Pedo-transfer function for saturated hydraulic conductivity of lowland paddy soils

In paddy field, soil saturated hydraulic conductivity (K _s) plays as an important component in the calculation of irrigation requirement of the water balance equation and also for irrigation efficiency. Several laboratory and field methods can be used to determine K _s. Laboratory and field determinations are usually time consuming, expensive and labour intensive. Pedo-transfer functions (PTF) serve to translate the basic information found in the soil survey into a form useful for broader applications through empirical regression of functional relationships, such as simulation modelling. Since PTFs have not been applied to paddy soils in the study area, a lot of field measurements will require high labour input to determine K _s hence high cost. This study attempts to seek a simplified method for determining K _s values based on common existing soil properties through PTF technique. Soil samples (n = 408 samples) were collected randomly depending on the soil series within the 2,300 ha Sawah Sempadan rice cultivation area. Both field work and laboratory work were carried out. The samples were then analysed for the following properties: dry bulk density (D _b), soil particle percentage (Sand-S, Silt-Si and Clay-C), organic matter (OM) and geometric mean diameter (GMD). The measured K _s values were obtained by using the falling head method. The parameters were then used as inputs for developing a K _s model by regression analysis using Statistical Analysis System (SAS) package. Stepwise regression analysis was applied to determine the best fit model based on R ² and significant level. The results of the study showed that there is a high spatial variability of the saturated hydraulic conductivity in the paddy area. The best regression model for estimating K _s was based on C, D _b, OM and GMD with the dependent variable (K _s) in a form of natural logarithm. The model inputs introduced by stepwise regression are commonly available therefore, this model is useful to replace the conventional method.     

Simulation of salt and water movement and estimation of water productivity of rice crop irrigated with saline water

The HYDRUS-ID model was experimentally tested for water balance and salt build up in soil under rice crop irrigated with different salinity water (ECiw) of 0.4, 2, 4, 6, 8 and 10 dS m⁻¹ in micro-lysimeters filled with sandy loam soil. Differences of means between measured (M) and HYDRUS-1D predicted (P) values of bottom flux (Q _o) and leachate EC as tested by paired t test were not found significant at P = 0.05 and a close agreement between RMSE values showed the applicability of the HYDRUS-1D to simulate percolation and salt concentration in the micro-lysimeters under rice crop. Potential ET values of rice as obtained from CROPWAT matched well with model predicted and measured one at all ECiw treatments. The model predicted root water uptake varied from 66.1 to 652.7 mm and the maximum daily salt concentration in the root zone was 0.46, 2.3, 4.5, 6.7, 8.4 and 10.2 me cm⁻³ in 0.4, 2, 4, 6, 8 and 10 dS m⁻¹ ECiw treatments, respectively. The grain production per unit evapotranspiration ( \textWP_{\textET\texta} {\text{WP}}_{{{\text{ET}}_{\text{a}} }} ) value of 2.56 in ECiw of 0.4 dS m⁻¹ treatment declined to 1.31 with ECiw of 2 dS m⁻¹. The \textWP_{\textET\texta} {\text{WP}}_{{{\text{ET}}_{\text{a}} }} reduced to one-fifth when percolation was included in the productivity determination. Similarly, the water productivity in respect of total dry matter production (TDM) was also reduced in different treatments. Therefore, the model predicted values of water balance can be effectively utilized to calculate the water productivity of rice crop.     

Combination of On-Line Solid-Phase Extraction with LC-MS for the Determination of Potentially Hazardous Glycoalkaloids in Potato Products

A simple and rapid method for the determination of naturally occurring, potentially hazardous glycoalkaloids (GAs) in potatoes and their products has been developed. The procedure is based on the on-line solid-phase extraction of the acetic acid extracts from potato products and combined with liquid chromatography (LC)-mass spectrometry (MS) in a fully automated system (Symbiosis™, Spark Holland Instruments, Emmen, The Netherlands). As sorbent material HySphere™ 18HD was used for alkaloid enrichment. GAs were eluted with the LC gradient and directly analysed by MS. Detection of the analytes was achieved in the sensitive multiple reaction monitoring mode using two characteristic ions (m/z 98 as a qualifier for GAs and m/z 868.3 as a quantifier for α-solanine or m/z 852.4 for α-chaconine). Typical validation data for method precision (v _k α-solanine = 5.3–6.5, v _k α-chaconine = 3.4–15.4), accuracy (average recovery of α-solanine = 84%, average recovery of α-chaconine = 87%) and linearity over the range from 1 to 1,000 ng ml⁻¹ (R ² = 0.9915 for α-solanine, R ² = 0.9939 for α-chaconine) with detection limits of 0.3 ng ml⁻¹ for α-chaconine and 0.5 ng ml⁻¹ for α-solanine were obtained. GA contents of commercial potato products were determined by the new on-line method and afterwards compared with those obtained with an established high-performance LC routine procedure. Better performance of the on-line procedure was obvious from the standard deviations of both methods. Other advantages included a strong reduction of overall analysis time, human intervention and solvent consumption as well as waste production. The time required for the on-line analysis was 5 min, which would allow processing of almost 100 samples in 8 h.     

A Comparative study of redox parameters and electrochemical impedance spectroscopy of polycarbazole derivatives on carbon fiber microelectrode

In this study, N-Carbazole and its derivatives (N-Vinylcarbazole, N-Ethylcarbazole, N-Vinylbenzylcarbazole, and N-Benzylcarbazole) were electrochemically polymerized on carbon fiber microelectrodes (diameter ∼7 μm) by cyclic voltammetry within a potential range from 0.0 to 1.4 V. Redox parameters, Scanning electron microscopic (SEM) images were determined and also capacitance behaviors of polymers were examined via electrochemical impedance spectroscopy (EIS). EIS measurements of polycarbazole derivatives were given comparatively. The existence of a capacitance behavior is shown by Nyquist, Bode magnitude, Bode-phase, Admittance plots relationship. Although the highest low frequency capacitance (C_LF=12901 μA cm⁻²) and maximum phase angle of 81.9 ° at a frequency of 1 Hz were obtained for N-Vinylbenzylcarbazole, the lowest anodic and cathodic potential difference (ΔE=0.04 V) and double layer capacitance (C _dl =0.11 μA cm⁻²) were indicated in 0.1 M LiClO₄/PC.     

