Greatest Increase In Growth Research Articles

Morfofisiologia de feijão-caupi sob estresse salino e aplicação de nanobioestimulante de carbono na fase vegetativa

ABSTRACT Several technologies have been implemented to improve plant performance in irrigated crops, and one of them is the use of nanobiostimulants. Therefore, the aim of the present study was to explore the effects of applying different concentrations of a carbon-based biostimulant on the morphophysiology of cowpea plants subjected to varying electrical conductivities of irrigation water. The experiment was performed in a completely randomized design, in a 2 × 6 factorial scheme, with two electrical conductivities of irrigation water (ECw: 0.35 and 4.0 dS m-1) and six concentrations of nanobiostimulant applied through the leaves (0, 80, 160, 240, 320, and 400 mg L-1), with four replications. Growth and gas exchange variables were evaluated 31 days after sowing (V9 stage). Concentrations between 240 and 320 mg L-1 of carbon-based nanobiostimulant promoted greater increases in growth and physiological variables, but they caused decreases in non-photochemical quenching. Water electrical conductivity of 4.0 dS m-1 reduced the number of leaves (17.1%), stem diameter (10.0%), SPAD index (10.3%), net photosynthesis (10.9%), stomatal conductance (46.4%), transpiration (34.5%), instantaneous carboxylation efficiency (22.4%), and photochemical quenching (4.5%); in contrast, it increased the ratio between internal and ambient CO2 concentration (18.0%), leaf temperature (2.9%), water use efficiency (32.5%), and non-photochemical quenching (12.4%). Concentrations of 240 to 320 mg L-1 of the nanobiostimulant enhance the development and gas exchange of cowpea plants under non-stress conditions, whereas the concentration of 240 mg L-1 promotes the maximum increase in plant height under salinity.

Effect of humic acid on the growth of seedling tomato (Solanum lycopersicum) and melon Cucumis melo)

This study evaluated the effect of HS extracted from mineral coal on the growth of tomato (Solanum lycopersicum) and melon (Cucumis melo) plants to determine the role that humic substances (HS) play as promoters of plant growth. Three concentrations of HS were evaluated in 200 grams of soil. The fertilizer (urea 0.3%) and humic acid in concentrations of 0.05%, 0.1%, and 0.2% were added directly and at the same time to the amount of soil, using a control sample without the addition of humic acid. Increase measurements were made at three-day intervals up to 45 days. Plants treated with high concentrations of HS demonstrated a significant increase in roots (p>0.05). In both plants, the concentration of 0.2% in HS showed the greatest increase in growth, with the melon plant showing the greatest variation as time passed, with its highest peak in 36 days (13.1 ± 0.05cm) of the experiment, while in the tomato plant the maximum growth occurred in 30 days (9.2 ± 0.01 cm). The Dunnett test showed that there was no statistically significant difference between the control and the concentrations of 0.05% and 0.1% (p>0.05), while among the control and the soil sample with a concentration of 0.2% there was a statistically significant difference (p<0.05). The results show a notable influence of humic acid on the growth of the studied plants, especially at high concentrations.
 Keywords: fertilizer, horticulture, humic acid, soils.

Growth Characteristics by Plug Tray Cell Size, Soil Type, and Fertilizer Concentration for Plug Seedling Production of Veronica pusanensis Y.N. Lee

Background and objective This study was conducted to establish a stable seedling production system for Veronica pusanensis Y.N. Lee, a plant that is endemic to the Korean Peninsula and is a critically endangered species, distributed along the coast of Busan, Korea. Methods In order to investigate the plug cell size (72, 128, 200 cells), soil type (commercial substrate, and mixed substrates with peat moss and perlite at ratios of 1:1, 3:1, and 4:1), and fertilizer concentration (Peters 0, 500, 1,000, and 2,000 mg·L−1) conditions, the plug tray was filled with soil and seeds were sown. The sown trays were placed in the growth chamber (25°C, 70% RH, PPFD 100 μmol·m−2·s−1) for three repetitions per treatment. Results There was no difference in the growth of seedlings according to plug cell size. Therefore, it appears to be economically superior to produce seedlings in a 200-cell plug tray. In soil type, the seedling growth increased as the ratio of peat increased, but leaf chlorosis occurred from the 7th week after sowing. Examining the growth of seedlings based on fertilizer concentration, the greatest increase in growth was found to have occurred in the 1,000 mg·L−1 treatment. Conclusion Therefore, for the production of V. pusanesis seedlings, it was noted that when mixed soil with peatmoss and perlite at a ratio of 4:1 is filled in 200-cell plug trays, and the seedlings are fertilized with Peters 1,000 mg·L−1 once a week, growth will increase the most, demonstrating excellent cost-effectiveness. However, to mass-produce high-quality seedlings in a short period, it will be necessary to use a plug tray smaller than 200 cells or to conduct various fertilization composition studies.

