酸性醇醚磷酸酯中单、双酯含量的测定

以三氯氧磷和醇醚为原料合成的醇醚磷酸酯中含有大量盐酸,盐酸的存在影响产品中单、双酯含量的确定.通过测定氯离子含量可间接确定醇醚磷酸酯中的盐酸含量,从而可较准确的测定单酯、双酯、三酯及磷酸含量.     

Calcium Effects on Acetic Acid Toxicity in Rice

Recent soil‐management practices such as no‐tillage and minimal tillage, when applied to the irrigated rice crop, promote changes in soil composition as a result of anaerobic degradation of organic matter. Several short‐chain organic acids are formed, such as acetic acid. The objective of this work was to determine the effect of calcium (Ca) on plant development under stress by acetic acid toxicity. The experiment was conducted in hydroponics by testing different Ca (0.2, 1.0, and 5.0 mmol L^?1) and acetic acid (0 and 2.5 mmol L^?1) concentrations. The variables evaluated were the root system morphological parameters (total length, radius, area, dry‐matter weight, and main root growth), shoot parameters (shoot dry matter, plant height), and concentration and total accumulated nitrogen (N), phosphorus (P), potassium (K), Ca, and magnesium (Mg) in the plants. The growth of the root system and the shoots of rice plants were not affected by the addition of Ca to the treatments containing acetic acid.     

Development of buffer methods and evaluation of pedotransfer functions to estimate pH buffer capacity of highly weathered soils

The pH buffer capacity of a soil (pHBC) determines the amount of lime required to raise the pH of the soil layer from its initial acid condition to an optimal pH for plant growth and the time available under current net acid addition rate (NAAR) until the soil layer acidifies to a critical pH leading to likely production losses. Accurate values of pHBC can also be used to calculate NAAR from observed changes in soil pH. In spite of its importance, there is a critical shortage of pHBC data, likely due to the long period of time needed for its direct measurement. This work aimed to develop quick, simple and reliable methods of pHBC measurement and to test these methods against a slow (7‐day) titration used as benchmark. The method developed here calculates pHBC directly from the pH buffer capacity of the buffer solution and the increase in soil pH and corresponding decrease in pH of the buffer solution following mixing and equilibration. The pHBC values calculated using Adams and Evans or modified Woodruff buffers were in accord with those measured by slow titration. Buffer methods are easily deployed in commercial and research laboratories as well as in the field. The advantage of using buffer solutions to calculate pHBC instead of lime requirement is the broad application of this soil property. The pHBC of a soil is an intrinsic property that would not be expected to need remeasurement over periods of less than decades. Recurring lime requirement can be calculated from the soil's pHBC, initial and target pH values. A large proportion of the variability in pHBC was explained by the soil organic carbon content. This relationship between pHBC and soil organic carbon content allowed us to develop local pedotransfer functions to estimate pHBC for different regions of Australia.     

Relationship between Dry Weight at Heading and the Number ofSpikelets on Individual Rice Tillers

Abstract

The objectives of this study were to identify the growth parameters involved in determining the number of spikelets on an individual tiller (ST) and to elucidate how ST is determined in rice (Oryza sativa L.). We examined the correlation of ST with the dry weight (DWT), leaf area (LAT), and the amount of nitrogen (NT) at heading for individual tillers grown under different conditions that were expected to affect spikelet production. In 1999, the japonica rice cultivars “Mineasahi” (short-duration), “Hinohikari” (intermediate-duration), and “Akebono” (long-duration) were transplanted in a paddy field on two different dates (EARLY and LATE). In 2000, Hinohikari was grown under three different treatments (gibberellic acid application, nitrogen topdressing, and thinning of hills at panicle initiation) and without treatment (control). Covariance and partial correlation analyses indicated that ST was positively and essentially correlated with DWT rather than with LAT and NT. The regression of ST on DWT was stable within each cultivar regardless of the treatment, year, tiller order, and number of differentiated spikelets. The slope of the regression was the steepest in the short-duration cultivar. These results suggest that the steep slope is desirable for high-yielding cultivars with large panicles. We conclude that ST is mostly determined by dry matter production of an individual tiller regardless of the number of differentiated spikelets. We present a diagram showing the relationship between dry matter production and the number of differentiated, surviving, and degenerated spikelets on an individual tiller.     

