Abstract:
Rice is the staple diet in Sri Lanka and the extensive levels of agrochemicals used in rice
cultivation has caused serious environmental and health problems. Therefore, various
microorganisms including endophytic fungi of plants are being investigated as an
alternative for agrochemicals. As endophytic fungi have the ability to enhance plant
growth and control diseases, they can be used to increase crop production as well as for
disease management. Thus assessing the ability and rate of colonization of a particular
plant by fungal endophytes is very important. Therefore, this study was aimed at assessing
the colonization rates of endophytic fungi present in two newly improved rice varieties
grown in selected geographical locations across Sri Lanka with a view of utilizing them
for increased productivity and disease management of the two varieties. Healthy plant
samples of Bg352 and Bw367 were collected during the Maha season (January, 2019)
from fields in different climatic zones of Sri Lanka i.e. fields in Anuradhapura,
Kurunegala, Gampaha and Kalutara districts. Endophytic fungi were isolated from a total
of 480 plant segments including leaf, stem and root pieces of the two varieties onto Malt
Extract Agar (MEA) after surface sterilization using previously optimized regimes.
Colonization rates (CRs) of endophytic fungi were determined and the difference in the
extent of colonization by endophytes between two varieties and between districts was
analyzed separately by one-way ANOVA. A total of 92 isolates (35 isolates from Bw367
and 57 from Bg352) were obtained from all plant parts of both varieties collected from
the four sites. The total CRs of endophytic fungi in all plant parts of Bw367 collected
from Kurunegala, Anuradhapura, Gampaha and, Kalutara were 3.3%, 11.6%, 25%, and
16.6% respectively whereas for Bg352, the CRs were 26.6%, 16.6%, 28.3% and 23.3%
respectively. The analysis of results showed that there was no significant difference
in the colonization rates of endophytes between the two rice varieties nor was
there a significant difference among the selected districts of the different
climatic zones indicating that endophytic fungal colonization rates in Bg352 and Bw367
was not affected by varietal difference or by climatic and associated conditions of the
different locations studied.
