Mujeebur Rahman Khan

The effect of fly ash on plant growth and yield of tomato

A gradual increase in fly ash concentrations in the normal field soil (0, 10, 20...100% volume/volume) increased the porosity, water holding capacity, pH, conductivity, C.E.C., sulphate, carbonate, bicarbonate, chloride, P, K, Ca, Mg, Mn, Cu, Zn and B. Fly ash additions to soil caused significant reductions in nitrogen content, it being almost nil in 90 and 100%. Tomato plants grown in the ash-soil mixture showed luxuriant growth with bigger and greener leaves. Plant growth, yield, (flowering, fruiting, fruit weight/plant, mean fruit weight), carotenoids and chlorophylls were mostly enhanced in the treatments with 40-80% fly ash, being optimal at 50 or 60%. From 60 or 70% onwards, the measured parameters tended to reduce. At 100% fly ash, yield (weight of fruits/plant) was considerably reduced. The boron content of tomato leaves displayed a gradual increase with fly ash addition from 20% onwards, while response of foliar nitrogen was just the opposite. The most economic level of fly ash incorporation was 40%, which improved the yield and market value of tomato fruits (mean weight) by 81 and 30%, respectively.

Effects of root-dip treatment with certain phosphate solubilizing microorganisms on the fusarial wilt of tomato

Root-dip application of Bacillus subtilis, Pseudomonas fluorescens, Aspergillus awamori, Aspergillus niger and Penicillium digitatum resulted in significant decline in the rhizosphere population of Fusarium oxysporum f. sp. lycopersici. A significant decrease in the severity of wilt occurred with A. awamori (37.1%) and P. digitatum (21.3%) compared to the control. Root-dip treatment with the phosphate solubilizing microorganisms tested resulted in significant increase in the yield of tomato, being greatest with A. awamori and P. digitatum in pathogen inoculated (36% and 33%) and uninoculated plants (19% and 23%). A chemical fungicide gave 24% better yield.

Biological Control of Fusarium Wilt of Chickepa through Seed Treatment with the Commercial Formulation of Thricoderma harzianum and/or Pseudomonas fluorescens

The effect of treating seed of chickpea (Cicer arietinum L.) cv. BG 256 with commercial formulations (2 g kg-1 seed) of Trichoderma harzianum and Pseudomonas fluorescens, singly and jointly, to control wilt caused by Fusarium oxysporum f. sp. ciceri was examined in chickpea plants growing in microplots under field conditions. On untreated control plants, the wilt fungus caused the characteristic symptoms of wilt and significantly (P=0.05) decreased dry weight and the yield of chickpea by 20 and 18% respectively (significant at P=0.05). On chickpea without wilt, treatment with P. fluorescens improved the yield by 36% and T. harzianum+P. fluorescens by 25%. Both biofungicides suppressed wilt severity (P=0.05), the most effective being T. harzianum+P. fluorescens (66%). Carbendazim reduced wilt severity by 51%. On chickpea inoculated with the wilt, yield increased by 39% with P. fluorescens, by 33% with T. harzianum+P. fluorescens, by 44% with T. harzianum, and by 20% with carbendazim as compared with the inoculated control. The soil population of the wilt fungus (cfu g-1 soil) in untreated plots increased during the first two months (P=0.05), but in the biofungicide/fungicide treated plots it gradually and significantly (P=0.05) decreased during the four months of the crop season. The greatest decrease in the soil population of the wilt fungus occurred with T. harzianum or T. harzianum+P. fluorescens, followed by P. fluorescens and carbendazim. The rhizosphere population of the bioagents increased significantly in those plots where wilt populations decreased. The greatest increase in the population of the bioagents was recorded for T. harzianum (108–120%), followed by P. fluorescens (65–119%) in the combined treatment, compared with the pre-plant control (December). When the bioagents were applied alone, the population of T. harzianum increased by 71–96% and that of P. fluorescens was by 46–103%.

Biomanagement of Fusarium wilt of tomato by the soil application of certain phosphatesolubilizing microorganisms

The effects of soil application of Bacillus subtilis, Pseudomonas fluorescens, Aspergillus awamori, A, niger and Penicillium digitatum on the plant growth, biomass production, yield and the rhizospheric population of Fusarium oxysporum f.sp. lycopersici on tomato were investigated in a field trial. Plant growth and yield variables of uninoculated plants were increased after application of all the tested phosphate solubilizers. Application of A. awamori and A. niger resulted in an 80% and 58% increase in the yield, respectively. The yield (weight of fruits/plant) of plants inoculated with F. oxysporum f.sp. lycopersici was significantly increased by all the phosphate-solubilizing microorganisms, especially with A. niger (53%), A. awamori (42%), P. digitatum (38%) and B. subtilis (28%). Application of phosphate-solubilizing microorganisms also decreased the rhizosphere population of the wilt fungus by 23?49%.

