Pankaj Baiswar

Compost Quality Prepared from Locally Available Plant Biomass and their Effect on Rice Productivity under Organic Production System

Low concentrations of native nutrients in soil, especially nitrogen and phosphorus, are a major constraint limiting crop productivity in highly leached acid soils of the subtropical Indian Himalayas. This is coupled with the negligible use of fertilizers and pesticides, which restricts the productivity of field crops. Further, this area has acute shortage of farmyard manure (FYM) and other organic manures. In a 2-year field study (2004-06) the performance of eight different types of composts prepared from rice straw (Oryza sativa), Eupatorium adhenophorum, Lantana camara, and grass/weed mixtures was evaluated and compared with the recommended combinations of NPK (80:60:40 kg/ha) and FYM on productivity of lowland rice (Oryza sativa L) under organic production. Two composting procedures were evaluated. One was the Microbial Enriched Compost (MEC), procedure consisting of mixing plant biomass and cow dung in equal proportion (weight basis) followed by addition of microbial inoculants in a slurry of fresh cow dung, virgin soil and well rotten compost mixed in a ratio of 1:1: 0.5 along with appropriate amount of water. The second was Microbial and Nutrient Fortified Compost (MNFC) consisting of MEC, 2.5% rock phosphate (w/w) and 1% neem cake. Bioinoculums such as cellulose decomposers (Aspergillus terrus, Trichoderma harzianum, T. viride, T. virens), P-solubilizing microbes (Bacillus polymyxa and Pseudomonas striata) and free-living N-fixers (Azotobacter spp) were used as microbial inoculants to hasten the composting and improve the nutritional quality of the composts. The matured composts had higher NPK contents and lower C/N ratio compared to the fresh dry biomass of the substrates (plant materials used for composting) and FYM. The bacterial population in matured rice straw MNFC compost was about five times higher and fungal and actininomycetes population was about 3 times higher than that recorded with decomposed FYM. The study indicated that the significantly (p = 0.05) higher grain yield was recorded with rice straw MNFC compost in both years (4.50 t/ha in 2005 and 4.68 t/ha in 2006) followed by the Eupatorium MNFC compost (4.33 t/ha and 4.56 t/ha). In general MNFC composts recorded significantly higher grain yields compared to MEC composts indicating superiority of nutritional quality of MNFC composts. The nutrient uptake and post harvest soil fertility status were found to be significantly improved due to application of various composts. Composting with locally available biomass results in higher rice crop productivity and in maintenance of soil health of acid soils of Northeastern region of India.

Simplicillium lanosoniveum, a hyperparasite on Aecidium elaeagni-latifoliae in India

A hyperparasite was observed on Aecidiumelaeagni-latifoliae during a survey in Umiam, Meghalaya. Morphological characterization using light, scanning electron microscopy and molecular characterization by sequencing ITS region, large subunit of nuclear ribosomal DNA and phylogenetic analysis revealed the identity of the pathogen as Simplicillium lanosoniveum. This is the first record of hyperparasite S. lanosoniveum on A.elaeagni-latifoliae from India.

First report of an Oidium sp. [neolycopersici] on Solanum betaceum in India

In February 2008, a severe outbreak of powdery mildew disease was observed on Solanum betaceum in India. Based on the morphological characters, the pathogen was identified as an Oidium [neolycopersici] sp. morphologically similar to O. neolycopersici. This is the first report of this fungus causing powdery mildew on S. betaceum in India.

Pseudoperonospora cubensis on Sechium edule in India

Sechium edule is commonly grown for its edible immature fruits, starchy roots, tender shoots and leaves by tribal populations in north-east India. Sechium edule is also grown in many South American and Asian countries. Downy mildew symptoms were observed on the leaves of S. edule. Based on the morphological characters the pathogen was identified as Pseudoperonospora cubensis. This is the first report of this organism causing downy mildew on S. edule in Meghalaya, India.

Erysiphe quercicola, a powdery mildew fungus on Khasi mandarin in North East India

Powdery mildew on Khasi mandarin (Citrus reticulata) is considered as one of the factors responsible for citrus decline in this region. Molecular identification was done for powdery mildew pathogen (anamorph) on Citrus reticulata based on nrDNA ITS region (ITS 1-5.8s and ITS2). Maximum likelihood analysis clustered the sequences from this study with Erysiphe quercicola.