Effectiveness of mycorrhizal fungi in the protection of juniper, rose, yew and highbush blueberry against Alternaria alternata

Abstract After conducting two-year observations in nurseries in the Małopolska province, Poland, the species of shrubs on which symptoms of discoloration and withering of the leaves/needles and shoots, and sometimes of whole plants, occurred most frequently were selected for further study. The species included juniper (Juniperus horizontalis ‘Wiltonii’, rose (Rosa ‘Star Profusion’), yew (Taxus × media ‘Hillii’) and highbush blueberry (Vaccinum corymbosum ‘Patriot’). The predominant fungus isolated from the diseased plants was Alternaria alternata (Fr.) Keissl. A pathogenicity test performed in the laboratory confirmed the pathogenic effects of A. alternata on all of the tested species of shrubs. In 2011-2014, a field experiment was conducted with A. alternata inoculum introduced into the growth substrate. The presence of the pathogen reduced considerably the annual growth of all the shrubs tested. The applied mycorrhizal inocula had an effect on some morphological characteristics of plants, such as height and number of shoots. Moreover, the plants whose roots had been treated with the mycorrhizal inocula and were grown in the substrate inoculated with the pathogen also achieved greater increases in growth in comparison with the plants treated with the pathogen as well as relative to the control. The protective role of mycorrhizal inocula against the damaging effects of the pathogen was evident in all the species of shrubs.

The Growth and Protein Expression of Inflammatory Bowel Disease-Associated Campylobacter concisus Is Affected by the Derivatives of the Food Additive Fumaric Acid.

Inflammatory bowel diseases (IBD) are chronic inflammatory conditions of the gastrointestinal tract with multifactorial etiology. Both dietary factors and the microbe Campylobacter concisus have been found to be associated with the condition. The current study examined the effects of sodium fumarate, a neutralized product of the food additives fumaric acid and monosodium fumarate when in the intestinal environment, on the growth of C. concisus to determine the effects of these food additives on IBD-associated bacterial species. Through culture methods and quantification, it was found that neutralized fumaric acid, neutralized monosodium fumarate, and sodium fumarate increased the growth of C. concisus, with the greatest increase in growth at a concentration of 0.4%. Further examination of 50 C. concisus strains on media with added sodium fumarate showed that greatest growth was also achieved at a concentration of 0.4%. At a concentration of 2% sodium fumarate, all strains examined displayed less growth in comparison with those cultured on media without sodium fumarate. Using mass spectrometry, multiple C. concisus proteins showed significant differential expression when cultured on media with and without 0.4% sodium fumarate. The findings presented suggest that patients with IBD should consider avoiding excessive consumption of foods with fumaric acid or its sodium salts, and that the addition of 0.4% sodium fumarate alone to media may assist in the isolation of C. concisus from clinical samples.

The effects of elevated ozone and CO 2 on growth and defense of native, exotic and invader trees

