Shade House Conditions Research Articles

Genetic Basis for Productivity in Anthurium andraeanum Hort.

Anthurium andraeanum Hort. is an important tropical ornamental crop regarded as second only to orchids in its commercial importance. The genetic basis for productivity in anthurium was studied using parent–offspring regression analysis. Sixteen parental genotypes (4 years old) and 14 biparental progeny families (60 plants each, 4 years old) derived from the parents were used in the study. Yield expressed as number of cut flowers per plant per year (CFPY) was significant both between parental genotypes (P < 0.001) and between progeny families (P < 0.05). Mean CFPY of the parent genotypes was normally distributed and ranged from 4.8 in ‘Local Mina Red’ to 9.8 in ‘Kalapana’ with a mean of 7.5. CFPY in Year 1 was strongly correlated to that in Year 2 (Pearson’s r = 0.96; Spearman’s r = 0.93) and the broad sense heritability (H2) was high (87.6%) under controlled shadehouse conditions. CFPY in the progeny families varied from four to 14 with progeny means ranging from 5.7 in ‘Honduras/Local Mina Red’ to 7.2 in ‘Mirjam/Kalapana’. Progeny of seven and 10 crosses possessed mean CFPY greater than that of the more productive parent and the midparent values, respectively. The frequency distribution for productivity of the 840 progeny plants was skewed to the right with a modal class of six to seven. The correlation coefficient between progeny CFPY and midparent CFPY was large and significant (r = 0.90, P < 0.001). The regression of mean progeny CFPY on mean midparental CFPY was strong (y = 0.51x + 2.56; R2 = 0.81) with an estimated narrow sense heritability (h2) of 51.0%. A breeding strategy for improving per plant productivity based on the results is discussed.

Azospirillum brasilense and Glomus intraradices co-inoculation stimulates growth and yield of cherry tomato under shadehouse conditions

The response of cherry tomato to biofertilization with beneficial microorganisms was evaluated under shadehouse conditions. Seeds were inoculated and/or co-inoculated with Azospirillum brasilense (Az) and/or Glomus intraradices (Gi). Thereafter, seedlings of six treatments received two applications of a suspension containing Az + Gi at 15 and 30 days after the transplant, and were compared against a non-inoculated treatment which only received conventional inorganic fertilization. Seed co-inoculation with A. brasilense and G. intraradices plus two applications of Az + Gi at 15 and 30 days after transplant increased on average 6% plant height, 11% leaf area, 10.5% dry biomass and 16% yield of cherry tomato in comparison to traditional fertilization.

Influence of weather and growing environment on vegetable growth and yield

An experiment was conducted at the Department of Horticulture, Agricultural College and Research Institute, Tamil Nadu Agricultural University, Madurai, Tamil Nadu, India to screen ten vegetables for cultivation under shadenet house (33% shade) and open field for year round production of vegetables. Tomato, eggplant, chilli, cucumber, cluster bean, radish, amaranthus, coriander, bhendi and capsicum were grown in the summer and winter. The influence of environmental variables temperature, relative humidity and light intensity were studied. Tomato, eggplant, chilli, cucumber, radish, amaranthus and coriander registered better performance for growth and yield during both seasons. Cluster bean performed well in the open field during both seasons. Relative humidity was always higher under shadenet house than in open field during both seasons. Light intensity in the shadenet house was lower than in the open field. Mean weekly temperature during summer and winter were higher under open field conditions than in the shadenet house. Lower temperature caused plant height, number of branches, internodal length, average fruit weight and yield per plant to be higher in the shadenet house than in the open field. Hence, the growing of tomato, eggplant, chilli, cucumber, radish, amaranthus and coriander under shade house conditions will be more profitable irrespective of the seasons. Key words: Shadenet cultivation, season, quality.

Effect of Organic Cultivation of Capsicum annuum L. on Soil Microbial Properties under Open-Field and Shade-House Conditions

Two bell pepper (Capsicum annuum L.) varieties, viz., California Wonder and Gangavati Local, were raised under nine completely organic nutrient sources, along with recommended package of practices, and, under completely inorganic nutrient sources. Irrespective of the variety and growing environment, there was substantial increase in total bacterial count (22.97% and 24.98%), population of fungi (20.23% and 20.23%), actinomycetes (36.89% and 36.83%) and mycorrhiza (44.63% and 29.40%) in open-field and shade-house conditions, respectively, in all the nutrient combinations where organic sources were used, compared to the inorganic treatment. All organic nutrient sources used were found to be similar in their effect on soil microbes.