Effects of intermittent ozone exposures on powdery mildew of cucumber

Abstract Exposure of plants to O3 may influence foliar diseases caused by fungi. It is hypothesized that concentrations of O3 at or below economic threshold may enhance severity of the fungal disease, whereas higher levels may decrease the severity. To test this hypothesis, effects of intermittent exposures at 50, 100 and 200 ppb O3 and powdery mildew infection by Sphaerotheca fuliginea, using pre-, post- and concomitant-inoculation exposures were investigated on cucumber in closed-top exposure chambers. For impact assessment, plant growth, flowering, fruit-setting, foliar ozone injury, fungal colonization, conidia size and their germination were considered. Ozone (except 50 ppb) caused necrotic lesions on leaves and reduced the plant growth and fruit-setting of cucumber. Plants inoculated with S. fuliginea conidia developed powdery colonies in the intercostal region of leaves. Ozone injury was relatively moderate on fungus-inoculated plants. Powdery mildew development was, however, severe on the plants exposed to 50 ppb O3, but at higher concentrations there was significant decline in fungus colonization. Conidia examined from such plants (exposed to 100 or 200 ppb) were smaller in size and contained fewer fibrosin bodies and showed poor germination. Ozone exposures at 50 ppb, however, stimulated the conidial germination. In an in–vitro experiment, the conidia directly exposed to ozone on glass slides showed more or less similar response to the gas. Ozone at 50 ppb and S. fuliginea interacted synergistically and caused significantly greater decrease in the number of fruits/plant. At 200 ppb O3, the mutual effects were antagonistic. Fungus infection provided partial protection to plants against 200 ppb ozone, and mildew infection was also mild.

Single and interactive effects of O3 and SO2 on tomato

Abstract The stomata are main portals for the diffusion of gaseous pollutants into leaf tissue. We hypothesize that the open-closing response of stomata to gases may determine sensitivity of plants to pollutant(s) and that stomata would open wider in pollutant-injured plants. We also hypothesize that the nature of the interaction between O3 and SO2 on tomato would be governed by the concentrations of the gases. Tomato plants were exposed in exposure chambers to all possible combinations of 0.0, 0.05, 0.1 and 0.2 ppm of O3 and SO2 for 3 hr every third day on 27 occasions in 1988 and 1992. O3 and SO2 at 0.2 ppm induced chlorotic and necrotic lesions, and browning, respectively, on leaves. The sympoms were in traces at 0.1 ppm, while absent at 0.05 ppm of either gas. The degree of foliar injury, based on visual assessment, was considerably higher on plants exposed to a mixture at different combinations of 0.05 and 0.1 ppm. Both gases, singly (0.2 ppm) or jointly (0.05, 0.1 and 0.2 ppm) significantly depressed plant dry matter, yield and leaf pigments of tomato. The gases in all treatments consistently suppressed number of stomata and increased the width of their pores. The interactive effects of O3 and SO2 on dry matter and pore width were synergistic at 0.05+0.05, 0.05+0.1, 0.1+0.05 and 0.1+0.1 ppm, antagonistic at 0.2+0.2 ppm and more or less additive at 0.05+0.2 ppm and more or less additive at 0.05+0.2, 0.1+0.2, 0.2+0.5 and 0.2+0.1 ppm, respectively, in both years. The interaction for nubmer and size of stomata was antagonistic in those treatments, which caused synergistic effects on the rest of the assessments. A positive, invariant correlation was recorded in both years between widening of stomatal pores and percentage suppression in dry matter, yield, carotenoids and chlorophylls. Interactive effects of O3 and SO2 were dependent on the concentrations of the gases, e.g. the interaction was synergistic at 0.05 and 0.1 ppm but antagonistic at 0.2 ppm of both gases.

The interaction of SO2 and root-knot nematode on tomato

Intermittent exposure of tomato plants (cv. Pusa Ruby) to SO(2) at 286 microg m(-3) (3 h every heavy third day for 75 days) induced slight chlorosis of leaves. At 571 microg m(-3), considerable chlorosis with browning developed on the foliage. These symptoms were more pronounced and appeared earlier on SO(2)-exposed plants infected with Meloidogyne incognita race 1 (Mi), especially in post- and concomitant-inoculation exposures. Mi and/or SO(2) significantly reduced different parameters of plant growth. Synergistic (positive) interactions between SO(2) and Mi occurred in concomitant- and post-inoculation exposures at 286 and 571 microg m(-3), respectively. In other treatments, an antagonistic (negative) interaction was observed. However, in a few cases, additive effects of SO(2) and Mi were also recorded. Intensity of root-knot (galling) was enhanced at both concentrations of SO(2), while reproduction (egg mass production) of Mi was enhanced in concomitant-inoculation exposures at 286 microg m(-3) and inhibited at 571 micro m(-3). Exposure to SO(2) and/or Mi decreased the number and size of stomata but increased the number and length of trichomes on both the leaf surfaces. Stomatal aperture was significantly wider in the plants exposed to 571 microg SO(2) m(-3) alone and in pre-, post-, and concomitant-inoculation exposures at 286 or 571 microg m(-3). Stomatal aperture was directly related to foliar injury and reductions in growth, yield, and leaf pigments.

