STUDIES ON ROOT-KNOT AND RENIFORM NEMATODES ASSOCIATED WITH BLACK GRAM THESIS SUBMITTED FOR THE DEGREE OF doctor of $||tlo!8!opIip IN BOTANY MUNAWAR FAZAL DEPARTMENT OF BOTANY ALrGARH MUSLIM UNIVERSITY ALIGARH (INDIA) 1993 ABSTRftCT Plant parasitic nematodes are found in all agricultural regions of the world and any crop is likely to suffer damage from these parasites. Nematodes can cause diverse damage in plants, depending upon feeding habits. Most of them attack roots and frequently parasitize plants in mixed population of two or more genera, species, or^ races, ftmongst phyto-parasit ic nematodes, MeloidoQvne incognita and Rotylenchulus reniformis are the most important pests of black gram (Viqna munqo) and other pulses. They perodically cause crop devastation and economic misery. This grim situation justifies the adoption of proper management tactics to tackle nematode problem and maximize the crop yield. Control measures classified as chemical, biological, cultural etc., have their own limitations. Hence, implication of Integrated Nematode Management <INM) procedures to illeviate nematode damage become more effective. fit its best, INM offers growers way to reduce nematode damage to crops while reducing nematode management cost. In the process INM often reduces the amount of crop -protectant chemicals required to control nematodes, and thus decreasing possible environmental impacts. Investigation on the pathogenicity of Meloidoavne incogni ta and Rotylenchulus reniformis confirmed the destructive effect of these nematode species on black gram cv. Pant U-19. Lowest inoculum levels of both the nematode species caused no significant damage or plant growth reduction, but with the increasing inoculum levels there was an increased growth reduction. Intial tolerance limits of black gram cv. Pant U-19 to M. incognita and R.. reniformis were below 1,000 Jg and J/^/Kg eoil, t^espectively. Nematode infestation decreased the number of nodules per plant. However, a significant decrease was recorded at an initial inoculum level of 500 nematodes/Kg soil. Meloidoqyne incognita was more damaging than Rotvlenchulus reniformis. The rate of multiplication of each species decreased with the increase in inoculum level. The interaction between tl. incognita and R.. reniformis was studied using varying inoculum levels and their combinations. In single species inoculations, the extent of growth and nodulation reduction was nematode dependent. Meloidoovne incognita was more damaging pathogen than Rotvlenchulus reniformis. The reduction in plant growth and nodulation was directly proportional to the increase in inoculum levels of test pathogens. Both the nematodes in single species inoculation multiplied at varying rates. Their rates of population increase declined at higher inoculum levels. In most of the combinations, reduction in plant growth and nodulation on concomitant inoculation were higher than the sum total of reductions caused by the individual inoculation at the same inoculum levels, and thus showed a positive interaction. In combinations. A,COO M. incognita, plus £,000 R. reniformis. and 4,000 M- incognita plus 4,000 R.. reniformis. the interaction was negative. In concomitant inoculations, the interactive effect, of both the nematodes were mutually inhibitory, and thus showed a mutual antagonistic inter— relat ionship. Plant health was significantly improved as a result of bacterization and therefore the bacterized plants when inoculated with test nematodes, either singly or in various combinations of pre-, post-, and simultaneous inoculations, suffered a significantly lesser damage than unbacterized plants. Inoculation of one or both the nematodes, prior to Rhizobium was more damaging to plant growth than to the plant that were simulataneously inoculated with one or both the nematode/nematodes at the time of Rhizobium application. Application of Rhizobi um before inoculation of nematode species, either singly or in various combinations resulted in significantly lesser damage than when Rhizobi um was applied simultaneously alongwith one or both the nematode species or when inoculation was followed by Rh i zobi um application. The damage was significantly less when the plants were inoculated with R^. reni form is and treated with Rhi zobi um earlier than M. incognita as compared to that where the plants were inoculated with M. incoqriit a and treated with Rhi zobi um prior to R. renf ormis inoculation. R. renformis when introduced 10 days prior to M. incoqnit a and Rh i zobi um together, damaged the plant growth to 4 lesser extent as comapared to that when M" i-ncoani ta was introduced 10 days before ]R. reni formi s and Rh i zobi um together, The rate of multiplication of both the nematode species was poor in the presence