Significant Increase In Total Nitrogen Research Articles

Impact of Intercropping Five Medicinal Plants on Soil Nutrients, Enzyme Activity, and Microbial Community Structure in Camellia oleifera Plantations.

Intercropping medicinal plants plays an important role in agroforestry that can improve the physical, chemical, and biological fertility of soil. However, the influence of intercropping medicinal plants on the Camellia oleifera soil properties and bacterial communities remains elusive. In this study, five intercropping treatment groups were set as follows: Curcuma zedoaria/C. oleifera (EZ), Curcuma longa/C. oleifera (JH), Clinacanthus nutans/C. oleifera (YDC), Fructus Galangae/C. oleifera (HDK), and Ficus simplicissima/C. oleifera (WZMT). The soil chemical properties, enzyme activities, and bacterial communities were measured and analyzed to evaluate the effects of different intercropping systems. The results indicated that, compared to the C. oleifera monoculture group, YDC and EZ showed noticeable impacts on the soil chemical properties with a significant increase in total nitrogen (TN), nitrate nitrogen (NN), available nitrogen (AN), available phosphorus (AP), and available potassium (AK). Among them, the content of TN and AK in the rhizosphere soil of Camellia oleifera in the YDC intercropping system was the highest, which was 7.82 g/kg and 21.94 mg/kg higher than CK. Similarly, in the EZ intercropping system, the content of NN and OM in the rhizosphere soil of Camellia oleifera was the highest, which was higher than that of CK at 722.33 mg/kg and 2.36 g/kg, respectively. Curcuma longa/C. oleifera (JH) and Clinacanthus nutans/C. oleifera (YDC) had the most effect on soil enzyme activities. Furthermore, YDC extensively increased the activities of hydrogen peroxide and acid phosphatase enzymes; the increase was 2.27 mg/g and 3.21 mg/g, respectively. While JH obviously increased the urease activity, the diversity of bacterial populations in the rhizosphere soil of the intercropping plants decreased, especially the Shannon index of YDC and HDK. Compared with the monoculture group, the bacterial community abundance and structure of JH and YDC were quite different. The relative abundance of Actinobacteriota and Firmicutes was increased in YDC, and that of Acidobacteriota and Myxococcota was increased in JH. According to the redundancy analysis (RDA), pH, total potassium, and soil catalase activity were identified as the main factors influencing the microbial community structure of the intercropping systems. In conclusion, intercropping with JH and YDC increased the relative abundance of the dominant bacterial communities, improved the microbial community structure, and enhanced the soil nutrients and enzyme activities. Therefore, in the future, these two medicinal plants can be used for intercropping with C. oleifera.

Carbon-negative and high-rate nutrient recovery from municipal wastewater using mixotrophic Scenedesmus acuminatus

The efficiency of mixotrophic microalgae in enhancing the recovery of waste nutrients has been well established; however, the recovery rate is crucial in meeting the needs of field applications. This study evaluated the impact of media characteristics on nutrient recovery under mixotrophic conditions. The mixotrophic N recovery rate with S. acuminatus in modified BG-11 reached 2.59 mg L−1h−1. A mixotrophic growth optimization strategy was applied to achieve a high-rate nutrient recovery from municipal wastewater treatment plant effluents. The contribution of waste chemical oxygen demand (COD) to nutrient recovery was assessed using secondary effluent (SE) under heterotrophy. The results highlighted a significant increase in total nitrogen (TN) and total phosphorus (TP) recovery rates when glucose was supplied, indicating the additional carbon requirements for efficient nutrient recovery. The TN and TP recovery rates under mixotrophic conditions with the addition of trace metals and high cell density were enhanced by 91.94% and 92.53%, respectively, resulting in recovery rates of 3.43 mg L−1h−1 and 0.30 mg L−1h−1. The same conditions were used for nutrient recovery from primary effluent (PE), and the results were more satisfactory as the TN and TP recovery rates reached 4.79 and 0.55 mg L−1h−1, respectively. Additionally, the study estimated the carbon footprints (C-footprints) and areal footprints of mixotrophy-based nitrogen recovery. The findings revealed carbon footprints and areal footprints of −15.93 ± 4.57 tCO2e t−1 N recovery and 0.53 ± 0.19 m3 m−2d−1 wastewater, respectively. This high-rate nutrient recovery, achieved under a carbon-negative (C-negative) budget through mixotrophy, presents a novel strategy for efficiently recovering resources from municipal wastewater, thus facilitating resource recycling and ensuring environmental sustainability.

