TECHNIQUE FOR RAPID MULTIPLICATION OF GUAVA (PSIDIUM GUAJAVA L.)

Wedge method of grafting was tried in guava (Psidium guajava L.) cultivars Allahabad Safeda and Sardar under greenhouse (GH) as well as in open field conditions (OFC) for 3 consecutive years (2003-2005). The grafting operation performed in greenhouse gave significantly (P=0.05) higher success of grafts (64.5694.33%) as compared to open field conditions (51.30-78.63%) in both the cultivars. However, maximum success of grafts was obtained in greenhouse (88.63-94.33%) as well as in open field conditions (66.6-78.63%) when grafting was carried out during November to February in both cultivars. Grafting under greenhouse significantly reduced the time taken (11-13 days) for sprouting than, those grafted in open field conditions. Interaction effect of variety × greenhouse × month, variety × open field conditions × months and variety × factors (GH/OFC) × months had significant effect on success of grafts and earliness in grafts sprouting when grafting was performed in winter months. The temperature range of 20°C to 26°C and RH 70 to 80 per cent were found most conductive for maximum (>70%) success. INTRODUCTION Guava (Psidium guajava L.) is considered to be one of the exquisite, nutrionally valuable and remunerative crops (Singh et al., 2000). Besides its high nutritional value, it bears heavy crop every year and gives good economic returns (Singh et al., 2000). This has prompted several farmers to take up guava orcharding on a commercial scale (Singh et al., 2003). In recent years, guava is getting popularity in the international trade due to its nutritional value and processed products (Singh, 2005). However, the greatest handicap in guava plantation is discriminate multiplication of plants from unreliable sources by nurserymen (Singh et al., 2005). Non-availability of quality planting materials and consequent substitution of poor quality seedlings have adversely affected the guava production and productivity. The initial planting material is the basic requirement on which the final crop depend both in quality and quantity (Singh et al., 2005). The scenario is changing from traditional propagation with incorporation of science and technology to nursery management and trade (Singh and Bajpai, 2003). In view of the high return and the potential for processing, there is a tremendous scope for bringing substantial additional area under guava crop in India. So, a rapid and successful propagation technique is required as the area under crop is expanding and there is a demand to prepare the guava sampling throughout the year. While choosing a particular technique for propagation of guava, the time of operation and climatic conditions should be taken into consideration. In the present context, rapid methods of propagation becomes very important when planting materials are limited due to the scarcity of a clone or verities or due to sudden expansion in acreage. Though guava is propagated through budding (Gupta and Mehrotra, 1985; Kaundal et al., 1987), air layering (Singh and Singh, 1970; Sharma et al., 1978; Manna et al., 2001), stooling (Rathore, 1984; Pathak and Saroj, 1988) and inarching (Mukherjee and Majumder, 1983) these are still not commercially viable due to varying rate of success, absence of tap root system and cumbersome process. Preliminary trials carried out by the authors have indicated that the rapid and successful propagation through wedge grafting technique has been found possible throughout the year even in extreme climatic conditions such as severe cold (Singh et al., 2005). Therefore, it has 177 Proc. I IS on Guava Eds. G. Singh et al. Acta Hort. 735, ISHS 2007 become imperative to standardize the method of wedge technique for guava throughout the year under greenhouse as well as in open field conditions at Central Institute for Subtropical Horticulture, Lucknow. MATERIALS AND METHODS Preparation of Stock Seedling The technique envisaged growing of seedlings in polyethylene bag, grafting and hardening (Singh et al., 2005). Raising rootstock in polyethylene bags is recommended by Singh et al. (2005) as it gives better establishment of plants in the field on account of undisturbed tap root system. Fresh seeds of guava cvs. ‘Allahabad Safeda’ and ‘Sardar’ were extracted from ripe fruits and washed thoroughly to remove the pulp and other material clinging to the seeds. After extraction, seeds of both the varieties were sown in polyethylene bags (20 × 10 cm). Polyethylene bags were filled with soil, sand and FYM in 3:1:1 ratio. Further, all the polyethylene bags were covered with 100 micron (400 gauge) white polyethylene sheet soon after sowing. Seedlings were raised for rootstocks in the nursery for approximately 6 to 8 months and after attaining a stem diameter of 0.5 to 1.0 cm, were picked up for wedge grafting. Selection of Scion Wood The scion shoots 15 to 18 cm long of pencil thickness (0.5-1.0cm) with 3 to 4 healthy buds were used for grafting. Selected scion shoots were defoliated on the mother plant, about 5 to 7 days prior to detachment. At the same time, the apical growing portion of selected shoots was also beheaded, which helps in forcing the dormant buds to swell. Grafting Technique After selection of the scion material, rootstock (seedling) was headed back, leaving 15 to 18 cm long stem above the polyethylene bag. The beheaded rootstock was split open about 4.0 to 4.5 cm deep through the centre from cut end of the rootstock with grafting knife. A wedge shaped cut, slanting from both the sides (4.0-4.5 cm long) was made on the lower portion of the scion shoot. The scion stick was inserted into the split of the stock and pressed properly so that cambium tissues of rootstock and scion should come in contact with each other. The stock and scion combination was then tied with the help of 150 gauge, 2 cm wide and 25 to 30 cm long polyethylene strip. Using the above rootstock and scion material, wedge grafting was done from midJanuary to mid-December. Three replications were maintained with 30 plants in each replication. Thus, the total number of plants of Allahabad Safeda and Sardar for a particular month was 360 in greenhouse and open field conditions. The statistical analysis was carried out by applying software MSTATC. The cultivars were taken as Factor A, greenhouse and open field condition as Factor B, and month as Factor C. Success percentage was recorded after initiation of sprouting in scion. During the entire period of experimentation, temperature and relative humidity under both the conditions were also recorded. RESULTS AND DISCUSSION Days Taken for Sprouting Data pertaining (Tables 1, 2) to this character indicated that the plants grafted in greenhouse took less time to sprout as compared to open field conditions in case of both the cultivars. Among different months of grafting operation, the plant grafted in the month of January, February, June and December took less time (10-11 days) than rest of the months in greenhouse. Contrary to this the plant grafted in the open field conditions particularly in the month of March, May, July and September took less time (16-17 days) then that of other months. Overall, the plants grafted in open field conditions took maximum time (17-23 days) to sprout as compared to greenhouse. The combination