壳寡糖及其复合聚合氯化铝絮凝微藻富集的研究

［目的］ 为了找到可以加速微藻富集的合适絮凝剂。［方法］ 制备了壳聚糖的降解产物壳寡糖,用于绿色巴夫藻（Pavlovaviridis Tseng, Chen et Zhang）和小球藻（Chloreiia spp.） 絮凝富集。［结果］ 终浓度为30 mg/L以上的壳寡糖溶液对2种藻类具有显著的促沉降效应。当壳寡糖与6 mg/L聚合氯化铝混合使用时,壳寡糖/聚合氯化铝促沉降效应明显提高。［结论］ 壳寡糖可以用于微藻大规模生产的采收。     

Physiology of seawater acclimation in the striped bass,Morone saxatilis (Walbaum)

Several experiments were performed to investigate the physiology of seawater acclimation in the striped bass, Morone saxatilis. Transfer of fish from fresh water (FW) to seawater (SW; 31–32 ppt) induced only a minimal disturbance of osmotic homeostasis. Ambient salinity did not affect plasma thyroxine, but plasma cortisol remained elevated for 24h after SW transfer. Gill and opercular membrane chloride cell density and Na⁺,K⁺-ATPase activity were relatively high and unaffected by salinity. Average chloride cell size, however, was slightly increased (16%) in SW-acclimated fish. Gill succinate dehydrogenase activity was higher in SW-acclimated fish than in FW fish. Kidney Na⁺, K⁺-ATPase activity was slightly lower (16%) in SW fish than in FW fish. Posterior intestinal Na⁺,K⁺-ATPase activity and water transport capacity (J_v) did not change upon SW transfer, whereas middle intestinal Na⁺,K⁺-ATPase activity increased 35% after transfer and was correlated with an increase in J_v (110%). As salinity induced only minor changes in the osmoregulatory organs examined, it is proposed that the intrinsic euryhalinity of the striped bass may be related to a high degree of “preparedness” for hypoosmoregulation that is uncommon among teleosts studied to data.     

盐碱地池塘4种养殖模式的鱼产量及负荷力

在氯化物型盐碱地池塘中 ,采用围隔实验生态学方法对鲤、草鱼、罗非鱼和淡水白鲳等 4种鱼类混养模式的鱼产量、负荷力和搭配比例进行对比研究。结果表明 ,4种养殖模式中吃食性鱼类的日增重率和收获规格都随其本身放养密度的增大而减小 ,而鲢、鳙的日增重率和收获规格则随吃食性鱼类放养密度的增大而增大 ;吃食性鱼类的日增重率以淡水白鲳最快 ,草鱼生长最慢 ;吃食性鱼类的净产量为鲤模式 (CC) >罗非鱼模式 (TH) >淡水白鲳模式 (FP) >草鱼模式 (GC) ,混养的鲢在各种模式中的产量顺序为CC >GC >TH >FP ,鳙为CC >GC >FP >TH。CC、GC、TH、FP模式的总净产量分别为 4 .0 2～ 6 .5 5、3.0 5～ 5 .2 6、3.4 5～ 5 .86、2 .99～ 5 .34g/ (m2 ·d) ;FP、CC、TH、GC模式的负荷力分别为 0 .6 0 4、0 .4 92、0 .4 37和 0 .4 30kg/m2 。     

Environmental and chemical control of growth and flowering of Chamelaucium uncinatum Schauer

The main factor affecting floral initiation of Geraldton Wax-Flower (Chamelaucium uncinatum) is the photoperiod, while temperature is the major factor affecting flower development. Four weeks of short days (SD) are generally required for obtaining full flowering. The number of flowers produced per plant increases with increasing the number of SD. Under mild temperatures of $\text{20}\text{14°}\text{C}$ (day/night), plants initiated flowers even in long days (LD). However, fewer flowers were produced and on higher nodes as compared to SD plants. Chlormequat promoted flowering under prevailing summer conditions of high temperatures and LD. Under prevailing autumn conditions favourable for flower initiation, LD treatment or weekly sprays with gibberellic acid (GA) reduced the number of flowers per plant. Combined treatment of LD and GA reduced both the flowering percentage and the number of flowers per plant. Discontinuing the LD or the GA treatments caused a resumption of full flower initiation.     

Response of pea (Pisum sativum L.) to mepiquat chloride under varying application doses and stages

Grown as a monoculture, peas (Pisum sativum L.) exhibit severe lodging after flowering and lodging causes yield reductions considerable. This study was conducted to investigate the effects of dose (untreated, 25, 50, 75 and 100 g a.i. ha^?1) and stage (late vegetative, early blooming and early pod filling) of mepiquat chloride (MC) application on the growth, lodging control, seed yield and yield parameters of pea (Pisum sativum L.) under field conditions in Erzurum, Turkey in 2002 and 2003. Application doses of 25, 50, 75 and 100 g a.i. ha^?1 significantly reduced stem height by 5.3 %, 7.2 %, 7.5 % and 6.4 % and increased stem width by 7.5 %, 12.7 %, 12.3 % and 15.7 % respectively, when compared with the untreated control, and thereby reduced the tendency of the crop to lodging. Increases of the seed yield under different application doses of MC ranged between 13.7 % and 20.1 % over the untreated control. However, in all parameters investigated, except for stem width, higher application doses of MC gave no clear advantages compared with the application dose of 25 g a.i. ha^?1. Seed yield was also significantly influenced by application stage of MC and application at early blooming stage of crop, MC significantly increased seed yield by 11.4 % and 10.2 % when compared with the late vegetative and the early pod filling stages respectively. Furthermore, the interaction of application dose and stage was significant, and spraying of pea plants with 25 g a.i. ha^?1 MC at early blooming stage has the most beneficial effects on the characters evaluated.     

