T. asperellum fresh culture bioproduct (100 g/20 L of water) or
wettable pellet bioproduct (20 g/20 L of water) for 24 h. After the
spore suspension was drained off, soaked seeds were kept moist
and incubated for 24 h before sowing in 288-hole trays (12 mL/
hole). The 21-day-old seedlings were transplanted into small plots
(1 m2 3 m2) consisting of paddy field soil. The whole rice plants
were sprayed with each Trichoderma isolate three times with the
spore suspensions prepared from wettable pellet (625 g/500 L/ha)
or fresh culture (2.5 kg/500 L/ha) bioproducts at the booting stage
(60 d after sowing; DAS), 5% of panicle-forming stage (75 DAS) and
milk-forming stage (95 DAS).
A randomized complete block design was used with five treatments,
four replications for each treatment and 30 plants per
replication (plot). The first and second treatments were comprised
of rice seed soaking (Sk) and plant spraying (Sp) with each isolate of
T. asperellum (CB-Pin-01 and 01-52). The third treatment was rice
seeds soaked only with T. asperellum isolate 01-52. The fourth
treatment was rice seeds soaked with clean water, as the negative
control, while the fifth treatment was rice seeds soaked with
mancozeb (80% WP) (3 g/100 mL/100 g of seed) and the plants were
sprayed with a fungicide mixture (propiconazole þ difenoconazole
30% weight per volume emulsifiable concentrate) and this served
as the positive control. Chemical fertilizers were applied three
times to each plot as recommended by the Rice Department
(Bureau of Rice Research and Development, 2016). These included
N-P-K formulations of 16-20-0 (156.25 kg/ha), 46-0-0 (125.00 kg/
ha), and 46-0-0 (62.50 kg/ha) which were applied at 15, 45 and 55
DAS, respectively.