Effects of Soil Temperature on Growth and Root Function in Rice

Abstract

The objective of this study was to clarify the effects of soil temperature in the stage from late tillering to panicle initiation (SI) and during the grain-filling stage (SII) on grain setting, dry matter production, photosynthesis, non-structural carbohydrate (NSC), xylem exudation and abscisic acid (ABA) levels in rice (Oryza sativa L. cv. Koshihikari). Rice plants were exposed to four different soil temperatures during SI or SII: 17.5, 25, 31.5 and 36.5°C (ST18, ST25, ST32 and ST37, respectively). The yield, yield components, grain filling and quality in SI were negatively influenced by high soil temperature of 37°C. On the other hand, there was no significant difference in those characters among temperature treatments in SII. The root/shoot ratio was smallest in the ST37 plants in both SI and SII, mainly due to their lighter root weight. At 7 days after initiation of treatment (DAT) in both SI and SII, the photosynthetic and xylem exudation rate tended to increase slightly as soil temperature increased up to 32°C. At 21 DAT, however, the photosynthetic rate was lowest in ST37, with concurrent decrease of diffusion conductance and SPAD value. In addition, decrease of NSC concentration in stem and xylem exudation rate, and increase of ABA level in leaves and xylem exudate were observed in ST37 plants at 21 DAT. These results suggested that high soil temperature before heading especially influenced yield, grain quality and plant growth. Possible mechanisms of the effect of soil temperature are discussed.     

Pigeonpea Nutrition and Its Improvement

Abstract

Pigeonpea (Cajanus cajan [L.] Millsp.), known by several vernacular and trade names such as red gram, tuar, Angola pea, Congo pea, yellow dhal and oil dhal, is one of the major grain legume crops of the tropics and sub-tropics. It is a favorite crop of small holder dryland farmers because it can grow well under subsistence level of agriculture and provides nutritive food, fodder, and fuel wood. It also improves soil by fixing atmospheric nitrogen. India by far is the largest pigeonpea producer where it is consumed as decorticated split peas, popularly called as ‘dhal’ In other countries, its consumption as whole dry seed and green vegetable is popular. Its foliage is used as fodder and milling by-products form an excellent feed for domestic animals. Pigeonpea seeds contain about 20-22% protein and appreciable amounts of essential amino acids and minerals. Dehulling and boiling treatments of seeds get rid of the most antinutritional factors such as tannins and enzyme inhibitors. Seed storage causes considerable losses in the quality of this legume. The seed protein of pigeonpea has been successfully enhanced by breeding from 20-22% to 28-30%. Such lines also agronomically performed well and have acceptable seed size and color. The high-protein lines were found nutritionally superior to the cultivars because they would provide more quantities of utilizable protein and sulfur-containing amino acids.     

Effects of Inhibition of Different Rumen Microbial Activity on Rumen Fermentation and Fatty Acid Metabolism in Buffaloes

