Evaluating crude extracts of Monsonia burkeana and Moringa oleifera against Fusarium wilt of tomato

Fusarium wilt is one of the major soil-borne diseases of tomato crop globally. The study aimed to evaluate the efficacy of medicinal plants in the control of Fusarium wilt in tomato. Methanolic extracts of Monsonia burkena and Moringa oleifera were assessed in vitro and under greenhouse conditions. The in vitro experiments evaluated the effect of both extracts on Fusarium oxysporum f. sp lycopersici growth and response to varying concentrations. In greenhouse experiment, tomato seedlings cv. HTX14 were inoculated with conidial suspension of F. oxysporum and transplanted into pasteurised growth media amended with plant extract. Seedlings were treated with aqueous extracts at varying concentrations with an interval of 7 days between applications. Control treatments were treated with sterile distilled water. Both plant extracts significantly reduced pathogen growth in vitro and reduced wilt severity under greenhouse conditions. The highest mycelial growth suppression was observed in Mon. burkeana treatments. Under greenhouse conditions, both plant extracts significantly (P?≤?0.05) reduced Fusarium wilt severity and had a positive effect on plant growth parameters. A significant increase in soil-pH was also recorded in extract treated soil resulting in reduction in disease severity. The results further provide new scientific information on how their effect on soil pH can be beneficial in the control of Fusarium wilt.     

Variable inhibition of iron uptake by oat phytosiderophore in five soybean cultivars

Abstract

Greenhouse experiment was conducted to evaluate the effect of arbuscular mycorrhizal fungi (AMF) on plant growth, and nutrient uptake in saline soils with different salt and phosphorus (P) levels. The following treatments were included in this experiment: (i) Soil A, with salt level of 16.6 dS m^?1 and P level of 8.4 mg kg^?1; (ii) Soil B, with salt level of 6.2 dS m^?1 and P level of 17.5 mg kg^?1; and (iii) Soil C, with salt level of 2.4 dS m^?1 and P level of 6.5 mg kg^?1. Soils received no (control) or 25 mg P kg^?1 soil as triple super phosphate and were either not inoculated (control) or inoculated with a mixture of AM (AM1) and/or with Glomus intraradices (AM2). All pots were amended with 125 mg N kg^?1 soil as ammonium sulfate. Barley (Hordeum vulgar L., cv. “ACSAD 6”) was grown for five weeks. Plants grown on highly saline soils were severely affected where the dry weight was significantly lower than plants growing on moderately and low saline soils. The tiller number and the plant height were also lower under highly saline condition. The reduced plant growth under highly saline soils is mainly attributed to the negative effect of the high osmotic potential of the soil solution of the highly saline soils which tend to reduce the nutrient and water uptake as well as reduce the plant root growth. Both the application of P fertilizers and the soil inoculation with either inoculum mixture or G. intraradices increased the dry weight and the height of the plants but not the tiller number. The positive effect of P application on plant growth was similar to the effect of AM inoculation. Phosphorus concentration in the plants was higher in the mycorrhizal plant compared to the non mycorrhizal ones when P was not added. On the other hand, the addition of P increased the P concentration in the plants of the non mycorrhizal plants to as high as that of the mycorrhizal plants. Iron (Fe) and zinc (Zn) uptake increased with AM inoculation. The addition of P had a positive effect on micronutrient uptake in soil with low level of soil P, but had a negative effect in soil with high level of soil P. Micronutrient uptake decreases with increasing soil salinity level. Inoculation with AMF decreases sodium (Na) concentration in plants grown in soil of the highest salinity level but had no effect when plants were grown in soil with moderate or low salinity level. The potassium (K) concentration was not affected by any treatment while the K/Na ratio was increased by AM inoculation only when plant were grown in soil of the highest salinity level.     

Tomato growth responses to foliar application of ammonium sulfate in hydroponic culture

This study was done to evaluate the growth responses of tomato plants (Lycopersicon esculentum Mill.) to foliar application of ammonium sulfate in different concentrations of 0, 50, 100, or 200 mM once per week, as well as 50 mM in every other day under greenhouse and hydroponic culture system. The results showed that foliar application of ammonium restricted the plant height, yield, and vitamin C content of fruits, but it increased the chlorophyll content in treated plants. The highest and the lowest yield were obtained from zero (control) and 200 mM treated plants, respectively. Fruit hardness was not affected by treatments, while blossom end rot disorder was increased by higher concentrations of ammonium sulfate. In general, the result indicated that tomato plant is rather sensitive to foliar application of ammonium sulfate particularly to higher concentrations and application numbers.     