Initial growth of physic nut as a function of sources and doses of organic fertilizers

Organic fertilization provides low cost, supplemental nutrition for plant production. This study aimed to determine the best source and dose of organic fertilizer on the growth of physic nut (Jatropha curcas L.), a potential biodiesel producer. Physic nut seedlings were transplanted to 18 dm³ black plastic pots filled with soil mixed with four sources of organic fertilizer (chicken, fish, cattle manure or urban waste compost) at four dose levels (50, 100, 200 or 400 L m-3). Fertilized and control (no fertilization) plants were grown under shadehouse conditions and morphological plant features were assessed at 30, 60, 90 and 120 days after transplanting. Doses higher than 100 L m-3 of poultry manure mixed with claysoil should be avoided. The use of other sources such as cattle manure, fish manure and composting may be used and result in increase in height, leaf area, SPAD index up to doses of 200 L m-3 manure mixed in clay soil.

Consequences of changing rainfall for fungal pathogen-induced mortality in tropical tree seedlings.

Most general circulation models predict that most tropical forests will experience lower and less frequent rainfall in future as a result of climate change, which may reduce the capacity of fungal pathogens to drive density-dependent tree mortality. This is potentially significant because fungal pathogens are thought to play a key role in promoting and structuring plant diversity in tropical forests through the Janzen–Connell mechanism. Therefore, we hypothesize that the drying of tropical forests will negatively impact species coexistence. To test one prediction of this hypothesis, we imposed experimental watering regimes on the seedlings of a tropical tree, Pleradenophora longicuspis, and measured mortality induced by fungal pathogens under shade house conditions. The frequency of watering had a strong impact on survival. Seedlings watered daily experienced significantly higher mortality than those watered every three or every six days, while increasing the volume of water applied also led to increased mortality, although this relationship was less pronounced. These results suggest that the capacity of fungal pathogens to drive density-dependent mortality may be reduced in drier climates and when rainfall is less frequent, with potential implications for the diversity enhancing Janzen–Connell mechanism.

Stability of Tropical Residual Soil Slope Reinforced by Live Pole: Experimental and Numerical Investigations

The occurrence of numerous shallow slope failures in Malaysia has resulted in the slope stabilization using live poles as a cheaper and eco-friendly measure. Woody vegetations or live poles were used to reinforce the slope of residual tropical soil at three sites to improve stability of slopes as they provide an immediate shear strength enhancement and modify the saturated soil water regime (mechanical and hydrological effects). The branches of 11 trees/shrubs were tested for root and stem growth in containers under shade-house conditions and three species (Dillenia indica, Dillenia suffruticosa and Hibiscus tiliaceus) were shortlisted based on root growth, diameter and length of root, and survival rate for further evaluating their mechanical strength. Based on the results of the mechanical tests (bending, shear and tensile strength), two species (D. suffruticosa and H. tiliaceus) were finally selected for planting on the slopes. Laboratory tests were also carried out on these root and soil matrix for the determination of its shear strength parameters. The live poles from these two selected trees were planted on three slopes to be monitored for 12 months to observe their growth for the purpose of providing low-cost and environmentally suitable alternative to the conventional methods of slope stabilization. Finally, the stability analysis of the slopes was carried out using finite element software PLAXIS. It was observed that Dillenia suffruticosa and Hibiscus tiliaceus can be used to stabilize slopes against failure. The results obtained from PLAXIS showed that the factor of safety of the slopes increased significantly by the reinforcing effects of the live poles.