Critical water content and water stress coefficient of soybean (Glycine max [L.] Merr.) under deficit irrigation

The objective of this research was to investigate the critical water content (θ _c) and water stress coefficient (K _s) of soybean plant under deficit irrigation. This research was conducted in a plastic house at the University of Lampung, Sumatra in Indonesia from June to September 2000. The water deficit levels were 0–20%, 20–40%, 40–60%, 60–80%, and 80–100% of available water (AW) deficit, arranged in Randomized Completely Block (RCB) design with four replications. The results showed that the soybean plant started to experience stress from week IV within 40–60% of AW deficit. The fraction of total available water (TAW) that the crop can extract from the root zone without suffering water stress (p) was 0.5 and θ_c was 0.305 m³ m⁻³. The values of K _s at p=0.5 were 0.78, 0.86, 0.78, and 0.71 from week IV to week VII, respectively. The optimum yield of soybean plant with the highest yield efficiency was reached at 40–60% of AW deficit with an average K _s value of 0.78; this level of deficit irrigation could conserve about 10% of the irrigation. The optimum yield of soybean plant was 7.9 g/pot and crop water requirement was 372 mm.     

Spatial variation of infiltration rate and compactness in paddy fields

Percolation loss of water in rice fields is a major cause of low water use efficiency. Variation of infiltration rate and soil compactness in four paddy fields (with clay, silty clay, clay loam, and loam textures) was investigated in northern Iran. In each field, in longitudinal and transverse directions, points located 0.5, 2.5, 6.5, 12.5, … m from the bunds were selected and water infiltration rate and resistance to penetration of a pocket penetrometer were measured. The results showed that in clay soil, average final infiltration rate (f _c) in longitudinal direction, transverse direction, and center of the field was 0.216, 0.136, and 0.08 cm day⁻¹, respectively. The f _c for loamy soil was 2.77, 2.32, and 0.409 cm day⁻¹, respectively. Similar differences were observed in the other two soil textures. In general, effect of direction of the field for measuring infiltration rate was not statistically significant. Loam and clay loam soils, with resistance to penetration of 0.37 and 0.33 kg cm⁻², were not significantly different. But, clay and silty clay soils with resistance to penetration of 0.25 and 0.14 kg cm⁻² were significantly different (P < 0.05). Resistance to penetration of the penetrometer was not affected significantly (P < 0.05) by direction of measuring this parameter in the field. The conclusion is that if measured soil physical properties in a paddy field are going to be representative of the whole field, they should be measured at different locations, especially near the bunds. Another strategy for obtaining a representative infiltration rate or compactness for a paddy field is uniform puddling of the field.     

Decadal and Monthly Change of an Empirical Coefficient in the Relation between Solar Radiation and the Daily Range of Temperature in Japan: Implications for the Estimation of Solar Radiation Based on Temperature

Abstract: The need for solar radiation (R_s, MJ m^–2 d^–1) estimation remains a common concern for agronomists. Evaluation of crop productivity is primarily based on R_s data, which are difficult to collect because of cost and calibration requirements. Generally, historical R_s data are more difficult to obtain. This study focused on an estimation model based on the daily range of temperature and evaluated its accuracy from the viewpoint of crop productivity analysis. The variability of an empirical coefficient in the model (K_rs), which was derived from the relation between R_s and daily range of temperature (T_max – T_min) was analyzed using climatic data observed in Japan considering data availability and quality. K_rs had significant monthly differences, and it significantly increased from 1981 – 1985 to 2003 – 2007 at all 10 locations. Period-month interactions were not significant, except for in Utsunomiya, suggesting that the seasonal pattern did not change during the period. Weather data indicated that the increase in K_rs was caused not only by increased solar radiation but also by a decrease in T_max – T_min. The substantial differences in K_rs produced considerable bias for the estimated R_s when the estimation was conducted with a constant K_rs (0.16). Despite the bias, the model is considered to perform well given the present availability of R_s data. The results of this study suggest that the evaluation of the seasonal pattern of K_rs greatly improves the model accuracy.     

Effect of initial water content on saturated hydraulic conductivity in desalinization with slaking and drying

Soil slaking is an environment-friendly technique that is gaining importance in restoring saline soils. The objective of this article is to evaluate the effect of initial water content (IWC) on saturated hydraulic conductivity (K _s) in desalinization with slaking and drying. Accordingly, a slaking test was carried out during February, 2009 for evaluating the effects of slaking and drying on K _s, sodium adsorption ratio (SAR) and exchangeable sodium percentage (ESP) under various IWC. We prepared natural and air-dried soils of paddy field in Kojima Bay Polder, Japan to give different pre-drying, air-dried, and not dried (natural). The air-dried soils were resaturated. Each soil was well mixed, then dried to different initial moisture contents (60, 50, 40, 30, 20, and 10% by weight). The specimens were immersed into water in the pot for 24 h. The K _s was measured, and cations in slaked and unslaked soils were analyzed. The K _s was high under the water content below 30% in both the natural and the air-dried soils. But the effects were more pronounced in the natural soil. The air-dried soil showed far smaller K _s than the natural soil. In outer solution, the highest SAR was noted at 30% in the natural and 30 and 20% in the air-dried soils. Significant decrease in ESP of the soils (slaked + unslaked) was also observed at the same water content. Lower water content was more effective in decreasing the soil ESP after desalinization from saline soil. The natural soil showed lower ESP and higher porosity, which was considered as a reason for higher K _s of natural soil than that of air-dried soils. The results indicated that lower water content (10–30%) had no hazardous effect on K _s by slaking and drying of soil.     