Mycorrhizal Inoculation and High Arsenic Concentrations in the Soil Increase the Survival of Soybean Plants Subjected to Strong Water Stress

Soybean (Glycine max L.) cropping is increasing in marginal environments, including water-limited lands, some of which are loaded with arsenic (As). Plants inoculated with mycorrhiza increased their tolerance to water stress. We studied the effect of a sudden and severe water stress on soybean inoculated with the mycorrhizal fungus Glomus intraradices in soils with increasing concentrations of As. Soybean plants were grown in greenhouse with adequate water supply for 60 days. Irrigation was stopped completely and soil abruptly reached the permanent wilting point. Most inoculated plants survived under such limiting water stress, but noninoculated plants were clearly affected. Arsenic showed a negative effect on plant growth but improved plant survival under this severe water stress. It seems that the negative effects of As on plant water equilibrium explain why plants affected by As survived extreme water stress events.     

DO MAIZE AND PEPPER PLANTS DEPEND ON MYCORRHIZAE IN TERMS OF PHOSPHORUS AND ZINC UPTAKE?

Nutrient deficiency, especially zinc (Zn) and phosphorus (P), is a common nutritional problem for the production of some crops in Turkey. This problem results in the application of increasing amounts of several fertilizers. Mycorrhizal inoculation or the indigenous potential of mycorrhizae in the soil is a critical factor in crop production under low supply of Zn and P. The effects of selected mycorrhizal inoculation on growth and Zn and P uptake of maize and green pepper were investigated in Zn- and P-deficient calcareous soils from Central Anatolia. Soils were sterilized by autoclaving and plants were grown for 7 weeks in pots under greenhouse conditions with inoculation of two selected arbuscular mycorrhizal (AM) species (Glommus moseea and G. etunicatum) at three rates of P (0, 25, 125 mg P kg^?1 soil) and two rates of Zn (0 and 5 mg Zn kg^?1soil). Without mycorrhizal inoculation, shoot and root dry matter production were severely affected by P and Zn deficiencies, and supply of adequate amounts of P and Zn significantly enhanced plant growth. When the soil was inoculated with mycorrhizal inoculation, the increasing effects of P and Zn fertilization on plant growth remained less pronounced. In accordance with growth data, mycorrhizae inoculation enhanced P and Zn concentration of plants, especially under low supply of P and Zn. The results obtained indicate that maize and green pepper are highly mycorrizal–dependent (MD) plant species under both low P and Zn supply and mycorrhizae play an essential role in P and Zn nutrition of plants in P and Zn-deficient soils. Although addition of P and Zn increased plant growth and plants are mycorrhizal dependent on P and Zn nutrition however dependence is much more dependent on P nutrition.     

Effect of Salt Stress and Manganese Supply on Growth of Barley Seedlings

Abstract

Effect of supplemental manganese (Mn) on the growth of salt-stressed barley (Hordeum vulgare L.) was assessed to determine if a salinity-induced Mn deficiency was limiting plant growth. Sodium chloride (NaCl) was added to the black-cotton soil and salinity was maintained at 0.3, 4, 8, 12, and 16 dS m^?1. A negative relationship between percent seed germination and increasing salt concentration was obtained, however, results suggested that barley is salt tolerant at seed germination stage. Increasing concentration of NaCl significantly reduced plant growth. Also, salinity induced a Mn deficiency in shoots of plants. Manganese was added to the soil at control and at 8 dS m^?1 salinity. Supplemental Mn improved the growth of salt-stressed plants to a limited extent, but it did not improve the growth of control plants. Further, supplemental Mn increased the relative growth rate of salt-stressed plants and this increase was attributed to an increase in the net assimilation rate of salt-stressed plants and not to leaf area ratio. Salt concentration adversely affected the uptake of nitrogen and phosphorus by plants, which resulted in imbalance of nutrients in salt-stressed plants. It appears that factors other than Mn, such as ionic, water- and nutrient-stresses can limit the growth of salt-stressed plants and supplemental Mn has only a limited role in mitigation of adverse effect of salinity.     