Co-inoculation with phosphate-solubilzing and nitrogen-fixing bacteria on solubilization of rock phosphate and their effect on growth promotion and nutrient uptake by walnut

The aim of this work was to evaluate effects of co-inoculation with phosphate-solubilizing bacteria (PSB) and nitrogen-fixing bacteria (NFB) on solubilization of rock phosphate (RP) and their effect on growth promotion and nutrient uptake by walnut seedlings. Two PSB strains, Pseudomonas chlororaphis and Bacillus megaterium, and two NFB strains, Arthrobacter pascens and Burkholderia cepacia, were selected to investigate interaction between PSB and NFB in liquid medium. The maximum concentration of soluble phosphorus (P) was determined in the mixing culture of P. chlororaphis and A. pascens. A strong correlation was found between pH and soluble P concentration, as well as the total organic acid production and P solubilization. Co-inoculation with P. chlororaphis and A. pascens amendment with RP resulted in the highest plant height, shoot and root dry weight, P and nitrogen (N) uptake of walnut seedlings, and the maximum amounts of available P and N in soils under shade house conditions. However, mixed inoculation with B. megaterium and A. pascens failed to increase these parameters. The results demonstrated that co-inoculation with PSB and NFB amendment with RP could be a promising and alternative option for utilizing this potent source as P fertilizer in walnut plants and maintaining greater nutrient availability in soils.

Enhancing seedling growth of Jatropha curcas—A potential oil seed crop for biodiesel

The effects of aerosol smoke (AS), smoke-water (SW), potassium nitrate (KNO 3), naphthalene acetic acid (NAA) and indole-3-butyric acid (IBA) on germination and seedling growth of Jatropha curcas were investigated. Seed coat removal accelerated water imbibition and germination occurred within 48 h. Seeds subjected to AS failed to germinate over a 90 day period. There were no significant differences in germination percentage between the treatments and untreated control (intact- and shelled-seed). However, shelled-seeds had the shortest mean germination time (MGT). Seedlings developed from treated seeds were planted in trays under shade house conditions and growth traits measured after 3 months. Soaking intact-seeds in SW, KNO 3 and NAA (24 h) produced significantly heavier and longer seedlings, which resulted in higher vigour indices (VI) compared to the control treatments. These results provide empirical evidence of the stimulatory effect of SW, KNO 3 and NAA on J. curcas seedling growth and vigour and the continuation of the effect over time. The approach of treating intact-seeds of J. curcas with plant growth substances prior to planting will help in producing healthy seedlings and possibly improve crop productivity.

Isolation and characterization of phosphate-solubilizing bacteria from walnut and their effect on growth and phosphorus mobilization

The objectives of this work were to isolate and characterize walnut phosphate-solubilizing bacteria (PSB) and to evaluate the effect of inoculation with the selected PSB stains to walnut seedlings fertilized with or without insoluble phosphate. Thirty-four PSB strains were isolated and identified under the genera Pseudomonas, Stenotrophomonas, Bacillus, Cupriavidus, Agrobacterium, Acinetobacter, Arthrobacter, Pantoea, and Rhodococcus through a comparison of the 16S ribosomal DNA sequences. All isolated PSB strains could solubilize tricalcium phosphate (TCP) in solid and liquid media. Phosphate-solubilizing activity of these strains was associated with a drop in the pH of medium. A significantly negative linear correlation was found between culture pH and phosphorus (P) solubilized from inorganic phosphate. Three isolates Pseudomonas chlororaphis (W24), Bacillus cereus (W9), and Pseudomonas fluorescens (W12) were selected for shade house assays because of their higher phosphate-solubilizing abilities. Under shade house conditions, application of W24 or W12 remarkably improved plant height, shoot and root dry weight, and P and nitrogen (N) uptake of walnut seedlings. These increases were higher on combined inoculation of PSB with TCP addition. The most pronounced beneficial effect on growth of walnut plants was observed in the co-inoculation of the three PSB strains with TCP addition. In comparison, the isolate of W9 failed to increase available soil P, nutrient levels in plants, or to promote plant growth, suggesting that more insoluble phosphate compounds than tricalcium phosphate should be used as substrates to assess the phosphate-solubilizing ability of PSB under greenhouse conditions. The present results indicated that strains P. chlororaphis or P. fluorescens could be considered for the formulation of new inoculants of walnut, even of more woody plants.