Elevated ozone and CO₂ can differentially affect the performance of plant species. Variation among native, exotic and invader species in their growth and defense responses to CO₂ and ozone may shape CO₂ and ozone effects on invasions, perhaps in part also due to variation between native and invasive populations of invaders. We manipulated ozone (control or 100 ppb) and CO₂ (ambient or 800 ppm) in a factorial greenhouse experiment in replicated chambers. We investigated growth and defense (tannins) of seedlings of Triadica sebifera from invasive (USA) and native (China) populations and pairs of US and China tree species within three genera (Celtis, Liquidambar and Platanus). Overall, ozone reduced growth in ambient CO₂ but elevated CO₂ limited this effect. T. sebifera plants from invasive populations had higher growth than those from native populations in control conditions or the combination of elevated CO₂ and ozone in which invasive populations had greater increases in growth. Their performances were similar in elevated CO₂ because native populations were more responsive and their performances were similar with elevated ozone because invasive populations were more susceptible. Compared to other species, T. sebifera had high growth rates but low levels of tannin production that were insensitive to variation in CO₂ or ozone. Both China and US Platanus plants reduced tannins with increased CO₂ and/or ozone and US Liquidambar plants increased tannins with the combination of elevated CO₂ and ozone. The growth results suggest that intraspecific variation in T. sebifera will reduce the effects of CO₂ or ozone alone on invasions but increase their combined effects. The tannin results suggest that defense responses to CO₂ and ozone will be variable across native and exotic species. The effects of CO₂ and ozone on growth and defense of native and exotic species indicate that the benefit or harm to species from these global change drivers is an idiosyncratic combination of species origin and genus.

Differences in diet-induced flexibility in morphology and growth in a partially migratory species

Partial migration, in which some individuals of a population migrate while other individuals remain resident, is generally associated with ontogenetic shifts to better feeding or as a response to adversity, but its underlying mechanisms remain relatively unknown. Brown trout (Salmo trutta) exhibit partial migration, with some individuals remaining in fresh water (freshwater-resident) while others undertake an anadromous migration, gain most of their adult size at sea, and then return to fresh water to spawn. The option adopted by an individual trout is thought to be partly determined by its growth performance in early life, which in the stochastic and dynamic environment of freshwater streams may be dependent on its flexibility. To examine potential effects of parent type on phenotypic flexibility, we measured the metabolism, growth, and morphology of full-sibling groups of offspring from freshwater-resident and anadromous parents both before and after a switch in diet. We found that fry had a higher growth rate and a more rounded head and body shape when reared on chironomid larvae compared with when they were reared on Daphnia, but diet had no effect on standard metabolic rate. Interestingly, offspring of anadromous parents were less able to maintain their growth rate when fed on Daphnia than were those of freshwater-residents and showed a correspondingly greater increase in growth following a switch from Daphnia to chironomid larvae. Offspring of anadromous parents also showed less morphological flexibility in response to diet than did the offspring of freshwater-residents. We discuss how the migration history of the parents might interact with phenotypic flexibility in early life to influence the migration probability of the offspring.

Impact of Fertilization on Vinca (Catharanthus roseus L.) Grown in Binary Mixtures of Sugarcane Filter Press Mud and Vermiculite

Filter press mud (FPM) is a waste product of the sugar manufacturing industry that is primarily composed of soil, finely ground sugarcane (Saccharum spp.) stalks, and lime. It is widely used as a soil amendment wherever sugarcane is produced. This study sought to investigate the impact of fertilization with potassium nitrate on the growth of vinca (Cataranthus roseus L.) being grown in mixtures of FPM and vermiculite. The purpose of the study was to investigate the nutrient-supplying ability of the FPM-based growing medium. A completely randomized factorial design was installed into 18-count landscape trays, with each cell consisting of a different growing medium by fertilization treatment. While the bulk density of FPM-based growing media tended to be higher than FafardTM 2, plant growth was not stunted. Electrical conductivity and pH were not deleterious to the plants in any of the FPM treatments. Fertilization increased plant growth and development in all treatments in comparison to non-fertilized controls. The 1:1 FPM and vermiculite mixture by volume had the greatest increase in growth from fertilization while the least change in growth from fertilization occurred with the 100 percent FPM treatment. When using FPM as a growing medium, it appears that the fertilization practices might be decreased to take advantage of the nutrients released by the growing medium.