Impacts of climate change on soil nitrogen kinetics and rice production in Andisol paddy fields

We constructed a new rice growth model, SIMRIW_k, and discuss the impact of climate change on the growth and production of rice plants in relation to soil nitrogen (N) kinetics. We developed a model simulating N availability for rice plants associated with soil N kinetics and rice plant N uptake and combined it with the existing rice growth model SIMRIW to construct SIMRIW_k. The model parameters were determined from rice plant growth and soil N experimental data obtained over 25 years under four soil management regimes. SIMRIW_k successfully simulated the annual changes and upward trend observed during the 25 years in all treatments. The relationship between measured yields and SIMRIW_k calculations in all treatments over the 25 years formed one aggregation defined by the regression equation y = 1.00x and showed a significant correlation (r² = 0.894). According to SIMRIW_k, increasing temperature in the cold season increases the formation of easily decomposable organic N produced under dry conditions and N mineralization during the next warm season, suggesting that rice growth is influenced by both warm-season and cold-season temperatures. We forecast rice yield and soil N kinetics from 2016 to 2100 using SIMRIW_k and climate change predictions based on the IPCC’s climate change scenario RCP8.5. Atmospheric warming, a rise in CO₂ partial pressure, and increased soil N mineralization caused by soil warming will increase rice plant growth, but the decreased radiation absorbed owing to the shortened growing season and high-temperature sterility will prevent any significant change in yield. Furthermore, the acceleration of soil organic N decomposition will decrease soil organic N concentrations. Understanding the influences of climate change on soil organic matter kinetics is absolutely critical for predicting the future soil production capacity.     

EXOGENOUS APPLICATION OF POTASSIUM NITRATE TO ALLEVIATE SALT STRESS IN RICE SEEDLINGS

□ Overall growth characteristics of many plant species cultivated in soil affected by salinity could be alleviated by the application of potassium nitrate (KNO₃) to the soil. The aim of this research was to investigate salt-tolerance in a salt-sensitive rice cultivar, ‘Pathumthani 1’ (PT1), in response to the exogenous application of 11.8 mM KNO₃, in comparison to ‘Homjan’ (HJ), a salt tolerant cultivar. Water potential (ψ_w) in both the roots and leaves of PT1 seedlings under salt stress dropped significantly, while it was maintained in PT1 pretreated with KNO₃, and similarly in HJ. The reduction of leaf water potential was positively related to total chlorophyll degradation, leading to diminished chlorophyll fluorescence, directly affecting growth in plants exposed to salt stress. In salt-sensitive PT1, the application of 11.8 mM KNO₃ improved salt-tolerance via the conservation of water use efficiency, the maintenance of photosynthetic pigments, enhancement of chlorophyll a fluorescence, and stimulation of growth characters.     

Facilitation of seedling growth and nutrient uptake by indigenous arbuscular mycorrhizal fungi in intensive agroecosytems

