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Bacillus thuringiensis (B.t) is well known for its biocontrol potential against a variety of insects. Nematicidal potential of ten B.t isolates was tested against root-knot nematodes (Meloidogyne javanica (Treub) Chitwood) in vitro, under greenhouse as well as in field conditions. Eggs and second stage juveniles (J2) were exposed to 5 and 25% concentrations of bacterial cell-free aqueous extracts up to 96 h. B.t isolates showed lesser degrees of nematicidal activity at 5% concentration. However, some B.t isolates (B.t-14, B.t-16 and B.t-64) greatly reduced egg hatching and increased J2. All B.t isolates revealed suppressed egg hatching and increased mortality of J2 at 25% concentration. Soil applications with most of the B.t isolates under greenhouse and field conditions significantly improved height and fresh weights of root-knot nematode parasitized okra (Abelmoschus esculentus (L.) Moench). Some isolates, including B.t-64 reduced the number of galls and egg masses. B.t-64 reduced gall formation up to 70% under greenhouse conditions. However, 29% of decrease was observed in field conditions. Similarly, B.t-64 treated plants showed a 56% decreased in eggs/egg mass in a field experiment. Population of root-knot nematodes in the rhizosphere was decreased up to 61% in the field experiment as compared to control.

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The effect of various natural products from plants and animals were evaluated for the presence of antifungal activity against Pythium aphanidermatum causing damping-off of tomato. Among the plant species tested, bulbs of A. sativum (10%) and Allium cepa var. aggregatum (20%), leaves of Lawsonia inermis, Piper betle (20% each), Eucalyptus globulus and Vitex negundo (40% each) exhibited complete inhibition of the mycelial growth of P. aphanidermatum. Out of 4 animal excreta screened, Pig dung (40%) extract totally inhibited the mycelial growth of P. aphanidermatum. Garlic bulb, eucalyptus leaf and hen litter extract were found to retain the fungitoxicity when extracted at 80 °C for 10 minutes. A. sativum bulb followed by E. globulus leaf extracted in acetone was found to be significantly superior over other natural products. Among the natural products tested, the minimum mycelial dry weight of P. aphanidermatum was obtained with garlic bulb followed by eucalyptus leaf extract. The plant products combined together retained strong inhibitory effect in solid and liquid media against P. aphanidermatum. Upon mixing, the more loss of toxicity was observed when botanicals were mixed with animal excreta, particularly with pig dung. Among the natural products tested, the water extracts of A. sativum plus E. globulus and A. sativum plus L. inermis combinations recorded the maximum percentage of seed germination, growth and vigour of tomato seedlings, respectively. Also, when the various natural products tested by seed treatment, soil drenching and seed treatment plus soil drenching, garlic plus eucalyptus treatment recorded maximum seedling emergence and lesser damping off incidence in all three methods of application. Among the three methods, seed treatment plus soil drenching (St+Sd) was found to be superior than other two methods.

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The objective of this study was to investigate the effect of soil drench with three different concentrations of CdCl2 on growth criteria, ions content and water relations of Sorghum bicolor plants. Also particular interest was focused on the effect of grain presoaking with kinetin in order to ameliorate the toxicity effects exerted by the different levels of CdCl2. In general, the results showed, that the observed suppression in growth criteria (i.e. root length, root fresh and dry weights, plant height, shoot fresh and dry weights, cumulative leaf area as well as root/shoot ratio), ions content (i.e. K+, Na+, Ca2+ and Cd2+), water relations (i.e. total leaf conductivity, transpiration rate and relative water content) in response to CdCl2 was relieved either partially or completely when grains were presoaked in kinetin (50 ppm). The alleviating effect of kinetin for Cd2+ toxicity was more pronounced in response to 1 mM CdCl2 treatment.

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The objective of this study was to investigate the effect of soil drench with three different concentrations of CdCl2 on pigments content, photosynthetic activity, carbohydrate contents and productivity of Sorghum bicolor L. cv. 'Dorado' plants throughout various stages of plant growth and development. Also particular interest was focussed on the effect of grain presoaking with kinetin to ameliorate the toxicity effects exerted by the different levels of CdCl2. In the majority of cases, grain pretreatment with kinetin increased photosynthetic pigments, photosynthetic activity, Hill reaction as well as carbohydrate contents in leaves of cadmium treated sorghum plants. In general, the observed decrease in yield and yield attributes of sorghum plants in response to Cd2+ treatments was accelerated particularly when grains were presoaked in kinetin. The ameliorating effect of kinetin was more pronounced at 1 mM CdCl2. Grain priming with kinetin increased grain biomass (i.e. fresh and dry weights), carbohydrates, protein and ion contents in yielded grains of cadmium treated sorghum plants. Cadmium treatments altered the balance of growth bioregulators in developed grains of sorghum plants. Thus, CdCl2 at all the used concentrations exerted a significant decrease in growth promotor levels with an increase in growth inhibitory substances equivalent to abscisic acid. On the other hand, grain priming with kinetin increased the growth promotory substances and reduced abscisic acid levels.

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) Effects of root inoculation and fungicide soil drenches on sclerotinia blight of coneflower. Can. J. Plant Sci. 80, 909-915. Effects of root inoculation and fungicide soil drenches on sclerotinia blight of coneflower

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