INTRODUCTION Guava (Psidium guajava L.) also known as “Apple of tropics” is one of the most common and popular fruits grown in tropical and sub-tropical regions of India. Owing to its luscious, wider adaptability, prolific bearing and high remunerative in nature it is popular across the world and also due to its availability round the year and reasonable price it is called as Poor man’s apple (Das et al., 1995; Brijesh et al., 2014). In guava, various drawbacks are reported in conventional methods of propagation (air-layering, stooling, ground layering). Seed propagated plants have various disadvantages such as a long juvenile phase, lack of true-to-type progeny, genetic heterogeneity, segregation and recombination of characters (Martínez-De-Lara et al., 2004; Soni et al., 2016). In asexual method of propagation namely stooling, ground layering, budding, grafting, stem cutting, air layering and inarching are still not commercially feasible because of various disadvantages. In ground layering and stooling, there are more possibilities that soil media might carry nematodes along with the planting materials. When these planting materials are used, it becomes very difficult to manage nematode as it rapidly spreads and leads to heavy loss in production (Poornima et al., 2016). In case of budding (Gupta and Mehrotra (1985, Kaundal et al., 1987), air layering (Sharma et al., 1978; Manna et al., 2001) and inarching (Mukherjee and Majumder 1983) it has been reported that all these methods are time-consuming, wax and wane in success percentage, laborious, expensive, absence of tap root system and uneconomical (Soni et al., 2016; Singh et al., 2019). Stem cutting is an effortless method but due to guava stem being hard to root this is also not suitable therefore leaves can be an option for propagation. As root formation in the leaf is a key step in fruit crops’ vegetative propagation. The mechanism of root development could be divided into three stages: root induction, root initiation and root protrusion and all these stages are regulated through auxins. Owing to natural auxin synthesis in leaves and stem tip leading to more chances for root formation in leaf (Ljung et al., 2001). Hence, the objective of this experiment was framed in such a way to develop a new commercial method of clonal multiplication in guava. MATERIALS AND METHODS The research was carried out at Horticultural College and Research Institute, TNAU, Coimbatore, Tamil Nadu during 2020-21 in a Factorial Completely Randomized Design with five replications (10 leaves per replication) and two factors (F1: Varieties and F2: Plant growth regulators at different concentration). Mother block for each variety (Lucknow 49, Allahabad Safeda and Arka Kiran) are maintained within the premises of nursery. Mother block is one of the most important inputs which decides the fate of production efficiency of fruit orchard. They are planted at a closer spacing of 2x1m in order to accommodate more number of plants and to get continuous supply of propagation material. These plants are severely pruned once in a year in the month of February to keep them in vegetative phase to produce enough shoots for propagation purposes. They are maintained rigorously so as to keep the plants healthy and free of diseases and insect pests. Leaves for the purpose of this experiment were collected from the mother block mentioned above. 50 leaves from guava cv. Lucknow-49, Allahabad Safeda and Arka Kiran were collected and used in this study. The 4th mature leaves were collected from the shoot tip of current season growth during morning hours which were then washed under running water followed by a quick dip at 1% Bavistin solution prior to planting. The petiole portion of leaves was dipped in 500, 1,000 and 1,500 ppm of Indole butyric acid (IBA) solutions for 1 and 2 minutes. After dipping, the leaves were planted in 50 cavity (4.5 cm top diameter, 3.2 cm bottom diameter, 4 cm depth, 50 ml capacity) protrays containing well-decomposed cocopeat (pH7) mixed with Pseudomonas fluorescens & Trichoderma viride, and kept in a small polytunnel under shade net. Leaves were irrigated alternately using as prayer and frequent inspection was done to check for any kind of deformity. From the 30th day of planting, root formation was observations on root formation in leaf petiole were recorded. The rooted leaves were then dipped in 100, 200, 300, 400 and 500 ppm of benzyl adenine (BA) solution. The treated rooted leaves were transferred into polybags containing a potting mixture of red soil, sand and farmyard manure (2:1:1). Irrigation was done by sprayer when it is required. For root formation on leaves, data observed were number of days taken for rooting, rooting percentage and number of roots per leaf and root length (cm). For shoot formation, data observed were number of days taken for shoot formation, shoot formation (%), shoot length (cm) and survival percentage (%). Factor 1 