Assessment of Gerbera (Gerbera jamesonii Bolus ex. Hooker F.) Cultivars under Different Growing Conditions

A study was carried out on the growth performance of 9 cultivars of gerbera (Gerbera jamesonii Bolus ex. Hooker F.), at G.K.V.K. Bangalore, during 2011-12. Among the nine cultivars studied, there was a significant variation observed for growth, cut flower yield and quality parameters under polyhouse (NVPH) and shade house conditions. The results revealed that, plant height, number of leaves and plant spread (N/S and E/W) were highest under polyhouse condition compared to shadehouse. Among the varieties, cv. Kyillian recorded the highest plant height (40.1 cm), cv. Sonata recorded maximum number of leaves (23.5) and cv. Julia recorded the highest plant spread on both north to south and east to west side (70.0 and 66.9 cm). Flowering characters such as flower bud appearance, bud opening, 50 per cent flowering and days taken to first harvest were found to be significant. Flowering occurred early under polyhouse compared to shadehouse. Among the varieties, cv. Kyillian took less number of days for flower bud appearance and bud opening (44.5 and 10.4 days respectively). The cv. Dameblanche took less number of days (105.3 and 88 days) to 50 per cent flowering and first harvest. Flower quality parameters such as stalk length, stem diameter, flower diameter and number of ray florets were found to be significant. The highest flower quality parameters were recorded under polyhouse compared to shadehouse. The cv. Julia recorded maximum stalk length and stem diameter (67.9 and 0.83 cm respectively). Maximum flower diameter was recorded in cv. Kyillian (10.6 cm). Cultivar Arianna the recorded maximum number of ray florets (9.16). Significant differences were found among the yield parameters such as flowers per plant, total yield per plant and flowers per meter square. The highest yield parameters were recorded under polyhouse as compared to shadehouse. Among the treatments, cv. Sonata recorded the maximum number of flowers per plant; and flowers per meter square (4.4, 8.8 and 98.2, respectively).

Estimation of leaf nitrogen and silicon using hyperspectral remote sensing

The potential to estimate the nutrient status in important agricultural crops such as maize and sugarcane is of significant interest. In South African sugarcane agriculture, just like in global ecosystem, the estimation of Nitrogen (N) and Silicon (Si) is very important. These nutrients are one of the factors influencing the prevalence of the stalk borer Eldana saccharina Walker (Lepidoptera: Pyralidae). Therefore, the researchers aim at estimating leaf N and Si concentration as well as their ratio in sugarcane using hyperspectral remote sensing (spectroradiometry) for monitoring E. saccharina. A hand-held Analytical Spectral Devices (ASD) Field Spec® 3 spectroradiometer was used to take leaf spectral measurements of sugarcane plants from a potted-plant trial taking place under shade house conditions. In this trial, nitrogen and silicon nutrient applications as well as varieties used were known. In addition, watering regimes and artificial infestation of E. saccharina were carefully controlled. The study results indicate that the Red-edge Index (R740/R720) is linearly related to N concentration (R 2 = 0.81, Root Mean Square Error (RMSE) = 0.103) for N37 with the highest correlation coefficient. For Si, the index (R 750 -R 560 )/(R 750 +R 560 ) was linearly related to Si concentration (R 2 = 0.53, RMSE = 0.118) for N25. Finally, the N:Si ratio was linearly correlated to the index (R 1075 -R 730 )/(R 1075 +R 730 ) (R 2 = 0.67, RMSE = 1.508) for N37, hence this index can be used for early detection of E. saccharina damage or for identifying sugarcane that is prone to attack by E. saccharina. It was concluded that hyperspectral remote sensing has potential for use in estimating the N:Si ratio and E. saccharina potential infestations can be monitored rapidly and nondestructively in sugarcane under controlled conditions. It is recommended that an advanced study be conducted in field conditions using airborne and/or spaceborne hyperspectral sensors.

