内蒙古乌拉盖草原湿地中下游植被退化演替趋势分析

针对内蒙古锡林郭勒盟东乌旗乌拉盖草原湿地植被退化问题,采用植被生态调查方法进行生态损伤评估和植被演替趋势分析.调查结果表明:在乌拉盖河截流5年内,乌拉盖湿地中下游植被退化迅速,原生植被的建群种和优势种基本消失,群落高度和盖度迅速降低,原生植被群落重要值显著降低,次生植被群落重要值增加;植物种的数量大量减少,植物多样性严重降低;一年生草本植物数量和比例明显高于多年生草本植物,部分荒漠化严重地区还出现超旱生植物小果白刺(Nitraria sibirica Pall.);乌拉盖草原湿地已经从草原湿地植被演替为碱蓬盐化草甸植被和盐漠化裸地.     

核桃枝枯病病原菌鉴定及其生物学特性

In May 2018,a new shoot dieback disease was found in several walnut orchards in Rizhao,Shandong Province.The fungal pathogen was obtained on PDA plate from diseased walnut shoots using a tissue isolation method.The purified fungal isolates formed white to grey colonies on PDA plate and three single spore isolates SDWa1-SDWa3 were obtained.Based on morphological characteristics and analysis of rDNA internal transcribed spacer (ITS),calmodulin (CAL),translation elongation factor 1-α (TEF1) and β-tubulin (TUB) sequences,the fungal isolates were identified as Diaporthe nobilis,a new pathogen on walnut.The test of Koch's rule confirmed that D.nobilis was the pathogen of walnut shoot dieback.To determine optimal growing conditions for the pathogen,its biological characteristics test was conducted.The results showed that the optimal growth temperature and pH value were at 25℃ and pH 5-9,respectively.The optimum carbon source was glucose,and favourable nitrogen source was peptone.     

无瓣海桑种子特征及不同贮藏环境下萌发特性的研究

种子的萌发除了与自身的生理结构、萌发时外界条件有关外,不同的贮藏条件和时间处理对种子萌发也有影响.本实验以无瓣海桑种子为研究对象,通过无瓣海桑种子的基本特征及不同贮藏环境(常温、常温干燥、-4℃、-70℃分别对应Ⅰ、Ⅱ、Ⅲ、Ⅳ)和时间(15,30,45,60,90 d)下其种子萌发特性的分析发现:径级对无瓣海桑的果重和种子的粒数均有显著影响;低温处理可显著缩短种子的萌发时间,同时有助于保持无瓣海桑的种子活性;无瓣海桑种子的活力会随着贮藏时间的增加而下降,因此不适宜长期贮藏,但短期贮藏时低温干燥贮藏可较好地保持其种子活力.     

栽培措施对萝卜生长特性及产量的影响

研究不同栽培措施对萝卜生产的影响,结果表明:试验条件下,播种太早或太迟,对萝卜生长都不利,"瑞雪"萝卜最适播种期应为9月25日至11月5日;利用地膜覆盖,萝卜地上部和地下部的生产速度明显提高,生育期提早,产量比露地提高了36.64%;每667m2种植密度以6 500~7 500株为好。     

自动折叠喷洒臂的设计及运动学特性

为了解决当前卷盘式喷灌机所配套的喷灌车自动化水平较低的问题,设计了一种基于电动缸驱动的自动折叠喷洒臂,并在喷洒臂之间连接处设计了一种当喷洒臂完全展开时能够实现自密封的端面密封铰链.基于喷洒臂完全折叠时收拢于车架两侧,完全伸展时铰链左右铰合密封等特征建立各杆件参数约束方程,确定了喷洒臂的各杆件尺寸.通过矢量方程法对喷洒臂进行运动学分析,以电动杆推杆的转角、位移、速度、加速度为输入量,各杆件的角位移、角速度、角加速度为输出量,通过Simulink搭建喷洒臂的运动仿真框图并进行分析.结果表明:完全折叠时,喷管1与水平方向呈90°夹角;伸展过程中,各喷管运动平稳,且始终保持在水平直线方向;完全展开时,3个喷管转动90°,且各喷管铰接处完全闭合不发生水泄漏现象,说明设计具有一定的合理性.     