The weight of potatoes in water: Further studies on the relation between the dry matter and starch content

Summary The weight in water (m _u ) of 100 g air-free potatoes multiplied by the dry matter factor (K) equals the percentage dry matter (m _t ) in the tubers. The weight in water is unaffected by the water in the potatoes but is reduced by air in the intercellular spaces and must be corrected for this by a constantk. From the specific gravity of the dry matter the factorK is estimated as 2.50. From the weight in water and the percentage of dry matter estimated by oven-drying of 5.413 samples between 1937 and 1964.K is also estimated as 2.50. The amount of air in potatoes varies. In 1.911 samples examined between 1937 and 1948 air reducedM _u on average by 0.8g, therefore,m _t (m _u +0.8)·2.5 orm _t ·m _u 2.5–2.00., In 2,732 samples examined between 1952 and 1964 the reduction was 0.6 g therefore,m _t —(m _u —0.6) 2.5 orm _t ·m _u ·2.5+1.5. The percentage dry matter can be calculated more exactly from the weight in water of potatoes from which the air has been evacuated by immersing the tubers in water in a closed container and subjecting to vacuum (50–20 mm Hg) for about 30 minutes.

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Zusammenfassung Die Beziehung zwischen Unterwassergewicht (m _w ) und Trockensubstanzgehalt (m _t ) von 100 g Kartoffeln wurde untersucht. In den Jahren 1937 bis 1964 wurde bei 5413 Mustern zu 5 kg von verschiedenen Kartoffelsorten das folgende Verh?ltnis festgestellt:K−m _t /m _w −2,5 auf der Basis von zunehmendemm _w bei zunehmendemm _t (Tabelle 1). Das spezifische Gewicht (d) der Trockensubstanz wurde bestimmt auf Grund der Wasserverdr?ngung, und das Verh?ltnisd/(d−1) wird Trocken-substanzfaktor K genannt. Im Jahre 1952 wurde das mittlere spezifische Gewicht von 26 Mustern mit 1,6689 errechnet. Daraus kann geschlossen werden, dassK−m _t /m _w −1,6689/(1,6689-1)−2,5 ist. Dieser Wert für K stimmt mit der für die 5413 Munster erhaltenen Zahl überein. Wenn diese Bestimmung ohne Fehler ist, erhalten wir:m _t −m _w K. In der Regel jedoch wird die Bestimmung vonm _w einem systematischen Fehler unterliegen, allgemein ungef?hr gleichwertig dem Volumen von luftgefüllten Interzellularr?umen. Diese vergr?ssern das Volumen der Kartoffeln und dadurch auch deren Wasserverdr?ngung, jedoch ohne Erh?hung des Kartoffelgewichtes, so dassm _w reduziert wird. Der Umfang, durch den das Unterwassergewichtm _w reduziert wird, variiert stark von Muster zu Muster und macht so die Bestimmung vonm _w unsicher. Wenn man die Luft durch Vakuumbehandlung aus den Kartoffeln entfernt und dann die Interzellularr?ume sich mit Wasser füllen l?sst, wird der Wert vanm _w erh?ht undm _w K wird fast gleich gross wiem _t . Wird die Vakuumbehandlung unterlassen, so muss eine Konstantek zum _t hinzugez?hlt werden. Bei 1911 Mustern, die zwischen 1937 und 1948 untersucht wurden, hat man festgestellt, dass die Luftm _w im Mittel um 0,8 g herabsetzte, daher warm _t (m _w −0,8)−2,5 oderm _t m _w 2,5+2,00. Bei 2732 zwischen 1952 und 1964 geprüften Mustern betrug die Reduktion 0,6 g, alsom _t −(m _w +0,6)−2,5 oderm _t −m _w 2,5+1,50. Selbst wenn der Mittelwert für eine grosse Zahl von Mustern bestimmt wird, variiert der Wert vonk entsprechend der Sorte und den Wachstumbedingungen. Aus diesem Grunde sollte der Wertk mit gebührender Rücksicht auf die lokalen Bedingungen fixiert werden. Im Gegensatz zuk scheint es, als obK 2,50 mit einem hohen Grad an Genauigkeit, entsprechendd/(d−1)−K bestimmt worden sei. Durch Bestimmung vond bei 27 Kartoffeltrockensubstanzmustern im Jahre 1965 wurde festgestellt, dassd=1,6694 undK−2,494 ist. Wenn alle Interzellularr?ume mit Wasser gefüllt sind, wird der Trockensubstanzgehalt durch Multiplikation des Unterwassergewichtes der Knollen (m _w ) mit 2,50 errechnet. Anderseits gibt es keine Methode zur Bestimmung des St?rkegehaltes (m _s ) ausm _w . Das Verh?ltnis zwischenm _w undm _s muss durch direkte St?rkebestimmungen gefunden werden. In Tylstrup wurden 266 St?rkebestimmungen mittels derEwers-Methode (1908) vorgenommen. Die Ergebnisse zeigten, dass der St?rkegehalt in Prozent (m _s ) eventuell durchm _s −(m _w −2,39)–2,28 errechnet werden kann. Der 1948 bis 1951 ermittelte St?rkegehalt ist infolge Vorhandenseins von Pektin wahrscheinlich zu hoch. Wenn die Muster für die St?rkebestimmung durch Bleiacetat bei pH 8 gekl?rt werden, kann das Pektin beseitigt werden. Es scheint jedoch, dass zusammen mit und im Verh?ltnis zum Pektingehalt ausserdem etwas St?rke scheinbar verschwindet. Dies dürfte verhütet werden, wenn dem Muster HCl beigefügt wird, bis der pH ungef?hr 2 betr?gt, bevor das Bleiacetat dazugewird. Muster, die mit 0,116 N HCl fiitriert und ausgewaschen werden, ergeben nahezu gleiche Ergebnisse, ob Bleiacetat bei pH 2 oder 8 hinzugegeben wird. In Tylstrup wurden von 1962 bis 1964 an 165 Mustern St?rkebestimmungen vorgenommen. Diese Analysen zeigten, dassm _s =(m _w −2,42)−4,10 entspricht. Auf Grund der Unteruchungen in Tylstrup zwischen 1952 und 1964 wurde die Tabelle 4 vorbereitet, die erlaubt, den Trockensubstanz-und St?rkegehalt in Prozent vom Unterwassergewicht eines Kartoffelmusters zu ermitteln, und zwar in beiden F?llen, d.h. wenn die Luft aus den Knollen entfernt oder nicht entfernt worden ist.

