A novel screening method for rice allelopathic potential: the inhibitory‐circle method

Screening crop accessions for allelopathic activity is of paramount importance for crop allelopathy research. Previous bioassays often did not use a mixed culture of donor and target plants, did not use soil and were not conducted under natural conditions. In this study, we designed an inhibitory‐circle method in which a rice accession (donor plant) and Echinochloa crus‐galli (target plant) were cultured together in paddy soil under natural conditions. First, we determined that the highest allelopathic activity of allelopathic rice accession PI312777 was at the 5‐leaf stage, and the suitable distance of rice seedlings and E. crus‐galli was 12 cm apart. This method was then validated by a field test. A further 40 rice accessions were evaluated for allelopathic activity to E. crus‐galli using this method. Two rice accessions, PI312777 and Taichung Native 1, had highly allelopathic activity to E. crus‐galli (inhibitory rate > 50%), while another accession, Lemont, had non‐allelopathic activity. These experimental results were in accordance with previous studies using direct field experiments. The inhibitory‐circle method integrated three necessary conditions, that is donor and target plants grown together, with soil as the medium and under natural conditions for reliable results. The ‘inhibitory‐circle method’, which combined donor and target plants, soil medium and field conditions, can give reliable results in one step, compared with laboratory screening methods. Also, the ‘inhibitory‐circle method’ gave results in 30‐35 days, thereby substantially reducing the requirements for time, labour and cost.     

磷石膏在几种蔬菜作物上的应用试验

盆栽和田间试验结果表明，在施ＮＰ肥基础上，配合每亩施用１００－２００ｋｇ磷石膏，有利于增加土壤有效钙、硫和磷等养分，改善了蔬菜作物对钙素等养分的吸收利用，明显促进了蔬菜作物的生长发育。ＮＰ肥＋磷石膏处理比单施ＮＰ肥处理产量显著提高。甘蓝增产１０．８％－１３．１％，番茄增产９．６％－１０．８％，芹菜增产９．２％－１０．４％，白菜增产９．８％。经方差分析达到１％和５％极显著和显著水平。施用磷石膏改善蔬菜产品品质，适量施磷石膏对土壤主要农化性状无不良影响。     

Allelic variation, sequence determination and microsatellite screening at the XGWM261 locus in Chinese hexaploid wheat (Triticum aestivum) varieties

Wheat microsatellite XGWM261, due to its closely linked to the dwarfing gene Rht8, has been adopted as the diagnostic molecular marker of Rht8. Screening 408 Chinese and 98 exotic varieties showed 13 allele variants in locus of XGWM261, with 6 alleles only to be found in Chinese varieties and 2 only in exotic varieties, respectively. Sequencing results of the 13 alleles revealed their absolute fragment sizes with 216, 212, 210, 206, 204, 202, 200, 196, 194, 192, 190, 174, and 164 bp, respectively. Allelic distribution analysis showed that the 204, 192, 174, and 164 bp alleles were prevailing in Chinese varieties, and the diagnostic 192 bp allele to Rht8 had a very high percentage in the Yellow and Huai River Valleys Facultative Wheat Zone than in the Northern Winter Wheat Zone in China. The GT → AC substitution at position 35 was found in 216, 200, and 174 bp alleles. Moreover, the AG insertion immediately at the end of CT-repeat region was also found in 216, 200, 174, and 164 bp alleles.     

有限供水对春小麦不同类型品种的产量和生理效应

以红芒麦(旱地品种)、定西8139(2)(水旱地品种)和永良12号(水地品种)3种不同类型春小麦为材料进行有限供水试验,结果表明,有限供水能有效提高产量和水分利用效率(WUE),效应大小为:水地品种>水旱地品种>旱地品种.不同生育期,以拔节期效应最明显,灌浆期对旱地品种亦重要.相关分析表明,拔节期补水能有效促进幼穗发育,增加穗长和穗粒数;孕穗期和灌浆期补水对千粒重和经济系数影响最大;有限供水能改善春小麦的生理活动:ψw增高,Rs减小,Tr和Pn增加,Tr与ψ_w、Rs呈显着负相关.补水与干旱处理间的ψ_w差(水势变矩)与品种抗旱性有关,可作为抗旱性指标之一.     

森林培育措施对人工林红松木材力学性质的影响

森林培育措施是影响人工林木材材质的重要因素之一 ,木材力学性质是表明木材品质的主要因素 (成俊卿 ,1985 ) ,为实现林木定向培育 ,达到速生优质的目标 ,必须了解各种培育措施对木材各种性质的影响规律(Zobeletal.,1989;李坚等 ,1993)。人工林红松 (Pinuskoraiensis)是我国东北地区重要用材树种 (丁宝永等 ,1994 ) ,木材力学性质是由木材的生长速率、晚材率、木材密度及管胞的形态特征决定的 ,因此本文是在林分的生长速率、木材晚材率、木材密度及管胞的形态特征的影响基础上 (郭明辉 ,2 0 0 1;2 0 0 3)探索不同培育措施下人工林红松木材…     

长呼原油管道保温与不保温方案比选

基于长庆油田一呼和浩特石化原油管道工程项目沿线地形地貌和管输原油物性,依据相关标准,讨论了保温方案和不保温方案在设计参数、安全停输时间、经济投资等方面的差异.结果表明:相同管径下不保温方案的管道传热系数约为保温方案的2～3倍,加热油耗约为保温方案的2倍,安全停输时间比保温方案缩短15.5 h,同时总体投资比保温方案高出1 742×104元,费用现值比保温方案高出3.6×108元.因此该管道工程项目推荐采用保温方案,以减少热站数量和运行人员设置,降低运行管理费用.(表4,图4,参2)     

干酪乳杆菌LC2W抗菌物质的研究

采用异丙醇抽提的方法，从干酪乳杆菌LC2W（Lb．casei CGMCC NO．0828）细胞中抽提到痢疾志贺氏菌（S．dysenteriae CMCC（B）51387）具有拮抗作用的蛋白类物质。该物质对蛋白酶尤其是胰蛋白酶敏感，对热不敏感。采用SDS—PAGE聚丙稀酰胺凝胶电泳的方法测得抑菌物质的分子量分别为32．1，44．3，87．6kDa。     

淮北地区小麦高产栽培技术研究

本文通过对安徽省淮北地区小麦大田生产的穗粒结构调查与研究,系统地阐述了小麦产量构成三因素的相互关系以及苗情的调控指标,分析了高产与低产的原因,提出了淮北地区小麦高产栽培技术措施,并就高产栽培的关键问题进行了讨论。     

桉树体细胞培养研究进展

体细胞培养能获得稳定的遗传材料,还能通过变异获得抗性的育种材料。在现代科学技术的支撑下,通过体细胞培养来获得次生代谢物和进行细胞育种的技术不断完善。本文从桉树愈伤组织培养、原生质体培养、悬浮培养、体细胞胚胎发生和人工种子等五个方面对二十世纪八十年代以来桉树体细胞培养的研究进展进行了综述。