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1.
Little is known regarding the impact of calcium chloride applications during growth and development on tomato postharvest quality. This trial investigated supplemental calcium chloride applications on yield, nutrient content, texture, and postharvest quality of tomato fruit. Calcium (Ca) nutrient solution concentrations were: 60, 180, and 360 mg·L?1 calcium, while foliar applications were (0, 1, and 2% calcium chloride w/v). Plants grown with 60 mg·L?1 Ca had a high incidence of blossom end rot, which was not affected by calcium chloride sprays. Fruit nutrient concentrations were affected by calcium delivered through the nutrient solution. As fruit cluster position increased, fruit nutrient concentrations significantly decreased. Foliar calcium chloride sprays affected fruit soluble solids content and dry weight, but did not affect texture. Pericarp elasticity increased concomitantly with calcium in the nutrient solution. Postharvest disease incidence was not affected by calcium treatment, though weight loss during storage was negatively affected by calcium chloride sprays.  相似文献   

2.
Zhu  Jun  Luo  Ancheng  Zhou  Yan  Ndegwa  Pius M.  Schmidt  David 《Water, air, and soil pollution》2004,151(1-4):87-101
The effect of selected nutrient amendments and temperature on the biodegradation of pentachlorophenol (PCP) within a soil biopile was studied on a laboratory scale. This was accomplished by monitoring microbial populations, the concentration of PCP and the release of inorganic chloride ions in the contaminated soil. It was found that temperatures of 10, 15 and 20 °C had no significant effect on microbial populations and the percentage of PCP remaining in the soil. However, the nutrient amendments did have a significant effect on the parameters measured. The dairy manure, ammonium nitrate fertilizer and control treatments all experienced some fluctuations in the amount of PCP remaining in the soil over the incubation period and may have been due to the release of initially unextractable bound residues. PCP decreased by 76% in the municipal solid waste compost amended soil, while the concentration of inorganic chloride ions increased. The municipal solid waste compost treatment had significantly higher bacterial and fungal populations. Based on the results of this study municipal solid waste compost may be used as an effective supplemental nutrient amendment for the degradation of PCP in soil biopiles.  相似文献   

3.
In this paper, we presented a simple and inexpensive model of hydroponic system in laboratory. The six halopriming treatments were used in research. One-third strength nutrient solutions used in hydroponic systems. The ionic and osmotic stresses were induced by adding sodium chloride (NaCl) or polyethylenglycol-6000 to the nutrient solution. Each treatment was conducted three replications in a completely randomized design. The results showed that haloprimig significantly decreased the management (MGT) of Lolium perenne as compared with control. Haloprimed with NaCl for 72, 48 h and magnesium chloride (MgCl2) for 24 and 72 h showed significant difference as compared with non-treated seed in same stress level. Indeed, it shows that exposure to sodium chloride and magnesium chloride had a priming effect and seedling emergence was significantly increased in comparison to control. The beneficial effects of NaCl on seed germination is due to the uptake of Na+ and Cl? ions by the seed, thus maintaining a water potential gradient allowing water uptake during seed germination.  相似文献   

4.
Abstract

This paper presents a simple model for the changes in ion concentration and electrical conductivity (EC) of the recirculating nutrient solution in a closed-loop soilless culture of tomato (Lycopersicon esculentum Mill.). The model was designed on the basis of a balanced equation for plant nutrient uptake: for macrocations (K+, Mg2+ and Ca2+), a linear dependence of concentration on crop water uptake was assumed, while for non-essential ions, such as sodium (Na+), a non-linear function was used. The model was developed for closed-loop hydroponic systems in which crop water uptake (namely, transpiration) is compensated by refilling the mixing tank with complete nutrient solution. In these systems, EC gradually increases as a result of the accumulation of macro-elements and, principally, of non-essential ions, like Na+, for which the apparent uptake concentration (i.e., the ratio between nutrient and water uptake) is lower than their concentration in the irrigation water. For model calibration, data from both the literature and a previous work were used, while validation was performed with data from original experiments conducted with tomato plants in different seasons and using water with different sodium chloride (NaCl) concentrations (10 and 20 meq/L). The results of validation indicate that the model may be a useful tool for the management of closed-loop hydroponics, because it simulates rather well the salt accumulation that occurs in the recirculating nutrient solution when it is prepared with irrigation water of poor quality. Furthermore, the model is able to estimate the amount of crop evapotranspiration that leads to a value of EC at which flushing is necessary, thus enabling one to predict the water and nitrogen runoff of the semi-closed soilless culture.  相似文献   

