Morphological and Molecular Variability of Alternaria Spp. And . Management of Alterjvaria Blight of Chickpea

Abstract

Chickpea (Cicer arietinum) is commonly known as Chana, Gram etc. is the most important pulse crop in India. Chick pea contains 21.1 per cent protein, 61.5 per cent carbohydrates, 4.5 per cent fat. It is rich in calcium, iron and niacin. It is the most important pulse crop of India occupying an area of 73.7 lakh hectares with production of 8221 .10 tones. The major chick pea production areas are situated in Madhya Pradesh, Rajasthan, Uttar Pradesh, Haryana, Maharashtra and Punjab. Alternaria blight disease in Chickpea plant caused by the Alternaria alternata. Disease appeared at seedling, flowering and podding time. It first appeared on older leaves. The circular, water soaked, small spots appeared on leaves which later turned brown to dark brown. The survey conducted during Kharif season of the year 2011-12, the Chickpea crop was moderately to severely infected with Alternaria disease at C.R.C of S.V.P.U.A & T. Meerut. Pathogenicity tests of seven isolates were carried out to examine the pathogenic behaviour on the Chickpea plant. Re-isolation from lesions developed on artificially innoculated plants, which produced the same fungus. The isolated fungus Alternaria alternata initially produced whitish color which later converted into Blackish grey with compact colony. Mycelium was septate and highly branched. Conidia were septate with transverse and horizontal septa. The maximum diameter of the colony was observed at a temperature 27°C (90mm) in 10 days. In the management of Alternaria alternata with the seven different part of plant extracts in- vitro were evaluated at same concentration. Ajwain showed 1 00% inhibition at 20% concentration. In antagonist Trichoderma harzianum showed maximum inhibition effect on the pathogen growth in comparision to Pseudomonas . fluorescens. Hexaconazole and Propineb gave completely inhibition at 1000 ppm concentration. Molecular Variability in five isolates out of seven isolates of Alternaria spp. differed with each other in respect of morphological, pathogical and molecular basis. The amount of genetic variation on molecular basis was evaluated by polymerase chain reaction (PCR) amplification with a set of twelve random primers. Eleven primers showed the polymorphism in the range of 20-100 per cent, however maximum polymorphism (100%) was observed by primer-3, primer-4. The Jaccard similarity coefficient values among five isolates of Alternaria spp. ranged from 0.44 to 0. 73. The UPGMA based dendrogram separated these isolates into two major clusters.