Plant Parasitic Nematodes: A Major Constraint to Pulses Production and Their Management Options$

Abstract

 Pulses are very important in meeting the nutritional security in vegetarian Indian population besides playing important role in sustainable production system through improving soil health by fixing atmospheric nitrogen through rhizobium nodules present on root system. In India, pulses are grown over an area of 28.78 million  ha with production of 27.75 million tones. The average productivity of 995 kg/ha of these crops is below the potential yield of over 2000 kg/ha. Several factors are responsible for low and unstable yield of Pulse crops, most important being biotic and abiotic stresses. Plant parasitic nematodes are one of the important biotic  stresses to the pulses production. Several plant parasitic nematodes have been reported in the rhizosphere of pulse crops. But economic losses are caused by a few nematode species. These include root-knot nematodes (Meloidogyne incognita and M. javanica), reniform nematode (Rotylenchulus reniformis), pigeonpea cyst nematode (Heterodera cajani) and root lesion nematode (Pratylenchus thornei). The yield losses range from  5-70% depending upon the initial population of the nematode present in the field. Generally, nematode  problems in the field are not realized and are over looked. Sometimes they are confused with other soil  problems such as nutrient deficiency, salinity and water stress. Once the nematode problem is identified in standing crop, there is no chemical available to immediately overcome the nematode problem. Strategic approach is required to manage the nematode problems in crops to be grown afterward. Nematodes can be managed in pulse crops by integrating different farming practices. Deep summer ploughing after light irrigation in areas of hot summer, using trap crops and suitable cropping sequences can be effective in reducing nematode populations. Amendment of soil with FYM, green manuring or non-edible deoiled seed cakes of neem (Azadirachta indica), Melia azadirachta, karanj (Pongamia glabra), mahua (Madhuca indica), castor (Ricinus comunis), etc., improves soil fertility and organic matter status besides reducing nematode  population density through their constituent or decomposition products which are toxic to nematodes and promote antagonistic microbial activity. Many biocontrol agents are effective against plant parasitic nematodes. Use of these bicontrol agents could be one of the components of nematode management strategy. Although resistance against nematodes is not reported much in pulses, exploitation of resistant or tolerant sources available against nematodes can play important role in reducing the losses due to nematodes. New  techniques based on RNAi and biotechnology may also help in combating nematode problems in pulses. The awareness of farmers and other extension workers through training programmes about the seriousness  of the nematode problems and utility of farm practices which directly or indirectly related to change of  environment that may restrict the population below the economic threshold level and save the crops from the ravages of these noxious pests infesting pulse crops, is very much required.