Downy Mildew and its effect on Quality of Pearl Millet Hybrids

Pearl millet (Pennisetum glaucum(L.) R Br.) is one of the most important crop that can be grown in the areas having adverse agro-climatic conditions viz. hot and dry weather and less fertile sandy soils with low moisture, hence called nutritious poor mans crop. In Punjab, pearl millet is primarily grown for fodder purposes, with a small acreage under grain crop. However the area under pearl millet as a fodder crop is about 20, 000 ha. Cultivation of pearl millet not only helps in diversification but could also helps in breaking wheat/cotton-paddy monoculture system of the state and could also help in preserving the precious ground water resources. The yield potential of pearl millet was significantly increased with the introduction of improved hybrids. These high yielding dual purpose pearl millet hybrids are being preferred by the farmers than traditional varieties. Downy mildew (Sclerospora graminicola (Sacc.) Schroet) is an important disease of pearl millet which is causing considerable losses both to the grain and fodder crop especially in Rajasthan. The first ever pearl millet hybrid HB-1 succumbed to downy mildew disease during 1970’s. At the same time the disease severity could adversely affect the fodder quality. Little information is available regarding the effect of downy mildew on nutritional quality of bajra. Hence the screening of pearl millet hybrids against downy mildew is important to know the prevalence on different hybrids/varieties and its affect on fodder quality. Fifteen elite test hybrids and one composite viz., PHB 2363, PHB 2871, PHB 2872, PHB 2879, PHB 2880, PHB 2898, PHB 2909, PHB 2912, PHB 2914, PHB 2917, PHB 2918, PHB 2921, PHB 2929, PHB 2942, PHB 2168 and PCB 47 were tested against downy mildew at Punjab Agricultural University Ludhiana. The hybrids along with composite were evaluated in randomized block design with three replications and plot size of 10 m² under natural conditions with plant to plant and row to row spacing of 15 cm and 50 cm, respectively, during Kharif 2009. Incidence of downy mildew was recorded when the crop was 30 and 60 days old. Disease data of hybrids based on the means of three replications were assessed and compared with the composites. The healthy and diseased plants of hybrids/composites were collected from field and were analyzed for biochemical parameters. Forage samples, collected from three replications, were pooled for chemical analysis. Data revealed that per cent downy mildew disease incidence after 30 DAS was negligible on all the hybrids and after 60 DAS also the entries were found to be moderately resistant and per cent disease incidence ranged from 0.42–1.67. The most significant finding of the present study was the unexpected rise in the crude protein content of diseased plants. The protein of the micro-organisms might have contributed towards higher protein in the diseased plants. The total soluble sugars showed significant differences between diseased (26.18 %) and healthy plants (31.76 %) of pearl millet hybrids. This indicated that the soluble sugars were greatly affected in downy mildew infected hybrids. The neutral detergent fiber as well as acid detergent fiber was also found to be lower in the diseased as compared to healthy plants. Similarly hemicellulose component was also showed lower values in healthy compared to diseased plants.