A modified in-growth core technique was employed to determine the contribution of indigenous arbuscular mycorrhizal fungi (AMF) to plant growth and nutrient uptake in intensive agroecosystems at two Experimental field sites at Shangzhuang (Experiment I) and Quzhou (Experiment II) in North China. The growth cores (26.5 cm depth, 5 cm diameter for maize plants, and 4 cm for alfalfa and tomato plants) were covered with 40-μm nylon mesh (restriction of hyphal growth) and buried in the soil. They either remained static (static mesh) or were regularly rotated (rotated mesh) to disrupt hyphal penetration into the cores. A non-rotated 0.45-μm mesh (block mesh, inhibition of hyphal growth) treatment which remained static was also included to compare with the rotated mesh treatment (Experiment I). Growth cores from the two experimental sites had different soil types and two contrasting low P levels. The soil in the growth cores was sieved and sterilized before being placed into the growth core. Three plant species, namely maize, tomato and alfalfa were selected. The growth periods for maize plants were 35 days (Experiment I) and 39 days (Experiment II), respectively, and the corresponding growth periods for tomato and alfalfa were 67 days (Experiment I) and 53 days (Experiment II). At harvest the AMF species inside and outside the in-growth cores were identified by polymerase chain reaction (PCR), cloning and sequencing. Irrespective of plant species or genotype (maize), root colonization rates and hyphal length density (Experiment I) were generally suppressed in the rotated mesh treatment. The inhibition of hyphal growth by block mesh was comparable to that by the rotated mesh treatment. The growth of all three plant species in static mesh at the two Experimental sites, at both low (Experiment I) and sub-optimal soil P supply levels (Experiment II), was significantly higher than in the rotated (or block mesh) treatment. Root colonization rates of three maize genotypes were positively correlated with plant P concentration (Experiment II). Uptake efficiencies of P and N were significantly higher in static mesh than in the rotated (or block) treatment. AMF species detected (Experiment I) were all Glomerales, including the genera Glomus and Rhizophagus. One identified species of Rhizophagus intraradices and one Glomus viscosum-like phylotype were the dominant species. We conclude that the indigenous AM are crucial for early seedling growth, particularly for plants with small seeds and low P reserves and when seedlings exhibit P deficiency. The facilitation effect is highly relevant to enhanced root P (and possibly N) uptake and P delivery by the fungal mycelium. Our results have implications for the importance of maintenance of intact hyphal networks in intensive agroecosystems.     

Biological Evaluation of Seaweed Composting

Large quantities of green seaweed, linked probably to eutrophication, are cast ashore every summer on the Puerto Madryn beaches (Patagonia, Argentina, 42°S, 65°W). This algal biomass interferes with recreational uses of the beach, and therefore must be periodically collected and disposed. Part of this algal biomass was composted with the objective to produce an amendment to improve physical and nutritional characteristics of some local soils used in intensive horticulture, and at the same time to find a way to reduce environmental pollution. The compost was then biologically evaluated by determining the growth rate of tomato plants cultivated on various substrata (washed sand, sandy loam soil, and sandy loam soil plus inorganic fertilizers) to which different doses of compost were added. Results showed that in all cases the addition of compost increased water holding capacity and plant growth. The increase of tomato plants (Licopersicum esculentum var. platense) was proportional to the compost doses. Also, plants grown on sustrata containing at least ten percent compost had significant benefits compared to control plants, improving growth and water stress resistance. Although the quality of this seaweed compost was limited by excessive amounts of sand and low nitrogen content, it proved to be a good amendment that improved both physical and nutritional characteristics of local sandy loam soils used in intensive horticulture. According to these results, composting is a useful technology both to solve environmental pollution problems and to produce a valuable organic fertilizer for soils.     

Influence of Zeolite,Selenium and Silicon upon Some Agronomic and Physiologic Characteristics of Canola Grown under Salinity

The effect of soil applied zeolite, foliar application of selenium and silicon on the agronomic and physiologic traits of canola grown under salt stress conditions was investigated in two-year field experiment during 2012 and 2013. The experimental design was randomized complete blocks, arranged in factorial with 27 treatments forming combinations of zeolite (0, 5 and 10 ton ha^?1), selenium (0, 2 and 4 g liter^?1) and silicon (0, 2 and 4 g liter^?1) and three replicates. The results indicated that zeolite improved plant growth in terms of plant height and increased yield and yield components of canola. In addition, biological yield, harvest index and oil percentage increased due to zeolite application. Zeolite could decrease respiration, malondialdehyde and proline in salt-stressed plants. Soluble sugars and potassium content increased in response to zeolite application while sodium content significantly decreased. Selenium led to an increase in plant height, silique number, seed number in silique, biological yield, harvest index and oil percentage, while respiration, malondialdehyde, proline and sodium decreased on account of selenium application. Similarly, silicon had a significant effect on growth and agronomic traits and increased them. Silicon promoted chlorophyll synthesis while preventing malondialdehyde, proline and sodium accumulation in plant tissues. Catalase and superoxide dismutase activities were suppressed by using silicon on plants. Interaction between zeolite and selenium was significant on leaf relative water content, photosynthesis, chlorophyll content and activity of antioxidant enzymes. In addition, seed weight, seed yield, photosynthesis and soluble sugar content were affected by selenium and silicon application.     

