Bio-Efficacy of Compost Extracts for the Control of Choanephora Wet Rot Okra (Abelmoschus Esculentus L.)

Bio-efficacy of aqueous extracts prepared from rice straw (RST) and empty fruit bunch of oil palm (EFB) composts for the control of Choanephora wet rot of okra (Abelmoschus esculentus L.) was studied. The physiochemical and microbiological properties of both the finished composts showed that they were within the range of compost standards. RST compost extracts has higher N, PI K content of 1.14, 3.36, and 1.42 % with respect to EFB extract with 1.01. 2.51, and 1.20 %, respectively. The aqueous extracts produced therefore are suitable as foliar sprays for the improvement of growth of okra plants. Twelve days of brewing was the best extraction time based on the properties of the compost extracts obtained and their ability to inhibit the growth of C. cucurbitarum in vitro. The percent germination was reduced by 80 to 83 % in the presence of RST and EFB extracts. The effect was further demonstrated by using filter (0.2 pm) and heat - sterilized extracts (autoclaving at 121'~ for 20 minutes) for assessing their potential effect on mycelial growth, conidial germination of C. cucurbitarum and production of inducible resistance related compounds in pre - treated plants. Non - sterilized extracts from both composts gave significantly reduced (P 10.05) mycelial growth of C. cucurbitarum (84 and 79 % for RST and EFB extracts, respectively) and enhanced host resistance through production of inducible compounds such as total phenols, peroxidase (PO), polyphenol oxidase (PPO) and phenylalanine ammonia lyase (PAL) in okra plants. The eficacy was perceptibly reduced by filter sterilizing the RST and EFB extracts to 57 and 55 %, respectively, whereas heat sterilization nullifies their activity totally, suggesting that the activity of both extracts were biological in nature. The higher activity of filter-sterilized extracts associated with mycelial growth inhibition and percentage disease reduction as compared to heat - sterilized extracts infers that chemical factors and nutrient composition of the extracts also played a role in the activity. Humic acids (active component of humic substances in compost) extracted from RST and EFB compost extracts when tested in vitro reduced mycelial growth of C. cucurbitarum by 100 and 64.2 % at 1 % concentration, respectively. The bio-efficacy was further enhanced by fortifying the extracts with T. harzianum, an established biocontrol agent against many pathogens. Trichoderma - fortified extracts (3 x l ~ - ~ cmf ul-') from RST when tested on okra in glass house and field conditions showed significant increase in plant growth and yield. There was reduction of 91.9 % in Choanephora wet rot of okra at 12 weeks of assessment in field and was comparable to Dithane M- 4503 and significantly higher to T. harzianum fortified EFB extracts

Effect of seed bacterization on plant growth response and induction of disease resistance in chilli

This study aimed to examine the induction of disease resistance, and growth response in chilli plants elicited by plant growth promoting endophytic bacteria [Pseudomonas aeruginosa (UPMP3), Burkholderia cepacia (UPMB3), and Serratia marcescens (UPMS3)]. Seed bacterization with UPMP3 and UPMB3 significantly increased peroxidase (PO), polyphenol oxidase (PPO), and phenylalanine ammonia-lyase (PAL) activities. This increase corresponded to greater reduction in pre- and post-emergence damping-off caused by Sclerotium rolfsii. UPMS3 alone or as mixture with UPMP3 and UPMB3 did not show any significant reduction in disease incidence. However, all the isolates tested did not inhibit the seed germination and seedling establishment in chilli

Foliar application of microbial-enriched compost tea enhances growth, yield and quality of muskmelon (Cucumis melo L.) cultivated under fertigation system

Microbial-enriched compost tea (CT) is a water extract of compost that is amended with nutrient supplements during brewing to enhance their microbial diversity. The potential use of fertigation nutrients via drip irrigation system followed by weekly foliar application of microbial-enriched CT on growth of muskmelon (Cucumis melo L.) and suppression of powdery mildew caused by Golovinomyces cichoracearum DC. was studied under rain shelter conditions. Full and half strength fertigation nutrients in combination with weekly foliar application of microbial-enriched CT, fungicide (Daconil®@2 g L−1) or water as a control were utilised in this study. The study showed that there was no added advantage in using full strength fertigation nutrients in terms of chlorophyll content, mean flower formation, mean fruit set, disease severity, and disease progress (AUDPC) or epidemic rate. A repeat trial was also conducted using half strength fertigation nutrients (twice a day) in combination with weekly foliar application of microbial-enriched CT or Daconil®, as a result there was reductions in the disease severity by 38 and 21%, respectively. In addition, a delay in disease onset for two weeks was observed in the plants treated with either microbial-enriched CT or Daconil®. The experimental results revealed significant variations in the yield and fruit qualities amongst the treatments. There were 18.3, 16.21, 8.81, 7.11 and 7.50% increases in mean fruit fresh weight (kg), total soluble solids concentration (°Brix), firmness (N), linear increment in the diameter (cm) and mesocarp size (cm) of muskmelon fruits, respectively after the application of half strength fertigation nutrients in combination with the weekly foliar application of microbial-enriched CT as compared with the control. Thus, it is rational to conclude that a reduced strength of the nutrients in the fertigation systems in combination with weekly foliar application of microbial-enriched CT could be used successfully as a biofertiliser and a bioprotectant on muskmelon crop without compromising their fruit quality

