Cultural studies of 7 isolates of Trichoderma spp. on seven different media: Colony appearance is one of the important cultural characteristics which helps in study the colony form, pigmentation, days required to sporulation.
SMV: SMV colony appeared dark green on CMA, TSM and SDA. Whereas on PDA and OMA white colony were recorded. Yellowish green colour was recorded in MEA. Even type of mycelial on PDA, OMA, TSM and MEA but uneven growth on CMA, V-8 and SDA. It produces green conidial production which was denser in center then towards the margin. 4 concentric rings were produced only on the MEA. However, no concentric rings were recorded on all six media. CMA, TSM and SDA sporulation was observed at 48h (2 days). In case of V-8 and MEA sporulate at 72 h (3days). whereas in PDA and OMA sporulate at 96 h (4days). Maximum colony diameter of 90.00 mm was recorded on potato dextrose, OMA and V-8 followed by 80.00 mm on SDA at 96 h (4days) after incubation (Table 3) (Fig. 1). However, the least mean colony diameter was observed on TSM (15.00 mm) followed by CMA (61.67 mm) and MEA (71.67 mm) (Table 4) (Fig. 8).
GMV: GMV isolate produced white mycelium growth on all the seven media later it to yellowish green and dark green at 5th DAI. Whereas mycelial appeared even type of mycelial on all the media with green conidial production which was denser in center then towards the margin. It produces dark green colony appear on OMA, TSM and MEA. Whereas on PDA, CMA and V-8 greenish yellow colony were recorded. A maximum of 3 concentric rings was recorded on PDA followed by 2 concentric rings in CMA and one on CMA and V-8 juice agar. However, no concentric rings were recorded on MEA and SDA. In all the media GMV was sporulated at 48h (2days) after incubation but on TSM sporulated at 72 h (3days) after incubation (Table 3) (Fig. 2). However, no sporulation was recorded on SDA. 90.00 mm mean colony diameter of was observed on CMA and malt extract agar, followed by of 89.67 mm on OMA and TSM. Least growth of 87.33 mm was recorded on SDA (Table 4) (Fig. 9).
PSV: The mycelia of PSV isolate was hyaline in all the seven media, later it turned to yellowish green to dark green in colour. The colony appeared flat and even on PDA, OMA, TSM and MEA medium but uneven growth was observed in CMA and V-8 media. In all the six media colony appeared green to dark green in colour. Whereas in V-8 colony was light yellow in colour. It produced two concentric rings on MEA, one concentric ring on PDA and OMA, however there were no concentric rings on the other media. In all the seven media the conidia was green in colour and was denser in center than towards the margin. The sporulation was observed at 48h after inoculation on PDA and CMA. In case of OMA and MEA sporulation were observed at 72 h after inoculation. However, no spores were recorded on V-8 juice medium even after 5 DAI. Sporulation on TSM and SDA were noticed at 96 h after inoculation (Table 3) (Fig. 3). The data revealed that the maximum colony diameter of 90.00 mm was recorded on all the six media by PSV isolate except in TSM where it was 33.33 mm. A maximum mean colony diameter of 90.00 mm was observed on all media except on TSM (Table 4) (Fig. 10).
SDKd: The mycelia of SDKd isolate was hyaline in all the seven media, later it turned to yellowish green to dark green in colour. Uneven type of colony appeared on all the media except TSM and MEA. In CMA, MEA and SDA colony appeared dark green in colour whereas in OMA and TSM yellowish green mycelium was observed. In case of PDA and V-8, light yellow and colourless mycelium was recorded. It produced green conidial production was denser in center then towards the margin. A maximum of 3 concentric rings was recorded on CMA and SDA followed by 2 in MEA and one on PDA and OMA. However, no concentric rings were recorded on TSM and V-8 media. The sporulation was observed at 48 h (2 DAI) on MEA and SDA. Whereas in PDA, OMA and TSM sporulation was observed at 96 h (4 DAI). In CMA sporulation was observed at 72h (3 DAI) (Table 3) (Fig. 4). It produced maximum mean colony diameter (90.00 mm) on OMA and MEA media was recorded. This was followed by SDA (88.33). Least mean colony diameter was observed on TSM (31.67 mm) followed by CMA (61.67 mm) (Table 4) (Fig. 11).
CPV: CPV isolate produced white mycelium growth on all the seven media later it turned to yellowish green to dark green in colour at 5th DAI. Colony appeared flat and even type of mycelial form on all the media with green conidia produced which was denser in center than towards the margin. It produced dark green colour colony on CMA and MEA. In case of PDA and OMA it produced white and green colour colony but in case of TSM, V-8 and SDA yellowish green, whitish yellow and transparent colony was recorded. Three concentric rings on OMA and CMA, two concentric rings on PDA followed by one concentric ring on V-8 and MEA were recorded. No concentric rings on the other media like TSM and SDA. It sporulated at 48 h after incubation in all the media but in case of PDA and V-8 sporulation was recorded at 72 h after incubation (Table 3) (Fig. 5). 90.00 mm mean colony diameter was recorded on PDA, OMA and MEA(90.00 mm) followed by CMA (88.00 mm) and V-8 juice (87.33 mm). However least growth was observed on TSM (33.00 mm) followed by SDA (80.00 mm) (Table 4) (Fig. 12).
