套蒜次数对大棚基质栽培番茄生长及基质理化性质的影响

探讨大棚基质栽培番茄套蒜1次和2次后对基质理化性质的变化及对番茄生长、产量的影响,为制定合理的套作措施提供理论依据。设置3个处理,分别是连作3茬番茄的基质中番茄单作、套过1次大蒜的基质中番茄单作和番茄/大蒜在套过1次大蒜的基质中继续套作。结果表明,番茄整个生育期内基质pH为7.3~7.7,变化幅度很小;由于施肥的影响,基质电导率在结果前期最高,之后随番茄、大蒜生长对养分的吸收较多导致其持续下降。番茄结果中期以前,套蒜1和2次基质的碱解氮含量均显著低于番茄单作,这是由于套蒜对基质速效氮消耗多于单作;套蒜显著提高基质中速效磷和速效钾的含量;增加基质中细菌和放线菌数量,降低真菌比例,且套作2次大蒜基质中的放线菌数量少于套作1次的基质。不同套蒜次数对秋茬番茄生长和产量无显著影响。因此,推荐在实际生产中通过基质栽培番茄套作大蒜来提高经济效益。     

Schistosoma bovis whole egg antigen did not protect Zebu calves against experimental schistosomosis

Six calves were immunized with whole egg antigen of Schistosoma bovis emulsified in Freund's adjuvant. The immune response was monitored by agar-gel immunodiffusion (AGID) and enzyme-linked immunosorbent assay (ELISA). Using AGID and ELISA, antibodies to whole egg antigen were detected in sera from all immunized calves, but not in sera from control calves. The immunized calves and six control calves were challenged 6 months after the beginning of the immunization with 20 000 cercariae of Schistosoma bovis administered percutaneously to the shaved tail. There was no significant difference between the immunized and the control calves as judged by fecal and tissue egg counts, worm recovery and hematological parameters. There was a lack of association between antibody production and protection.     

Response of Sunflower to Sulfur Rate and Time of Application under Two Tillage Systems in a Silty Clay Soil of Dera Ismail Khan Pakistan

ABSTRACT

Sulfur (S) availability is a characteristic of conservation tillage. We studied the effects of S on sunflower yield and fatty acid profile under conventional and conservation tillage in silty clay soil of D.I. Khan, Pakistan. Conventional tillage consisted of disk plowing followed by tiller and rotavator, while conservation tillage comprises tiller and disc harrowing. Treatments comprise six sulfur levels (S₁ = 0, S₂ = 20 kg S ha^?1 at sowing, S₃ = 10 kg S ha^?1 at sowing +10 kg S ha^?1 25 days after sowing (DAS), S₄ = 40 kg S ha^?1 at sowing, S₅ = 20 kg S ha^?1 at sowing + 20 kg S ha^?1 25 DAS, and S₆ = 20 kg S ha^?1 at sowing + 10 kg S ha^?1 25 DAS + 10 kg S ha^?1 50 DAS) replicated thrice. After 2 years of experimentation, soil samples were collected (from 0 to 0.30 m depth) for organic matter (OM), total soil N (TSN), and available sulfur analysis. Conservation tillage significantly increased OM, TSN, and S contents in 0–0.30 m soil compared to conventional tillage. Likewise, sunflower plants showed higher achene yield, better fatty acid profile, and net economic returns in conservation tillage than in conventional tillage. Application of 20 kg S ha^?1 at sowing and 10 kg S ha^?1 at each 25 and 50 DAS recorded significantly higher achene yield, higher oil, and linoleic acid contents; however, oleic and oleic/linoleic ratio did not increase with higher S rates. Conservation tillage was effective in increasing OM, TSN, and available S besides increasing yield and economics in silty clay soil.     

The feasibility of using an industrial sewage sludge produce in Pakistan as agricultural fertilizer used for cultivation of Sorghum bicolor L

Abstract

In the present study we evaluate the feasibility of using untreated industrial sewage sludge by liming before use as a fertilizer, produced in Pakistan. In a pots experiment, limed industrial sewage sludge (LSW) and non-limed sewage sludge (NLSW), were amended with soil separately and grown sorghum. After maturity, the sorghum grains were analysed for total contents of potentially toxic metals (TPTM), As, Cd, Cr, Cu, Ni, Pb and Zn. The proportion of different mobility fractions of each element in LWS and NLSW, a modified BCR sequential extraction procedure (Community Bureau of Reference) and single extractions with mild extractants (deionized water and CaCl₂) were used. In LSW, the availability of most of the elements under study was reduced, probably due to the increased pH of soil, while this was the reverse in the cases of Cd and Cu, their mobility was slightly increased by lime-treated sludge. The sorghum grains grown in LSW have low level As, Cr, Ni, Pb and Zn as compared to grains grown in NLSW, except Cu and Cd, which, however, never exceeded legal limits. Thus the research showed that liming, by augmenting soil alkalinity, allows a safe agricultural use even of industrial sludge, which is environmentally hazardous for its great content of heavy metals.     

Faba bean (Vicia faba L.) varieties reveal substantial and contrasting organic phosphorus use efficiencies (PoUE) under symbiotic conditions

Background

The excessive use of inorganic P (Pi) in soils is alarming as it is causing numerous environmental problems and may lead to the depletion of rock phosphate reserves earlier than expected. Hence, to limit the over-dependence on Pi, there is the need to investigate organic phosphorus (Po), which is the dominant P form of soil P pool, as an alternate P source for plant growth.

Aim

The present study seeks to investigate organic P use efficiency of eight varieties of faba bean grown symbiotically.