5.
J.J. Oertli 《Geoderma》1973,9(2):81-95
The absorption of an ion is balanced, electrically, by either an uptake of an equivalent amount of counter ions or an exchange for ions of the same charge. An ion such as phosphate can be removed from a many-component solution in different ways, e.g., together with potassium, calcium, or magnesium, or in exchange for hydroxyl ions. In each individual case the status of the nutrient in the soil is expressed by a different chemical potential, and without further knowledge it is not possible to say which potential best expresses the availability. Schofield's phosphate potential implies phosphate uptake associated with calcium. This potential, like Woodruff's potassium potential, has been chosen arbitrarily and does not apply to the general process of phosphate uptake.A physiologically meaningful nutrient potential must be selected relative to the uptake process. Thus, if nutrient A is taken up with counter ion B, then AB's chemical potential is of interest. The fact that uptake processes are not sufficiently understood and proposed mechanisms are not generally accepted puts serious limitations on the usefulness of the potential concept. A few possibilities for selecting nutrient potentials are discussed.Since the nutrient capacity is the differential between nutrient content and potential, the above problem of selection is also inherent in the capacity.  相似文献   

6.
用电子鼻区分霉变燕麦及其传感器阵列优化   总被引：1，自引：4，他引：1  
应用电子鼻对燕麦（Avena sativa L）霉变程度进行区分,为了提高区分准确度,对电子鼻传感器阵列进行了优化的研究。每天随机选择10个燕麦样品进行电子鼻检测,试验连续进行5 d,将检测数据耦合入非线性双稳态随机共振系统,以外部Gaussian白噪声激励系统产生共振,选择输出信噪比特征值进行主成分分析,初期试验主成分1和主成分2贡献率之和为96.43%,且相同霉变程度样品离散度较大,不同霉变程度样品之间距离较近。为了提高电子鼻对霉变燕麦样品区分效果,进行了电子鼻传感器负荷加载分析,优化选择了传感器阵列,优化后主成分1和主成分2贡献率之和为99.31%,相同霉变程度燕麦样品的聚合度更高,使不同霉变程度燕麦样品之间的区分更加明显,为进一步的定量化检测奠定了基础。  相似文献   

7.
This trial was carried out to study the evolution of the nutrient parameters of the nutrient solution applied to tomato plants (Lycopersicum sculentum Mill. Forteza) cultivated in Mediterranean greenhouse conditions under different fertigation management models. The dynamic model is based on soil water content, which was measured by tensiometers, and on soil solutions obtained with suction cups (porous ceramic cup water samplers). The local traditional method consists of following technical recommendations, and the classical model requires the estimation of Crop Factor (Kc) and knowing the nutrient extraction. Nutrient solution and water applied are functions of the fertigation management criteria. The water used for fertigation was classified as C4-S3 according to the Riverside classification system. The cultivation period lasted from 15 August to 20 April. The nutrient parameters studied in nutrient and soil solution were pH, electrical conductivity (EC), nitrate (NO3 ?), phosphate (H2PO4 ?), potassium (K+), calcium (Ca2+), magnesium (Mg2+), sodium (Na+), and chloride (Cl?). The pH shows similar trends under the different treatments. Electrical conductivity is in the range of 2.8–4.5 dS m?1. Chloride, sodium, magnesium, and sulfate are exclusively modified by the salt concentration in the irrigation water, so it can be assumed that the three treatments vary equally. Nitrate, potassium, phosphate, and calcium are modified depending on each fertigation management method. Soil solution is modified by the nutrient solution applied. Dynamic management allows low nutrient concentration in the nutrient solution to be maintained and keeps soil nutrient concentration low, reducing fertilizer losses and therefore aquifer contamination.  相似文献   

8.
□ Plants from 60-day-old Lime Thyme (Thymus citriodorus) cuttings were potted in a medium of coconut fiber and peat moss and were treated with three different nutrient solutions: T1, T2, and T3. T1 was a standard nutrient solution; T2 was incremented with macronutrients up to an electrical conductivity (EC) of 2.8 dS m?1; and T3 was the same as T1 but incremented up to an EC of 2.8 dS m?1 with sodium chloride. The plants were then grown for 90 days in a greenhouse with natural daylight in Almería, Spain. Root growth was not affected by the treatments. The dry weight of the leaves and the total dry weight of the plants benefited from the salinity. The specific salinity of the sodium chloride negatively affected growth compared to the same salinity in the complete nutrient solution.  相似文献   