Histopathological changes induced by Meloidogyne incognita in some ornamental plants

Histopathological changes induced by the root-knot nematode (Meloidogyne incognita) in five ornamental plants, specifically, Calendula (Calendula officinalis), Centaurea (Centaurea montana), Papaver (Papaver somniferum), Chrysanthemum (Chrysanthemum morifolium) and Dianthus (Dianthus caryophyllus), were investigated. Based on the galling index (GI), Centaurea was classified as susceptible, Calendula as moderately susceptible, and Papaver as moderately resistant, while Chrysanthemum and Dianthus were highly resistant to M. incognita infection. The histopathology of the galled roots of Centaurea, Calendula, and Papaver during later stages of infection showed that nematodes were localized entirely within the cortex and generally oriented horizontally to the vascular cylinder. Most of the females were mature, and a few of them were associated with egg masses. Giant cells with a variation in cell sizes were observed in the galled roots of all three of the plant species and exhibited a granular cytoplasm and hypertrophied nuclei as a typical reaction to nematode feeding

Bio-intensive management of fungal diseases of fruits and vegetables utilizing compost and compost teas

Compost has been used in agriculture and horticulture for a long time as a fertilizer or a soil conditioner. However, in recent years the focus has been placed on the disease-suppressive effects of the compost and its aqueous extracts. Several composts and their water extracts have been investigated on different diseases especially on those caused by soilborne pathogens throughout the world. Conversely, an increase in disease incidence has also been reported. Therefore, it remains the fact that compost application can suppress the diseases in positive, neutral, and even negative manner. This makes the utilization of compost intricate as a robust prevalent approach to mitigate plant diseases. The mechanisms involved in the disease suppression are not fully known. The disease-suppressive effect of the compost could be attributed to various mechanisms including the presence of antagonistic microbes and unidentified chemical factors in them, antibiosis, and induction of systemic resistance in plants and improvement of the overall health of plants. This chapter focuses on the influence of compost and compost teas on the suppression of foliar and soilborne fungal diseases of fruits and vegetables. The factors limiting and enhancing their efficacy will also be discussed

Microbial starter for the enhancement of biological activity of compost tea.

Compost tea is gaining importance as an alternative to chemical fertilizers and pesticides. The microbial population in the compost tea contributes toward its effectiveness. An attempt was made to enhance the biological activity of compost tea by fortification with microbial substrates. Humic acid and yeast extract (4:7 w/w 100 g-1 compost) when used as microbial starter during brewing of compost tea significantly (P less than or equal to 0.05) enhanced the microbial population. There was a ten to hundred fold percentage increase for total bacteria, fungi and actinomycetes compared to control. The stability of microbial enriched compost tea was maintained up to four months of storage based on significantly higher number of viable cell counts when compared to compost tea without substrates (control). The viable microbial cell counts over a storage period of six months was 8.5x10(9), 4.6x10(6), 3.5x10(4), 3.9x10(4), 1.4x10(5), 4.8x10(4) and 7.3x10(5) for other bacteria

Role of benzoic and salicylic acids in the immunization of oil palm seedlings-challenged by Ganoderma boninense

