Effects of fly ash and Helminthosporium oryzae on growth and yield of three cultivars of rice Lamabam P. Singh, Zaki A. Siddiqui * Department of Botany, Aligarh Muslim University, Aligarh 202002, India Received 14 November 2001; received in revised form 22 January 2002; accepted 21 April 2002 Abstract A 120-day greenhouse experiment was conducted to study the effects of various fly ash concentrations (0%, 20%, 40%, 60%, 80% and 100% vol/vol) with normal field soil and Helminthosporium oryzae on the growth and yield of three cultivars (Pusa Basmati, Pant-4 and Pant-10) of rice, Oryza sativa L. Application of 20% and 40% fly ash with soil caused a significant increase in plant growth and yield of all the three cultivars. Forty percent fly ash caused a higher increase in growth and yield than did 20%. Sixty percent, 80% and 100% fly ash had an adverse effect on growth and yield of all the three cultivars, the maximum being with 100% fly ash. Inoculation of H.oryzae had an adverse effect on the growth and yield, Pant-10 suffered higher damage by H.oryzae than Pusa Basmati and Pant-4. Pant-10 also exihibited higher infected leaf area and greater disease symptoms of H. oryzae than did Pusa Basmati and Pant-4. Plants grown in 100% fly ash suffered higher reductions in growth and yield with H. oryzae than plants grown in pure soil or in 20% or 40% fly ash. In general, plant growth was best in Pusa Basmati followed by Pant-4 and Pant-10, while yield was higher in Pant-4 followed by Pant-10 and Pusa Basmati. Ó 2002 Elsevier Science Ltd. All rights reserved. Keywords: Cultivars; Fly ash; Growth; Helminthosporium; Rice; Yield 1. Introduction Rice(Oryzasativa L.)isamostimportantcerealwhich feeds more than half of the world population. It is grown world wide in more than 144.641 million hectare and more than 10% of total arable land with an annual pro- duction of over 468.275 million ton (Bajaj, 1991). Brown leaf spot caused by Helminthosporium oryzae Breda de Haan is a major disease occurring in almost all the rice growingareasandisresponsibleforthelossesinyieldupto 90%(Padmanabhan,1977).Thegrainsbecomeshrivelled and discoloured, the plants are stunted and sometimes all the leaves wither and the whole field presents a highly characteristics burnt or scorched appearance. Fly ash formation depends on the ash content of coal and Indian coal, contains a relatively high proportion of ash that leads to 10–30% fly ash formation. The amount of fly ash produced annually in India was around 90 million ton during 1995 and is likely to exceed 140 million ton during 2020 (Kalra et al., 1998). Its disposal is a major concern now-a-days. The common practice is to dispose of these residues in the dumping sites of the power plants. This dumping covers huge areas of the productive land and such residues effect the quality of surface and ground water, soils and vegetation. Addition of small amounts of fly ash to soil neutral- izes the acidity to a level suitable for agriculture, de- pending on the initial pH of the soil (Moliner and Street, 1982), and increases the availability of sodium, potas- sium, calcium, magnesium, boron, sulphates and other nutrients but not nitrogen (Elseewi et al., 1981; Druzina et al., 1983; Wong and Wong, 1989). Use of fly ash in manufacturing of cement and concrete has started in India, but even then a large portion of the ash will re- quire other environmental friendly uses. Utilization of fly ash to improve agriculture productivity would not only be a solution to the problem but might also de- crease the use of inorganic non-nitrogenous fertilizers. The present investigation was carried out to study the effect of fly ash amendments on the growth and yield of three cultivars of rice both in the presence and absence of H. oryzae. Bioresource Technology 86 (2003) 73–78 * Corresponding author. E-mail address: zaki_63@yahoo.co.in (Z.A. Siddiqui). 0960-8524/03/$ - see front matter Ó 2002 Elsevier Science Ltd. All rights reserved. PII:S0960-8524(02)00111-6