Biochemical and Molecular Characterization of Pyrene and Anthracene Metabolizing Bacteria Isolated from Oil Contaminated Water and Soil in Malaysia

Poly aromatic hydrocarbon (PAH) contamination of soil and water forces the evolution of microorganisms to be able to utilize PAH as a source of carbon. In this study pyrene and anthracene utilizing bacteria were isolated from water and used engine oil contaminated soil from the Strait of Mallaca (Port Dickson) and mechanic workshops in Kedah and Kuala Lumpur, Malaysia, respectively. The samples were enriched in pyrene oranthracene supplemented BSM medium and isolates were characterized using standard biochemical tests and PCR amplification of the 16S rRNA gene followed by sequencing and bioinformatic analysis. Thirteen different species were isolated, including known PAH degrading bacteria Bacillus thuringiensis and Bacillus megaterium, and bacteria with no prior association with PAH degradation, Salmonella enterica and Bacillus toyonesis. Analysis showed that all isolates degraded 99% of the PAH within seven days. Two isolates (KLA1022 and JIP1005) achieved 95% PAH use within two days and also showed a greater increase in growth. The identification of species that hadn’t previously been reported as PAH degraders suggests significant adaptability and potential for further research that can contribute to efforts to clean pollution from the Malaysian environment.

Increase in peroxisome number and the gene expression of putative glyoxysomal enzymes in Chlamydomonas cells supplemented with acetate.

We cultured Chlamydomonas reinhardtii cells in a minimal culture medium supplemented with various concentrations of acetate, fatty acids, ethanol, fatty alcohols, or sucrose. The presence of acetate (0.5 or 1.0%, w/v) was advantageous for cell growth. To determine whether peroxisomes are involved in fatty acid and fatty alcohol metabolism, we investigated the dynamics of peroxisomes, including changes in their number and size, in the presence of acetate, ethanol, and sucrose. The total volume of peroxisomes increased when cells were grown with acetate, but did not change when cells were grown with ethanol or sucrose. We analyzed cell growth on minimal culture medium supplemented with various fatty acids (carbon chain length ranging from one to ten) to investigate which fatty acids are metabolized by C. reinhardtii. Among them, acetate caused the greatest increase in growth when added to minimal culture media. We analyzed the transcript levels of genes encoding putative glyoxysomal enzymes. The transcript levels of genes encoding malate synthase, malate dehydrogenase, isocitrate lyase, and citrate synthase increased when Chlamydomonas cells were grown on minimal culture medium supplemented with acetate. Our results suggest that Chlamydomonas peroxisomes are involved in acetate metabolism via the glyoxylate cycle.

Transgenic tobacco overexpressing Brassica juncea HMG-CoA synthase 1 shows increased plant growth, pod size and seed yield.

Seeds are very important not only in the life cycle of the plant but they represent food sources for man and animals. We report herein a mutant of 3-hydroxy-3-methylglutaryl-coenzyme A synthase (HMGS), the second enzyme in the mevalonate (MVA) pathway that can improve seed yield when overexpressed in a phylogenetically distant species. In Brassica juncea, the characterisation of four isogenes encoding HMGS has been previously reported. Enzyme kinetics on recombinant wild-type (wt) and mutant BjHMGS1 had revealed that S359A displayed a 10-fold higher enzyme activity. The overexpression of wt and mutant (S359A) BjHMGS1 in Arabidopsis had up-regulated several genes in sterol biosynthesis, increasing sterol content. To quickly assess the effects of BjHMGS1 overexpression in a phylogenetically more distant species beyond the Brassicaceae, wt and mutant (S359A) BjHMGS1 were expressed in tobacco (Nicotiana tabacum L. cv. Xanthi) of the family Solanaceae. New observations on tobacco OEs not previously reported for Arabidopsis OEs included: (i) phenotypic changes in enhanced plant growth, pod size and seed yield (more significant in OE-S359A than OE-wtBjHMGS1) in comparison to vector-transformed tobacco, (ii) higher NtSQS expression and sterol content in OE-S359A than OE-wtBjHMGS1 corresponding to greater increase in growth and seed yield, and (iii) induction of NtIPPI2 and NtGGPPS2 and downregulation of NtIPPI1, NtGGPPS1, NtGGPPS3 and NtGGPPS4. Resembling Arabidopsis HMGS-OEs, tobacco HMGS-OEs displayed an enhanced expression of NtHMGR1, NtSMT1-2, NtSMT2-1, NtSMT2-2 and NtCYP85A1. Overall, increased growth, pod size and seed yield in tobacco HMGS-OEs were attributed to the up-regulation of native NtHMGR1, NtIPPI2, NtSQS, NtSMT1-2, NtSMT2-1, NtSMT2-2 and NtCYP85A1. Hence, S359A has potential in agriculture not only in improving phytosterol content but also seed yield, which may be desirable in food crops. This work further demonstrates HMGS function in plant reproduction that is reminiscent to reduced fertility of hmgs RNAi lines in let-7 mutants of Caenorhabditis elegans.

