Exploring the compatibility of intra and inter specific grafting and budding in Artocarpus species

Abstract

The Artocarpus genus, part of the Moraceae family, includes over 60 genera and more than 1000 species, many of which bear large, nutritious fruits. While Artocarpus heterophyllus (jackfruit) is widely recognized and cultivated, other species such as breadfruit (Artocarpus altilis) and wild jackfruit (Artocarpus hirsutus) remain largely underutilized, especially in regions like Kerala. Breadfruit (Artocarpus altilis (Parkinson) Fosberg.) is a tropical staple fruit crop that remains underutilized and neglected despite having high nutritional value and potential for achieving food security. Breadfruit is typically propagated through suckers, root cuttings, or air layering, but these methods produce limited planting materials and result in trees without taproots, increasing their susceptibility to wind damage. Anjili/wild jack (Artocarpus hirsutus Lam.), another underutilized fruit crop of genus Artocarpus, earlier recognized as a timber tree, is gaining momentum among people as a fruit crop recently. It is mainly propagated through seeds and its vegetative propagation methods are not yet standardized. Grafting or budding offers a wide range of benefits such as wider adaptability, true-to-type nature, low juvenile phase, dwarfism, etc. Interspecific grafting and budding using different species as rootstocks improve disease resistance and stress tolerance and also provide better tap root system while intraspecific grafting and budding, combine desirable traits like higher yields and better quality. Hence the study entitled “Exploring the compatibility of intra and inter specific grafting and budding in Artocarpus species” was undertaken to identify the compatible rootstocks and standardize propagation methods in Artocarpus altilis and A. hirsutus at Department of Fruit Science, College of Agriculture, Vellanikkara during 2023 – 2024. The study consisted of two experiments. The first experiment was the identification of compatible rootstocks and suitable methods of propagation for A. altilis. These experiments were conducted in combination of two factors – methods of propagation (P) and types of rootstocks (R). Three different Artocarpus species including A. hirsutus (Anjili or wild jack) (R1), A. camansi (Breadnut) (R2), and A. heterophyllus (Jackfruit) (R3) were used as rootstocks for patch budding (P1) and softwood grafting (P2) methods. The treatments included P1R1 (patch budding on A.

hirsutus), P1R2 (patch budding on A. camansi), P1R3 (patch budding on A. heterophyllus), P2R1 (softwood grafting on A. hirsutus), P2R2 (softwood grafting on A. camansi) and P2R3 (softwood grafting on A. heterophyllus). The different growth parameters such as days to sprout, number of leaves, number of branches and shoot length were recorded at 15 day intervals. Success percentage, number of roots, average length of roots and anatomical observations were noted 120 days after grafting/budding (DAG/DAB). All parameters showed significant variation across propagation methods, rootstock types, and their interactions. Among the propagation methods, patch budding (P1) achieved highest success percentage but early sprouting was observed with softwood grafting (P2). However, P1 outperformed P2 in all other parameters, including maximum number of leaves, greater shoot and root length, and higher number of roots. While evaluating the three different rootstocks, A. camansi (R2) exhibited the highest success rate followed by A. hirsutus (R1). A. heterophyllus (R3) failed to produce successful grafted or budded plants. Early sprouting was observed for R1 while R2 outperformed R1 in morphological parameters like the number of leaves, shoot length, number of roots and the average length of roots. In examining the combined effects of propagation methods and rootstock types, patch budding on A. camansi (P1R2) yielded the highest success rate, followed by patch budding on A. hirsutus (P1R1) and softwood grafting on A. camansi (P2R2). All other treatment combinations failed to survive. P2R2 showed the shortest sprouting time while highest leaf number was observed in P1R2. Maximum shoot length was observed for P2R2 from 45 to 90 DAG followed by P1R2, while in the later stages at 105 and 120 DAG/DAB highest shoot length was recorded by P1R2 succeeded by P2R2. P1R2 recorded more roots while length of roots was found on par values for P1R1, P1R2 and P2R2. Anatomical studies conducted at 120 DAG/DAB revealed a well-developed connection between stock and scion in P1R2 indicating the compatibility of A. camansi with breadfruit. In the second experiment, the design, factors, treatment combinations and observations were same as that of the first experiment and was conducted to identify the compatible rootstocks and suitable methods of propagation for A. hirsutus. The results showed that softwood grafting (P2) recorded highest success rate, early

sprouting, maximum number of branches, leaves, and greatest root and shoot length while maximum number of roots was found for patch budding (P1). Among the rootstocks, maximum success percentage, shortest sprouting time, highest leaf and branch count, and greatest shoot and root length were observed for A. hirsutus (R1) whereas a maximum root number was observed for A. camansi (R2). Here also A. heterophyllus (R2) failed to produce a union with A. hirsutus. While assessing the treatment combinations, softwood grafting on A. hirsutus (P2R1) yielded better result in terms of success rate, shortest sprouting time, maximum number of leaves and branches, and highest shoot and root length but the maximum number of roots was recorded for patch budding on A. camansi (P1R2). All other treatment combinations failed to give positive results. In addition to these experiments, the seed and seedling characters of five Artocarpus species (T1 – A. heterophyllus, T2 – A. hirsutus, T3 – A. camansi, T4 – A. lacucha, T5 – A. gomezianus subsp. zeylanicus) were studied to document the morphological variations in seeds and seedlings. Seed traits such as weight, length, width, and thickness were measured, along with germination percentage and the number of days required for germination. Seedling growth parameters, including height, stem girth, number of leaves and leaf area were recorded for three months after sowing. The results revealed that T3 (A. camansi) had highest seed weight, width, thickness, early germination, maximum germination percentage, highest shoot length, stem girth, and leaf area. Longest seed was observed for T1 (A. heterophyllus) and maximum leaf count was observed for T2 (A. hirsutus). The present study revealed that patch budding is the best propagation method and A. camansi and A. hirsutus can be used as rootstocks for breadfruit. Patch budding on A. camansi showed a higher success percentage followed by patch budding on A. hirsutus. For anjili, softwood grafting was found better than patch budding and A. hirsutus was found to be the more compatible rootstock followed by A. camansi. Softwood grafting on A. hirsutus recorded highest success rate followed by patch budding on A. camansi. These successful treatment combinations can be utilized commercially after field evaluation for the propagation of breadfruit and anjili.