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101.
Use of synthetic iron (Fe) chelates is the most common and effective way to treat Fe chlorosis in plants. Most commercial products contain Fe‐EDDHA or Fe‐EDDHMA but their efficacy can be quite different. Commercial products with EDDHA or EDDHMA as active components were chosen based on the data obtained by Lucena et al. (1992) in their chemical test. The chelates present extreme differences in behavior in the mentioned chemical tests. The analysis of the products revealed that the total Fe concentration is greater than the one indicated by the manufacturer in spite of a lesser amount of FeY‐ present. The plant response to these commercial products was tested using short‐term greenhouse hydroponic cultures. Sunflower and corn were chosen because of their different behavior under Fe‐stress conditions. No significant difference between plants treated with Fe‐EDDHA or Fe‐EDDHMA chelates were observed. Since the purity index indicates there are too many differences between commercial formulations of the same type of chelate, the differentiation between groups cannot be determined with commercial products. Index I3, described by Lucena et al. (1992), does not correlate with the plant response because it did not consider the purity percentage of the products. 相似文献
102.
A study was made of the effects of different levels of cadmium (Cd) in the nutrient solution (0.0, 1.5, and 6.0 mg/L Cd) on the assimilation of nitrate (NO3 ‐) and the uptake and distribution of cationic nutrients in pea (Pisum sativum cv. Argona) seedlings. Cadmium treatment resulted in an accumulation of NO3 ‐ in the root, indicating an alteration in NO3 ‐ translocation to the shoot. This was related to a decrease in the nitrate reductase (NR) activity in the shoot, severely inhibiting NO3 ‐ assimilation, and associated to a reduction in fresh tissue weight and in their relative water content. The concentration of potassium (K) decreased in both root and shoot, but its relative distribution between those tissues was not affected by the presence of Cd. Among other cationic nutrients, manganese (Mn) was the most affected, its concentration constantly decreased concomitantly with the increase in Cd supply. The distribution of Mn between shoot and root revealed that more was accumulated in the shoot than in the root, opposite to the distribution of NO3 ‐ The ‘shock’ addition of 6.0 mg/L Cd in a short‐term experiment confirmed that the transport of NO3 ‐ to the aerial part was reduced after 72 h of treatment and Cd displaced Mn from its physiological positions in root tissues. 相似文献
103.
104.
M. Francisca Hernandez MiÑana E. Primo-Millo 《The Journal of Horticultural Science and Biotechnology》2013,88(5):595-601
Cytokinin amounts were determined in the ovaries of flowers and fruitlets on leafy and leafless inflorescences of seeded and seedless cultivars of Citrus sinensis, C. reshni and C. clementine. Flowers were sampled over a 65 day period from before anthesis to after fruit set, during the period from fructification to fruitlet expansion. Cytokinin activity appeared in both organic and aqueous phases obtained in the extraction process. Generally, the maximum activity in the organic phase occurred at anthesis, except in ‘Navelate’ orange, and decreased sharply following petal fall, whereas the aqueous phase had more cytokinins later, when the fruitlets had reached 1-2 cm diameter. The effect of pollination on cytokinin-like compounds was studied in seeded cultivars. The pollinated ovaries showed a peak in cytokinin activity at anthesis, in contrast to unpollinated ovaries. Partition chromatography of the organic phase on Sephadex LH-20 indicated five zones of cytokinin activity, four of which had the same elution volumes as ribosyl zeatin, zeatin, isopentenyl adenosine and isopentenyl adenine. 相似文献
105.
T. J. Kennedy E. A. Hernandez A. N. Morse T. A. Anderson 《Water, air, and soil pollution》2012,223(7):4527-4537
Safe drinking water is a luxury to approximately 800 million people worldwide. The number of people without access to clean water has been reduced, thanks to technologies like the biosand filter (BSF), an intermittently operated household scale slow sand filter. The BSF outlet (control diameter 0.5??) was modified in this study by reducing the outlet diameter (0.37?? and 0.25??) to determine the effects of hydraulic retention time on removal rates. Filters were dosed with 20?L of spiked lake water daily and observed for pH, dissolved oxygen (DO), fecal coliforms (FC), turbidity, nitrate, nitrite, sulfate, and ammonia until initial flow rates dropped below 0.2?L/min. Consistent with previous studies, the average turbidity was reduced to below 1?NTU; the average DO was reduced by 45?%. No significant difference was observed between the modified BSFs and the control BSF. Removal efficiency of FC was not significantly different between the modified BSFs (93.3?% and 91.9?%) and the control BSF (89.6?%). Mean FC reduction during the startup period (17?days) was significantly greater in the modified 0.25?? BSF when compared with the control during the same time period. After the first 17?days of the experiment, the average reduction efficiency of all filters was >97?%. While source water was below guideline values for nitrate, nitrite, ammonia, and sulfate during the course of the experiment, total nitrogen reduction was observed. The reduction indicates that the plastic BSF is capable of accomplishing limited denitrification during the filtering process. 相似文献
106.