Seedling biomass allocation and vital rates of cloud forest tree species: Responses to light in shade house conditions

Patterns of above- and below-ground biomass allocation in seedlings of nine common cloud forest (CF) tree species of western Mexico were examined under varying controlled light conditions using artificial shade houses. We analysed the relationships between vital rates (growth and survival) and four morphological traits (SLA, biomass allocation to stems, leaves and roots). We hypothesised that these traits represent differentiation axes in the way seedlings face the heterogeneous light regime typical of the CF understorey. For all species, traits between the different light levels, i.e. allocation to leaves, roots and stems differed among light levels. Five species had the largest SLA in the lowest light levels at the end of the experiment ( Citharexylum, Dendropanax, Fraxinus, Quercus and Magnolia). Juglans was the only species with a large SLA at the highest light level (377.47 cm 2 g −1). In contrast, light levels did not cause any significant variation in SLA of Persea and Simplococarpon at the end of the experiment. The relative height growth rates (RHGR) of the seedlings of five species were significantly different between light levels ( P < 0.05). Overall, all species grew better in the highest light levels. The RHGR of three species were correlated positively with SLA. In turn, allocation to stem, leaves and root biomass were strongly correlated with the RHGR of five species (e.g. Citharexylum, Dendropanax and Fraxinus). Survival did not vary significantly between treatments in any species, only in the case of Simplococarpon ( P < 0.05) and was correlated with all morphological variables. For this species, Peto and Peto's test showed a significantly larger survival of seedlings in the highest light level. The mean responses of these species based on all traits to the controlled light variation did not differed significantly. Our results show that these species display a wide range of resource allocation patterns when exposed to the varying light conditions that may be found in the forest understorey and highlight the role of morphological traits in this variation.

Effects of Single and Dual Applications of Selected Trichoderma and Bacillus Isolates on Performance of Dry Bean Seedlings Grown in Composted Pine Bark Growth Medium under Shadehouse Conditions

ABSTRACT A shadehouse pot trial was conducted to study the efficiency of single and dual inoculations with selected Trichoderma and Bacillus isolates on performance of dry bean plants (Phaseolus vulgaris L.) grown in composted pine bark (CPB) potting medium. All the plant treatments inoculated with Trichoderma spp. and/or Bacillus spp. had higher photosynthetic efficiency (Fv/Fm values). Of the treatments, only B. subtilis B69 showed a significant increase (P = 0.02) in Fv/Fm values over the growth period. The Trichoderma and Bacillus treated plants showed increase in dry shoot biomass. The greatest degree of nodulation was observed in Trichoderma and/or Bacillus treated plants. Increase in nitrogen concentrations were observed in leaves of plants inoculated with Trichoderma and Bacillus isolates. Only T. atroviride SY3A significantly increased phosphorus concentrations in leaves. These results depict and highlight the role these organisms can play in plant root-plant growth promoting rhizobacteria or plant growth promoting fungi (PGPR/PGPF) interaction in a nutrient-poor growth medium.

Potential Plant Species for Live Pole Application in Tropical Environment

Problem statement: Slope instability causing landslides, a major geologic hazard, is a risk common to most regions. Among all categories of landslides, shallow slope failures which affect many hill slopes and earthwork projects are the most wide spread and pose the most costly maintenance problem. One of the soil improvement methods that seem suitable for preventing shallow slope failures is the Live Pole technique. Approach: Due to the geographical variability in the application of this technique in different regions this study was carried out in a tropical environment. Results: This study initially describes the requirement for suitable live poles in tropical regions utilizing indigenous woody species and potential candidates. It then describes screening tests trials that these species were put through to observe their propagation from large live cuttings obtained from branches of small trees and shrubs, viz., tests for root and stem growth in a controlled medium under shade-house conditions with irrigation and then discusses the results of these for their suitability for field trials by replanting in selected natural soils. Conclusion/Recommendations: The results of these screening tests found two species, namely, Hibiscus tiliaceus (Ht) and Dillenia suffructicosa (Ds) which met the requirements for field test trials.

