DYNAMIC MODELS OF AQUIFEROUS CONTENT OF LIVING FUELS     

罗光裕 《林业研究》1994,5(1):41-44

RESEARCHSITELivingfue1splayedanimportantroleinheatconcentrationactionorinheatsourceofforestfire.Whenitshumiditydecreasestoacertainlevel,theybecameaheatsourcewhenthelivingcombustibl-eswerecombinedwithfire.Thus,itwasessentialhowtodeterminethemoisturesituationandthefOrestfiredangerdegreetobeforecastedaccurately.Thedynamicmodelspresentedinthispaperwereusefultosolvethisproblem.Everyyear,-therewerealotofforestfires,especiallythefireoccurrenceinDaxinganMountains,inthespringofl987.Itwasveryimpo…  相似文献   

低聚糖对雏鸡大肠粪便NH3-N含量及肠道菌群的影响   总被引：11，自引：0，他引：11  

王宝维  任慧英  朱新产  史美丽  王述柏  葛文华  刘光磊 《中国家禽》2003,25(8):8-10

试验选取1日龄罗曼蛋公雏250只，随机分为5组，试验组饲料或饮水中分别添加海藻糖(500mg／kg)、海藻胶(600mg／kg)、大豆寡糖(500mg／kg)、圆葱寡糖(500mg/d)。结果表明，四种低聚糖均可促进肠道乳酸菌及双歧杆菌的生长繁殖，对魏氏梭菌的生长呈现抑制作用。海藻糖、海藻胶对降低大肠粪便NH3—N含量效果不显著(P＞0．05)，而大豆寡糖效果显著(P＜0．05)，圆葱寡糖效果极显著(P＜0.01)。  相似文献   

高生物钙线椒新品种“陕椒2001”     

庄灿然 《辣椒杂志》2003,(4)

线辣椒为陕西省的传统名优特品种。也是唯一能在全国起拳头的出口创汇产品。因其具有“果色鲜红和品佳味香”的特点,在国  相似文献   

Evaluation of a combined penetrometer for simultaneous measurement of penetration resistance and soil water content     

Yurui Sun  Peter Schulze Lammers  Daokun Ma 《植物养料与土壤学杂志》2004,167(6):745-751

A combined penetrometer is an appropriate tool to measure the soil cone resistance and the water‐content profile. As a relatively new technique, a combined capacitance‐penetrometer for the simultaneous measurement of cone index and soil water content was developed at the Department of Agricultural Engineering of Bonn University in 2002. The objective of this study was the evaluation of the effectiveness and applicability of the innovated penetrometer with a focus on three aspects: (1) A capacitance sensor with two electrode configurations was calibrated for silt loam, sandy loam, and sand. The calibration results show that both electrode configurations have sufficient water‐content sensitivity, but soil‐specific calibrations seem necessary. (2) Under laboratory conditions, the dynamic resolution and response of the capacitance‐penetrometer were validated, and its radius of influence was determined. (3) The field measurement results demonstrate that this measurement technique can be used to improve the interpretation quality of soil cone index data.  相似文献   

Genetic diversity of herbicide-resistant and -susceptible Avena fatua populations in North Dakota and Minnesota     

L W MENGISTU  C G MESSERSMITH  & M J CHRISTOFFERS 《Weed Research》2005,45(6):413-423

Genetic diversity within and among 20 herbicide-resistant (HR) and 16 herbicide-susceptible (HS) Avena fatua multi-field populations was determined using 82 polymorphic loci resulting from two intersimple sequence repeat (ISSR) primers and one long-primer random amplified polymorphic DNA (LP-RAPD) primer. Collections from the Red River Valley of North Dakota and Minnesota, sampled in 1964 and 2000, represented A. fatua populations before and after intensive exposure to herbicides. A 1995 collection from south-west North Dakota represented A. fatua exposed to low herbicide selection. Despite differences in years of herbicide exposure among collections, both HR and HS populations from every collection maintained nearly similar levels of ISSR and RAPD diversity. Genetic differentiation among populations (G_ST) varied from 11% to 13% among HR populations and from 9% to 16% among HS populations, indicating that 84–91% of total variation remained within HS or within HR populations. Minimal difference in gene diversity between HR and HS is consistent with multiple origins of resistance, where HR A. fatua most likely evolved from diverse founding individuals.  相似文献   

