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An investigation was carried out to assess the effect of Prosopis cineraria on some ecological parameters of soil microfungi in an arid region of western Rajasthan. Nine soil samplings were done from the undercanopy of the tree and from the open areas for 2 years. Undercanopy soil of the tree possessed higher population of fungi and fungal biomass as compared to open field. Fungal parameters varied among different sampling periods. Soil samples analysed during different seasons for soil mycoflora revealed maximum fungal populations in rainy months. Fungal biomass and fungal population are directly proportional to organic matter (r = 0?78;Á0?78, respectively). The population of fungi is linearly related to fungal biomass with higher (r = 0?92) correlation at undercanopy as compared to open area (r = 0?72). Soil and climatic factors are responsible for enormous variation in fungal biomass. Organic carbon in the undercanopy is the critical factor that explained 76% variation in fungal biomass. Climatic factors did not affect undercanopy fungal biomass to any measurable extent; however, fungal biomass in the open area varied significantly due to rainfall and the model explained 73% variations in fungal biomass.# 2002 Elsevier Science Ltd.

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Prosopis juliflora is an invasive and allelopathic plant widespread in most parts of the world. P. juliflora is known to influence the growth of plants growing in its vicinity by the release of the allelochemicals during the decomposition of its litter. The negative effect is manifested by inhibition of the various physiological processes of the target plants. In the present study the effect of aqueous leaf extract of P. juliflora on the nitrogen metabolism of rice seedlings was assessed through the means of estimation of nitrate reductase (NR) activity of rice seedlings. For the study, aqueous leaf extract of dry mature leaves was prepared. From this, three concentrations viz., 1%, 10%, and 25% of the leaf extract were prepared by diluting with distilled water, while distilled water served as control. Rice seeds were incubated in different concentrations of extract for 10 days. Germination data was recorded and used for calculating the germination indices. After 10 days of exposure to the extract, seedlings were harvested and measurements for root and shoot length, fresh weights of root, shoot, and seed was taken and nitrate reductase activity of the seedlings was assayed. Germination and phenotypic results showed no negative affect by the extract. The activity of NR significantly increased with increase in the concentration of the extract. Our study revealed that the activity of NR was promoted by the extract addition.