Fertilization-induced changes in growth parameters and antimycobacterial activity of Euclea natalensis (Ebenaceae)

The effect of Nitrogen: Phosphorus: Potassium (NPK) (2:1:2 (44)) fertilizers on growth, accumulation of bioactive naphthoquinones (shinanolone, 7-methyljuglone, diospyrin, isodiospyrin and neodiospyrin) and antimycobacterial activity was investigated in seedlings of Euclea natalensis (Ebenaceae) grown in shadehouse and in field conditions. Seedlings were subjected to three differential fertilization regimes (40 g/l, 20 g/l and 10 g/l). Treatment 2 enhanced the vegetative performance of seedlings grown under shadehouse conditions. A significantly positive correlation was established between the concentration of shinanolone (P<0.01), isodiospyrin (P<0.05) and neodiospyrin (P<0.05) with fertilization from field-grown seedlings. Application of NPK fertilizers significantly (P<0.05) increased the accumulation of neodiospyrin in seedlings subjected to shadehouse conditions. The most potent naphthoquinone, 7-methyljuglone was found to be abundant in all the extracts and was quantified at a high mean concentration of 10.2 g/kg from shade-grown seedlings. Extracts acquired from field-grown seedlings were more active against Mycobacterium smegmatis with a lowest MIC value of 0.78 mg/ml. Extracts from the control group and Treatment 1 (10 g/l), which had less applied fertilizers, were more active against strains of M. tuberculosis with MIC value of 10 µg/ml. This shows the selectivity of E. natalensis against M. tuberculosis. Our study indicated that subjecting seedlings to homogenous environments coupled with higher levels of fertilizers could have a negative impact on the antimycobacterial activity of E. natalensis.

Dry mycelium of Penicillium chrysogenum protects cotton plants against wilt diseases and increases yield under field conditions

Previous studies have indicated that dry mycelium (DM) of Penicillium chrysogenum ( PEN), a waste product of the pharmaceutical industry, is effective in controlling fungal diseases in crop plants under greenhouse or shade-house conditions. In the present study, cotton was grown in fields amended with DM before planting, or squaring, or both, in Linqing and Liaocheng, Shandong province, China, and disease severity of Fusarium oxysporum f.sp vasinfectum ( Fov) and Verticillium dahliae ( Vd) was monitored from 2001 to 2004. Results from the first experiment in 2001 and 2002 showed that DM was effective in protecting, in an application mode-dependent manner, against these two pathogens. At a dose of 30 g m −2, either basal application alone or basal application plus side dressing of DM provided significant protection against Fusarium wilt and Verticillium wilt, but side dressing alone was not significantly effective in controlling the two diseases. In the second experiment in 2003 and 2004, it was shown that disease-control efficacy of DM was dependent on application rates. Averaged across two sites and both years (2003 and 2004), basal application plus side dressing at doses of 30, 90 and 150 g m −2 provided protection of 20.1, 34.6 and 42.7% against Fov, and of 26.8, 47.8 and 49.6% against Vd, respectively, compared to their corresponding DM-free controls. Increases in lint yield of cotton was also obtained by application of DM each year, which could be attributed to both disease control and nutritional effects of DM. DM (⩽2%) had no effect on mycelial growth of the pathogens in vitro, suggesting that the protection was probably attributable to induced resistance. It is concluded that DM of PEN may serve as an organic product for both disease control and plant nutrition in cotton production.

Influence of Arbuscular Mycorrhizae Indigenous to Peru and a Flavonoid on Growth, Yield, and Leaf Elemental Concentration of `Yungay' Potatoes

The influence of arbuscular mycorrhizal fungi (AMF) [two Peruvian mixed isolates, a pure isolate of Glomus intraradices] and the flavonoid, formononetin, were tested on growth, yield, and leaf elemental concentration of the Peruvian potato (Solanum tuberosum L.) `Yungay'. Plants started from tissue culture-produced prenuclear minitubers of `Yungay' were subjected to seven treatments, which included noncolonized (non-AMF) plants fertilized with Long Ashton nutrient solution modified to supply P at 11 and 44 μg·mL-1. All AMF plants received low P (11 μg·mL-1) and were inoculated with either a sierra-maize mixed isolate, sierra-papa mixed isolate, pure isolate of G. intraradices, sierra-maize mixed isolate + formononetin, or a sierra-papa mixed isolate + formononetin. Plants were grown in 3-L containers under shade house conditions in Lima, Peru. Non-AMF plants at low P had the poorest growth, while high P plants had the greatest overall growth. All AMF plants had greater growth, including a higher root to shoot ratio, higher phosphorus use efficiency [(g tuber)/(g P/kg tissue)], and a lower leaf to tuber ratio (indicating greater leaf efficiency in producing tuber dry matter), compared to non-AMF plants at low P. The mycorrhizal inoculation effect (MIE) ranged from +44% to +57%, indicating that `Yungay' was moderately to highly mycorrhizal dependent. Plants colonized with the sierra-papa isolate + formononetin had the same tuber development and leaf to tuber ratio, compared to high P, non-AMF plants. Formononetin increased extraradical hyphae formation. Mycorrhizal enhancement was in part due to greater P, Fe, and Mg uptake, a higher phosphorus-use efficiency and greater extraradical hyphae formation.

