Introduction

Pigeonpea is one of the important pulse crops in India. It plays a very significant role in Indian economy. Phytophthorablight disease of pigeonpea is very crucial factor responsible for decreased productivity of pigeonpea. The first suspected occurrence of PB on pigeonpea in India was reported in 1966 by Williams et al. (1968). Since then the disease has spread to most pigeonpea growing areas in Asia (Pal et al., 1970; Williams et al., 1975), Africa, America (Kannaiyan et al., 1984), Australia (Wearing and Birch, 1988), Dominican Republic, Kenya, Panama and Puerto Rico (Nene et al., 1996). High susceptibility of presently grown cultivars to Phytophthora drechsleri f. sp. cajaniis responsible for severe appearance of Phytophthora blight disease of pigeonpea. The only way to overcome this problem will be to ‘stack’ multiple resistances, based upon distinct mechanisms of action. Resistant source may be obtained by evaluating germplasms against Phytophthora drechsleri f. sp. cajani. Commonly used methods for screening of resistant germplasms include knife cut method.

Materials and Methods

Seventy three genotypes were planted in field of Institute of Agricultural Sciences, BHU, Varanasi, India in the month of July. One row of susceptible check (ICP-7119) was sown after every ten test rows to ensure enough inoculum. The seeds were sown at 10 cm distance in 3 meter rows. The row to row distance was 30 cm. All conventional agronomic practices were followed to keep the crop in good condition. When plant become 5 month old then 10 replications of eachgenotypes were inoculated with 15 mm mycelial disc of 12 days old culture (Knife cut method, Nene et al., 1981) of Phytophthora drechsleri f. sp. cajani. The infected plants were counted after 5-10 days of inoculation.

Table 1: Rating scale (1-9) for disease rating of Phytophthora blight of pigeonpea (Reddy et al., 1991)

Results and Discussion

Mean of lesion size of each genotype at different time interval is described inTable 2 and Table3. The data of Table 4 revealed that among seventy three genotypes, none was found immune or disease free against Phytophthora drechsleri f. sp. cajani. Five genotypes  namely WRG-220, GT-101, GAUT-001, BSMR-853, ICP-2376 showed resistant reaction against Phytophthora drechsleri f. sp. cajani; thirteen genotypes i.e. BSMR-528, PA-409, RVKT-260, RVKT-261, ICPL-87119, ICPL-87091, RVSA-07-24, RVSA-07-10, ICP-8863, BRG-11-1, BRG-2, BRG-3, BDN-2observed moderately resistant reaction; twenty seven genotypes namely WRG-222, WRG-197, PT-04-307, BSMR-2, JKM-189, NTL-900, IPAC-4, IPAC-8, PALAE-1, IPAC-68, MAL-13, IPA-8F, RVSA-07-31, KPL-43, RVSA-07-29, RVSA-07-22, WRP-1, GRG-811, GRG-333, BRG-1, CORG-9701, BRG-4, WRG-232, WRG-196, WRG-224, BSMR-579, BWR-133 expressed moderately susceptible reaction while, twenty eight genotypes i.e. AKTE-11-1, MA-6, ICP-7119, PA-406, IPA-204, BAHAR, KPL-44, IPA-15F, GRG-2009, ST-3R, BRG-11-1, BSMR-736, UPA S-120showed susceptible reaction against Phytophthora drechsleri f. sp. cajani.

Table 2: Screening of genotypes by artificial inoculation (Knife cut method) under field conditions recorded 5 days after inoculation with P. drechsleri f. sp. cajani (KJ412453)

Table 3: Screening of genotypes by artificial inoculation (knife cut method) under field
conditions 10 days after inoculation with P. drechsleri f. sp. cajani (KJ412453)

Table 4: Screening results of different genotypes under field conditions

This statement is in harmony with the experiment conducted by Kannaiyan et. al. (1981) in which a simple pot culture technique was used to screen 2,835 pigeon pea (Cajanus cajan) accessions and cultivars and seven Atylosia spp. for resistance to Phytophthora drechsleri f. sp. cajani. Seventy seven germplasm accessions, three cultivars, and two species of Atylosia were found to be resistant. The resistance of 75 of the accessions and cultivars was confirmed under field conditions. Similarly, Pande et.al. (2006) observed 122 lines (33 lines in wilt and sterility mosaic sick plot and 89 lines including wild Cajanus spp. in other fields), 33 were resistant and 61 moderately resistant, 21 moderately susceptible and 7 susceptible to Phytophthora blight of pigeonpea. Of the three wild Cajanus species, Cajanus sericeus was found resistant, C. scarabaeoidesmoderately resistant andC. cajanifolius susceptible to Phytophthora blight of pigeonpea.

Summary and Conclusion

Genotypes screening is done in field for checking the resistance of pigeonpea against Phytophthora drechsleri f.sp. cajani causing Phytophthora blight of pigeonpea. Seventy three genotypes were used for screening and inoculation was done by knife cut method on pigeonpea plants. The result shows that eighteen genotypes are either resistant or moderately resistant not showing any symptoms or very restricted symptoms of Phytophthora blight and could be used for developing resistant varieties against Phytophthora blight of pigeonpea.

References

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