V1: Lucknow 49 V2: Allahabad Safeda V3: Arka Kiran Factor 2 G1: 500 ppm IBA G2: 1,000 ppm IBA G3: 1,500 ppm IBA RESULTS AND DISCUSSION Guava is a crop that is conventionally propagated by stooling but due to compromise in the quality of planting material as well as nematode infection, leaf propagation which has not been commonly used in fruit crops was given a trial in this experiment in order to get a perception on its success rate that can be a novel technique for producing a good quality planting materials as observed by Neelavathi et al., 2021. The present experiment was carried out at a shade net where the optimum temperature (28-30oC) and humidity (75±5%) required for successful rooting of the leaves were maintained by making a tunnel inside the shade net using polyethylene sheet of 200 microns (Fig.1)without which required humidity was not possible to maintain under only a shade net. Rymbai and Satyanarayana Reddy (2010) also reported that climate and media plays a crucial role in rooting. Irrigation water also plays an important role in the success of this experiment as the salt content in the water of Tamil Nadu is high which leads to the burning of leaves. Therefore, Siruvani water (The world’s 2nd tastiest water) was used for irrigating the leaves on an alternate basis with the help of a sprayer as the leaves are very brittle at the initial stage of propagation. In order to maintain the humidity of the experimental site, water was sprayed on the ground as well as the wall of the shade net. The success of the propagated leaves was being judged by visual appearance. The change in colour of the midrib and vein to yellow was observed after 15 days of planting (Fig. 2). For this experiment, 4th matured leaf from shoot tip from three different varieties were taken and treated with different concentrations of IBA. Out of these three varieties taken for the study, only Lucknow 49 treated with 1,500 ppm of IBA (dipped for 1 and 2 minutes) rooted in 33.80 days and 32.60 days respectively and the rest of the leaves dried (Table 1), which may be due to the varietal differences, lower concentrations of exogenous IBA and the presence of auxin inhibitor biochemical compounds (Lomax et al. 1995) and also due to the lack of endogenous auxin synthesis. Treatment duration highly stimulates cambial activity thereby resulting in the mobilization of reserve food material to the site from the leaf to the petiole through the midrib and veins that enhance earlier root formation (Shahzad et al., 2019). IBA is a non-toxic auxin (Hartmann et al., 2002) and effective in encouraging the rooting of a large number of plant species (Teklehaimanot et al., 1996). Higher rooting percentage was observed in T7 (72%) followed by T6 (70%). Root length and number of roots per leaf were measured at 30th and 60th day of planting and has been found to differ due to the treatment duration as well the maturity stage of leaf i,e., 4th mature leaves from shoot tip. Survival percentage recorded the highest in T7 (82.15%) followed by T6 (79.38%). Interaction between auxin and cytokinin plays an important role in root and shoot regeneration. The fourth matured was leaf dipped in 1500 ppm IBA for 2 minutes (T7) recorded highest root length (19.08 cm) and number of roots per leaf (31.58) on 60th day after planting (Table 2, Fig. 3). Similar result was observed in grape cutting at higher concentrations (Shahzad et al., 2019). A tremendous increase in the root length and number of roots per leaf was observed after 30th day of planting as the rooted leaves were carefully uprooted from protrays and treated with BA for initiation of shoot formation. The rooted leaves were treated with 200 and 300 ppm of BA dipped for one minute. Cytokinin such as BA increases biosynthesis of nucleic acids and mitotic activity in apices of buds those responsible for shoot formation (Chvojka 1964). Higher concentration of BA (300 ppm) was found to produce better result in terms of time taken for shoot formation (28.40 days after treatment), shoot formation percentage (83.33%), number of shoot per rooted leaves (4) and survival percentage (80%) (Table 3). Exogenous application of BA promotes shoot regeneration (Cornejo-Martin et al., 1979). Similar studies were conducted using cytokinin in Rudbeckia laciniata,Ruta graveolens, Gratiola officinalis which plays an important role in shoot formation (Custers 1986). The ratio of auxin-cytokinin I s an important factor to be considered for root and shoot formation as the leaves were initially treated with IBA which were further treated with BA on 30th day of planting might be the reason for its interaction in formation of successful root and shoot propagated through guava leaf. Exogenous application of BA promoted shoot formation but this action appeared to depend on the presence of other regulators in the medium and also on the plant species used (Cornejo-Martin et al., 1979; Van Aartrijk et al., 1985).