Assessment of allelopathic interference of Chenopodium album through its leachates,debris extracts,rhizosphere and amended soil

Abstract

A study conducted to assess the allelopathic interference of invasive weed Chenopodium album indicated that aqueous leachates of C. album plant parts (roots, whole plant, and leaves), debris extracts and rhizosphere soil deleteriously affected the germination and initial growth of two test plants – Cassia occidentalis (a weed) and Phaseolus aureus (a crop). Further, the plant growth in terms of height, biomass, chlorophyll and protein content was significantly lesser in soil amended with C. album debris. Aqueous leachates, debris extracts, rhizosphere soil and debris amended soil were found to contain significantly higher amounts of water-soluble phenolics – the known phytotoxins. These phytotoxins in root, above-ground parts and leaves were phenolic acids, namely gallic, chlorogenic, caffeic, vanillic, p-coumaric, syringic and ferulic. Among these, chlorogenic acid was present in the maximum amount in the leaves and roots. The study concludes that C. album releases phenolics into the soil and these are probably involved in the growth inhibitory effect of C. album.     

Effect of salinity and nitrogen on growth,sodium, potassium accumulation,and osmotic adjustment of halophyte Suaeda aegyptiaca (Hasselq.) Zoh

Suaeda aegyptiaca is an important native annual halophyte in salt-affected soils around coastal areas of the Persian Gulf. In order to study the effects of different levels of saturation paste soil salinity (10, 20, 40, 60, and 80 dS m^?1) and nitrogen supply (25, 50, and 75 mg kg^?1 N as urea) on growth and physiological characteristic of S. aegyptiaca, a greenhouse factorial experiment in completely randomized design was conducted with three replications. Salinity treatments were established after early growth of plants and nitrogen was applied in two steps. Results showed that increasing salinity up to 20 dS m^?1 led to increase in dry weight (DW) of plants and this decreased by increasing salinity. Also, DW of plants was significantly increased by application of 75 mg kg^?1 nitrogen. Increasing salinity significantly decreased plant height, chlorophyll index, and total nitrogen content; while proline content and total soluble solids (TSS) were significantly increased. The electrolyte leakage (EL) and sodium concentration were increased under salinity stress. However, further increase in salinity decreased these two parameters. By increasing the nitrogen levels, relative water content (RWC), chlorophyll index, proline, and total nitrogen contents were increased, whereas EL was decreased.     

Grain Yield and Active Substances of Milk Thistle as Affected by Soil Salinity

The ripe seeds of milk thistle (Silybum marianum L. Gaertn) contain active substances of flavonoides that are important in the pharmaceutical industry. Evidence showed that stress conditions such as salinity can affect growth and development of plants, including active substances of some medicinal plants. Silymarin and silybin are important active materials of milk thistle whose concentrations correspond to some degree of plant stress. To test for this relationship, a pot experiment was conducted using a completely randomized design with seven level of salinities (0.35, 1, 3, 6, 9, 12, and 15 dS/m) for two genotypes, Ahwaz wild type and cultivated German origin (Royston). At the harvest, the results have showed that both genotypes grow satisfactorily and had a normal size in soils up to salinity of 9 dS/m, compared to the control plants. However, growth parameters such as plant height, number of leaves per plant, number of capitula per plant, main shoot capitulum's diameter, and seed yield and yield components per plant was reduced with salinity greater than 9 dS/m in both genotypes. However, concentrations of active substances (silymarin and silybin) in seeds significantly increased compared to the control plants. Results from the high‐performance liquid chromatography (HPLC) analysis indicated that the amount of silybin was approximately four times greater in plants cultivated under a salinity of 15 dS/m than in the plants grown under nonsaline conditions. Our results suggested that both types of milk thistle survive under salinity as high as 15 dS/m levels and produced seeds with rich in active substances.     