First report of leaf blight of Basella alba caused by Rhizoctonia solani AG 1-IB in India.

Thick succulent leaves of Malabar spinach (Basella alba L.) are used for human consumption in India. Symptoms of leaf blight were observed on this plant in October 2010 at Umiam, Meghalaya, India. Symptoms started from the lower leaves and spread to the upper part. Water-soaked lesions covered the whole leaf and gradually the leaves shredded and got detached from the plants. Whole plants were seen defoliated due to severe infection. Lesions were visible on the stem also. The pathogen was isolated on potato dextrose agar amended with streptomycin (100 ppm). Fungus isolated from infected plants had typical characters associated with Rhizoctonia solani J. G. Kühn [teleomorph Thanatephorus cucumeris (A.B. Frank) Donk], i.e., hyphal ramification angles of ~90°, basal constriction, and a septum next to the lateral hyphae (2). Nuclear staining with DAPI (2-(4-amidinophenyl)-1H-indole-6-carboxamidine) confirmed that hyphal cells were multinucleate (1). Molecular analysis was conducted using sequence data (JQ675535) containing ITS1 and 5.8S and ITS 2 of nrDNA, which was obtained after amplification using universal primers ITS1 and 4. BLAST search revealed 99 to 100% similarity with AG 1-IB (GU585667, GU270581). Living culture has been deposited in Agharkar Research Institute, Pune, India (NFCCI No. 2601). Phylogenetic analysis was also conducted using MEGA 5. It also placed the isolate in AG 1-IB clade with 99% bootstrap support in MP (maximum parsimony) analysis. Three healthy plants were inoculated using colonized PDA bits from actively growing culture. Sterilized PDA bits were kept on control plants. Plants were sprayed with water and covered with cheesecloth for 3 days. Inoculated plants developed symptoms after 5 days whereas control plants remained healthy. Inoculations were also done on detached leaves kept in a moisture chamber using colonized PDA bits. In this case, symptoms developed within 3 days. Detached leaves with sterilized PDA bits remained healthy. R. solani was also reisolated from inoculated plants. To our knowledge, this is the first record of AG 1-IB based on molecular evidence on B. alba from India. This new host may accelerate the spread of this pathogen to other crops. References: (1) M. M. Kulik and P. D. Dery. Biotech. Histochem. 70:95, 1995. (2) B. Sneh et al. Identification of Rhizoctonia species. APS Press, St Paul, MN, 1991.

First report of the mycoparasite Verticillium epiphytum on Uromyces mucunae in India.

Hyperparasitised uredinial and telial pustules of Uromyces mucunae, the rust pathogen of Mucuna pruriens were observed during screening for rust resistance. Morphological examination using light and scanning electron microscope revealed the presence of Verticillium epiphytum. This is the first record of V. epiphytum on U. mucunae from India.

Molecular evidence of Erysiphe pisi on pea and E. trifoliorum on white clover in northeast India

Phylogenetic analysis was conducted using the ITS region of nrDNA for confirmation of the identity of anamorphic powdery mildew pathogens on pea and white clover. Maximum likelihood and bayesian analysis clearly indicated that the pathogen responsible for powdery mildew on pea in northeast India is Erysiphe pisi rather than E. trifoliorum (syn. E. trifolii) which has been reported from north and central India. The pathogen E. trifoliorum was found associated with white clover. Reliable identification should be the first step in any breeding program.

Identification of Nyssopsora thwaitesii on Schefflera in northeast India.

During a routine survey rust was found on Schefflera wallichiana in Meghalaya in November-December 2012. Microscopic studies with light and scanning electron microscopy revealed the pathogen to be Nyssopsora thwaitesii. Molecular characterisation of the pathogen was also done by sequencing (18S), ITS region and large subunit (25S) of nrDNA of N. thwaitesii. This is the first identification of this pathogen on S. wallichiana from northeast India.

Molecular evidence reveals presence of Rhizoctonia solani AG 1-IB on Tagetes patula in India

Rhizoctonia solani was isolated from marigold (Tagetes patula) showing web blight symptoms in Meghalaya, India. Fluorescence microscopy was used to confirm its multinucleate character. Molecular characterization using ITS1-5.8-ITS2 region of nrDNA proved that it belonged to AG1-IB subgroup. To our knowledge, this is the first record of AG1-IB on marigold from India.