Nutrient cycling and biomass flows in a low-quality forest stand improvement system in the Lesser Khingan Range of China

The material flow and bulk internal flow analyses were used to establish a material accumulation and cycling model for a low-quality forest stand improvement system and a series of processes were considered. The model was applied in a one-hectare low-quality forest plot in the Lesser Khingan Range of China. Results showed that during 1997–2007, the stands absorbed 270.19 kg of N, 74.28 kg of P, and 124.39 kg of K from soils, 51.82 kg of N and 2.38 kg of P were directly absorbed by foliage, and 16.25 kg of K was released to soils by eluviation. Until 2007, the accumulated nutrients in the stands included 236.91 kg of N, 65.28 kg of P, and 108.55 kg of K. When horizontal strip clearcutting was applied in 2007, 50% accumulated nutrients in the stands were shifted due to harvesting operations, and 212.74 kg of N, 26.97 kg of P, and 98.88 kg of K were accumulated in soils, declining by 9.47% for N, 3.68% for P, and 17.60% for K, respectively, compared with year 1997. 94.61 t per hectare of biomass was generated, of which the biomass in stands accounted for 87.36%. The felled tree biomass was 36.89 t per hectare, of which 84.90% and 10.03% of biomass were utilized in terms of logs and other means, and the rest was left on site.     

杂交稻三香优410的特征特性及栽培技术

三香优410在建瓯种植,表现出丰产性好、抗性较强、米质优良等特性,栽培上要注意选好秧田、培育壮秧、合理密植、科学施肥、做好水管、病虫防治。     

大英县近10年降水变化特点分析

利用大英县2004 ～2013年逐日降水资料,采用统计学方法,对大英近10年降水的实际变化特点、季节差异等进行简要阐述,并对直接影响工农业生产和人们生活、外出旅游以及交通运输等的暴雨进行了重点统计分析.结果表明,2004～2013年大英县年雨量和暴雨日数分布特征均呈单峰型,峰值均出现在7月;暴雨雨量、雨日与年降雨量存在明显的正相关关系;夏季同月雨量差距巨大;初秋的9月出现暴雨的概率较大,月雨量、暴雨出现次数均为全年的次高值;大英县出现秋绵雨的概率达50％,集中出现在9、10月.     

土壤pH值对极小种群毛枝五针松生理特性的影响

幼苗建成期是毛枝五针松(Pinus wangii)天然更新的关键阶段,为找出影响毛枝五针松幼苗存活的关键生态因子,采用植物生理学方法,研究在7个酸碱度土壤培育下,毛枝五针松松针超氧化物歧化酶(SOD)、过氧化物酶活性(POD)活性和脯氨酸、可溶性糖质量分数及丙二醛(MDA)摩尔质量浓度的变化。结果表明:毛枝五针松在弱碱土壤中抗逆性更强,形态观察得知其在弱碱性土壤中生长更好;生理指标测定结果表明,土壤在p H=7.69~8.42时最适宜毛枝五针松幼苗的生长发育。     

防护条件下梭梭幼苗生长及养分吸收特性

以新疆古尔班通古特沙漠南缘管件防护与传统移栽2种方式移栽的梭梭幼苗为实验材料,通过野外监测与室内分析,探讨了管件防护条件下梭梭幼苗的生长及养分吸收特性。结果表明:整个生育期内,管件防护梭梭幼苗的各生长指标与传统移栽苗相比,增幅最大的为茎粗,其次为株高。年周期内管件防护梭梭幼苗的生物量呈递增趋势,单株生物量累积可达45.25 g·株~(-1);净增加27.10 g·株~(-1),是传统移栽苗的1.38倍(P0.05)。管件防护梭梭幼苗体内的氮素、磷素、钾素含量呈先升高后降低趋势,在同化枝生长期达到峰值,分别为11.376 g·kg~(-1)、1.066 g·kg~(-1)和23.340 g·kg~(-1),较传统移栽苗高24%、15%和8%,差异显著;而其梭梭幼苗氮素、磷素、钾素的总积累量却呈递增趋势,年净增积累量分别为0.297 g·株~(-1)、0.027 g·株~(-1)和0.560 g·株~(-1),是传统移栽苗的2.23倍、1.72倍和1.65倍;各时期梭梭幼苗体内的氮素、磷素、钾素含量及总积累量均高于传统移栽苗。