Effect of commercially available rhizobacteria strains on growth and production of lettuce, tomato and pepper

Seven microbial products of the genus Bacillus were evaluated under greenhouse and shadehouse conditions for efficacy on lettuce, tomato and pepper as plant growth promoters. Treatments were applied as a drench (106 cfu ml1) directly onto seedlings in composted pine bark growth medium. Variation in activity was observed between Bacillus preparations, and from one host to another. Three of the Bacillus preparations, Bacillus chitinosporus, B. uniflagellatus and B. subtilis significantly increased lettuce growth when seedlings were not supplemented with a nutrient source, NutriStart-AC (P < 0.001). Biostart® 2000 (a combination of B. chitinosporus, B. laterosporus and B. licheniformis) was the only microbial preparation to significantly increase seedling growth on tomato (P < 0.01) whereas B. uniflagellates and B. licheniformis were the only organisms to significantly increase fruit yield on pepper (P < 0.04 and P < 0.01 respectively). When seedlings were inoculated with bacteria and subsequently treated with a bacterial nutrient supplement, NutriStart-AC, B. chitinosporus (P < 0.001), B. uniflagellates (P < 0.02), B. laterosporus (P < 0.03), B. pumilus (P < 0.05) and Biostart® 2000 (P < 0.001) preparations all significantly promoted lettuce seedling growth. On tomato, all Bacillus preparations, with the exception of B. laterosporus, significantly increased seedling growth when NutriStart-AC was added as a supplement. However, only one preparation, Bacillus subtilis (P < 0.02) significantly increased pepper fruit yield when seedlings were supplemented with NutriStart-AC.

Controle químico da queima de folhas e da mela de estacas de eucalipto, causadas por Rhizoctonia spp.

Visando ao controle químico da queima de folhas e mela de estacas de eucalipto (Eucalyptus spp.) em viveiros florestais, avaliou-se a eficiência de 12 fungicidas em inibir in vitro o crescimento micelial de um isolado epifítico de Rhizoctonia solani AG1-IB (RH-2). Sete fungicidas que inibiram totalmente o crescimento micelial do fungo, a concentrações inferiores a 100 ppm, foram pré-selecionados: methyl-tolclophos, benomyl, pencycuron, iprodione, thiabendazol, thiram e captan. Avaliou-se, ainda, a sensibilidade (EC50 = dose provável que inibe o crescimento micelial em 50%) aos fungicidas methyl-tolclophos, benomyl, iprodione e pencycuron de mais oito isolados patogênicos ao eucalipto, que diferem entre si quanto a virulência, morfologia, grupo de anastomose, número de núcleos por célula vegetativa e padrões eletroforéticos de proteínas e isoenzimas. Embora variações nos valores de EC50 entre algumas combinações de fungicidas e isolados tenham ocorrido, todos os isolados foram sensíveis aos quatro fungicidas testados (EC50 &lt; 11 ppm). Sob condições controladas, pulverizações com iprodione (1,5 g/l), benomyl (1 g/l), methyl-tolclophos (1,5 g/l), thiram ( 2,1 g/l), captan (2 g/l) e pencycuron (2 g/l) reduziram significativamente (alfa=5%) a incidência de folhas lesionadas por R. solani AG1, em brotações de mudas envasadas. Associadas à poda de limpeza, pulverizações de brotações de eucalipto em jardim clonal (no campo) com iprodione (1 g/l) ou com mistura de benomyl (0,5 g/l) + captan (1 g/l), alternada com mistura de benomyl (0,5 g/l) + thiram (1 g/l), reduziram a incidência da mela de estacas na casa de vegetação (alfa=5%).