Effects of soil application of fly ash on the fusarial wilt on tomato cultivars

A study was carried out in microplots to evaluate the effect of fly ash on the plant growth and yield of tomato cultivars, Pusa Ruby, Pusa Early Dwarf and New Uday, and on wilt disease caused by Fusarium oxysporum f.sp. lycopersici . Fly ash was applied to soil by broadcast or in rows at the rate of 1, 2, 3 and 4 kg ash m-2 in place of inorganic fertilizers. In control plots, NPK (about 40 : 20 : 20 kg acre-1) and compost were added in place of fly ash. Ash application greatly increased the soil contents of P, K, B, Ca, Mg, Mn, Zn, carbonates, bicarbonates and sulphates. Plants grown in the ash-treated plots, especially at 3 or 4 kg dose, showed luxuriant growth and greener foliage, and plant growth and yield of the three cultivars were significantly increased in comparison with the plants grown in plots without fly ash. The wilt fungus, F. oxysporum f.sp. lycopersici at the inoculum level of 2 g plant-1 caused significant suppression of growth and yield in all three cultivars. Application of fly ash, however, checked the suppressive effect of the fungus, leading to a significant increase in the considered variables compared with the inoculated control. Soil population of the fungus (colony-forming units g soil-1) gradually decreased with an increase in ash dose. Row application was found to be relatively more effective in enhancing the yield of tomato cultivars and suppressing the wilt disease. The greatest increase in the yield of fungus inoculated and uninoculated plants due to broadcast or row application at 3 or 4 kg ash m-2 was recorded in tomato cv. Pusa Ruby (39 - 61 and 9 - 24%), followed by Pusa Early Dwarf (31 - 61 and 17 - 34%) and New Uday (21 - 35 and 4 - 22%).

Effects of the root-knot nematode, Meloidogyne incognita, on the sensitivity of tomato to sulfur dioxide and ozone

Abstract Infection of plants with root-knot nematode leads to an increase in transpiration rate. We hypothesize that, in infected plants, the diffusive intake of gaseous pollutants would be greater and the interaction between the nematode and pollutant(s) would be governed by the degree of stomatal opening. Tomato plants infected with the root-knot nematode, Meloidogyne incognita were exposed to air containing 0, 50 or 100 ppb of SO2 or O3 for 5 h every third day on 27 occasions in 1988 and 1989. Plants exposed to the gases at 100 ppb had chlorotic and/or necrotic leaves, small shoots and roots, reduced leaf pigment levels and low yield, compared to untreated plants. Greater foliar injury developed on plants exposed to SO2 + O3 mixture. Symptoms were even greater on nematode-infected exposed plants. M. incognita alone reduced tomato yield by 14.4% and induced a 3.6% increase in the width of stomatal pores and a 15.6% increase in the transpiration rate. A positive correlation was observed between stomatal pore width and rate of transpiration. Interaction between SO2 and O3 depended on the presence (significant) or absence (insignificant) of nematodes. Most effects of nematode infection and gas exposures (especially mixtures) were synergistic. Disease intensity (galls per root system) was increased, but nematode reproduction (egg masses per root system, eggs per egg mass) reduced on plants exposed to SO2 and/or O3.

Effects of ammonia and root-knot nematode on tomato

Abstract Tomato plants inoculated with 2000 juveniles (JJ2) of root-knot nematode ( Meloidogyne incognita race 1) or intermittently exposed to 152 μg NH 3 m −3 exhibited significant suppression in growth, yield and leaf pigments compared with uninoculated or unexposed plants. However, NH 3 at 76 μg m −3 did not cause significant effects. The leaves of nematode-inoculated or uninoculated plants exposed to NH 3 (152 μg m −3 ) turned yellow in all treatments. Root galling and reproduction efficiency of M. incognita increased at 76 μg NH 3 m −3 but was suppressed at 152 μg m −3 . Fecundity, however, declined at both levels. The nematode and NH 3 interacted synergistically at 76 μg m −3 and antagonistically at 152 μg m −3 . Reductions in the plant growth, yield and photosynthetic pigments of the tomato were greatest in post- or concomitant-inoculation treatments at 152 μg NH 3 m −3 and concomitant inoculation treatment at 76 μg m −3 . Nitrogen content of foliage and roots increased significantly at both levels of the gas, being greater in post- and concomitant-inoculation treatments at 152 μg and 76 μg m −3 , respectively. Meloidogyne incognita or NH 3 decreased the number and size of stomata but increased the width of stomatal pores. Length and number of trichomes increased in the exposed plants, but remained unaffected in plants inoculated with the nematode alone. A positive correlation mostly occurred between width of stomatal pore and percent reduction in the plant growth, yield and leaf pigments of tomato.