提高杂交玉米制种质量和产量的措施

<正>近几年,种子市场竞争激烈,为稳步经营,必须从源头抓起,在抓好种子产量的同时,还要提高种子质量。为提高杂交玉米制种产量和质量,应重点抓好以下几个环节的工作:一、地块选择选择灌排方便、土地平整、保墒性能好、肥力中等以上、隔离条件好的地块。前茬以油菜、小麦、草木樨、豆类、各种瓜菜等作物为最佳,不宜选前茬为向日葵、玉米、棉花、甜菜的地块。二、隔离条件空间隔离,为保证种子质量,制种田四周要有一     

C语言中函数参数传递问题探讨

讨论了C语言函数调用中的各种参数传递形式。通过举例分析探讨,总结出了函数参数传递的一些规律,可以有效地帮助学生在学习C语言时加深理解。     

基于Atmega64的直流电动机软起动器设计

直流电动机是重要的生产设备，起动是影响其寿命的关键因素。以蓄电池系统供电的直流电动机为研究对象。设计一种靠单片机控制，以IGBT为功率开关元件，采用PWM斩波降压的新型软起动器。相比传统的机械式起动器，它能实现连续无级的调节电动机起动，冲击转矩和冲击电流小，起动重复性好。     

全球化背景下少数民族大学生国家认同研究

世界的全球化与现代化浪潮,逐步撼动着民族国家的根基,冲击着少数民族大学生既有的国家认同理念,进而导致他们政治认同上的弱化性、文化认同上的兼容性、身份认同上的多重性。少数民族大学生的国家认同关系到社会和谐、民族团结和国家统一,以价值共识引导少数民族大学生国家认同,以历史文化培育少数民族大学生国家认同感,以公民教育促进少数民族大学生国家认同。     

Effects of Bacillus amylolyticus on Rumen Dry Matter Digestibility,Fermentation Parameters and Metabolites of Dairy Cows北大核心CSCD

This experiment was conducted to study the effects of Bacillus amylolyticus on rumen dry matter digestibility, fermentation parameters and metabolites of dairy cows. Experiment 1: six dairy cows with permanent fistula and had the similar parity (2 to 3 fetuses), body weight [(662 ±57) kg], lactation days [(160 ± 22) d] and milk yield [(36.1 ±3.8) kg / d], were randomly divided into 3 groups with 2 cows per group. Using 3 ×3 Latin square design, each group was extra fed 0 (control group), 5 ×109 and 5 ×1010 CFU / d Bacillus amylolyticus, the trial period was 3 periods, 13 days for each period, including 10 days for the pre-trial period and 3 days for the trial period. At the beginning of the trial period, the rumen dry matter digestibility of cows was measured by nylon bag method. Experiment 2: thirty dairy cows with similar parity [(2.5 ±0.3) fetuses], initial body weight [(559.2 ± 7. 4) kg], milk yield [(35. 2 ± 1. 5) kg / d] and lactation days [(99 ± 22) d] were randomly divided into three groups with 10 cows in each group. Cows in the 3 groups were extra fed with 0 (control group), 5 ×109 and 5 ×1010 CFU / d Bacillus amylolyticus, respectively. The pre-trial period was 10 days and the trial period was 42 days. The rumen fluid was collected on the last day of the trial period, and the rumen fermentation parameters and metabolites were determined. The results showed as follows: compared with the control group, 1) supplementary feeding of 5 × 1010 CFU / d Bacillus amylolyticus could significantly improve the rumen dry matter digestibility of dairy cows at 12, 24, 36, 48 and 72 h (P <0.05), supplementary feeding of 5 ×109 CFU / d Bacillus amylolyticus could significantly improve the rumen dry matter digestibility of dairy cows at 36 and 48 h (P <0.05); 2) supplementary feeding of 5 ×109 CFU / d Bacillus amylolyticus could significantly increase the contents of isobutyric acid, butyric acid, isovaleric acid, valeric acid, total volatile fatty acid and microbial protein in the rumen of dairy cows (P < 0. 05), supplementary feeding of 5 × 1010 CFU / d Bacillus amylolyticus could significantly increase the contents of isobutyric acid and isovaleric acid in the rumen of dairy cows and significantly reduce the rumen acetic acid / propionic acid (P < 0. 05), supplementary feeding of 5 ×109 and 5 ×1010 Bacillus amylolyticus had no effects on rumen pH and ammonia nitrogen content (P >0.05); 3) eleven metabolic pathways related to differential metabolites were detected, and ascorbic acid and alginate metabolism were significantly enriched (P < 0. 05) . In conclusion, Bacillus amylolyticus can increase the rumen dry matter digestibility, and improve the rumen fermentation function of dairy cows by affecting the content of rumen metabolites. By comprehensive analysis, supplementary feeding of 5 × 109 CFU / d Bacillus amylolyticus can achieve better effect. © 2023 Authors. All rights reserved.     