Methods

The plants were grown in pots (6 kg soil) under greenhouse condition with three P source, namely, phytic acid (organic P, Po), KH₂PO₄ (inorganic P, Pi), and no-P. The P was applied at the rate of 1.79 g kg⁻¹ soil.

Results

The plants grown with Po and Pi produced similar amounts of root, shoot, and total dry matters. Despite producing statistically similar dry matters, P uptake by Pi-fertilized plants was twofold higher than by Po-fertilized plants. Meanwhile, Pi differed significantly from Po in terms of nodulation characteristics such as nodule dry biomass and individual nodule dry biomass. However, Po varied significantly from Pi in P utilization and acquisition efficiencies. Principal component analysis of Pi and Po revealed no significant variation and close association, confirming the nonsignificant differences between the two P treatments. Among the varieties tested, Tiffany tended to accumulate more dry matter, coupled with highest organic P utilization efficiency (0.48 g mg⁻¹) as well as the highest organic P beneficiary factor (80%).

Conclusion

These results provide a solid basis for further comparisons at physiological, biochemical, and molecular levels between Tiffany (Po-efficient) and Fuego (Po-inefficient) varieties, offering deep insights into and making it easier to understand the mechanisms that allow soil Po to be utilized under symbiotic conditions.     

Effective Bioremediation of Endocrine-Disrupting Phthalate Esters,Mediated by <Emphasis Type="Italic">Bacillus</Emphasis> Strains

Phthalic acid esters (PAEs) is a class of refractory organic compounds, widely used as additives or plasticizers in plastic industry. PAEs are ubiquitous endocrine-disrupting pollutants and can be degraded by microorganisms. The present study described the assimilation of four PAE mixture (dimethyl, diethyl, dipropyl, and dibutyl phthalate) by two bacillus species: Bacillus thuringiensis and Bacillus cereus, isolated from different agricultural soil and their consortium. Among which, the optimal degradation of 82–96% was achieved by B. thuringiensis. This is the first report on the metabolic breakdown of four basic PAE mixture. The optimum conditions for biodegradation were found to be pH 7, temperature 30 °C, inoculum size 10 mL, and concentration 400 mg/L. Moreover, the respective biodegradation followed the first-order kinetic model. Our results proffered supplementary confirmation of the wide spectrum of PAE utilization by B. thuringiensis and suggest the possibility of applying it for the remediation of PAE contamination waste.     

Residues of methomyl in strawberries,tomatoes and cucumbers

An accurate and rapid high performance liquid chromatography method was developed to monitor residues of methomyl in plant extracts. The rate of disappearance of foliage-applied methomyl from strawberries, tomatoes and cucumbers was studied. Residues reached levels of 0.55, 0.2 and 0.6 mg kg^?1 seven days after methomyl had been applied to strawberries, tomatoes and cucumbers, respectively. Results also showed that rinsing treated fruits with tap water removed considerable amounts of methomyl. Samples of strawberries, tomatoes and cucumbers were collected from local markets at Ismailia, and checked for methomyl residues. Residues in 12.5% of tomato and 25% of strawberry samples were above 0.2 mg kg^?1.     

Effects of Temperature during Seedling Stage on Growth and Nutrient Absorbance of Gerbera jamesonii Growing in Organic Substrate

The effects of different temperature treatments during the seedling stage on growth and nutrient absorbance of Gerbera jamesonii cv ‘Sunshine Coast’ growing in the organic substrate were investigated. The temperature treatments were conducted in growth chamber where the day/night temperature were set to 15/10, 20/15, 25/20, and 30/25°C individually. The results showed that the fresh and dry weight of aboveground part and that of roots, average number of leaves and lateral roots were greater at 30/25°C than other treatments. The highest level of macro elements nitrogen (N), phosphorus (P), and potassium (K) in the leaf samples were also detected at 25/20°C and 30/25°C. However, there was no significant influence of different temperatures on zinc (Zn) levels in leaves. In general, the day temperature 25～30°C and night temperature 20～25°C are thought to be the better temperature condition for gerbera growth as well as the nutrient uptake and accumulation in the plants during the seedling stage.     

玉米铬毒性研究：氧化损伤、渗透调节物质积累、抗氧化防御以及铬的吸收

Agricultural production systems are immensely exposed to different environmental stresses in which heavy metal stress receives serious concerns. This study was conducted to explore the deleterious effects of different chromium(Cr) stress levels, i.e., 0, 30, 6090, 120, and 150 μmol L-1, on two maize genotypes, Wandan 13 and Runnong 35. Both genotypes were evaluated by measuring their growth and yield characteristics, Cr accumulation in different plant tissues, alterations in osmolyte accumulation, generation o reactive oxygen species(ROS), and anti-oxidative enzyme activity to scavenge ROS. The results showed that Cr stress decreased the leaf area, cob formation, 100-grain weight, shoot fresh biomass, and yield formation, while Cr accumulation in different maize tissues was found in the order of roots leaves stem seeds in both genotypes. The increased Cr toxicity resulted in higher free proline soluble sugars and total phenolic contents, and lower soluble protein contents. However, enhanced lipid peroxidation was noticed in the forms of malondialdehyde, hydrogen peroxide(H2O2) and thiobarbituric acid reactive substance accumulation, and electrolyte leakage. The hyperactivity of superoxide dismutase, peroxidase, catalase, ascorbate peroxidase, especially glutathione peroxidase and glutathione reductase indicated that these anti-oxidative enzymes had a central role in protecting maize from Cr toxicity, especially for Wandan 13. Moreover, higher uptake and less translocation of Cr contents into the grains of Wandan 13 implied its importance as a potential candidate against soil Cr pollution.