This study was aimed to evaluate the effects of inhibiting rumen bacteria,fungi and protozoa with adding linoleic acid and linolenic acid on in vitro rumen fermentation and fatty acid metabolism in buffaloes.Both fatty acids were supplemented with substrate and roughage (3:7) at the rate of 3% on dry matter (DM) basis in an in vitro batch culture system,there were 5 repetitions for each group.At the same time,four groups were set up:Control group and inhibition groups of protozoa,bacteria and fungi.After 24 h of incubation,total gas production,CH₄,pH,VFA,NH₃-N,MCP and LFA concentrations were measured.The results showed that:①With the addition of linolenic acid,compared with control group,the gas production decreased significantly after inhibition the growth of bacteria and protozoa,CH₄ production increased significantly after inhibition of the growth bacteria and fungi,and CH₄ production decreased significantly after inhibition of the growth protozoa (P<0.05).With the addition of linoleic acid,compared with control group,the gas production decreased significantly after inhibiting the growth of bacteria,fungi or protozoa,and CH₄ production was significantly lower than other groups after inhibition of protozoa (P<0.05).② After inhibiting the growth of bacteria,fungi or protozoa,the pH and MCP concentration were affected significantly with the addition of linolenic acid (P<0.05),there was no significant effect on NH₃-N concentration with the addition of linoleic acid (P>0.05).③ Compared with control group,the content of acetic acid and propionic acid was reduced significantly after inhibiting the growth of bacteria,fungi or protozoa (P<0.05).The butyric acid was reduced significantly after inhibiting the growth of bacteria with the addition of linolenic acid (P<0.05).The butyric acid was reduced significantly after inhibiting the growth of bacteria,fungi or protozoa with the addition of linoleic acid (P<0.05).④ Compared with control group, the concentrations of C11:0, C12:0, C13:0, C14:0, C14:1n5, C15:1n5, C16:1n7, C16:0, C18:3n3, C18:2n6c, C18:0, C20:2n6, C20:3n6, C20:1, C20:3n3, C20:0, C21:0, C22:6n3, C22:2n6, C22:0 was reduced significantly after inhibiting the growth of bacteria with the addition of linolenic acid, the concentrations of C12:0, C13:0, C14:0, C15:0, C16:1n7, C16:0, C17:0, C18:3n6, C18:3n3, C18:2n6c, C18:1n9t, C18:0, C18:2(cis-9,trans-11), C18:2(trans-10,cis-12), C20:2n6, C20:1, C20:0, C21:0, C22:6n3, C22:0, C23:0, C24:1n9, C24:0 was reduced significantly after inhibiting the growth of bacteria with the addition of linoleic acid (P<0.05).The results revealed that the addition of linoleic acid and linolenic acid could significantly manipulate in vitro rumen fermentation parameters,CH₄ yield and fatty acid composition after inhibiting the growth of bacteria,fungi or protozoa.Protozoa greatly contributed to total gas and CH₄ production while bacteria significantly affected rumen fatty acid metabolism.     

Evaluation of some systems for classifying soil sensitivity to acid deposition in the South African highveld

Abstract. The Skokloster and Stockholm Environmental Institute (SEI) approaches were applied to the assessment of 145 soils of the South African highveld region in terms of sensitivity to acid deposition. The critical load class calculated by variants of these methods was compared with the acid neutralizing capacity (ANC) determined by pH measurement of soil suspended in a dilute acetate buffer solution. This rapid index of ANC correlates well both with ANC determined by an established but more laborious method which involves titration and equilibration of soil with HCl, and with a number of soil properties related to base status. The correlation between Skokloster or SEI critical load classes and ANC was weak. It was concluded that ANC determination would be a preferable basis for classifying these soils in terms of their sensitivity to acid deposition, since the method is direct and integrates the contribution of various soil properties to acid sensitivity instead of requiring the relative contribution to be calculated according to somewhat arbitrary weightings given to broadly defined classes of soil properties.     

热水溶出茧层丝胶蛋白的结构变化

对不同时间热水溶出的茧层丝胶的氨基酸组成、热分解温度和分子结构等进行了测定分析．结果表明，随着热水溶出时间的延长，茧层丝胶蛋白中的酸性氨基酸因易溶于水而略有下降，热分解温度因受取向性、结晶性的影响而有所增高，分子结构也由无规则卷曲转化为β构象．丝胶蛋白被降解而成分子大小不一的混合类型     

午潮山常绿阔叶林气候生态效应定位研究

午潮山常绿阔叶林气候生态效应，经过８年（１９８８￣１９９５）定位观测研究，取得了若干规律性数据，加深了对常绿阔叶林生态系统气候生态学特征的认识，为持续经营、保护、利用和发展常绿阔叶林，提供了一定的科学依据。文中较系统地论述了午潮山常绿阔叶林的日照、温度、湿度，林内降水量再分配，酸雨等问题。