MATERIALS AND METHODS

Seeds of two varieties of deshi jute, namely D-154 and BJC- 7370 were collected from JAES, Manikganj. Different seed samples of each variety were collected in brown paper bags after harvest and preserved in a refrigerator. The seeds samples were analysed for the presence of desired seed borne fungal pathogens i.e. Macrophomina phaseolina, Botrydiplodia theobromae, Colletotrichum corchori by blotter method following International Rules for Seed Testing Association (Anonymous, 1999). Fungal Pathogens associated with the seed samples were detected and identified by observing their growth characteristics on the incubated seeds under stereo microscope at 25X magnification. Both D-154 and BJC-7370 were categorized on the basis of health test analysis and samples of each variety having different level of infections viz. 0, 5, 10, 15 and 20% were selected to determine the effect of different levels seed borne infections on fibre yield contributing characters of jute.

The experiment was conducted at Kishoreganj regional station of Bangladesh Jute Research Institute (BJRI). One thousand seeds were taken from each level of infected seed samples for sowing in 2.5 X 4 m² plots. Seeds were sown in line sowing method with line to line 30 cm distance as per recommended by BJRI (1990). Weeding was done carefully whenever necessary and no plant protection measure was adopted for insect and disease control in the field. Seedling emergence data was taken after 10 days of sowing at field condition. Number of disease affected plants were recorded after 1 month of sowing and before harvesting of the crop. During the time of harvesting, 5 healthy plants and 5 diseased plants were collected randomly from each plot as per treatment to make average plant height and base diameter. Dry fibre weight was recorded in gm for each experimental plot according to different treatments.

The experiment was conducted in a Randomized Complete Block Design (RCBD) with 5 treatments and 3 replications. Analysis of variances were carried out and Duncan’s Multiple Range Tests (DMRT) judged the response of different treatments (Gomez and Gomez, 1984).

Results and Discussion

Means of seedlings emergence after 10 days of sowing in vivo
Findings showed that seedling emergence in vivo after 10 days of sowing, differed significantly according to different treatments. Findings also revealed that as the level of seed borne infections increases, the seedling emergence decreases gradually. Seedling emergence was found maximum (58.67%) in variety D-154 when plants were raised from 0% infected seeds and minimum (38.67%) in BJC-7370 when plants were raised from 20% infected seeds (Table 1).

Table 1:	Means of Seedling emergence (%) after 10 days of sowing and infected major fungal diseases after 1 month of sowing in vivo according to different to treatments
in a column, means followed by a common letter are not significantly different at the 5 % level by DMRT

Islam (1987) reported that, seed germination decreased with the increase of seed borne infections, which supports the above findings.

Infestation of major fungal diseases after 1 month of seed sowing in vivo
It has been evident from the findings that, both D-154 and BJC-7370 were affected by stem rot, black band and anthracnose after 1 month of sowing in the experimental plots. Means of major fungal diseases in jute plants due to different level of seed borne infections differed significantly. Highest disease infestations were observed in jute plants raised from 20.00% infected seeds (In D-154 stem rot =20.67 %, black band =20.33% and anthracnose =15.00% and in BJC-7370, stem rot = 20.33%, black band =14.00% and anthracnose =18.33%) and lowest disease infestations were observed in jute plants raised from 0.00% infected seeds (In D-154, stem rot =1.67 %, black band =2.33% and anthracnose =1.67% and in BJC-7370, stem rot =1.00%, black band =2.33% and anthracnose = 2%). Findings evident that, disease development in the experimental plots increases with the increase of initial seed borne infections. Dead seedlings were noticed in the experimental plots and means of dead seedlings according to different treatments also differed significantly. (Table 1). While conducting the test for the detection of growing seed borne fungal pathogens in jute seeds, Begum (1989) found that, Colletotrichum corchori, Botryodiplodia theobromae and Macrophomina phaseolina caused germination failure, seed rot and produce disease symptoms on the growing seedlings. Islam (1987) in his findings reported that, disease development in jute plants due to Macrophomina phaseolina, Botryodiplodia theobromae and Colletotrichum corchori increases gradually with the increase of seed borne infections.

Infestation of major fungal diseases in D-154 before harvest
Means of major fungal diseases in D-154 raised from different level of infected seeds differed significantly. The minimum infestation was observed in jute plants raised from 0% infected seeds (stem rot = 5.35%, black band = 3% and anthracnose = 2.33%). Findings showed the combinations of diseases in jute plots raised from different level of infected seeds and disease development in the experimental plots increases with the increase of initial seed borne infections. Dead plants were observed in the experimental plots and the means of dead plants accordingly to different treatments also differed significantly.