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Résumé On a recherché la relation entre le poids sous eau (m _w ) et la teneur en matièrè sèche (m _t ) de 100 g de pommes de terre. Durant la période 1937–1964, sur 5413 échantillons de différentes variétés de pommes de terre, chaque échantillon pesant 5 kg, on a trouvé que cette relation était:K=m _t /m _w =2,5 sur la base d'une augmentationm _w avec une augmentation dem _t (Tableau 1). Le poids spécifique (d) de la matière sèche est déterminé sur la base du déplacement d'eau et la relationd/(d−1) désignele facteur K de la matière sèche. En 1952 le poids spécifique moyen de 26 échantillons a été trouvé être 1,6689. De deci on peut déduire queK=m _t /m _w −1,6689/(1,6689−1)=2,5. Cette valeur deK s'accorde avec le chiffre obtenu à partir de 5413 échantil-Si la détermination est faite sans erreur nous obtenons:m _t =m _w K. Cependant, la détermination dem _w sera, généralement, entachée d'une erreur systématique largement égale au volume des espaces intercellulaires remplis d'air. Ceux-ci accroissent le volume de pommes de terre et ainsi le déplacement d'eau, sans accro?tre le poids des pommes de terre etm _w sera diminué. L'importance de la réduction varie grandement d'un échantillon à l'autre, rendant de la sorte la détermination dem _w incertaine. En évacuant l'air des pommes de terre par traitement par le vide et permettant alors aux espaces intercellulaires de se remplir d'eau, la valeur dem _w augmente etm _w K devient plus étroitement égal àm _t . Si le traitement par le vide est omis, une constantek doit être ajoutée àm _t . Sur 1911 échantillons examinés entre 1937 et 1948 on a trouvé que l'air réduisaitm _w de 0,8 g en moyenne et, par conséquent,m _t −(m _w +0,8) =2,5 ou m _t −m _w =2,5+2,00. Pour 2732 échantillons examinés entre 1952 et 1964, la diminution était de 0,6 g, par conséquent,m _t −(m _w +0,6)=2,5 oum _t −m _w =2,5+1,5. Même si la valeur moyenne pour un grand nombre d'échantillons est déterminée, la valeur dek variera suivant à la fois la variété et les conditions de croissance. Pour cette raison, la valeurk devrait être fixée en égard aux conditions locales. Au contraire dek il semblerait queK=2,5 a été déterminé avec un degré élevé de sécurité suivantd/(d−1)−K. En déterminantd sur 27 échantillons de matière sèche de pommes de terre en 1965 on a trouvé qued=1,6695 etK=2,494. Si tous les espaces intercellulaires sont remplis d'eau, la teneur en matière sèche est déterminée en multipliant le poids sous eau des tubercules (m _w ) par 2,5. D'autre part, il n'existe aucune méthode pour déterminer la teneur en amidon (m _s ) à partir dem _w . La relation entrem _w etm _s doit être trouvée par des déterminations directes d'amidon. A Tylstrup, 266 déterminations d'amidon ont été faites par la méthodeEwers (1908). Les résultats montrent que le pourcentage d'amidon (m _s ) peut être déterminé parm _s =(m _w +2,39)−2,28. Le pourcentage d'amidon trouvé de 1948 à 1951 est probablement trop élevé en égard à la présence de pectine. Si les échantillons pour détermination de l'amidon sont clarifiés au moyen d'acétate de plomb au pH d'environ 8, la pectine peut être enlevée. Il se révèle cependant qu'apparemment de l'amidon dispara?t aussi en même temps et proportionellement à la teneur en pectine. Ceci peut être évité en ajoutant HCl à l'échantillon jusqu' à ce que le pH soit d'environ 2, avant d'ajouter l'acétate de plomb. Les échantillons filtrés et lavés avec 0,116 N HCl donneront des résultats presque identiques, soit que l'acétate de plomb soit ajouté au pH 2 ou 8. Les déterminations d'amidon ont été faites sur 165 échantillons à Tylstrup de 1962 à 1964. Les analyses montraient quem _s −(m _w +2,42)−4,10. Sur la base des recherches à Tylstrup entre 1952 et 1964 on a établi le Tableau 4 qui permet de déterminer le pourcentage de matière sèche et le pourcentage d'amidon à partir du poids sous eau d'un échantillon de pommes de terre, à la fois quand l'air est ou n'est pas enlevé des tubercules.

     

Comparison of color techniques to measure the color of parboiled rice

A combination of digital camera, computer and graphic software can provide a less expensive and more versatile technique to determine the surface color of parboiled rice compared to instrumental color measurement. The instrument was used to measure rice powder and whole rice. Pearson correlation coefficients and sample paired t-test on total color difference (ΔE), L and b values were calculated. The value of ΔE of samples from the instrumental technique was 0.69–4.61 (powder), 4.7–10.2 (whole rice) with a coefficient of variance (CV) ranging from 3.5 to 25.3% and from 15.4 to 46.6%. Meanwhile, the digital image technique gave a ΔE value ranging from 4.2 to 13.77 with a CV from 6.3 to 21.2%, respectively. A highly significant correlation (R² = 0.7451, R² = 0.8074, R² = 0.7518,) was obtained for ΔE between instrumental (powder and whole rice), Vision Builder and instrumental (powder), and instrumental (whole rice) and Vision Builder. The chromatic b value of instrumental for powder had a significant correlation with the Vision Builder data (R² = 0.7741). The results suggest that although the digital image provided the surface color of parboiled rice, it was less accurate than the instrumental for powder. Therefore results from the digital image should be interpreted with caution.     