氯化钾缓解肉仔鸡热应激的研究

120只28日龄艾维茵(AVIAN)肉仔鸡随机分为1、2、3、4组.1组为对照组,饮自来水;2、3、4组为试验组,分别饮添加0.18％、0.26％、0.34％氯化钾的自来水.舍温控制在34±1℃.试验期为4周.结果,各组鸡增重、采食量、饲料效率、饮水量的顺序均为第4组→第3组→第2组→第1组.饮水中添加KCI,肉仔鸡血清K~ 浓度高于对照组,而直肠温度、呼吸率及血清尿酸浓度则相反.血清Na~ 前两周3、4组显著低于1组,以后趋于一致.血细胞压积(PCV)、血液PH、CO_2分压(PCO_2)、氧分压(PO_2)、碳酸氢根(HCO_3)和血清中总蛋白、白蛋白、白/球比以及血糖,组间均差异不显著.本试验表明,饮水中添加KCI能较好地缓解热应激对肉仔鸡生长的影响,增强肉仔鸡对高温的耐受性,并可提高其生产性能.     

氯化胆碱对烟草植株生长的促进效应

对烟草喷施不同浓度（０，５０，２００，３００，５００和１０００ｍｇ·Ｌ－１）的氯化胆碱（ＣＣ）后，可提高烟草的株高，尤其对茎粗生长、叶数和叶面积等有明显的促进作用。ＣＣ对增强烟草苗期根系活力和提高苗期的抗寒性也有明显作用。其中以喷施２００和３００ｍｇ·Ｌ－１的ＣＣ者对烟草生长的促进效果最大。     

氯化钠影响下蓝藻Anabaena 7120的固氮活性和去铵阻抑

正常培养液中NaCl浓度增高时,蓝藻固氮活性明显下降,去铵阻抑速率也减慢。NaCl浓度越高,阻抑程度越大。如果NaCl浓度过高,固氮酶活性即完全丧失,铵阻抑效应也不能消除。低光照度、光合抑制剂、O_2、N_2以及N_2+CO_2都加剧高浓度NaCl对蓝藻固氮酶活性和去铵阻抑的阻抑,而外源蔗糖、H_2和H_2+O_2则有一定程度的促进。     

Organic chlorine and chloride in submerged paddy soil: a case study in Anhui province, southeast China

Abstract. Efforts to understand the fate of organochlorine compounds in arable soil have concentrated on anthropogenic compounds, in spite of the fact that organochlorine compounds are both produced and mineralized in soil through natural processes. In order to understand the fate of chlorinated pesticides, it is necessary to take account of the natural chlorine cycle. The present study is a first attempt to illuminate the relationship between the natural chlorine cycle and agricultural practices. The concentration and storage of organic chlorine (Cl_org) and chloride (Cl_inorg) were determined in topsoil of a paddy field compared to an adjacent afforested hill at a sampling site in the Meicun area, Anhui Province, China. The concentration of Cl_org, as well as the chlorine-to-carbon ratio, was significantly lower in the paddy field samples than in the forest soil samples. A weak relationship between the concentration of Cl_org and the organic carbon content was observed in the paddy field, in contrast to the observations made in the adjacent forest soil as well as those made in previous studies, which have suggested a positive correlation between organic carbon content and Cl_org. The similarity between our results at the forest site and the previous studies, which have been carried out in temperate regions, suggests that it is the land use rather than the climate that makes the current paddy soil results different. Our results suggest that the contribution of Cl_org to the paddy soil from above-ground litter and from production within the soil are small or negligible compared with the contribution from pesticide application and wet and dry deposition.     

Drought and salinity: A comparison of their effects on mineral nutrition of plants

The increasing frequency of dry periods in many regions of the world and the problems associated with salinity in irrigated areas frequently result in the consecutive occurrence of drought and salinity on cultivated land. Currently, 50% of all irrigation schemes are affected by salinity. Nutrient disturbances under both drought and salinity reduce plant growth by affecting the availability, transport, and partitioning of nutrients. However, drought and salinity can differentially affect the mineral nutrition of plants. Salinity may cause nutrient deficiencies or imbalances, due to the competition of Na⁺ and Cl^– with nutrients such as K⁺, Ca²⁺, and NO . Drought, on the other hand, can affect nutrient uptake and impair acropetal translocation of some nutrients. Despite contradictory reports on the effects of nutrient supply on plant growth under saline or drought conditions, it is generally accepted that an increased nutrient supply will not improve plant growth when the nutrient is already present in sufficient amounts in the soil and when the drought or salt stress is severe. A better understanding of the role of mineral nutrients in plant resistance to drought and salinity will contribute to an improved fertilizer management in arid and semi‐arid areas and in regions suffering from temporary drought. This paper reviews the current state of knowledge on plant nutrition under drought and salinity conditions. Specific topics include: (1) the effects of drought and salt stress on nutrient availability, uptake, transport, and accumulation in plants, (2) the interactions between nutrient supply and drought‐ or salt‐stress response, and (3) means to increase nutrient availability under drought and salinity by breeding and molecular approaches.