Variability in Phyllosphere Mycoflora of Tea (Camellia sinensis L. O. Kuntze) From Cachar District of Assam.

Phyllosphere is a unique ecosystem for microorganisms, comprising both biotic and abiotic factors. It may aquire the ability to prevent plant pathogens and become resistant to adverse conditions. The present study has been conducted to observe the seasonal variation and species diversity at Silcoorie Tea Estate of Cachar District of Assam. The sampling was carried out for one year (May-2012 - Apr-2013) seasonally after an interval of one month from different sites and different clonal varieties. A total 18 fungal species has been isolated representing 9 saprophytic and 7 parasitic including three unidentified ones. The species composition was seasonal, clonal, and leaf age dependent with considerable environmental fluctuations. The meteorological parameters seem to play an important role in species variability of the phyllosphere mycoflora. ABSTRACT Introduction: The habitat adjacent to the leaf surface is known as the phyllosphere and the surface of the leaf is called Phylloplane, (Prece and Dickinson, 1971; and Blackman, 1981). The current inventory of the world's bio- diversity is incomplete and we have only a small idea of our true mi- crobial diversity (Stanley, 2002). The leaf surface is a major habitat for microorganisms and study of microbial diversity is an important aspect of functional ecology. The microorganisms on the leaf surface depend on the season and age of the leaf. With diverse ecological functions, leaf surface microflora is considered to be one of the important groups of microorganisms concerned (Ruinen, 1965). Microorganisms on leaf surface play an important role in the plant ecology and can be manip- ulated to enhance plant growth and to reduce plant diseases. Evuch (2008) used phylloplane fungi as biocontrol agent against Colletotri- chum leaf disease. The present work aims for the isolation, cultural and morphological characterization of phyllosphere fungi to observe seasonal variation and species diversity of the selected tea garden of Cachar District of Assam. Study site: For the present study Silcoorie Tea Estate, Cachar District of Assam was selected. The tea estate is one of the largest gardens which situated in the valley of the river Barak in between 24° 8' to 24° 5' North Latitude and 94.28° East longitudes as an elevation varying from 40m above m. s. l. Materials and Methods: Healthy leaves of three different growth stages from the tea clone TV21 (Quality category), TV7 and TV9 (Standard category), TV19 and TV23 (yield category) were collected aseptically in a sterile polythene bag, leveled properly and taken in to the laboratory. Isolation of phyllosphere fungi: The isolation of fungi was done by leaf impression method and seri- al dilution method (Aneja, 2003). The cultures were plated in both Czepex- dox- Agar and Potato Dextrose Agar medium and were incu- bated at 30°C in the BOD incubator for 5days. The colonies developed were examined regularly and counted. Fungi were identified by (Greg- ory, 1961; Gilman, 1975; and Ellis and Ellis, 1988). Results and Discussion: In the entire sampling period a total 18 fungal species were observed. Among this 9 isolates were identified as saprophytic, 7 as parasitic in nature and three were unidentified sterile mycelia forms. The most dominant fungal species were Aspergillus niger (23.28%), A. flavus (22.80%) and Penicillium sp (25.00%). The most prevalent species were Alternaria alternata (21.90%), Curvularia lunata (16.96%), Trichoder- ma sp (12.62%), A. fumigatus (06.12%) and Fusarium sp (04.83%) which were observed in rainy season. The less frequent species were Colletotrichum sp (03.10%), Geotrichum sp (02.87%), Cladosporium cladosporoids (02.63%), Pestalotiopsis sp (02.60%) and Epicoccum sp (1.10%) and Streptomyces sp (0.95%). The population of fungi was different in different seasons. The highest population was observed during the month of July to October and sud- den decrease started from November up to May. Breeze and Dix (1981) noticed that in summer, the biomass of yeasts on leaves of Acerpla- tanoids was 50 times greater than of hyphal fungi. Seasonal studies on other tea growing areas also reported the low population of microbes on leaf surface during April and May which might be attributed to in- creased precipitation which removed appreciable quantities of micro- flora from the leaf surface (Tanti et al, 2012). The fungal population also showed a significant diversity isolated from different tea varieties. The fungal population recorded from TV23 and TV19 (yield category) was highest than TV7 and TV9 (standard category) where as TV21 exhibited lowest population. Ingold (1971) revealed that the spores deposited on leaves are influenced by the interaction of factors such as spore size, wind speed and the moisture conditions of both the spore and the leaf. The leaf age dependent variation showed gradual increase of the fun- gal population with the increase in the leaf age the possibility might be due to decrease in biochemical content of the leaves with increase in age of leaves. Osono (2008) examined and compared the seasonal and leaf age-dependent variations in the endophytic and phyllosphere fungal assemblages of Camellia japonica and found that frequency of the epiphyte Cladosporium cladosporoids varied with both season and leaf age.