Relative efficiency of vermicompost as direct application manure in pisciculture

Wide variation (>10.28 times) of fish yield (Cyprinus carpio Linnaeus, 1758) was obtained in a trial arranged in concrete cisterns (100 l) receiving compost (T-2), Diammonium phosphate (=DAP) (T-3) and vermicompost (T-4) as direct application fertilizer and manure in those systems. Significant (P < 0.005) differences were observed in diversity and abundance of plankton in response to manure application among treatments. Highest phyto- and zooplankton population was found in the cistern treated with vermicompost followed by DAP, compost and control. In all the treatments dry weight and population of both phyto- and zooplankton population were significantly (P < 0.005) higher than control. The highest production of fish was obtained in the cisterns treated with vermicompost (3,970.56 kg ha⁻¹ 90 day⁻¹), followed by diammonium phosphate (3,080.45 kg ha⁻¹ 90 day⁻¹), compost (1,952.64 kg ha⁻¹ 90 day⁻¹) and the lowest in the control (385.92 kg ha⁻¹ 90 day⁻¹). Vermicompost might be cost-effective manure in carp culture, replacing the expensive chemical fertilizer diammonium phosphate.     

Poly(trimethylene terephthalate) fiber melt-spinning: Material parameters and computer simulation

In this work, the method, in principle of the box complex algorithm was adopted to obtain stress-induced crystallization coefficient C and the strain-optical coefficientA _op with the value of 295 and 1.5×10⁻⁹, respectively, and some parametersA ₁=0.27,A ₂=5.06,a=3.5,b=1.8 relative to the elongational viscosity of poly(trimethylene terephthalate)(PTT) fiber. The vitrification distance as a function of the take-up velocity and mass throughput was also gotten. The effects of spinning conditions on filament temperature, velocity gradient, spinning tension, birefringence and crystallinity, and effect of viscoelasticity on take-up velocity had been discussed.     

The oxygen uptake,in air and in 5% O2, and the carbon dioxide output,of stored potato tubers

Summary Oxygen uptake at harvest varied from c. 40 ml kg⁻¹h⁻¹ at 10°C, in very immature, to c. 3–5 ml kg⁻¹h⁻¹ in mature tubers. The O₂ status of the tuber normally would allow uptake by a low-affinity oxidase (K _m =1.5×10⁻⁴ M) as well as by cytochrome-c-oxidase (suggestedK _m =7×10⁻⁸ M). Separation was attempted by measuring uptake in air and 5% O₂, oxygen status being derived from internal atmosphere analyses or periderm permeability. At harvest, low-affinity uptake was probably c. 20–30% of the total in mature and tentatively c. 10% in immature tubers. it fell almost to zero and then re-appeared during storage. Total uptake fell to c. 1.5–2.5 ml kg⁻¹h⁻¹ at 10°C, irrespective of maturity, then rose during sprout growth. The mid-storage temperature-coefficient, 20°C/10°C, was c. 1.2–1.3, but uptake at 2°C (sweetened tubers) could be higher than at 20°C. Later, increased respiration accompanying sprouting changed this pattern. CO₂ production was on average similar to O₂ uptake but at certain periods diverged. This is discussed. It also showed a delayed response to changed conditions with consequent temporarily aberrant RQ's.