9.
This study focused on using quartz porphyry (QP) as a water treatment to improve hydroponic production of komatsuna (Brassica rapa L. nothovar; Japanese mustard spinach). We compared the chemistries of the control and QP-treated nutrient solutions and found that magnesium (Mg2+) and calcium (Ca2+) concentrations increased linearly up to day 21 following sowing in both conditions, then declined slightly. The QP treatment reduced sodium (Na+) and chloride (Cl?) concentrations for the whole cultivation period. In both the control and QP-treated solutions, nitrate (NO? 3) and sulfate (SO2? 4) showed the same trend to a daily increase. In spite of these similarities, however, komatsuna production was better with the QP-treated nutrient solution compared to control. Treatment with QP during cultivation in August–September reduced the harmful effects of Na+, chloride (Cl?), nitrite (NO? 2), and SO2? 4 by reducing concentrations of these ions, possibly leading to decreased salinity and toxicity effects in the plants. Mineral concentrations during October–November differed from those of August/September, resulting in variation among the different growth parameters for komatsuna.  相似文献   

10.
Abstract

Nutrient solutions containing three levels of phosphate, nitrate, and chloride were applied to cigar‐wrapper tobacco (Nicotiana tabacum L.) plants growing in sand culture for a period of 18 days. Concentrations of other nutrient elements in the nutrient solutions were held constant and the solutions were applied to pots as needed to maintain favorable moisture conditions for plant growth. Plants were in the two leaf stage when transplanted and were maintained on a single nutrient solution for 38 days before treatments were started. At the end of an eight weeks growing period, plant leaves were harvested and analyzed for Ca, Mg, and Mn. Dry matter yield was significantly (P=0.01) increased when 2 mM/1 of Ca(NO3)2 replaced an equivalent amount of Ca(H2PO4)2 or CaCl2 in the nutrient solution. Nitrate significantly (P=0.05) increased Ca and Mg content and decreased Mn concentration in leaf tissue in comparison to chloride. Calcium and Mg content were significantly (P=0.05) decreased and Mn content of tobacco leaves was increased by phosphate in comparison to nitrate and chloride.  相似文献   

11.
In hydroponic plant nutritional research, nutrient solutions can be considered as aqueous solutions of inorganic ions. In this aqueous solution, the ions are submitted to the laws of aquatic inorganic chemistry. This means that the ions are involved in the dynamic equilibria between complexation, dissociation, and precipitation reactions. These chemical reactions seriously impact elemental speciation and bioavailability. As a result, plant roots experience a different nutritional composition. Ions withdrawn from the‐nutrient solution due to precipitation reactions, change the nutritional composition and are not available for uptake by plant roots. Like complexes, precipitates can buffer a nutrient solution, exchanging nutrients as these decrease by plant uptake. This research looks into the precipitation reactions that occur in hydroponic nutrient solutions. In the concentration range of nutrient solutions, no precipitates are formed involving potassium (K+), nitrate (NO3 ‐), ammonium (NH4 +), or sulphate (SO4 2‐), while calcium (Ca2+) and magnesium (Mg2+) form mainly at a higher pH precipitates with hydrogen phosphate (HPO4 2‐). Preparing nutrient solutions with tap water, calcium carbonate (CaCO3) is likely to precipitate. A good knowledge of the chemical reactions occurring in nutrient solutions is the first prerequisite in hydroponic plant nutritional research.  相似文献   

12.
All buffering agents used to stabilize pH in hydroponic research have disadvantages. Inorganic buffers are absorbed and may become phytotoxic. Solid carbonate salts temporarily mitigate decreasing pH but provide almost no protection against increasing pH, and they alter nutrient absorption. Exchange resins are more effective, but we find that they remove magnesium and manganese from solution. We have tested 2(N-Morpholino)ethanesulfonic acid (MES) as a buffering agent at concentrations of 1 and 10 mol m-3 (1 and 10 mM) with beans, corn, lettuce, tomatoes, and wheat. MES appears to be biologically inert and does not interact significantly with other solution ions. Relative growth rates among controls and MES treatments were nearly identical for each species during the trial period. The pH was stabilized by 1 mol m-3 MES. This buffer warrants further consideration in nutrient research.  相似文献   

13.
The effect of chloride and sulphate on the nitrate accumulated in lettuce plants (Lactuca sativa L., cv. deci minor) under low light conditions was examined. The plants were grown on a complete nutrient solution for circa 45 days and then chloride was substituted for the nitrate in the nutrient solution. In another experiment, sulphate was substituted for the nitrate in the nutrient solution. Approximately 5 days later a reduction in growth occurred. The nitrate in the plants was not completely exhausted and was very slowly available for reduction both in the leaf blades and midribs. It was immaterial whether sulphate or chloride was substituted for nitrate in the nutrient solution. Chloride was taken up from the solution but sulphate was not. In plants in both treatments, sugars accumulated concomitantly with the decrease in nitrate content.

The actual nitrate reductase activity in the leaf blades decreased several days after the chloride and sulphate treatments began and was negligible on day 12. Nevertheless, the potential nitrate reductase activity of the treated plants was still 50% of the control.