Effectiveness of potassium in mitigating the salt-induced oxidative stress in contrasting tomato genotypes

To check the efficacy of potassium in alleviating oxidative stress under salt stress, salt-tolerant (Indent-1) and salt-sensitive (Red Ball) tomato (Lycopersicon esculentum Mill.) genotypes were exposed to three levels of sodium chloride (NaCl) (0, 75, 150 mM) and two levels of potassium (4.5 and 9 mM) in solution and foliar form. Thirty days of treatments revealed that increasing NaCl stress increased lipid peroxidation (malondialdehyde, MDA) and correspondingly the activity of antioxidant enzymes (superoxide dismutase, SOD; catalase, CAT; and glutathione reductase GR) in both genotypes. However, higher potassium (K) level in solution or foliar spray during the salt-induced stress decreased MDA and antioxidant activity and increased the growth in salt-tolerant genotype than in the salt-sensitive genotype. Decrease in MDA concentration, activity of antioxidant enzymes, and increase in the growth of tomato plants by the application of potassium under salt stress suggest that potassium is an effective ameliorating agent against salt-induced oxidative damage.     

Metabolite profiling of shoot extract,root extract,and root exudate of rice under nitrogen and phosphorus deficiency

ABSTRACT

Root exudate is derived from plant metabolites and its composition is affected by plant nutrient status. A deficiency of mineral nutrients, such as nitrogen (N) and phosphorus (P), strongly affects the type and amount of plant metabolites. We applied a metabolite profiling technique to investigate root exudates of rice plants under N and P deficiency. Oryza sativa was grown in culture solution containing two N levels (0 and 60 mg N L^?1) or two P levels (0 and 8 mg P L^?1). Shoot extracts, root extracts, and root exudates were obtained from the rice plants 5 and 15 days after transplanting and their metabolites were determined by capillary electrophoresis/time-of-flight mass spectrometry. Shoot N concentration and dry weight of rice plants grown at ?N level were lower than those of plants grown at +N level. Shoot P concentration and dry weight of rice plants grown at ?P level were lower than those of plants grown at +P level. One hundred and thirty-two, 127, and 98 metabolites were identified in shoot extracts, root extracts, and root exudates, respectively, at the two N levels. One hundred and thirty-two, 128, and 99 metabolites were identified in shoot extracts, root extracts, and root exudates, respectively, at the two P levels. Seventy-seven percent of the metabolites were exuded to the rhizosphere. The concentrations of betaine, gamma-aminobutyric acid, and glutarate in root exudates were higher at both ?N and ?P levels than at their respective high levels. The concentration of spermidine in root exudates was lower at both ?N and ?P levels than at their respective high levels. The concentrations of the other metabolites in root exudates were affected differently by plant N or P status. These results suggest that rice roots actively release many metabolites in response to N and P deficiency.     

Effect of halotolerant endophytic bacteria isolated from Salicornia europaea L. on the growth of fodder beet (Beta vulgaris L.) under salt stress

The aim of this study was to determine the influence of selected halotolerant endophytic bacteria isolated from the roots of Salicornia europaea on the growth parameters of Beta vulgaris under different concentrations of salinity. Two endophytic strains were selected as inocula for the pot experiment: Pseudomonas sp. ISE-12 (B1) and Xanthomonadales sp. CSE-34 (B2). Surface-sterilised seeds were incubated in the bacterial inoculation suspensions before sowing and cultivated in a sterile mixture of sand and vermiculite (1:1). Six salinity treatments were taken into account: 0, 50, 100, 150, 200 and 300 mM NaCl. Inoculation of seeds with B1 and B2 positively affected germination percentage and germination index and shortened mean germination time, which led to a quickening of the growth stages of seedlings. After 42 days inoculated plants had, in general, a greater root length, higher dry biomass, lower tissue water content and lower specific leaf area compared with the control. While the positive effect of B2 bacteria was visible only at low salinity, strain B1 stimulated plant growth at higher salinities (200 and 300 mM NaCl). We suggest that the superior growth promotion observed for B1 may be related to the higher metabolic activity of these bacteria.     