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Zusammenfassung Die Atmung von unreifen Knollen wurde w?hrend der Lagerung bei 10°C über fünf Lagerperioden sowie bei 2 und 20°C für eine Periode studiert. Die Aufnahme von Sauerstoff im Zeitpunkt der Ernte schwankte zwischen ca. 40 ml kg⁻¹h⁻¹ bei 10°C in sehr unreifen und ca. 3–5 ml kg⁻¹h⁻¹ in reifen Knollen. In früheren Arbeiten wurde im Knollensaft eine Sauerstoffkonzentration zwischen 3.2×10⁻⁴ M bei 5°C und 2×10⁻⁵ M bei 37°C festgestellt (siehe auch Tabellen 4 und 5). Dies würde bedeuten, dass bei normalen Lagertemperaturen ein Endoxydationssystem mitK _m =1.5×10⁻⁴ M, wie früher angenommen, f?hig w?re, sich zu einem betr?chtlichen Teil seiner H?chstrate mit Sauerstoff, zus?tzlich zu der Sauerstoffaufnahme durch Cytochrom-c-Oxydase, zu verbinden. Hierfür wirdK _m =7×10⁻⁸ M auf der Rechnungsbasis früherer Ergebnisse angenommen. Die Trennung des Oxydase-Systems mit geringer von jenem mit hoher Affinit?t wurde durch Messung der Sauerstoffaufnahme in Luft und in 5% O₂ vorgenommen; der Sauerstoffstatus für ?hnliche Knollenmuster wurde durch Messungen der Zusammenh?nge der inneren Atmosph?re oder der Periderm-Durchl?ssigkeit errechnet. Bei der Ernte betrug die Aufnahme bei geringer Affinit?t wahrscheinlich 20–30% des Totals in reifen Knollen (Tabelle 1) und, versuchsweise, ca. 10% in unreifen Knollen (Tabelle 3), obwohl sie kurz nach der Ernte wahrscheinlich über 25% in unreifen Knollen ausmachte (Tabelle 2). Die Ursache des sehr starken Rückganges in der Sauerstoffaufnahme bei unreifen Knollen unmittelbar nach der Ernte lag beim fast vollst?ndigen Rückgang der Aufnahme von Cytochrom-c-Oxydase (das heisst Aufnahme in 5% O₂—Tabelle 3). Sp?ter jedoch, w?hrend der Lagerung, fiel die Aufnahme bei geringer Affinit?t fast auf Null (Abb. 2 und 3), obwohl sie w?hrend des Keimwachstums wieder einsetzte. Die Gesamtaufnahme war also in der Mitte der Lagerungsperiode unbeeinflusst durch die Ver?nderungen im Sauerstoffverh?ltnis im Bereich 5–100% O₂, obwohl sie zu Beginn und am Ende der Lagerung beeinflusst war (Tabelle 6). Die Gesammtaufnahme fiel, unabh?ngig von der Reife, auf ein Minimum von ca. 1,5 bis 2,5 ml kg⁻¹h⁻¹ vor Beginn des Keimwachstums und stieg dann wieder w?hrend des Aufwuchses (Abb. 2 und 3). Die oben beschriebenen, übereinstimmenden Trends wurden durch kurze Schwankungen in der Aufnahme bis zum Ausmass von ungef?hr ±10% des mittleren Wertes bei nicht bewegten Knollen überlagert, aber Manipulation der Knollen k?nnte bedeutende Erh?hungen in der Aufnahme verursachen, besonders wenn die Knollen welk sind (Abb. 1). Die Erzeugung von Kohlendioxyd war im Mittel gleich wie dei Sauerstoffaufnahme, aber in gewissen Perioden wich sie konsequent ab (siehe zum Beispiel Abb. 3, 20°C). M?gliche, darin verwickelte Mechanismen wurden in Betracht gezogen. Es ergab sich auch eine Versp?tung von mehreren Studen als Reaktion auf ver?nderte Bedingungen mit nachfolgend zeitweilig abweichenden RQ's. Der für die Mitte der Lagerungszeit gültige Koeffizient für die Temperatur 20°C/10°C betrug 1,2–1,3 (Tabelle 8), aber Aufnahme bei 2°C (süsse Knollen) konnte h?her sein als bei 20°C. Die die Keimung—früher und kr?ftiger bei 20°C als bei 10°C—begleitende Atmung ?nderte sp?ter dieses Bild, und der Koeffizient für die Temperatur 20°C/10°C war über 3 (Tabelle 8). W?hrend der ersten zwei Wochen der Lagerung bei 2°C stieg die Atmung merklich an und fiel dann wieder (Abb. 3 und 4) trotz der Tatsache, dass der Gehalt sowohl an Saccharose wie an reduzierenden Zuckern für einige Zeit weiter anstieg (Tabelle 7)—Atmung ist ein Index für den Umsatz, der nicht notwendigerweise mit dem Zuckergehalt in Beziehung steht. Es gab einen Hinweise auf die ?nderung im Grad, bis zu welchem die Aufnahme bei geringer Affinit?t zu der anf?nglichen Erh?hung in der Sauerstoffaufnahme bei 2°C beitrug, von der vollst?ndigen Abwesenheit in Knollen, die unmittelbar nach der Ernte bei 2°C gelagert wurden (Abb. 3) bis zur gr?ssten Mitwirkung in Knollen, die einige Monate nach der Ernte zwischen 2°C und 10°C gelagert wurden (Abb. 4). Wenn süsse Knollen nach Lagerung bei 2°C wieder bei 10°C aufgestellt wurden, stieg die Sauerstoffaufnahme sofort zu einem H?chstwert an (ungef?hr das Doppelte vom Wert bei 2°C; Abb. 4), gefolgt von einem Rückgang.

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Résumé L'auteur a observé la respiration de tubercules immatures et m?rs au cours de la conservation, à 10°C pendant cinq saisons, et à 2 et 20°C pendant une saison. L'absorption d'oxygène à la récolte varie de c. 40 ml kg⁻¹h⁻¹ à 10°C dans les tubercules très immatures à c. 3–5 ml kg⁻¹h⁻¹ dans les tubercules m?rs. Une étude précédente a montré une concentration en oxygène dans le jus de tubercule allant de 3,2×10⁻⁴ M à 5°C jusque 2×10⁻⁵ M à 37°C (voir aussi les tableaux 4 et 5). Ceci indiquerait que, à des températures normales de conservation, un système final d'oxydase avecK _m =1,5×10⁻⁴ M, comme il a été précédement proposé, serait capable de combinaison avec l'oxygène dans une proportion appréciable de sa proportion maximale, en addition à l'absorption d'oxygène par le cytochrome-c-oxydase. Pour celuici,K _m =7×10⁻¹ M est proposé sur la base de calculs à partir des résultats antérieurs. La séparation entre les systèmes d'oxydase de basse et de haute affinité est tentée par mensuration de l'absorption d'oxygène dans l'air et dans 5% O₂, les situations en oxygène étant calculées sur des échantillons semblables de tubercules à partir de mesures de la composition de l'atmosphère interne ou de la perméabilité du périderme. A la récolte, le prélèvement par le système de basse affinité était probablement de c. 20–30% du total chez les tubercules m?rs (tableau 1) et de c. 10%, déterminé expérimentalement chez les tubercules immatures (tableau 3), quoique peu après la récolte, il était probablement supérieur à 25% chez les tubercules immatures (tableau 2). La chute très rapide, immédiatement après la récolte de l'absorption d'oxygène chez les tubercules immatures est due en presque totalité à la chute du prélèvement par le cytochrome-c-oxydase (voir prélèvement dans 5% O₂—tableau 3). Plus tard cependant, le prélèvement par le système de basse affinité tombe presque à zéro pendant la conservation (fig. 2 et 3), quoiqu'il réapparaise au cours du développement des germes. Par conséquent l'absorption totale n'est pas affectée par les modifications dans la tension de l'oxygène, dans les limites 5–100% O₂, dans le milieu de la période de conservation bien qu'il soit affecté au commencement et à la fin de la saison (tableau 6). L'absorption totale tombe à un minimum de c. 1.5 à 2.5 ml kg⁻¹ h⁻¹, indépendamment de la maturité, avant le début de la croissance des germes (fig. 2 et 3). Se situant au-dessus des tendances manifestes décrites ci-dessus, des fluctuations de courtterme apparaissent dans l'absorption dans une mesure de quelque ±10% de la valeur moyenne dans les tubercules non remués, mais les manipulations sont susceptibles de provoquer des augmentations marquées de l'absorption, particulièrement lorsque les tubercules sont flétris (fig. 1). La production d'anhydride carbonique est, en moyenne, correspondante à l'absorption d'oxygène quoique, à certaines périodes, elle s'en écarte considérablement (voir par ex. fig. 3, 20°C). L'auteur considère différents mécanismes possibles impliqués dans ces phénomènes. L'étude montre aussi un retard de plusieurs heures dans la réaction aux changements de conditions, avec comme conséquence un co?fficient RQ's temporairement aberrant. Au milieu de la période de stockage, le co?fficient de température 20°C/10°C est c. 1.2–1.3 (tableau 8). Mais le prélèvement à 2°C (tubercules affadis) pourrait être plus élevé qu'à 20°C. Ultérieurement, la respiration accélérée accompagnant la germination, plus précoce et plus active à 20° qu'à 10°, modifie cet aspect et le co?fficient de température 20°C/10°C est une excès de 3 (tableau 8). Durant les deux premières semaines de conservation à 2°C, la respiration slélève remarquablement et tombe ensuite de nouveau (fig. 3 et 4) en dépit du fait que les teneurs aussibien en sucrose qu'en sucres réducteurs continuent à s'élever pendant quelque temps (tableau 7), la respiration étant l'indication du renversement, qui n'est pas nécessairement lié au niveau des sucres. Une indication se révèle du changement dans le degré auquel le système d'absorption de basse affinité contribue à l'accroissement initial de l'absorption d'oxygène à 2; C, à partir de l'absence complète d'absorption dans les tubercules placés à 2°C immédiatement après la récolte (fig. 3), jusqu'à la participation majeure dans les tubercules placés à 2°C après avoir été à 10°C plusieurs mois après la recolte (fig. 4). Si les tubercules affadis sont placés de nouveau à 10°C, venant de 2°C, il se produit une élévation immédiate de l'absorption de l'oxygène jusqu'à une valeur de pointe qui est approximativement double de celle à 2°C (fig. 4) qui est suivie par une chute.