Effects of PGPR and antagonistic fungi on the growth, enzyme activity and Fusarium root-rot of pea

The effects of plant growth-promoting rhizobacteria (PGPR) (Bacillus pumilus and Pseudomonas putida) and antagonistic fungi (Aspergillus awamori, Aspergillus niger and Trichoderma harzianum) were studied alone and in combination in glasshouse experiments on the growth, chlorophyll catalase and peroxidase activity and on the Fusarium root-rot of pea caused by Fusarium solani f. sp. pisi. Application of PGPR and antagonistic fungi caused a significant increase in growth, chlorophyll, catalase and peroxidase activities of both root-rot fungus inoculated and un-inoculated pea plants. Use of P. putida was more effective in reducing disease severity and improving the growth of root-rot fungus-inoculated plants than A. niger and T. harzianum. The greatest increase in growth, chlorophyll, catalase and peroxidase activities of root-rot fungus-inoculated plants and reduction in disease severity was achieved when A. awamori or B. pumilus was used with P. putida compared to other tested combinations.

Efficacy of root-associated fungi and PGPR on the growth of Pisum sativum (cv. Arkil) and reproduction of the root-knot nematode Meloidogyne incognita.

The effects of root-associated fungi (Aspergillus awamori and Glomus mosseae) and plant growth promoting rhizobacteria (PGPR) (Pseudomonas putida, Pseudomonas alcaligenes and Paenibacillus polymyxa) were studied alone and in combination in glasshouse experiments on the growth of pea, enzyme activity (peroxidase and catalase) and reproduction of root-knot nematode Meloidogyne incognita. Application of A. awamori, G. mosseae and PGPR caused a significant increase in pea growth and enzyme activities of both nematode inoculated and uninoculated plants. A. awamori was more effective in reducing galling and improving the growth of nematode inoculated plants than P. alcaligenes or P. polymyxa. The greatest increase in growth, enzyme activities of nematode-inoculated plants and reduction in galling and nematode multiplication was observed when A. awamori was used with P. putida or G. mosseae as compared to the other combinations tested. Percentage root colonization was higher when AM fungus inoculated plants were treated with P. putida both in presence and absence of nematode.

Variation in photosynthesis and growth of mustard cultivars: Role of ethylene sensitivity

Ethylene is involved in various aspects of plant growth and development. We studied ethylene sensitivity in four mustard (Brassica juncea L. Czern and Coss.) cultivars, Pusa Jai Kisan, Alankar, Basanti and SS2 using chemicals that modify ethylene production and examined its role in determining photosynthesis and growth. Pusa Jai Kisan showed maximum sensitivity to ethylene and was more responsive to ethylene modulators than SS2, which exhibited minimum sensitivity to ethylene. In the presence of ethephon (ethylene-source), Pusa Jai Kisan exhibited greatest increase in growth and the activity of ribulose-1,5-bisphosphate carboxylase (Rubisco), net photosynthesis, stomatal conductance and intercellular CO2 concentration, and maximal decrease in these characteristics with ethylene action inhibitor, norbornadiene (NBD). Glucose treatment did not inhibit Rubisco activity, net photosynthesis and growth in ethylene-sensitive plants, but these characteristics were maximally inhibited in ethylene-insensitive plants. Our results show that ethylene sensitivity has a role in determining photosynthesis and growth of mustard plants. The selection of an ethylene-sensitive mustard type would help in augmenting photosynthesis and growth and also provide new insight into the ethylene-mediated physiological responses.

