Rice straw decomposition in rice-field soil

Rice straw, buried in a rice-field during the dry season decomposed at a rate of 0.0075 day-1. Seventy five percent of the biomass, 70 percent carbon, 50 percent nitrogen and 30 percent phosphorus remained after 139 days of decomposition. Rice straw decomposition furnished 33% N and 8% P of the total nitrogen and phosphorus provided by man.     

稻草—凤尾菇—蚯蚓—肉鸡食物链的氮流与能流研究

稻草养菇、菇渣喂蚓、以蚂喂鸡是通过营养关系将三个生产过程有机地连接起来,形成农业生态系统特有的食物链。关于这三个环节各自的经济效益及栽培技术方面的研究工作已经做了很多,而作为一条食物链的整体状况,主要是能流和物流状况。尚未见到更深入具体的报道。作者试图通过实验定量分析和评价该食物链中每一链节上以及整体上的氮流和能流状况,进而对其生产应用价值做一初步探讨。     

Three-year measurement of methane emission from an Indonesian paddy field

Yearly and seasonal (rainy and dry seasons) variations of CH₄ emission from a Sumatra paddy field were measured for 3 years. The mean CH₄ emission rates during the growth period were in the range of 16.0–26.1 mg CH₄ m^-2 h^-1 for the chemical fertilizer plots and 23.3–34.9 mg CH₄ m^-2 h^-1 for the plots with rice straw application, respectively. The increase in the amounts of CH₄ emission by rice straw application were from 1.3 to 1.6 times. There was no significant difference in the mean CH₄ emission rates between rainy and dry seasons.Total amounts of CH₄ emitted during the period of rice growth were in the ranges of 29.5–48.2 and 43.0–64.6 g CH₄ m^-2 for the plots applied with chemical fertilizer and those with rice straw application, respectively. Nearly the same amounts of CH₄ were emitted in the first and second half of the growth period, irrespective of rice straw application.     

Specific molecular marker of the genes controlling linolenic acid content in rapeseed

In rapeseed, which is an agronomically important oilseed, variation in the linolenic acid content of the oil has been obtained through chemical mutagenesis treatment. Conventional breeding of this quantitative trait, however requires specific molecular markers. By means of biochemical experiments, we have established that the induced variation in linolenic acid content is associated with the fad3 gene encoding the microsomal ¹⁵ desaturase. Using a pair of primers specific to this gene and a doubled haploid progeny derived from a low linolenic x high linolenic acid F₁hybrid, we have identified a polymorphism of the fad3 alleles between the low- and the high-linolenic acid genotypes. The structure exon/intron of the fad3 DNA sequence seems to be very similar to that of the Arabidopsis fad3 gene. The choice of the primer pair allows specific amplification of one of the two rapeseed fad3 genes. The value and contribution of specific markers to conventional plant breeding is discussed.     

麦秸覆盖夏玉米对其苗期生长发育的生化他感作用研究初报

麦秸覆盖夏玉米对其苗期生长发育的生化他感作用研究初报张玉铭,马永清（中国科学院石家在农业现代化研究所,０５００２１）ＡｌｌｅｌｏｐａｔｈｉｃＥｆｆｅｃｔｏｆＷｈｅａｔＳｔｒａｗＭｕｌｃｈｉｎｇｏｎＳｅｅｄｌｉｎｇＧｒｏｗｔｈａｎｄＤｅｖｅｌｏｐｍｅｎ...     