     

Short-term diurnal and temporal measurement of methane emission in relation to organic carbon, phosphate and sulphate content of two rice fields of central Gujarat, India

Methane emission from two rice fields of Lambhvel village, Anand district, Central Gujarat, India, was measured for whole cultivation period during pre-summer season. Along with the methane emission, soil chemistry of the two rice fields (Organic Carbon, PO₄⁻² and SO₄⁻²) was determined. The methane emission ranged from 0.10 to 0.56 mg/m² per h, having maximum emission during noon period (11 a.m. to 1 p.m.) of the day at the Rice field-1. Besides, at rice field-2, the methane emission ranged between 0.15 and 0.94 mg/m² per h, having maximum peak during same period (11 a.m. to 1 p.m.) of the day. The results of the current investigation confirm that the methane emission vary substantially between two rice fields, and suggest that soil chemistry and water level might control the methane emission in both the rice fields and suppressed by the phosphate and sulphate concentrations. The greater methane emission was declined with the age of rice plantation. Correlation analysis, ANOVA and F test showed that the methane emission from both the sites has positive correlation with organic carbon and negative correlation with sulfate and phosphate content of the soil and the details of these reasons will be discussed in this paper.     

Relationships and influence of yield components on spaced-plant and sward seed yield in perennial ryegrass

Adequate seed production is essential for cultivar success in perennial ryegrass turf and forage industries, but improvement is limited by the complexity of yield components and low-rank correlations between selection and production environments. This study examined seed yield components among 20 perennial ryegrass entries in both spaced plantings (selection environment) and swards (production environment) at two locations in Minnesota. Competitive (23 plants/m²) and non-competitive (3 plants/m²) spaced-plant nurseries were tested. Competitive spaced-plant total yield was highly correlated with sward yield (r_s = 0.64 and 0.66, p < 0.01) at both locations, whereas the non-competitive environment showed no correlation. Structural equation modelling (SEM) was used to explore the indirect and direct relationship of fall vegetative growth, winterkill, and yield components on total seed yield in all environments. Fertile tiller number (spikes plant⁻¹/m⁻²) exhibited both strong direct and indirect influence on total seed yield in all environments. However, the importance of fertile tiller number in the SEM was reduced with increased plant competition. The SEM showed that both weight per spike and seed yield per spike influenced total yield in spaced plants; however, neither consistently predicted total sward yield. The ratio of these two traits (g seed spike⁻¹/g spike⁻¹) gave an index of fertility that was easy to measure and had a superior correlation with sward yield at two locations (r_s = 0.81 and 0.54, p < 0.05) when spaced plants were under competition. Results suggest that increasing competition in spaced plantings and selecting for spike fertility may more accurately identify superior plant material compared to lower competition environments.     

Total Phenolics Level,Antioxidant Activities and Cytotoxicity of Young Sprouts of Some Traditional Korean Salad Plants

The aim of this investigation was to study the antioxidant and anticancer activities of young sprouts of some traditional Korean salad plants. Total phenolics, antioxidant and anticancer activities of the methanol extracts from young sprouts of 11 salad plants were determined. The highest amount of phenolics was found in methanol extracts of Euonymus alatus (235.7 mg kg⁻¹), followed by Hypericum ascyron (197.1 mg kg⁻¹), Zanthoxylum piperitum (194.1 mg kg⁻¹) and Zanthoxylum schinifolium (142.5 mg kg⁻¹). Methanol extracts of E. alatus, H. ascyron, and Z. piperitum at 63 mg kg⁻¹ exhibited the highest dose-depend DPPH radical scavenging activity by 91.2, 91.2 and 83.9%, respectively. According to the MTT results, the methanol extracts from Stellaria aquatica, Eleutherococcus sessilifolrus and Z. schinifolium showed the highest anticancer activities against Calu-6 (IC50 < 25.0 μgml⁻¹) and from S. aquatica—the highest anticancer activities against SNU-601 (153.3 μgml⁻¹), following by E. sessilifolrus (196.7 μg ml⁻¹) and Amaranthus mangostanus (303.1 μgml⁻¹). Total phenolics were highly correlated with the DPPH, suggesting that they contribute to the antioxidant properties of the studied plants. In conclusion: young sprouts of Korean salad possess antioxidant and anticancer properties and could be used as a supplement to proper drugs.     