Effects of tea oil camellia (Camellia oleifera Abel.) shell-based organic fertilizers on the physicochemical property and microbial community structure of the rhizosphere soil.

Soil microorganisms play important roles in promoting soil ecosystem restoration, but much of the current research has been limited to changes in microbial community structure in general, and little is known regarding the soil physicochemical property and microbial community structure. In this study, four organic fertilizers were first prepared based on tea oil camellia shell (TOCS). Our findings indicate that the application of BOFvo increased both total pore volume and BET surface area of the rhizosphere soils, as well there was a remarkable enhancement in total organic matter (TOM), total nitrogen (TN), available nitrogen (AN), total phosphorus (TP), total potassium (TK), and available potassium (AK) contents of the rhizosphere soils. Meanwhile, in comparison to the CK and CF groups, the utilization of BOFvo led to a substantial increase in both average yield and fruiting rate per plant at maturity, as well resulted in a significant increase in TN and TP contents of tea oil camellia leaves. Furthermore, our findings suggest that the application of TOCS-based organic fertilizers significantly enhances the microbial diversity in the rhizosphere soils with Proteobacteria and Ascomycota being the dominant bacterial and fungal phyla, respectively, and Rhodanobacter and Fusarium being the dominant bacterial and fungal genus, respectively. Redundancy analysis (RDA) indicates that the physicochemical characteristics of TOCS-based organic fertilizers had a significant impact on the composition and distribution of microbial communities in the rhizosphere soils. This study will facilitate the promotion and application of TOCS-based organic fertilizers, thereby establishing a foundation for the reuse of tea oil camellia waste resources.

Role of Biotransformation of Acacia nilotica Metabolites by Aspergillus subolivaceus in Boosting Lupinus termis Yield: A Promising Approach to Sustainable Agriculture

Biotransformation plays a significant role in sustainable agriculture. This process involves utilizing microorganisms, such as bacteria and fungi, to transform organic compounds and metabolites into bioactive compounds which have beneficial effects on plant growth, yield, and soil characters. Accordingly, the present study aims to explore the role of biotransformation of Acacia nilotica metabolites by Aspergillus subolivaceus in boosting L. termis yield, as an important strategy in agricultural sustainability. A pilot experiment was performed on five fungal strains (Fusarium oxysporium A. aculeatus, Aspergillus. subolivaceus, Rhizopus oryzae and Trichoderma viride) which were grown on different parts of plants (A. nilotica leaves; green tea leaves, green pepper fruits and pomegranate fruits), and the results indicated that the most active metabolite for the growth of L. termis seeds was the fungal metabolite of A. subolivaceus growing on A. nilotica. More specifically, we assess how metabolites produced by Aspergillus subolivaceus using A. nilotica leaves affect the biochemical properties and chemical composition of L. termis seeds. A. subolivaceus was grown on leaves from A. nilotica to obtain metabolites and fractionated into four extracts. Two concentrations of each extract were examined by pretreating the seeds of L. termis. The study found that all four extracts contributed to an increase in yield and some biochemical properties of the yielded seeds. The best results were obtained by treating the L. termis seeds with an extract obtained from diethyl ether, which led to a significant increase in total nitrogen, amino nitrogen, glucose and protein contents of the seeds. According to 1H NMR guided GC/MS analysis, our results showed an increase in phytochemicals such as terpenes, fatty materials, and flavonoids including 3′,4′,7-trimethoxyquercetin and 4-methyl-p-menth-8-en-3-one, which have not been stated before from A. nilotica suggesting that biotransformation may have occurred due to the presence of A. subolivaceus.