Biocontrol of root-knot nematode Meloidogyne incognita by the isolates of Pseudomonas on tomato

Biocontrol of root-knot nematode Meloidogyne incognita was studied on tomato using 15 isolates of fluorescent Pseudomonads isolated from pathogen suppressive soils. Pseudomonas aeruginosa (isolates Pa8, Pa9 and Pa3) caused greater inhibitory effect on hatching of M. incognita than other isolates. In addition, isolates Pa8, Pa9 and Pa3 caused greater colonisation of tomato roots and also caused a greater increase in the growth of tomato seedlings. These isolates also caused a greater increase in growth of tomato and higher reduction in galling and nematode multiplication in a green house test than is caused by other isolates. Isolates Pf1, Pf5, Pf6 and Pa13 were unable to increase growth of tomato and caused less reduction in galling and nematode multiplication compared to other isolates. Only 10 isolates produced siderophores on chromo-azurol sulfonate (CAS) agar medium and isolate Pa12 showed greater production of siderophore followed by Pa11, Pa9, Pf10, Pa3 and Pf5. Similarly, isolates Pa14, Pa12, Pf10, Pa9, Pa8, Pa7 and Pa6 produced greater amount of HCN than the other isolates tested. Isolates Pa8 and Pa9 showed greater production of IAA than the other 13 isolates tested. This study suggests that P. aeruginosa isolates Pa8 and Pa9 may be used for the biocontrol of M. incognita on tomato.

Interactive effects of land use history and natural disturbance on seedling dynamics in a subtropical forest

Human-impacted forests are increasing in extent due to widespread regrowth of secondary forests on abandoned lands. The degree and speed of recovery from human disturbance in these forests will determine their value in terms of biodiversity conservation and ecosystem function. In areas subject to periodic, severe natural disturbances, such as hurricanes, it has been hypothesized that human and natural disturbance may interact to either erase or preserve land use legacies. To increase understanding of how interactions between human and natural disturbance influence forest regeneration and recovery, we monitored seedlings in a human- and hurricane-impacted forest in northeastern Puerto Rico over a approximately 10-yr period and compared seedling composition and dynamics in areas that had experienced high- and low-intensity human disturbance during the first half of the 20th century. We found that land use history significantly affected the composition and diversity of the seedling layer and altered patterns of canopy openness and seedling dynamics following hurricane disturbance. The area that had been subject to high-intensity land use supported a higher density, but lower diversity, of species. In both land use history categories, the seedling layer was dominated by the same two species, Prestoea acuminata var. montana and Guarea guidonia. However, seedlings of secondary-successional species tended to be more abundant in the high-intensity land use area, while late-successional species were more abundant in the low-intensity area, consistent with patterns of adult tree distributions. Seedlings of secondary-forest species showed greater increases in growth and survival following hurricane disturbance compared to late-successional species, providing support for the hypothesis that hurricanes help preserve the signature of land use history. However, the increased performance of secondary-forest species occurred predominantly in the low-intensity land use area, suggesting that hurricanes act to homogenize differences in species composition between areas with differing land use histories by increasing secondary-forest species regeneration in areas that experienced little direct human disturbance. Our results suggest that, through effects on seedling dynamics, hurricanes may extend the signature of land use history beyond the average recovery time of forests not subject to intense natural disturbance events.

Biocontrol of root-knot nematode Meloidogyne incognita by the isolates of Bacillus on tomato

Fifteen isolates of Bacillus, isolated from the root-knot nematode suppressive soils, were used for the biocontrol of Meloidogyne incognita on tomato. Bacillus isolates B1, B4, B5 and B11 caused greater inhibitory effect on hatching of M. incognita than caused by other isolates. In addition, these isolates (B1, B4, B5 and B11) caused greater colonisation of tomato roots and also caused greater increase in the growth of tomato seedling than caused by other isolates. All the isolates of Bacillus were able to increase growth of tomato and caused reduction in galling and nematode multiplication in green house tests. Isolates B1, B4, B5 and B11 caused a greater increase in growth of tomato and higher reduction in galling and nematode multiplication than other isolates in a green house test. These isolates were also tested for hydrogen cyanide (HCN) and indole acetic acid productions. Only one isolate (B13) produced HCN out of 15 tested. On the other hand, isolates B5, B11, B4 and B1 showed greater production of IAA than the other 11 isolates tested. This study suggests that Bacillus isolates B5, B11, B4 and B1 may be used for the biocontrol of M. incognita on tomato.

