http://jsrr.net 119 ISSN: 2249-7846 (Online) Science Research Reporter, 4(2):119-127, (Oct. - 2014) © RUT Printer and Publisher (http://jsrr.net) ISSN: 2249-2321 (Print); ISSN: 2249-7846 (Online) Received: 30-07-2014, Revised: 02-09-2014, Accepted: 21-09-2014e Full Length Article Studies on Pineapple (Ananas comosus) cultivation as an intercrop in rubber replant: effects on soil microorganisms Aparna C. Therumthanam, Jiby John Mathew, Sajeshkumar N.K andPrem Jose Vazhacharickal * 1 Department of Biotechnology, Mar Augusthinose College, Ramapuram, Kerala, India * premjosev@gmail.com ABSTRACT Pineapple cultivation is a popular practice among the rubber planters at the time of re-plantation especially in the district of Kottayam, Pathanamthitta, Idukki and Ernakulam of Kerala State in India. The growers were applying large amount of fertilizers, hormones, herbicides and pesticides at the time of cultivation. A field study was conducted at Theekoy Grama Panchayat (Meenachil Thaluk), Kerala State, to evaluate the bacterial population changes occurred in the fields due to the pineapple cultivation. Soil samples were collected from three farms and subjected to bacterial enumeration analysis. Bacterial enumerations were conducted by using enumeration methods like pour plate, spread plate and MPN. Our study showed that there was reduction in the number of soil bacteria during the cultivation period than before and after cultivation periods with Ananas comosus. It may be interpreted that the use of fertilizers, hormones, herbicides and pesticides reduces the growth of microbes at the time of cultivation and the soil regains its natural microbial flora slowly. Decline in soil bacteria may interfere with soil fertility and challenges the sustainability of intensive production systems. Further investigations should be conducted to find out the reasons for this phenomenon. Key words: Inter cropping; Most probable number; Multiple tube dilution method; Natural rubber; Soil microorganisms. INTRODUCTION Soil microorganisms play a major role in maintaining fertility of the soil, recycling of essential nutrients, promoting plant growth and improving microbial biomass carbon. The intensive use of fertilizers and agro-chemicals reduce the soil microbial diversity and affecting the quality of soil. Pineapple (Ananas comosus) is cultivated predominantly for its fruit contains manganese and vitamins and are popular in pizzas, condiments and confectioneries (Purseglove, 1972; Bartoloméet al.,1995; Elss et al., 2005). The cropping pattern in Kerala is dominated by plantation crops especially natural rubber (Hevea brasiliensis) which accounts for 92% of total natural rubber production in India in the year 2003 (Rajasekharan and Veeraputhran, 2002).The gestation period of rubber is around seven years and intercropping in the initial years provide additional income to the farmers (Rajasekharan and Veeraputhran, 2002; Joy, 2014). The major intercrops reported were cassava (Manihot esculenta), rice (Oryza sativa), banana (Musa spp), ginger (Zingiber officinale), turmeric (Curcuma longa), elephant yam (Amorphophallus paeniifolius) and pineapple (Ananas comosus) (Rajasekharan and Veeraputhran, 2002).During the past 30 years, intercropping of rubber plantations during the first three years of planting with pineapple (Ananas comosus) is very popular among the rubber planters especially in Kottayam, Pathanamthitta, Idukki and Ernakulam districts of Kerala State in India (Joy, 2014). In rubber production strategy, the aim is for maximum output of rubber, but in a monocrop rubber plantation which is usually planted at 3.5 x 3.5 m spacing (500 trees/ha), 75% of the total land area