Basal stem rot (BSR) infection of oil palm, caused by Ganoderma boninense, is one of the key constraining components in palm oil production causing considerable economic losses around the world. Although it was reported a century before, till date no effective controller has been identified, the alteration of lignin content in oil palm can control the BSR is one of the hypothesis. Since the degradation of lignin is the rate limiting step in the infection process of BSR disease. Two naturally occurring phenolic compounds such as benzoic acid and salicylic acid are known to play a key role in the plant defence as well as in the lignin synthesis. The goal of this research is to evaluate the effect of these two naturally occurring phenolic compounds against G. boninense. In this study, oil palm seedlings were immunized with various concentrations (1–15 mM) of benzoic acid and salicylic acid, prior to G. boninense inoculation. After challenging the oil palm seedlings with G. boninense, BSR progression along with the changes in defence enzymes (Phenylalanine ammonia lyase, Peroxidase, and Polyphenol oxidase), and the total lignin contents were examined and evaluated. The exogenous application of the phenolic compounds have not only suppressed the BSR infection but also promoted the plant growth significantly (P ≤ 0.01). The disease suppression was due to the increased production of defence enzymes particularly polyphenol oxidase which had increased lignin content in the seedlings. An absolute disease reduction was registered in seedlings treated 10 and 15 mM benzoic acid with a significant (P ≤ 0.01) increment in the production of lignin along with the defence enzymes. Whereas the salicylic acid exhibited an ambivalent behavior, at 1 mM salicylic acid induced the disease by 60% however as the concentration had increased to 5 mM suppression in the BSR was observed. The efficiency of phenolic compounds as an agent of disease reduction is found to be concentration dependent. The outcome of this study has found that benzoic acid at 15 mM concentration is a superior controller for the BSR disease suppression in oil palm. This study would pave the way towards a new management strategy to replace the chemical controls by naturally occurring phenolic compounds to control BSR effectively in oil palm ranches

Proficiency of biocontrol agents as plant growth promoters and hydrolytic enzyme producers in Ganoderma boninense infected oil palm seedlings

Basal stem rot (BSR) is a major disease encountered by Malaysian oil palm caused by Ganoderma species. Pseudomonas aeruginosa has been shown to improve plant growth and is classified as a Plant Growth Promoter Bacterium (PGPB) while Trichoderma species has been reported as the most common biocontrol agents (BCAs) of oil palm rhizosphere. Therefore, based on preliminary trials P. aeruginosa (UPM P3) and Trichoderma asperellum (UPM29) were selected as BCAs to control Ganoderma infection in oil palm. Both BCAs were screened for their antagonistic properties against G. boninense (UPM13), plant growth promoting traits and enzymatic activities. The result of dual culture test demonstrated that P. aeruginosa and T. asperellum were able to inhibit G. boninense growth with the percentage of inhibition radial growth (PIRG) values of 71.42% and 76.85%, respectively. Besides that, both showed positive results for phosphate solubilizing activity and indole acetic acid (IAA) production. However for siderophore production test, only T. asperellum exhibited positive siderophore production. These BCAs were also tested for their ability inproducing hydrolytic enzymes such as chitinase, cellulose, and 1, 3, β-glucanase

Physiological responses of crop plants against Trichoderma harzianum in saline environment

The physiological response of crop plants against Trichoderma harzianum (Th-6) in a saline habitat was studied. Trichoderma harzianum (Th-6) is an endophytic fungus that shows salt tolerance and establishes a symbiotic relationship with a host plant. To evaluate the role of Trichoderma harzianum (Th-6) in mitigating the consequences of salinity stress on crop plants, seeds of maize and rice were coated with Trichoderma before sowing and salt treatment. Later, after germination, twenty-one day old seedlings were subjected to NaCl concentrations (50, 100 and 150 mM). Salinity negatively affected all investigated physiological parameters in both crops. Treatment of seeds with Trichoderma improved plant growth and Th-treated plants exhibited substantial physiological adjustment in a saline environment compared to Th-untreated plants. The Th-treated plants under salt stress showed higher relative water content and stomatal conductance, better photosynthetic performance and higher pigment concentrations, as well as higher catalase and superoxide dismutase activities. Moreover, proline content in salt stress environment was higher in Th-treated plants, while H2O2 content declined. The physiological role of Trichoderma harzianum in mitigating the salt related consequences of both crop plants is discussed

N-Saccharinylmethyl ether

In the title mol­ecule [systematic name: 1,1,1′,1′-tetra­oxo-2,2′-(oxydimethyl­ene)bi(1,2-benzothia­zol-3-one)], C16H12N2O7S2, the benzisothia­zole ring systems are individually planar [maximum deviations of 0.0497 (13) and 0.0195 (19) Å] and their mean planes are inclined at a dihedral angle of 62.76 (4)°. The crystal structure is stabilized by weak inter­molecular C—H⋯O inter­actions. Two O atoms bonded to two S atoms and four aryl H atoms belonging to two symmetry-related mol­ecules lying about an inversion center form a hydrogen-bonded 10-membered ring with graph-set notation R 4 2(10)