Do regenerative grazing management practices improve vegetation and soil health in grazed rangelands? Preliminary insights from a space-for-time study in the Great Barrier Reef catchments, Australia

Regenerative grazing, which generally involves some form of rotational grazing with strategic rest, is increasingly seen as a profitable management approach that will accelerate landscape recovery. However, there is limited quantitative evidence supporting the benefits of this approach in northern Australia. This space-for-time study collected vegetation and soil data from a range of properties in the Burdekin catchment in Queensland that have implemented regenerative grazing strategies for between 5 and 20 years. Data were also collected at adjacent control sites that did not undergo regenerative grazing, but where more traditional continuous set-stocking grazing approaches were applied. Coincident data were also collected from several sites where grazing had been excluded for ~30 years. Data suggested that improvements in vegetation, soil and land condition can be obtained from implementing regenerative grazing principles, although it is likely to take at least 3–5 years, and up to 15–20 years for statistically significant improvements to be measurable at a site, particularly for areas that are moving from a degraded baseline condition. Vegetation attributes such as plant biomass and basal area and litter incorporation all appeared to be better surrogates than percentage ground cover for representing improved landscape condition and soil health. Sites that maintained remotely sensed percentage ground cover at or above the minimally disturbed reference benchmark levels for >10 years, as well as having statistically higher biomass, basal area and litter, had significant increases in total nitrogen (TN) and soil organic carbon (SOC) relative to the local control site. Although there are indications that regenerative grazing can lead to improvements in land condition, this study does not enable us to conclude whether regenerative grazing will accelerate improvements compared with other best-practice grazing land management (GLM) approaches, and further research on the social and economic dimensions of regenerative grazing is needed.

Influence of tied-ridge-furrow with inorganic fertilizer on grain yield across semiarid regions of Asia and Africa: A meta-analysis

BackgroundIn semiarid areas, low productivity of crops has been attributed to lack of appropriate soil moisture conservation practices since droughts and soil erosion are rampant in most areas of this region. Consequently, ridge-furrow rainwater harvesting is widely used in these regions across the globe. Despite ridge-furrow being widely practiced, tied-ridge-furrow has not been extensively adopted by small-scale farmers in semi-arid regions. Consequently, the effectiveness of tied-ridge-furrow as a viable method of increasing crop yield has received less attention.MethodologyFor large-scale implementation, a detailed assessment of how ridge furrow, tied–ridge-furrow with fertilizer, tied-ridge-furrow with mulching and tied-ridge-furrow without mulching or fertilizer influence crop yield in different agro-environments under varying climatic conditions is needed. This study used the PRISMA guidelines to determine the impact of tied-ridge-furrow rainwater harvesting technique with mulching or fertilizer on sorghum (Sorghum bicolor) and pearl millet (Pennisetum glaucum) grain yields.ResultsSorghum grain yield increased by 17% greater in tied-ridge-furrow without mulching or fertilizer in comparison to flat planting. This may be due to increase in soil organic carbon in the region (9 g kg−1). Grain yield of millet significantly increased by 20–40% in Africa from 18 study observations in tied-ridge-furrow with fertilizer application as compared to tied-ridge-furrow without mulching or fertilizer treatments. This might be due to the significant increase in total nitrogen by 13–42% in the soil at <50 mg kg−1 quantity which had an effect size of 469.14 [65.60, 872.67]. In terms of soil texture, grain yield of millet and sorghum significantly increased in heavy textured soils (clay loam, silt clay, and clay soils) with an effect size of 469.14 [65.60, 872.67] compared to light and medium-textured soils of zero effect sizes. Millet and sorghum grain yields in tied-ridge-furrow with mulching, on the other hand, were not significantly different from those in flat planting. This may be due to the mulching materials used in those tests.ConclusionIn view of yields of sorghum and millet increased significantly by 32% and 17% in tied-ridge-furrow without mulching or fertilizer treatment compared to flat planting and tied-ridge-furrow with fertilizer treatment compared with tied-ridge-furrow without mulching or fertilizer treatment, respectively, this study recommend the use of fertilizers in a tied-ridge-furrow system to increase grain yield in semiarid areas compared to flat planting. Again, the study recommends more research on tied-ridge-furrow systems with other organic mulches and fertilizers in semiarid areas.