油葵杂交种含油率与地理位置的关系研究   总被引：8，自引：2，他引：6  

王鹏冬  杨新元  白冬梅  张学武  贾爱红  张捷 《中国油料作物学报》2002,24(4):38-42

对2001年全国油用型向日葵杂交种联合区域试验中12个杂交种的子实含油率和籽仁含油率与地理位置关系进行了分析。结果表明:油葵杂交种子实和籽仁含油率与海拔高度存在着明显正相关,相关系数分别为0.7607和0.8228,个别杂交种的直接回归达显著水平;杂交种间与纬度相关不一致,有正相关、负相关,相关系数最大为-0.7177和-0.5767,最小为-0.0754和0.0019。对两因素综合分析比较,海拔高度对含油率的影响比纬度大,二者偏回归系数T检验值分别为2.0534(海拔)>0.8222(纬度)、8.0523 (海拔)>4.4233 (纬度)。  相似文献   

施肥对红三叶群落营养元素含量和积累量的影响   总被引：1，自引：0，他引：1  

杜占池  钟华平 《四川草原》2001,(4):14-16

本文研究了施肥对红三叶群落地上部和地下部 1 0种营养元素的影响 ,结果如下 :( 1 )从含量看 ,施氮肥后 ,地上部B明显降低 ,地下部B明显升高 ;施磷肥后 ,地上部N、B显著下降 ,地下部K、P、N上升幅度较大。 ( 2 )就积累量而言 ,施氮肥后 ,地上部大多数元素增高 ,地下部多数元素降低或无变化 ;施磷肥后 ,无论地上部还是地下部 ,大多数元素均有所增高  相似文献   

花生DNA导入大豆育种效果的研究   总被引：3，自引：0，他引：3  

王丕武  张晓玲 《吉林农业科学》1994,(3):18-20,55

利用花粉管通道在大豆自花授粉后将花生ＤＮＡ导入栽培大豆受体中，引起受体的结荚习性、株高、成熟期，主茎节数、分枝数、产量性状和化学品质等性状的广泛变异。对变异株进行选择，获得了产量比受体提高１１．９％～２５．１％，蛋白质含量提高３．９％～５．３％的变异株系。实验结果表明：利用外源ＤＮＡ导入技术进行生态性状、产量性状和化学品质方向的育种是可能的。  相似文献   

植物在水分胁迫下脯氨酸积累的研究─—Ⅳ关于植物体内脯氨酸积累的直接触发因子     

马宗仁 《草业科学》1994,(1)

依据干旱胁迫下数种植物幼苗体内游离脯氨酸、叶气孔、叶水量的变化，剖析了植物与环境因子、气孔因子、氧气因子、酶因子及能量因子之间的相互依存关系，提出了ＰＲＯ积累系统（ＰＡＳ）。认为水分胁迫下植物体内ＰＲＯ的大量积累是氧化受抑和合成受激共同调控的结果。氧气最有可能为直接触发因子。  相似文献   

Stoffbildung, CO₂-Gaswechsel, Kohlenhydrat- und Stickstoffgehalt von Winterweizen bei erhöhter CO₂-Konzentration und Trocken-streß     

J. Müller 《Journal of Agronomy and Crop Science》1993,171(4):217-235

Dry Matter Production, CO₂ Exchange, Carbohydrate and Nitrogen Content of Winter Wheat at Elevated CO₂ Concentration and Drought Stress
Methods of mathematical modelling and simulation are being used to an increasing degree in estimating the effects of rising atmospheric CO₂ concentration and changing climatic conditions on agricultural ecosystems. In this context, detailed knowledge is required about the possible effects on crop growth and physiological processes. To this aim, the influence of an elevated CO₂ concentration and of drought stress on dry matter production, CO₂ exchange, and on carbohydrate and nitrogen content was studied in two winter wheat varieties from shooting to milk ripeness. Elevated CO₂ concentration leads to a compensation of drought stress and at optimal water supply to an increase of vegetative dry matter and of yield to the fourfold value. This effects were caused by enhanced growth of secondary tillers which were reduced in plants cultivated at atmospheric CO₂ concentration. Analogous effects in the development of ear organs were influenced additionally by competitive interactions between the developing organs. The content and the mass of ethanol soluble carbohydrates in leaves and stems were increased after the CO₂ treatment and exhausted more completely during the grain filling period after drought stress. Plants cultivated from shooting to milk ripeness at elevated CO₂ concentration showed a reduced response of net photosynthesis rate to increasing CO₂ concentration by comparison with untreated plants. The rate of dark respiration was increased in this plants.  相似文献