Table 2:	Infestation of major fungal diseases in D-154 before harvest according to different treatments

Table 3:	Infestation of major fungal diseases in BJC-7370 before harvest according to different treatments
In a column, means followed by a common letter are not significantly different at the 5 % level by DMRT, SR= Stem Rot, BB= Black Band, AN = Anthracnose

Table 4:	Mean comparison of plant height, base diameter and fibre weight of variety D-154 and BJC-7370 according to different treatment
In a column, means followed by a common letter are not significantly different at the 5 % level by DMRT

Minimum dead plants was 0.33% and maximum was 19.83% observed in D-154 raised from 0 and 20% maximum infected seeds respectively (Table 2). According to Islam (1987), though there was no initial seed borne infections in test seed samples, diseased plants were observed in field condition by the pathogens, on the other hand the higher the total seed borne infections of the three pathogens (Macrophomina phaseolina, Botryodiplodia theobromae and Colletotrichum corchori) the higher the diseased development in the field conditions.

Infestation of major fungal diseases in BJC-7370 before harvest
Results (Table 3) evident that means of different fungal diseases in BJC-7370 raised from different level infected seeds differed significantly. Maximum infestation was observed in jute plants raised from 20.00% infected seeds (stem rot = 37.58%, black band = 36.52% and anthracnose = 37.17%) while minimum was observed ( stem rot = 4.55%, black band =5.37%, anthracnose = 3.00%) when plants were raised from 0.00% infected seeds. Diseases development was positively co-related with initial seed borne infections. Mean of dead plants also differed significantly according to different treatments. Maximum dead plants (21.83%) were observed in jute plants raised from 20% infected seeds and minimum dead plants (0.00%) were observed in jute plants raised from 0% infected seeds.

Fakir and Islam (1993) reported that the rate of transmission of three test pathogens (Macrophomina phaseolina, Botryodiplodia theobromae and Colletotrichum corchori) transmit from seed to plant to seed was positively correlated with the increase of initial seed borne infections.

Means of plant height according to different treatments
It is evident from the findings that, the means of plant height of D-154 and BJC-7370 according to different treatments were significantly different for both healthy and diseased jute plants. Plant height of the jute plants gradually decreases with the increase of seed borne infections. Maximum plant height (289.67 cm) observed in healthy D-154, when initial seed borne infections was 0% and minimum plant height (191.00 cm) in diseased BJC-7370 when initial seed borne infections was 20% (Table 3). The major fungal diseases of jute are stem rot, anthracnose and black band caused by Macrophomina phaseolina, Colletotrichum corchori and Botryodiplodia theobromae respectively are responsible for death of seedlings, seedling infections and spread of diseases to the standing crops causing considerable loss in yield and quality of fibre (Imam-Fazli and Ahmed, 1960).

Means of base diameter (mm) according to different treatments
Means of base diameter of healthy and diseased jute plants according to different treatments differed significantly in both D-154 and BJC-7370. Jute plants raised from 0.00% infected seeds had maximum base diameter (190.50 mm in D-154 and 21.63 mm in BJC-7370) and that of from 20% infected seeds had minimum base diameter (13.27 mm in D-154 and 13.17 mm in BJC-7370). As the initial seed borne infections increases, the size of the base diameter gradually decreases. (Table 3). Major fungal diseases of jute are stem rot, black band and anthracnose caused by Macrophomina phaseolina, Botryodiplodia theobromae and Colletotrichum corchori respectively are seed borne and transmit from seed to plant to seed quite frequently (Akanda and Fakir, 1985). They are also responsible for yield loss of fibre and seeds (Roy and Mandal, 1967; Ahmed, 1698).

Means of fibre weight (gm/m²) according to different treatments
Fibre weight was recorded more in jute plants raised from 0% infected seeds and less in that of raised from 20.00% infected seeds. Amount of fibre weight decreases with the increase of seed borne infections. Findings also evident that the means of fibre weight due to different treatments differed significantly in both D-154 and BJC-7370. Maximum fibre weight (244.40 gm/m²) was recorded in D-154 when plants were raised from 0% infected seeds and minimum fibre weight(118 gm/m²) was recorded in BJC-7370 when plants were raised from 0% infected seeds (Table 3). Biswas et al. (1985) reported that yield loss of jute fibre decreased gradually with increase of stem rot disease in the field.

It is concluded that, (I) both D-154 and BJC-7370 of jute had less seedling emergence in the field with the increase of initial seed borne infections, (ii) stem rot, black band and anthracnose were noticed after one month of seed sowing in the field, (iii) as the initial seed borne infections increases, disease development in the field also increases and (iv) fibre yield contributing characters ( plant height and base diameter ) and fibre weight decreases with the increases of initial seed borne infections.