EFFECT OF NITROGENOUS SOIL AMMENDMENTS ON SOIL PHYSICO-CHEMICAL PROPERTIES AND PERFORMANCE OF CASTORBEAN PLANT (Ricinus communis) IN RIVERS STATE, NIGERIA

The castor bean seed when cooked and fermented, is a staple food condiment in Nigeria, but itsproduction is low in the humid rainforest zone of Southern Nigeria. A field experiment was conducted inthe Rivers State University Teaching and Research Farm in Port Harcourt Nigeria, to evaluate the effectof various nitrogenous soil amendments on the growth and yield of castor bean plant (Ricinus communis).The treatments included 120kgNha-1equivalent of urea, NPK 20-10-10, poultry droppings, piggery dungand no amendment (control). These were replicated thrice and laid out in randomized complete blockdesign. A Chinese improved variety of castor bean plant (Zibocastor No 5) was planted at a spacing of 1mx 1m within and between row, at a population of 5,000 seeds per hectare. Results showed that the variousnitrogenous soil amendments significantly affected all growth and yield parameters measured, butgermination was negatively affected. Piggery dung gave the best values of 52.6cm, 24.0, 85.0cm2, 191.5,and 350gplant-1for plant height, number of leaves, leaf area, number of capsules and capsule weightrespectively, when compared to the control with 24.5, 8.0, 40.0cm2, 28.4, 153gplant-1. Results of thephysico-chemical properties of the soil showed significant increase in total nitrogen and availablephosphorus, and a decrease in exchangeable calcium and magnesium with no significant changes in pH;following soil amendment and cropping. Amending the soil with piggery dung increased yield by 397.0%over the control.

Inoculation with a psychrotrophic-thermophilic complex microbial agent accelerates onset and promotes maturity of dairy manure-rice straw composting under cold climate conditions

The objective was to determine the effects of psychrotrophic-thermophilic complex microbial agent (PTCMA) comprised of a psychrotrophic bacterium consortium (PBC) and a thermophilic cellulolytic fungi consortium (TCFC), on composting in a cold climate. Mixtures of dairy manure and rice straw were inoculated with PTCMA, PBC, TCFC and sterile water (control) and composted at an initial ambient temperatures of −2 to 5°C. In compost piles inoculated with PBC or PTCMA, temperatures reached the thermophilic phase (>55°C) faster (8–11d) than piles inoculated with TCFC or control. Furthermore, compost inoculated with TCFC or PTCMA had greater decreases in total organic carbon and carbon-to-nitrogen ratios, as well as significant increases in total nitrogen, degradation of cellulose and lignin and germination index than PBC inoculation or Control compost. Consequently, inoculation with both (i.e. PTCMA) accelerated the onset and promoted maturity of composting under cold-climate conditions.

Halotolerant Rhizobacteria Promote Growth and Enhance Salinity Tolerance in Peanut.

Use of Plant growth promoting rhizobacteria (PGPR) is a promising strategy to improve the crop production under optimal or sub-optimal conditions. In the present study, five diazotrophic salt tolerant bacteria were isolated from the roots of a halophyte, Arthrocnemum indicum. The isolates were partially characterized in vitro for plant growth promoting traits and evaluated for their potential to promote growth and enhanced salt tolerance in peanut. The 16S rRNA gene sequence homology indicated that these bacterial isolates belong to the genera, Klebsiella, Pseudomonas, Agrobacterium, and Ochrobactrum. All isolates were nifH positive and able to produce indole -3-acetic acid (ranging from 11.5 to 19.1 μg ml−1). The isolates showed phosphate solubilisation activity (ranging from 1.4 to 55.6 μg phosphate /mg dry weight), 1-aminocyclopropane-1-carboxylate deaminase activity (0.1 to 0.31 μmol α-kB/μg protein/h) and were capable of reducing acetylene in acetylene reduction assay (ranging from 0.95 to 1.8 μmol C2H4 mg protein/h). These isolates successfully colonized the peanut roots and were capable of promoting the growth under non-stress condition. A significant increase in total nitrogen (N) content (up to 76%) was observed over the non-inoculated control. All isolates showed tolerance to NaCl ranging from 4 to 8% in nutrient broth medium. Under salt stress, inoculated peanut seedlings maintained ion homeostasis, accumulated less reactive oxygen species (ROS) and showed enhanced growth compared to non-inoculated seedlings. Overall, the present study has characterized several potential bacterial strains that showed an enhanced growth promotion effect on peanut under control as well as saline conditions. The results show the possibility to reduce chemical fertilizer inputs and may promote the use of bio-inoculants.