Growth and nutrient uptake of tomato in response to application of saline water,biological fertilizer,and surfactant

The importance of using low-quality water, such as saline waters, for food production has been increased in the recent decades. An experiment was conducted to evaluate the effect of diluted seawater (electrical conductivity (EC) of 6 dS m^?1) on growth and nutrient uptake of tomato. We examined if surfactant (0, 1, 2, 4 mg L^?1) and biological fertilizer (compost tea + arbuscular mycorrhizal fungi propagules) have potential to alleviate the adverse effects of salinity on tomato plant. Salinity stress significantly reduced all plant growth parameters. Under salinity stress, nitrogen (N) and potassium (K) contents in tomato shoot were lower, while phosphorus (P), sodium (Na), and calcium (Ca) contents were higher than non-salinized plants; showing ionic imbalance in this condition. Biological fertilizer improved root weight in saline condition. Under salinity stress surfactant application at the rate of 1 mg L^?1 helped tomato plants to maintain their ionic balance, especially declining Na uptake, and improved plant growth.     

Boron Foliar Application in Nutrition and Yield of Beet and Tomato

The objective of this work was to evaluate the effect of the application of boron (B) by foliar spraying for the yield of beet (Beta vulgaris L.) and tomato (Solanum lycopersicum L.) crops. An experiment for each crop was done in a greenhouse at the São Paulo State University (UNESP), Jaboticabal campus, in Brazil. The experiments evaluated the B concentrations of 0, 0.085, 0.170, 0.255, and 0.340 g L^?1; applied in the 20, 35, and 50 days after the transplant (DAT) of beet cv. ‘Tall Top Early Wonder’, and in the 20, 40, and 60 DAT for the tomato cv. ‘Raisa N’. The plants were cultivated in pots with washed sand with 5 dm³ for the beet crop and 10 dm³ for the tomato crop. The beet and tomato crops were harvested 58 and 154 DAT, respectively. The leaves and fruits numbers; the foliar area; the dry matter of leaves, bark and roots; the fresh and dry matter of the fruits and the tuberous root; the dry matter of the total plant and the B foliar content were evaluated. The total dry matter of beet and tomato the plant were influenced by the concentration of the foliar B spray. The highest yield of the tuberous root and the total plant dry matter of beet occurred with B foliar concentration of 0.065 g L^?1 and it was associated with the B foliar content of 26 mg kg^?1. The highest yield of fruit and total plant dry matter of tomato occurred with the B foliar spraying of 0.340 g L^?1 and it was associated with the B foliar content of 72 mg kg^?1.     

连作番茄根区病土对番茄生长及土壤线虫与微生物的影响

探索连作番茄根区病土对番茄根结线虫病的诱导效果及引起连作障碍的微生态机制,可为深入了解番茄连作障碍发生机理及探究番茄连作障碍防治方法提供科学依据。本研究利用盆栽试验,测定了番茄在健康土壤及接种病土土壤中生物学特性变化及根结线虫侵染状况,并分析鉴定了土壤中微生物及线虫的种类与数量。结果表明,接种连作番茄根结线虫病株根区病土会对番茄生长及根结线虫侵染产生影响:1)番茄苗期根系根结数达9个?株~(-1),健康土壤无根结;土壤线虫数量较健康土壤增加390.4%;收获期番茄根结线虫侵染率达62.7%,病情指数为80.0%。2)番茄生长受到抑制,叶片防御酶活性降低,收获期茎叶及根系鲜质量较健康土壤分别减少50.2%及33.1%,苗期番茄叶片PPO活性较健康土壤降低15.8%,POD活性较健康土壤增加24.0%,差异均达显著水平(P0.05)。3)番茄根系更易感染有害菌,根系内病原菌甘蓝假单胞菌数量较健康土壤增加463倍,根区土壤细菌、真菌及放线菌总数分别增加46.3%、94.5%及134.0%。4)食细菌线虫、食真菌线虫及植物寄生性线虫数量分别为健康根区土壤的3.3倍、1.6倍及7.3倍,其中的植物寄生线虫95.6%为根结线虫。综上所述,接入连作番茄根结线虫病株根区病土不仅导致番茄遭受根结线虫侵染,而且会导致土壤线虫总量及植物寄生线虫所占比例大幅增加,并使番茄根系内有害细菌数量显著增加,对番茄生长造成显著抑制作用,同时影响番茄的生理生化特性,受线虫侵染番茄防御性酶活性降低,使其更易被根结线虫及病原菌侵染,番茄根区土壤线虫、微生物及根系内优势细菌的种类与数量及其之间的作用发生改变。