Growth and yield studies of potato development in a semi-arid region. 2. Effect of water stress and amounts of nitrogen top dressing on growth of several cultivars

Summary Five potato cultivars were subjected to water deficits as well as to excess water and to corresponding amounts of nitrogen top dressing (N.t.) applied in the irrigation water. The rates of growth in response to water-N. t. were highest for all cultivars whenK _p=1.06 (pan evaporation coefficient) and N.t=173 kg/ha. In the drier treatments (0.87>K _p>0.14 and 127>N.t.>12 kg/ha) and in the wetter treatment (K _p=1.27; N.t.=201 kg/ha), the growth rates decreased. The cultivars differed in their haulm size, especially atK _p=1.0, N.t.=173 kg/ha. At 70 days after planting cv. Cardinal had about half the haulm weight of cv. Désirée. Nevertheless, both cultivars exhibited similar bulking rates. On the other hand, cv. Spunta, which had high bulking rates at the earlier stage of growth, had a marked advantage in yield production in the drier treatments (K _p=0.29−0.14; N.t.=44−12 kg/ha). The maximum leaf area indices (LAI) were obtained atK _p=1.06, N.t.=173 kg/ha and were similar for all cultivars. LAI and leaf area duration (LAD) decreased with increasing water stress. In Cardinal, Désirée, Spunta and cv. Up-to-Date there was a common linear function relating to tuber weigth and to LAD; in cv. Alpha, this function had lower values of tuber weight. Contribution from the Agricultural Research Organization, The Volcani Center, Bet Dagan, Israel. No. 840-E, 1983 Series.     

Nitrogen and phosphorus leaching losses from paddy fields with different water and nitrogen managements

While many water-saving rice production techniques have been adopted in China, the environmental effects of these techniques require further investigation. This study aims to assess nitrogen (N) and phosphorus (P) leaching losses under real conditions in different water and N managements. Two water and three N treatments are conducted in the Taihu Lake region of China. Results show that the total N leaching losses during the rice season under flooding irrigation (FI) are 12.4, 9.31, and 7.17 kg ha⁻¹ for farmers’ fertilization practices (FFP), site-specific N management (SSNM), and controlled-release nitrogen fertilizer management (CRN), respectively. Under controlled irrigation (CI), the respective losses were 7.40, 5.86, and 3.79 kg ha⁻¹ for the same management methods. The total P leaching losses during the rice season under FI were 0.939, 0.927, and 0.353 kg ha⁻¹ for FFP, SSNM, and CRN, respectively. Under CI, the losses were 0.424, 0.433, and 0.279 kg ha⁻¹, respectively, for the same management methods. Ammonium and nitrate N accounted for 42.2–65.5% and 11.8–14.7% of the total nitrogen leaching losses under different water and N management methods, respectively. Due to significant decrease of volumes of percolation water and nitrogen and phosphorus concentrations in percolation water, N and P leaching losses were reduced in the CI treatment compared to the FI treatment under the same N management. The reduction of N input and application of controlled-release nitrogen fertilizer can reduce N and P leaching losses from paddy fields.     

Using water quality variables to predict light attenuation coefficient: case study in Shihmen Reservoir

The amount of photosynthetically active radiation (PAR) in the water column is of fundamental importance in determining the growth of aquatic plant and aquatic primary production. Light attenuation in aquatic ecosystems has important ecological implication and water quality applications. In the present study, the light attenuation through the water column in the Shihmen Reservoir, Taiwan was measured. A light attenuation coefficient (K _e) can be derived from the PAR measurements at each stations. The linear regression analysis reveals that Secchi disk depth is a sample alternative measure of light transmitability and provides a reasonable estimate of the light attenuation coefficient in the Shihmen Reservoir. We conducted multiple-regression analysis for the K _e, chlorophyll a, and total suspended solids (TSS). Because the concentration of chlorophyll a is roughly <5 μg/L in the Shihmen Reservoir, the chlorophyll contribution to the attenuation coefficient will be <0.1 m⁻¹, which is negligible. K _e correlated with TSS concentration yields a good correlation, indicating the TSS should be a good water quality variable for predicting water column light attenuation coefficient in the Shihmen Reservoir.     

Surface modification of okra bast fiber and its physico-chemical characteristics

The effect of chemical treatment i.e. bleaching, alkalization and graft copolymerization on the morphology changes of okra bast fiber has been investigated by means of infrared spectroscopy (IR), scanning electron microscopy (SEM), water absorption and tensile properties measurements. The graft copolymerization reaction of bleached fiber with acrylonitrile monomer (AN) has been carried out under the catalytic influence of K₂S₂O₈ and FeSO₄ redox system. The maximum graft yield (11.43 %) has been found at 70°C temperature, 3×10⁻² mol/l acrylonitrile, 5×10⁻³ mol/l K₂S₂O₈, 5×10⁻³ mol/l FeSO₄ and for 90 min. On the contrary, the fiber has been treated with 10 % NaOH solution, which is much effective to remove the impurities. Based on findings of water absorption, tensile properties and SEM micrograph, the AN-grafted fiber has been showed better properties than bleached and alkali treated fibers. The degree of modification of okra bast fiber by chemical treatment has been evaluated by IR measurement.