Bioaugmentation of Mesorhizobium cicer, Pseudomonas spp. and Piriformospora indica for Sustainable Chickpea Production.

Chickpea establishes symbiotic association with Mesorhizobium to fulfill its nitrogen (N) requirement. Integrating chickpea rhizosphere with potential native mesorhizobia and other plant growth promoting microorganisms can contribute multiple benefits to plants. The present investigation was undertaken to study interactions among Piriformospora indica (PI) with potential plant growth promoting rhizobacteria (PGPR) viz. Pseudomonas argentinensis (LPGPR1), Pseudomonas sp. (LPGPR2) along with national check Pseudomons sp. (LK884) and Mesorhizobium cicer (LGR33, MR) to examine the synergistic effect of consortium for improving growth, symbiotic efficiency, nutrient acquisition and yield in two chickpea (Cicer arietinum L.) varieties viz. desi PBG1 and kabuli BG1053. In-vitro, seed germination with consortium MR + PI + LPGPR1 was the best compatible treatment followed by MR + PI + LK884 and MR + PI + LPGPR2. Significant improvement in the growth, symbiotic parameters and grain yield was observed with MR + PI + LPGPR1 and MR + PI + LK884 treatments. Significantly high chlorophyll and leghaemoglobin content was recorded with MR + PI + LPGPR1 (1.57 and 1.64mgg(-1) fresh weight of leaves and 5.19 and 4.39mg/g(-1) fresh weight of nodules) in desi PBG1 and kabuli BG1053 chickpea varieties, respectively. At 90 DAS, MR + PI + LPGPR1 treatment significantly improved nodule dry weight (ranged between 84.0 and 141.7mg plant(-1)) as compared to MR alone treatment (ranged between 62.3 and 123.3mg plant(-1)). Data revealed significant increase in total nitrogen (N) and phosphorus (P) content of shoot with MR + PI + LPGPR1 by 1.2 and 1.5 fold, respectively over MR alone treatment. On the basis of overall mean, MR + PI + LPGPR1 significantly improved the yield by 8.2% over Mesorhizobium alone application. It seems from foregoing study that tripartite combination of different micro-organisms can be explored as biofertilizer for improvement in chickpea productivity.

Plant growth stimulation of wheat (Triticum aestivum L.) by inoculation of salinity tolerant Azotobacter strains

Five salinity tolerant Azotobacter strains i.e., ST3, ST6, ST9, ST17 and ST24 were obtained from saline soils. These Azotobacter strains were used as inoculant for wheat variety WH157 in earthen pots containing saline soil under pot house conditions, using three fertilizer treatment doses i.e., control (no fertilizer, no inoculation), 90 Kg Nha(-1) and 120 Kg Nha(-1). Inoculation with salinity tolerant Azotobacter strains caused significant increase in total nitrogen, biomass and grain yield of wheat. Maximum increase in plant growth parameters were obtained after inoculation with Azotobacter strain ST24 at fertilization dose of 120kgN ha(-1) and its inoculation resulted in attaining 89.9cms plant height, 6.1g seed yield, 12.0g shoot dry weight and 0.7 % total nitrogen. The survival of Azotobacter strain ST24 in the soil was also highest in all the treatments at 30, 60 and 90days after sowing (DAS). However, the population of Azotobacter decreased on 90 DAS as compared to counts observed at 60 DAS at all the fertilization treatments.