It is suggested that the availability of nitrate from the storage pool is the limiting process for nitrate reductase activity, and is independent of the metabolic demand. For commercial growers it may be of advantage to use hydroponics in which the nitrate can be removed easily several days before harvest, to reduce high nitrate contents in vegetables, particularly under low light conditions.  相似文献   


14.
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15.
The pH of a nutrient solution is a property that is inherent to its composition. Changing the pH of a nutrient solution affects its composition, elemental speciation and bioavailability. The term ‘speciation” indicates the distribution of elements among their various chemical and physical forms like: free ions, soluble complexes, chelates, ion pairs, solid and gaseous phases, and different oxidation states. For a standard nutrient solution elemental speciation is calculated for a pH range from 2 to 9. For each cation the formation of precipitates, ion pairs, complexes, and chelates is illustrated as a function of pH. The calculation of elemental speciation in nutrient solutions is an indispensable tool in the design, the analysis and the interpretation of experiments with the mineral composition of nutrient solutions in plant nutritional research.  相似文献   

16.
Toasting changes both the quantity and the quality of the extractable substances in oak wood of barrels used for the aging of fine wines and spirits. Mastery and repeatability of toasting are vital in the production of quality barrels to be used for aging wines and spirits. Toasted wood components, which can be extracted by the wines or spirits during the aging process, are normally analyzed by maceration in standard alcohol solutions at concentrations adapted to the various products and can be used to control the intensity of the wood toasting. These kinds of analyses are accurate but time-consuming and need specialized laboratories. In this work, the feasibility of monitoring barrel toasting levels using an electronic nose with a metal oxide odor sensor array (MOS) was studied. The results of oak toasting level differentiation obtained via the MOS network were identical to those obtained by analyzing extractable compounds in liquid or gas phase as described in a previous paper. The results presented in this work at the laboratory scale could be used to implement a nondestructive monitoring system based on the analysis of headspace of barrels under industrial conditions.  相似文献   

17.
Both chloride (Cl) and sulphate (SO4) were found to impair the uptake of phosphorus (H232PO4) through the roots of potato in a hydroponically conducted experiment. Radioactive phosphorus (32P) was used as the marker. The presence of either Cl and SO4 alone in the nutrient solution made no difference on the impairment. Both ions also inhibited the long‐distance transport of P from roots to shoots. The inhibition by Cl was much greater than that by SO4, and increased with the concentration of Cl rising from 0 to 15.5 mM in solution.  相似文献   

18.
The reaction between soil and added fluoride was accelerated by incubating at a high temperature. Desorption of the fluoride was then studied using solutions of chloride salts of several cations at a range of solution : soil ratios and for periods which ranged from 1 h to 4 days. Fluoride desorbed was related to the experimental variables by a regression equation. When the solution : soil ratio was small and hence only small amounts of fluoride were desorbed, decreasing the concentration of salts increased the concentration of fluoride in the solution. The concentration in the solution was lower for calcium chloride than for sodium or potassium chloride. Amongst the monovalent cations, the concentration of fluoride was highest for salts of the cations of lowest atomic number. Thus the greater the average distance between the charge conveyed to the surface by the adsorbed fluoride and the cation which balanced it, the higher the fluoride concentration in the solution. As the solution : soil ratio was increased, the differences between the cations in their effects on fluoride desorption decreased and seemed to disappear as the solution : soil ratio became very large. This contrasts with previously observed effects on phosphate. It is suggested that the difference may have arisen because appreciable desorption of fluoride occurs by exchange with hydroxyl ions rather than by escape of the fluoride ion together with its counter ion.  相似文献   

19.
周鸣铮  沈冬莲 《土壤学报》1963,11(3):318-324
钾的分析是土壤、肥料、植物灰分、矿物等样品分析中的重要项目,然而惯用的钾分析方法均不够理想。氯铂酸法试剂昂贵;亚硝酸钴钠法近年来虽然有很大的改进,但尚有一些缺点;火焰光度法需要特殊设备。因此,设计出一种既简单又准确的钾分析方法,是当前农业科学研究及土壤肥料实际工作中的一项重要任务。  相似文献   

20.
A method has been developed to discriminate between different dosages of garlic flavoring in tomato sauce with the help of a mass spectrometry based sensory system. Four fragment ions m/z 73, 81, 114, and 120 were selected as "sensor array" during direct injection of the sample headspace into the mass spectrometer. Tomato sauces blended with different types of flavoring could be discriminated, and concentration gradients could be monitored. Fragment ions were chosen after volatile components had been analyzed and identified by SPME-GC/MS and HS-GC/MS (full scan). HS-GC/MS profiles of m/z 73, 81, 114, and 120 were recorded in the selected ion monitoring mode.  相似文献   

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