农作物秸秆还田机械化技术及作用要点

农作物秸秆还田机械化技术,就是用秸秆粉碎机将摘穗后的玉米、高梁、稻麦等农作物秸秆就地粉碎,均匀地抛撒在地表,随即耕翻入土,使之腐烂分解,达到大面积培肥地力的一项农机化适用技术。要提高秸秆还田的效果,在作业过程中必须注意以下几点技术要求。1　配合施用氮磷化肥　　秸秆直接还田时,作物与微生物争夺速效养分的矛盾,特别是争氮现象,可通过补充化肥来解决。通常秸秆的碳氮比约为80～100:1,为此,应适当增施氮素化肥,对缺磷土壤则应补充磷肥。据试验,玉米秸秆腐解过程需要的碳、氮、磷比例为100:4:1左右。2　秸秆粉碎与翻埋方法　…     

腐植酸对西瓜种子萌发及其生理特性的影响

以小果型西瓜"黄蜜隆"为试材,采用室内浸种法,研究了不同浓度的腐植酸对西瓜种子萌发及芽苗生长和生理特性的影响,以期探明腐植酸促进西瓜种子萌发作用效果及其生理机制.结果表明:不同浓度腐植酸处理均可不同程度提高根系活力、叶绿素和脯氨酸含量及超氧化物歧化酶(SOD)活性,降低丙二醛(MDA)含量,从而使种子萌发整齐,种子的活力指数提高,芽苗生长粗壮.综合考虑,以1 200 mg·L-1处理效果最佳,其发芽势、芽苗株高显著高于对照,活力指数、芽苗胚轴粗度、胚轴长度和鲜质量/干质量分别比对照提高43.31％、5.64％、29.96％、25.26％,且均高于其它处理.相关性分析结果表明,种子发芽势、芽苗株高、胚轴长度、胚轴粗度、鲜质量/干质量等指标与腐植酸浓度关系密切,可通过改变腐植酸的浓度调节种子发芽势和芽苗生长;根系活力、超氧化物歧化酶(SOD)活性对腐植酸处理的响应起关键作用,可作为主要的生理调节因子.     

大豆资源对斜纹夜蛾的抗性鉴定

利用网室采集的57份大豆资源的叶片,室内喂养刚孵化的斜纹夜蛾幼虫,以幼虫重为指标,鉴定大豆资源对斜纹夜蛾的抗性.综合2001年和2002年的鉴定结果,品种间、年份间、品种与年份互作差异均达极显著水平.根据标准品种分级法对抗性鉴定结果进行划分,从供试的大豆资源中筛选出4个高抗和3个高感的标准品种,可以用于抗性的分级及抗虫新基因的发掘.     

盐碱地水产养殖技术100问(一)

我省是一个贫水的省份,内陆养殖用水日趋紧张,但我省的地下半咸水和盐碱荒地资源丰富,开发利用这些资源,将会对我省水产业发展提供更广阔的空间。中国水产科学院东海水产研究所连续几年在沧州市研究利用地下半咸水开发盐碱荒地养虾项目取得了阶段性成果,解决了盐碱荒地利用中的关键技术难题。在此基础上,我省水产部门立项推广该成果。为了配合项目开展,进一步开发利用覆盖沧州、保定、邯郸、衡水、廊坊、唐山的荒废盐碱地资源,促进农民增收和农村经济综合发展,本刊拟连续刊登中国水产科学院东海水产研究所王慧研究员编写的“盐碱地水产养殖技术100问”。希望读者学习并从中受益。     

盐碱地水产养殖技术100问(二)

15 怎样计算池塘水体? 虾池采用全池泼洒消毒剂防治虾病时,必须正确计算虾池水体体积、计算用药量.计算水体体积,需要测量出池塘水面积和平均水深,然后计算出池水体积.按照池水体积,就能计算出适当的用药量.