Management of food industry waste employing vermicomposting technology

This paper reports the vermicomposting of food industry sludges (FIS) mixed with different organic wastes employing Eisenia fetida. A total of 10 vermicomposting units containing different wastes combinations were established. After 15weeks significant increase in total nitrogen (Ntotal) (60–214%), total available phosphorous (Pavail) (35.8–69.6%), total sodium (Natotal) (39–95%), and total potassium (Ktotal) (43.7–74.1%), while decrease in pH (8.45–19.7%), total organic carbon (OCtotal) (28.4–36.1%) and C:N ratio (61.2–77.8%) was recorded. The results indicated that FIS may be converted into good quality manure by vermicomposting if spiked with other organic wastes in appropriate quantities.

082 Identification and Partial Characterization of Seasonally Regulated Proteins in Apple Bark Tissues

During autumnal leaf senescence, leaf nitrogen is translocated to bark and root tissues for storage. By definition, proteins that accumulate in large amounts in winter and are absent in summer are called storage proteins. These storage proteins are believed to play an important role in spring growth and helping trees to tolerate and/or recover from both abiotic and biotic stress. Little knowledge exists regarding storage proteins in apple, their physiological function, or how management practices impact them. Our objectives in this research was to characterize seasonally regulated proteins in apple, develop knowledge about their physiological function, and determine how they are affected by management practices. Results of the first-year studies have identified four major proteins that exhibit a seasonal pattern of accumulation in bark tissues of apple. One of these is a pathogenesis-related protein, meaning that it plays a role in disease resistance. Another of these proteins is a stress-related protein important in the use of carbohydrates under stress conditions. A third protein is a vegetative storage protein serving as a reserve for nitrogen. The last protein has not been completely identified. Greatest seasonal fluctuation of these proteins occurred in current season and 1-year-old bark tissues. Experimental studies that achieved varying levels of nitrogen in shoot tissues of young Fuji apple trees were examined for the effect on the accumulation of these proteins. Results indicated that despite a significant increase in total nitrogen, increases in the accumulation of these proteins were only slight. Instead, it appears that most of the nitrogen was present as free amino acids rather than stable proteins. These data indicate that more knowledge is required to determine the benefits and feasibility of elevating the levels of specific proteins in dormant apple trees or trying to manipulate the type of amino acids that accumulate.

Single and multi-strain rhizobial inoculation of African acacias in nursery conditions

Inoculation experiments were conducted in Kenya on seven African Acacia species/subspecies ( Faidherbia albida, Acacia karroo, A. arenaria, A. nilotica ssp. kraussiana, A. tortilis ssp. spirocarpa, A. tortilis ssp. heteracantha, A. senegal) in sterilised and untreated soil. The untreated soil contained 10 3 rhizobia g −1. In six of seven species in untreated soil the multi-strain inoculated plants contained significantly more total nitrogen than control plants. The exception was A. arenaria in which significant increase in total nitrogen was achieved only with the single strain inoculum in sterile soil. In A. tortilis ssp. spirocarpa the single strain was better than the multi-strain inoculum. Significant increases over controls in dry weight ranged from 19 to 75% and in total nitrogen from 11 to 89%. Nitrogen derived from fixation (Ndff) was determined for three species/subspecies using the natural abundance 15N method. Values for fixation for the best treatments in these species were A. nilotica 53%, A. tortilis ssp. heteracantha 45% and A. tortilis ssp. spirocarpa 44%. These are conservative values because of the relatively small δ 15N values (−2.85‰ for A. nilotica and −2.52‰ for both species of A. tortilis) determined as the 100% fixation values. We conclude that: inoculation can result in substantial gains in nitrogen fixation in African acacias; multi-strain inoculation is preferable to single strain inoculation in some circumstances; A. nilotica and A. tortilis have at least moderate nitrogen fixation potential and the wide genetic variation found suggests that substantial improvement may be obtained by selection for this character.