红壤旱坡地桔园覆盖的生态效应及经济效益评价

柑桔是南方红壤地区栽培的主要果树种类,栽培面积达1126×106ｈｍ2。柑桔是一种常绿果树,生长量大,挂果期长,周年需要消耗大量的水分。我国南方红壤地区虽然雨水充沛,但降水季节分布不均,柑桔果实迅速生长的7～10月正是该地区雨水少、蒸发量大的伏秋干旱季节。经常性的伏秋干旱是制约我国柑桔产量和质量进一步提高的主要障碍因素之一。桔园夏秋进行秸秆覆盖可以降温[1]、保水[2]、防止杂草生长[3]等,但桔园应用地膜覆盖及常年连续覆盖对桔园的生态效应方面的研究较少,为此我们开展了这方面的工作,并通过连续3ａ的产量及产值分析覆盖桔园的经…     

Organosolv pulping of wheat straw by use of phenol

A central composite design was used to investigate the influence of the cooking conditions (time, temperature and phenol concentration) for wheat straw with phenol-water mixtures on the properties of the pulp obtained (yield and holocellulose, -cellulose, lignin and ethanol-benzene extractable contents) and the pH of the resulting wastewater. A second-order polynomial model consisting of three independent process variables was found to accurately describe the organosolv pulping of wheat straw. The equations derived predict the yield, the holocellulose, -cellulose, lignin and ethanol-benzene extractable contents of the pulp, and the pH of the wastewater with multiple-R, R² and adjusted-R² high values. The process variables must be set at low variables in order to ensure a high yield and pH. Conversely, if high holocellulose and -cellulose contents, and low lignin and ethanol-benzene extractable contents are desired, then a high temperature (200°C), long cooking time (120 min), and intermediate phenol concentration (65%) must be used.     

Improvements of the bioavailability of straw: acid and enzyme hydrolysis of wheat straw pretreated with saturated lithium chloride in hydrochloric acid

Wheat straw was pretreated with saturated lithium chloride in 4 m hydrochloric acid at 50°C for 1 h, then hydrolysed at 100°C for 1 min, to give 84% conversion to monosaccharides. Particle sizes, 150–355 mesh, were easily hydrolysed. Samples pretreated with saturated lithium chloride in 1 m hydrochloric acid at 27°C for 24 h were hydrolysed by Trichoderma viride cellulase (MVA 1284) [1,4-(1,3;1,4)-β-d-glucan 4-glucanohydrolase, EC 3.2.1.4] to give 20–23% monosaccharides for particle sizes of 150–250 mesh, and 82–95.4% for particle sizes of 250–355 mesh.     

麦草栽培姬菇配方的数学模型研究

借助二次通用旋转组合设计法研究了麦草栽培姬菇配方的数学模型,以探讨利用麦草替代棉籽壳的新配方.试验结果得出了配料的取值范围及最佳栽培配方,即麦草79％,麸皮15％,玉米粉4％,过磷酸钙1％,黄豆饼粉1％.在实际生产中很有应用价值.     

Enzymatic hydrolysis of lignocellulosic materials: II. Experimental investigations of theoretical hydrolysis--process models for an increased enzyme recovery

Stream pretreatment of wheat straw solubilized most of the xylan present. Xylose and other sugars were recovered by washing the substrate with water but only a minor part (34%) was monomeric. Treatment of this solutions with celulases and hemicellulases improved the yield of monomeric sugars to 69%, the main product being xylose. Some xylose was also obtained during enzymatic hydrolysis of the solid substrate although the pretreatment step contributed 64% (mean value) of total xylose formed. A reference model, No. 1, and two other models, Nos. 2 and 4, described in the first part of this article series (this issue) have been studied experimentally and results confirm the theoretical conclusions. An uninterrupted hydrolysis over a given time period leads to a lower degree of saccharification than when hydrolysate is withdrawn several times. Saccharification is also favored if the residue is removed at a late stage, i.e., at the end of the 24 h hydrolysis cycle. Extended recirculation of the enzymes during a 4 x 24-h experimental period gave the following average yields of saccharification on a 24-h basis: 65% (Reference), 73% (Model 2), and 79% (Model 4). It is concluded that enzyme recovery with model 4 is 70% or more, while the Reference and Model 2 attain a lower level of recovery. The design of an improved hydrolysis model is also discussed.