ashok et al. (2020) [13] .

Interaction effect

Interaction effect between time of grafting (G) and length of scion stick (L) with regards to fresh weight of root was non-significant. Maximum fresh weight of root (25.75) recorded in G 5L3 , was at par with G 4L3 (25.50) and G 5L2 (24.75). However minimum fresh weight of root (21.37) was recorded in G 1L1 . The highest fresh root weight in G 5L3 may therefore be due to the combined benefit of suitable grafting conditions and optimum scion length.

Effect of scion stick

The data showed in Table 6 in regards to different length of scion revealed that maximum dry weight of root (8.75) was recorded in L 3 which was followed by L 4 (7.83) and L 2 (7.75) respectively. Minimum dry weight of root (6.95) was recorded in L 1 . The greater root dry weight with L 3 may be attributed to stronger root growth and better movement of food materials towards the roots, resulting in increased dry matter accumulation. Similar result was reported by Amrita et al. (2019) [11] and Ashok et al. (2020) [13] .

Interaction effect

Interaction effect between time of grafting (G) and length of scion stick (L) with regards to dry weight of root was non-significant. Maximum dry weight of root (10.50) was recorded in G 5L3 . However minimum dry weight of root (5.00) was recorded in G 1L1 . The maximum value in G 5L3 may be because of a better balance between shoot and root growth, which favoured greater dry matter accumulation in the roots.

Conclusion

Based on present investigation entitled "Standardization of grafting technique in Annona atemoya L. (Hanumanphal)", it can be concluded that minimum days required for sprouting, days taken for first leaf opening and mortality percentages, maximum number of sprouts, leaf area, success rate, fresh weight of shoot, dry weight of shoot, length of root, fresh and dry weight of root can be made successfully on 15 th December (G 5 ) and 10 cm (L 3 ) long scion sticks. Whereas, maximum days required for sprouting, days taken for first leaf opening and mortality percentages, minimum number of sprouts, leaf area, success rate, fresh weight of shoot, dry weight of shoot, length of root, fresh and dry weight of root were recorded when graft made on 15 th December (G 1 ) and 6 cm (L 1 ) long scion sticks.

References

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