Variability in soils and vegetation associated with harvester ant (Pogonomyrmex rugosus) nests on a Chihuahuan Desert watershed

The effects of harvester ant (Pogonomyrmex rugosus) nests on the density and cover of spring annual plants and on soil characteristics were measured at three locations characterized by different soils and dominant vegetation on a desert watershed. There were few differences in vegetation and soils associated with harvester ant nests at locations at the base of the watershed where brief periods of flooding and sediment deposition occur at periodic intervals. At mid-slope locations, there were significant increases in total nitrogen, inorganic phosphorus, and cover (biomass) of four species of spring annuals at the edges of nest disks when compared with reference sites. The spring annuals that exhibited increased cover were species that increase biomass as a function of available nitrogen. At a clay-loam, Scleropogon-Hilaria, grassland site, there were significant reductions in the concentrations of Ca2+ and Mg2+, significant increases in nitrate and total nitrogen, but a significant increase in cover in only one species of annual plant. The data demonstrate that the effects of ants on soil properties and vegetation vary with site location and soil type.

Interaction of root-knot nematode and mycorrhizal fungi on common beanPhaseolus vulgaris L.

The interactions of root-knot nematode and VAM fungus on common bean plants (Phaseolus vulgaris L.), and the sequence of nematode infection were studied in the greenhouse. The inoculation with VAM fungus caused a significant increase in plant height and fresh weight compared with non treated plants.Meloidogyne infection unsignificantly decreased plant height and dry weight. When fungus was inoculated at 15 and 30 days prior toM. incognita infection, a significant increase in fresh weight was observed. There were no significant differences in total nitrogen (mg/plant) between plants inoculated withM. incognita alone or those inoculated with bothM. incognita and VAM fungus at the same time or 15 days after the fungus inoculation. Plants preinoculated with VAM fungus 30 days prior to nematode infection had a significant increase in total nitrogen. The inoculation with VAM fungus caused a significant increase in phosphorus content. However, it was significantly decreased in plants inoculated with nematode alone and in plants inoculated with VAM fungus andM. incognita at the same time. Gall index and final nematode population were significantly increased when nematodes were treated at the same time with fungus, although there were significant decrease in nematode final population and gall index when the plants were treated with nematodes at 15 and 30 days after mycorrhizal infection. A decrease in percentage of fungal colonization was observed when nematodes were inoculated with fungus at the same time.

The Effects of Autumn Foliar Urea Sprays on Storage Forms of Nitrogen Extracted from Bark and Wood of Apple Shoots

SummaryFollowing the application of urea sprays in October on Golden Delicious apple trees, increased amounts of nitrogen were translocated from the leaves into storage tissues. Trees receiving 10% urea spray had significantly higher levels of total nitrogen in bark in both January and February than either those receiving soil application or control treatments. However, there was also a significant increase in total nitrogen in bark from January to February in the sprayed trees, due mainly to an increase in protein nitrogen in January. In February the soluble nitrogen increased while the protein remained constant. There were no significant differences between treatments in wood total nitrogen levels in January. In February the trees receiving the 10% urea spray had significantly higher total nitrogen levels than those receiving either the soil application or control treatments. In the sprayed trees there was an increase in wood total nitrogen from January to February due to an increase in soluble nitrogen...

Taxonomy of Azotomonas species.

The ability of two strains of Azotomonas insolita and one strain classified only as Azotomonas species to use molecular nitrogen was investigated by use of several techniques. Molecular (15)N(2) incorporation by growing cultures of Azotomonas was inconsistent and limited. In addition, attempts to demonstrate nitrogen fixation in growing cultures by the radioactive (13)N(2) technique were negative. Experiments were done in which the total nitrogen content of a culture was determined by a micro-Kjeldahl method. None of these experiments resulted in a significant increase in total nitrogen. Attempts to show a diauxie effect, that is, transition from growth on NH(4) (+) to N(2), were also unsuccessful. Nitrogen fixation by cell-free extracts of A. insolita was negative, as determined by reduction of N(2) to NH(3), and reduction of cyanide, of acetylene, and of azide. These negative results suggest that the taxonomic reclassification of the genus Azotomonas should be considered.