高产小麦磷钾效应和适宜氮磷钾配比研究

黄泛冲积石灰性土壤在适宜施氮水平下磷钾不同用量及配比对小麦生长的影响表现为:(1)磷肥以中量施用水平(每公顷施用P2O5120kg)增产效果最好,分别比未施磷、低量施用水平(每公顷用P2O548kg)增产30.82%、20.27%,高量施用水平(每公顷施用P2O5192kg),虽然比中量施用水平表现出增产,但增产幅度很小,只有2.85%;(2)钾肥对小麦的增产效应小于磷肥,只有在施用磷肥的基础上配施钾肥,才能使钾的效应得到充分发挥;(3)小麦全生育期氮磷钾施用比例1∶0.5∶0.5为最佳,每公顷施用N240kg、P2O5120kg、K2O120kg效益最高。     

Late season nitrogen fertilization of soybeans: effects on leaf senescence, yield and environment

Nitrogen demand from soybean seeds during seed filling is very high and has been proposed as the cause of nitrogen remobilization and leaf senescence. Previous research has not shown consistent effects of late season fertilization on seed yield, while its effects on leaf senescence have not been evaluated. Two field experiments were performed to determine the effects of a late season N fertilization on leaf senescence and fall, seed yield and its components, and residual soil nitrate, and to evaluate the potential risk of groundwater contamination. Two rates of nitrogen (50 and 100 kg N ha^–1) were applied at the R3 and R5 development stages. Nitrogen fertilization, either at R3 or R5, increased soil nitrate availability during the seed-filling period. Seed yield, seed number and protein content were not affected by N fertilization. The addition of 100 kg N ha^–1 produced a small delay of 1–2 days in the leaf fall, and slightly increased seed size (3.6%). Our results suggest that increasing soil N availability during the seed-filling period is not an effective way to delay leaf senescence or to increase seed growth and yield of soybean. Nitrogen fertilization increased the level of residual nitrate in the top soil at one site (the one with lowest seed yield), increasing the risk of nitrate leaching during subsequent fallow.     

除草剂对不同栽培方式水稻药害的评价

选取酰胺类、磺酰脲类、硫代氨基甲酸酯类、杂环类、脲类、苯氧羧酸类等常用化学除草剂,以超常规剂量用移液和喷雾两种方式对抛栽和直播籼、粳稻进行药剂试验。研究结果明确了各种除草剂对水稻的药害症状;籼粳稻对各药剂的敏感差异;以及清水冲洗、搁田、施肥等措施对某些除草剂品种造成的水稻药害的缓解作用。     

羟丙基糯米粉糊的特性及应用初探

研究了羟丙基糯米粉糊的性质，以及流变特性和温度影响流变特性的规律，并对其在蚝油食品中作为增稠稳定剂的应用做了初步研究。结果表明，糯米粉经羟丙基化后，凝沉性更弱，受热易于成糊和分散，糊的粘度提高，冻融稳定性极佳，透明度大为提高，但是抗剪切稳定性反而降低。在实验测定的温度下，羟丙基糯米粉糊呈现假塑性流体的特征且假塑性随醚化程度的提高而增强。应用试验表明其增稠效果好、稳定性高，可用做增稠稳定剂。     

四唑嘧磺隆水分散粒剂在稻田环境中的残留动态

为评价除草剂四唑嘧磺隆在水稻上使用后的残留动态及环境安全性，在北京海淀区进行了50％四唑嘧磺隆水分散粒剂在水稻上的残留动态和最终残留试验研究。样品经丙酮提取抽滤后，再经液液分配及氧化铝柱净化、浓缩、定容后，用紫外检测器的液相色谱进行测定。其有效成分四唑嘧磺隆的最低检出量为0．02ng，在稻田水、土壤、鲜植株、稻壳、糙米样品中的平均回收率为82．4％-105．0％，变异系数为1．1％～14．1％，符合农药残留分析的要求。结果表明：四唑嘧磺隆在水稻植株上的半衰期为2．4d，在土壤巾的半衰期为5．5d，在稻田水中的半衰期为1．9d，施药后7d四唑嘧磺隆在水稻植株上的消解达到80％以上。50％四唑嘧磺隆水分散粒剂按80、120g／hm。使用，施药1次，收获时，四唑嘧磺降在糙米、稻壳、稻草、土壤中的残留量均未检出。     

