MICROPROPAGATION OF GUAVA (PSIDIUM SPP.) : A REVIEW

Abstract Guava (Psidium guajava L.) is one of the most common and important commercial fruit crops cultivated in both tropical and subtropical regions of the world. In India major share of the fruits production is utilized for fresh consumption. Micro propagation is a rapid process to develop identical progeny from offspring. This is the growing of plants from meristematic tissue or somatic cells of superior plants on suitable nutrient media under controlled environmental conditions. In guava, micro propagation was achieved for the first time in 1987 by M. N. Amin and V.S. Jaiswal on Allahabad safeda. Since then significant progress has been made in the different areas of in vitro culture of guava since the first reports. In most cases, Murashige and Skoog (MS) revised medium (1962) was used as mineral medium for culturing Psidium species and cultivars for regeneration and/or proliferation, sub culturing and subsequent rooting. The lower concentration of major elements in WPM (Woody Plant Medium) was more suitable for micro propagation of some guava genotypes. Starting material for establishment of guava in vitro culture consists mostly of actively growing shoot tips or nodal segments as explants (1.0-3.0 cm size) collected during in spring are best suited for in vitro propagation of guava. Establishment of in vitro cultures of woody plants is greatly hampered by the browning of the explant and culture medium. In guava, several strategies have been employed to overcome the harmful effects of browning either through neutralization or through the avoidance of toxic substances in the medium.BAP (0.5 -2.0 mg/l) is the most frequently used cytokinin for guava micropropagation. The success of transplanting and survival of plants greatly depends on the quality of roots. Rooting Psidium spp. in vitro has proven to be difficult; however, several workers were successful in rooting. IBA is mostly used for inducing rooting followed by NAA, however use of dual auxins (IBA & NAA) resulted higher frequency of rooting. In guava, acclimatization has been accomplished in various substrates by progressively decreasing the relative humidity