C. Judith Betsy 《Journal Of Applied Aquaculture》2013,25(1):40-49
Cryopreservation of fish gametes can help in producing quality fish seeds. Success of cryopreservation is evaluated by the post-thaw motility of the spermatozoa. The changes in the seminal plasma during cryopreservation would alter the energy supply for the motility of the spermatozoa, and thus energy supplementation is found to be useful during cryopreservation. Cyprinus carpio spermatozoa were cryopreserved along with egg yolk as a co-cryoprotectant after 1:100 dilution with 0.85% physiological saline as extender and DMSO as cryoprotectant (85:15). The diluents contained egg yolk at three different concentrations, viz., T1 (5%), T2 (10%), and T3 (15%). The diluted milt was equilibrated for 10 min at 5°C and loaded into 0.25 ml straws. The loaded straws were then frozen with LN2 vapor for 5 min and immersed in liquid nitrogen. Observations were made once in 7 days for 42 days on motility parameters based on which the duration, score, pattern, and percentage were determined. There were significant differences in the motility duration between treatments, and egg yolk at 5% (T1) concentration was found to support the cryopreserved spermatozoa better than the other concentrations; the difference in motility duration was statistically significant (P > 0.005). 相似文献
107.
Michael L. Dunn Sergio O. Serna‐Saldivar Diana Sanchez‐Hernandez Robert W. Griffin 《Cereal Chemistry》2008,85(6):746-752
The corn tortilla plays an integral role in the Mexican diet and is an ideal vehicle for micronutrient fortification. Approximately 60% of corn tortillas in Mexico are produced from nixtamal, with the remainder prepared from masa flour. A process for continuous fortification of nixtamal tortillas was evaluated in two commercial mills in Mexico. A commercial powder dosifier was used to add micronutrient premix containing iron, zinc, folic acid, niacin, riboflavin, and thiamin to nixtamal (1 g/kg) as it was milled. After training and preliminary sampling, mills produced fortified tortillas unassisted for four weeks. Masa flow rates over a four‐day period were 10–12 kg/min in both plants. Premix flow from the dosifier showed good stability, with an average coefficient of variation of 1.6%. Initial results indicated consistency in the fortification process, with significantly increased variation during the four‐week production period. Fortified tortillas had significantly higher levels of all nutrients tested. Micronutrient losses were <11% in all cases except folic acid, which showed an 80% loss. Despite processing losses, fortification resulted in a nearly fivefold increase in folic acid compared with control tortillas. The new fortification process is technically viable and was well received by millers. 相似文献
108.
Carlos E. Hernandez Ho-Hsien Chen Chi-I. Chang Tzou-Chi Huang 《Industrial Crops and Products》2009,30(3):359-365
The direct esterification of chlorogenic acid (5-CGA) by immobilized Candida antarctica lipase B (Novozym 435) in supercritical CO2/t-butanol has been studied. The Taguchi approach was applied to evaluate the effects of temperature (35–55 °C), pressure (150–250 bar), t-butanol (2–10%, v/v), and the enzyme amount (10–30 mg/ml), on the ester concentration and overall conversion. Optimum reaction conditions were established at: 150 bar, 55 °C, 10% t-butanol (v/v), 20 mg/ml of lipase. Addition of 20 mg/ml of molecular sieves (3 Å) was also necessary to minimize the inhibiting effect of the increasing water concentration. Maximum conversions reached 77, 82 and 85% in 25 h using geraniol, pentanol and heptanol as aliphatic chain donors, respectively. HPLC analysis demonstrated the selective esterification of 5-CGA from a coffee pulp aqueous-methanolic extract, which reached a conversion to heptyl ester of 65% at the optimal condition. The supercritical CO2 selectivity towards the esterified product was the working principle of this study, by which minimized interphase transport limitations and enhanced mass-transfer phenomena substantially improved the reaction kinetics. 相似文献
109.
110.
Rocio?BallesterosEmail author Jose?Fernando?Ortega David?Hernandez Miguel?Angel?Moreno 《Precision Agriculture》2018,19(5):840-857
Biomass monitoring is one of the main pillars of precision farm management as it involves deeper knowledge about pest and weed status, soil quality, water stress, and yield prediction, among others. This research focuses on estimating crop biomass from high-resolution red, green, blue imaging obtained with an unmanned aerial vehicle. Onion, as one of the most cultivated vegetables, was studied for two seasons under non-controlled conditions in two commercial plots. Green canopy cover, crop height, and canopy volume (Vcanopy) were the predictor variables extracted from the geomatic products. Strong relationships were found between Vcanopy and dry leaf biomass and dry bulb biomass. Adjusted coefficient of determination (\({\text{R}}_{\text{adj}}^2\)) values were 0.76 and 0.95, respectively. Nevertheless, crop management practices and leaf depletion at vegetative stages significantly affect the accuracy of the canopy model. These results suggested that obtaining biomass using aerial images are a good alternative to other sensors and platforms as they have high spatial and temporal resolution to perform high-quality biomass monitoring. 相似文献