Membrane degumming of crude rice bran oil: Pilot plant study

The procedure for the classical chemical refining of vegetable oils consists of degumming, alkali neutralization, bleaching, and deodorization. Conventional refining of rice bran oil using alkali gives oil of acceptable quality, but the refining losses are very high. A critical work has been carried out to study the application of membrane technology in the pretreatment of crude rice bran oil. Oils intended for physical refining should have a low phosphorus content, and this is not readily achievable by the conventional acid/water degumming process. The application of membrane technology for the pretreatment of rice bran oil has been investigated. The process has already been successfully applied to other vegetable oils. Ceramic membranes, which are important from the commercial point of view, were examined for this purpose. The results showed that the membrane‐filtered oils met the requirements of physical refining, with a substantial reduction in color. It was observed that most of the waxy material was also rejected. Experiments were carried out to establish the relationship between permeate flux and rejection with membrane pore size, trans‐membrane pressure and micellar solute concentration.     

Effect of nitrogen,phosphorus and soil and crop residues management practices on maize (Zea mays L.) yield in ultisol of eastern Cameroon

The shortening of fallow period in several areas in tropical Africa has reduced soil fertility and exposed soils to erosion and run-off. Fertilizer application and crop conservation practices are needeed to sustain high crop yield and to conserve the natural resource base for upland crop production in the continent. Field trials were carried out to evaluate the effect of fertilizer application and soil and crop residues management practices on yield of maize (Zea mays L.) planted on a Plinthudult soil at Bertoua, Eastern Cameroon. Maize yields increased significantly with nitrogen and phosphorus fertilizer application. Under the rainfall pattern prevailing in the area, the amount of nitrogen required for maximum yield was higher in the second season. On the other hand, the amount of phosphorus required for maximum yield appeared to decrease with time. The burning of crop residues and weeds prior to planting together with no-till practive gave higher yield of maize than other soil and crop residues management practices.     

Rice bran‐filled biodegradable low‐density polyethylene films: Development and characterization for packaging applications

Rice bran was incorporated into low‐density polyethylene (LDPE) at different concentrations by compounding in a twin‐screw extruder and blown into films of uniform thickness. The rice bran incorporation influenced physical, mechanical, barrier, optical, thermal properties, and biodegradation of LDPE. The mechanical and optical properties decreased as the percentage of rice bran increased. The effect of rice bran on the morphology of LDPE blends was examined using scanning electron microscopy. Oxygen transmission rate and water vapor transmission rate increased with the increased content of rice bran. Addition of rice bran did not alter the melting temperature (T_m) of the blends; however the thermal stability decreased, while glass transition temperature (T_g) increased. Kinetics of thermal degradation was also investigated and the activation energy for thermal degradation indicated that for up to 10% filler addition, the dispersion and interfacial adhesion of rice bran particles in LDPE was good. Aerobic biodegradation tests using municipal sewage sludge and biodegradation studies using specific microorganism (Streptomyces species) revealed that the films are biodegradable. © 2006 Wiley Periodicals, Inc. J Appl Polym Sci 102: 4514–4522, 2006     

Lowland rice response to potassium fertilization and its effect on N and P uptake

Not much is known about the response of lowland rice to K fertilization under Brazilian conditions. A field experiment was conducted during four consecutive years to determine the response of three lowland rice (Oryza sativa L.) cultivars to K fertilization on a Low Humic Gley soil. In the first two years, K was broadcast at rates of 0, 42, 84, 126, and 168 kg K ha^–1. In the last two years K rates were reduced to 0, 25, 50, 75, and 100 kg K ha^–1 and applied in a band. Potassium significantly (P < 0.01) increased grain yields but the response varied from cultivar to cultivar and year to year. Yield responses to K fertilization were superimposed on a general trend of increasing grain yields across the four growing seasons. Mean grain yields increased 14.3% with broadcast application of K in the first two years and 10.4% with banded application of K in the last two years when compared to the control treatments. Extractable soil K increased with K application rate and decreased with soil depth. Potassium was rapidly removed from the soil and yearly broadcast or banded application of K can be expected to result in a significant increase in grain yield of lowland rice in these soils.     

硼酸与硫酸镁对硼收率影响的分析

介绍了在硼酸生产工艺中影响硼收率的主要因素。以生产系统中硼酸浓度和硫酸镁两个方面探讨了对硼收率影响的原因，并把分析结果应用于生产实践中，调整了部分工艺参数。证明：调整酸化浓度，控制母液中硼酸含量，硼的收率比以往确有提高，是一种不增加设备，不增加投资的行之有效的方法。