Document Type : Research Paper
Authors
1
Expert, Department of Plant Protection, Agriculture and Natural Resources Research Center, Yazd, Iran
2
Research Assistant Professor, Department of Plant Protection,Pistachio Research Institute, Rafsanjan, Iran
3
Expert,Pistachio Research Station Faizabad, Agriculture and Natural Resources Research Centerof Khorasan Razavi, Iran
4
Expert, Pistachio Research Station Damghan,Semnan Province Research Center for Agriculture and Natural Resources, Iran
5
Assistant Professors, Department of Plant Protection,Valiasr Universityof Rafsanjan, Iran
Abstract
To identify Trichoderma isolates for potential biocontrol of crown and root rot in
pistachio, 100 samples of soil taken from rhizosphere, fertilizer channels and from soil surface
were collected from Kerman, Yazd, Khorasane Razavi and Semnan provinces during 2009-
2011. Overall, 32 isolates of Trichoderma harzianum were obtained mostly from rhizosphere
soil using either general or special environmental surroundings. The antagonistic potential of
the isolates against P. melonis was screened using the dual culture technique. A total of 11
isolates were employed for further assessment of their capability to inhibit P. melonis, in
various assays under in vitro and as well in vivo conditions. Overall, the results indicated that
the incidecne of interactions through different mechanisms reduced mycelialy growth of P.
melonis to different degrees, ranging from 38.1 to 63.6%, 25.4 to 58.7%, 50 to 89.6% and 44.7
to 71.77% in the simultaneous vs non-simultaneous dual cultures, and volatile vs non-volatile
compounds, respectively. In greenhouse experiments, and in mixed inoculations with
Trichoderma harzianum strains and P. melonis it was observed that, root length and plant
height increased respectively from 1.5 to 2.7 and from 1.4 to 2.1 times of inoculation with
pathogen alone, as well as 1 to1.9 of root length and 1 to 1.6 times the plant height as
compared with non-inoculated control plants. Incidence of T. harzianum isolates before,
simultaneous with, and following pathogen inoculations (in pots) significantly influenced the
mortality of seedlings with the respective ranges of 0 to 31%, 0 to 56%, and 12.5 to 75%. This
is the first report on the introduction of T. harzianum isolates to pistachio orchards, along with
their interactions with gummosis (crown and root rot) causal agents.
Keywords
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