of Rh izobi um, when inoculated simultaneously o- sequentially as compared to inoculations with nematode alone. I' concomitant inoculation, the population of each nematode speciej inhibited the multiplication of the other. In simultaneoL'j inoculations the interactive effects of both the nematode species were mutually antagonistic. Sequential inoculation showed that prior establishment of one nematode species invariably inhibited the multiplication of the other nematode species subsequently inoculated. The chemicals, Furadan and Nemark <a neem product) at both the rates of application, significantly reduced the populations of both the nematode species(single as well as concomitant inoculation). The effects of Furadan and Nemark against Meloidogyne incognita were similar as well as at par to each other, while Nemark was significantly more effective than Furadan against Rotvlenchulus reniformis. Soil application of Paecilomvces lilacinus and ftcrophialophora fusispora proved to be beneficial against both the nematode species. The parasitic activity of P.1ilacinus was more pronounced than ft. fusispora against M. incognita, whereas, ft.fusispora was more effective against R.reni formis. Increasing dosages of either of the fungus were significantly more beneficial in reducing the population parametera of both the nematode species. Several organic additives in the form of fresh chopped leaves of wild plants of the family Compositae e.g. Eelipta alba, Bidens biternata and Erigeron bonariensis at two different dosages (5 and lOg/Kg soil) were found to be deleterious against the nematodes. However, the efficacy of different treatments varied from nematode to nematode. Water extracts of Helianthus annuus, Taaetes erect a and Zir^nia eleqans (Ornamental plants of the family Cornpositae) leaves were tested as soil drench treatment to ascertain their antinemic action as well as systemic activity against both the nematodes. These were applied at two different dosages (5ml and lOrnl/Kg soil). Soil application of these extracts protected black gram seedlings from M. incognita and R^. reniformis infection. Their effects, however, were fickle. Root-knot development, and population increase of both the nematode species greatly subdued by T.erecta leaf extracts. Incorporation of oil-seed cakss of neem (ftzad irachta indica) and mustard (Brassica campestris) into the soil proved to be highly pernicious against both the nematode species, whether present singly or concomitantly on black gram. In a similar study, amendment of soil with different fertilizer sources, such as ammonium sulphate, super phosphate and muriate of potash at higher dosages caused significant diminution in the rate of M. incognita multiplication. Diminution in the population parameter of R. reniformis was Bignificant in all the treatments with different sources of fertilizers except at lower dose of phosphorous. fin experiment to study the effect of chemicals (Furadan and Nemark) and bio-control fungi (P.1ilacinus and fi.fusispora) alone and in combination on M.incognita and R.reni formis infecting black gram singly or concomitantly revealed that the chemicals or bio-control fungi alone impoverished the nematode population and increased the plant growth. However, the integration of these components in various combinations was significantly better in reducing the nematode population and increasing the plant growth than when used alone. The best combination of these components for M. incognita, with regard to subjugation in reproduction factor and gall number, and increase in plant growth was noted when P.1ilacinus (2g mycelia/Kg soil) and Nemark (l.Og a.i./Kg soil) were combined together. The same is true with Q.fusispora (lOg mycelia/Kg soil) and Nemark (1.0 a. i./Kg soil) for R. reni f ormis. The results on the integration of bio-control fungi and chopped leaves <E.alba, B.biternata and E.bonariensis) for the control of M.incognita and R.reniformis, when present singly or concomitantly, showed that decline in the population parameters of both the nematode species was significantly more in combined applications than in individual applications of either of the components. Maximum reduction in the reproduction factor of M.incognita and in gall number was achieved in the combined treatment with higher dose of P.1ilacinus (£g mycelia/Kg soil) and E.alba (lOg/Kg soil). Ot the higher dose of P.1ilacinus combined with higher dose of E.bonariensis leaves, diminution in Rf value of R.reniformis was maximum. Integration of bio-control fungi and leaf extracts (H.annuus. T.erecta and Z.eleqans) resulted in significantly higher subjugation in population parameters of M.incognita and R.reni formis than individual application of either fungi or leaf extracts, in most of the