Biocontrol of root-knot nematode Meloidogyne incognita by Pseudomonas and Bacillus isolates on Pisum sativum

Biocontrol of root-knot nematode Meloidogyne incognita was studied on Pisum sativum using isolates of fluorescent Pseudomonads (Pf1, Pa2, Pa3, Pa4 and Pf5) and Bacillus (B1, B2, B3, B4 and B5). Pseudomonas isolates caused greater inhibitory effect on hatching and penetration of M. incognita than caused by isolates of Bacillus. Among Pseudomonas, isolate Pf1 caused greater inhibitory effect on the hatching and penetration of M. incognita followed by Pa3, Pa4, Pa2 and Pf5. Similarly, among Bacillus isolates, B2 caused greater inhibitory effect on the hatching and penetration of M. incognita followed by B4, B3, B5 and B1. Pseudomonas isolates also caused greater increase in the growth of seedlings of pea than caused by isolates of Bacillus. In a greenhouse experiment, isolate Pf1 caused a greater increase in pea growth and higher reduction in galling and nematode multiplication followed by Pa3 and Pa4. However, isolate B1 was least effective in improving pea growth and reducing galling and nematode multiplication in greenhouse tests. Pseudomonas isolates were tested for siderophores, hydrogen cyanide (HCN) and indole acetic acid production because Pseudomonas isolates were more effective than the isolates of Bacillus in improving growth of pea and reducing galling and nematode multiplication. Only three isolates of Pseudomonas produced siderophores on Chrome-Azurol Sulphonate (CAS) agar medium out of five isolates tested. Isolates Pf1 showed greater production of siderophores followed by Pa3 and Pa4. Similarly, isolate Pf1 produced greater amount of IAA followed by Pa3, Pa4, Pa2 and Pf5. On the other hand, Pf1 and Pa3 showed greater production of HCN followed by Pa4 and Pa2 and Pf5. This study suggests that Pseudomonas isolate Pf1 may be used for the biocontrol of M. incognita on pea.

Productivity and nitrogen use of maize as affected by in situ and ex situ green manuring in major and minor seasons of tropical Asia

Green manuring is considered an important agronomic practice for smallholder farming systems in the tropics. Different species of legumes and non-legumes are applied either asex situorin situgreen manures. Thus a field study conducted under rainfed conditions in Sri Lanka compared the effect ofin situandex situgreen manuring using two popular green manures (Crotolaria juncea— a legume andTithonia diversifolia— a non-legume) on the growth, seed yield and N use pattern of maize (Zea mays), the most popular upland cereal in the Asian tropics, grown with high and low N rates, in the two seasons that correspond to the monsoonal rains.In situgreen manuring, especially with crotolaria, increased the growth, seed yield and N use efficiency of maize when compared to theex situaddition of similar quantities of the green manure. The impact was also greater in the minor season, when the crop was subjected to moisture stress conditions. The benefits ofin situgreen manuring with tithonia were lower than those due to crotolaria.In situgreen manuring with tithonia also led to a greater increase in growth, seed yield and N use efficiency in maize compared toex situgreen manuring with this species. The green manures, especiallyin situapplication, also increased the benefits of enhanced rates of N fertilizer to the crops in both seasons, with greater use efficiency in the major season. The study showed the benefits of green manuring (bothinandex situ) for obtaining higher yields of maize in the growing seasons of the Asian tropics, especially thein situapplication of legume species.

Effects of phosphate solubilizing microorganisms and Rhizobium sp. on the growth, nodulation, yield and root-rot disease complex of chickpea under field condition

Effects of Phosphate solubilizing microorganisms ( Glomus intraradices , Pseudomonas putida , P. alcaligenes , P. aeruginosa (Pa28), A. awamori ) and Rhizobium sp. was observed on the growth, nodulation yield and root-rot disease complex of chickpea under field condition. Inoculation of Rhizobium sp. caused a greater increase in growth and yield than P. putida, P. aeruginosa or G. intraradices . The number of nodules per root system was significantly higher in plants inoculated with Rhizobium sp. compared to plants without Rhizobium sp. Inoculation of P. putida caused highest reduction in galling followed by P. aeruginosa , P. alcaligenes , G. intraradices and A. awamori while Rhizobium sp. caused almost similar reduction in galling as caused by P. putida .