RKd-Cu: RKd-Cu isolate appeared white mycelia on all the seven different media initially later yellowish green to dark green mycelia was recorded. Even type of mycelial growth on all media except on TSM and SDA where uneven growth was observed. It produces dark green conidia which was denser in center than towards the margin. In all the media colony appeared green to dark green colour except TSM, V-8 and SDA where colony was appeared to yellowish green, light yellow and colourless respectively. A maximum of 4 concentric rings was recorded on PDA and V-8 followed by 3 in CMA and MEA and 2 concentric rings on SDA and OMA. However, no concentric rings were recorded on TSM. Sporulation was observed on PDA, OMA and CMA at 48 h (2days) after incubation. In case of TSM, V-8 and MEA sporulation was observed at 72 h (3 days) after incubation. However, no sporulation was observed on SDA (Table 3) (Fig. 6). We recorded 90.00 mm on all the media except on CMA (78.00 mm) and V-8 (66.67mm). The minimum was observed on TSM (11.00 mm) (Table 4) (Fig. 13).
Commercial isolate: The mycelia of commercial isolate (T. viride) was hyaline in all the seven media, initially later it turned to yellowish green to dark green in colour. Flat and even type of colony was observed on all the different media with green conidia production which was denser in center than towards the margin. It produced dark green colour colony on CMA, TSM and MEA. In case of PDA and V-8 yellowish green colour was recorded. Whereas in OMA and SDA appeared light green and colourless colony was recorded. A maximum of 4 concentric rings was recorded on CMA followed by 3 on PDA and one on OMA and V-8. However, no concentric rings were recorded in SDA. At 48 h (2 days) spores were observed on PDA, CMA and MEA. Whereas, in OMA, TSM and V-8 sporulation were recorded at 72 h (3days). However, no sporulation was observed on SDA (Table 3) (Fig. 7). Minimum mean colony growth on Trichoderma specific medium (13.00 mm) followed by corn meal agar (80.00 mm) (Table 4) (Fig. 14).
The above Studies revealed that all isolates showed dark green to light green mycelial colour on all the seven media but in case of SDA produced a transparent even growth. Similarly, all isolates of Trichoderma obtained from non rhizospheric sources produce spores at different DAI. SMV isolate sporulate at 48 h on TSM, CMA and SDA. GMV isolate produce spores at 48h on all the media except TSM. In case of PSV isolate fast sporulation occurs on PDA and CMA. SDKd isolate sporulated early on MEA and SDA. CPV isolate sporulate at 48 h on OMA, CMA, MEA and TSM. Similarly, in case of rhizospheric source isolate RKd-Cu sporulate early on PDA and V-8. While, in case of commercial isolate earlier sporulation was observed on PDA, CMA and MEA.
Among the rhizospheric and non rhizospheric sources of Trichoderma isolate, GMV (non rhizospheric) have the capacity to produce the spores earlier (48 h) on maximum number of solid media (5) compare with other isolates and commercial isolate. Almost all the isolates showed earlier sporulation on CMA. So, these results showed that CMA was best for occurrence of sporulation.
Almost all isolates produced varying number of concentric rings on media. Among them, SMV and RKd-Cu isolate produced 4 concentric rings on PDA, V-8 and OMA respectively. Similarly, in commercial isolate produced 4 concentric rings on CMA followed CPV, GMV and SDKd produce 3 concentric rings. This data reveals that there is no difference in number of concentric rings produce by both rhizospheric and non-rhizospheric isolates. We also observed that there is no formation of concentric rings of all effective isolates on TSM. Results on colony appearance of Trichoderma spp. on different media are in conformity with Shah et al. (2012) wherein they reported that the colonies formed by T. harzianum and T. viride appeared dark green colonies with sufficient conidiation whereas, in T. Psuedokoningi colony formed almost whitish with little or no conidiation at 5th DAI. However, T. harzianum appeared with more pigment mycelial growth than T. viridae. Further, they reported that T. Psuedokoningii produced no pigmentation at all.
In case of mycelia growth studies, rhizospheric isolate PSV exhibited maximum mycelial growth (90.00 mm) on six different media compare with rhizospheric isolate RKd-Cu (4 media). Whereas, least colony diameter of all the isolates was seen on TSM. Among the different media OMA showed highest number of isolates exhibited maximum mycelia growth followed by MEA. Savitha et al. (2015) recorded that there was no significant difference in the growth rate among all the isolated Trichoderma spp. on potato dextrose agar and Malt extract agar except for Th16 which was slower on synthetic nutrient agar (80.00 mm). It indicates that among these three media, potato dextrose agar was the best media for mycelial growth of Trichoderma spp.
In conclusion, Highest growth rate and early sporulation is the important characteristics of good biocontol agent. Among the different isolates, non rhizospheric source isolates shows highest growth rate (PSV) and early sporulation (GMV) on higher number of different media over commercial isolate. So, apart from rhizospheric source, we can use the non rhizospheric sources viz., goat manure, Sheep manure, Coir pith, Sawdust and Padystraw for isolation of good biocontrol agents against different plant pathogens.