盐碱地紫花苜蓿品种筛选及耐盐性比较

为筛选适宜嘉峪关市盐碱地种植的紫花苜蓿优良品种,引进国内外10个紫花苜蓿品种,采用随机区组试验法进行了生产性能和耐盐性比较。结果表明,两茬鲜草和干草总产量位居前3位的品种是中兰2号、龙威和公农1号,鲜草产量分别为54 897.44、48 054.02、45 662.82 kg/hm2;干草产量分别为13 056.53、11 115.56、11 095.5 kg/hm2, 均与其他品种差异极显著。10个紫花苜蓿品种在耕层含盐量3.6 g/kg以下均能正常出苗,均具有一定耐盐性,中苜3号、中苜1号和中兰2号、龙威耐盐性较好。综合分析可得,中兰2号、龙威和公农1号这3个品种的丰产性、适应性、耐盐性等综合性状优良,适宜在嘉峪关市中轻度盐碱地种植。     

不同施氮水平下紫花苜蓿与玉米间作对白浆土腐殖质组成的影响

以紫花苜蓿间作玉米(以下简称玉米间作)以及玉米单作3年定位试验的白浆土为研究对象,以玉米单作为对照,探索玉米间作在不同施氮水平下对白浆土腐殖质组成的影响。通过140、175、200和225 kg/hm~2 4个施氮水平的设置,探索了两种栽培模式在玉米拔节期、抽雄期和灌浆期对白浆土总有机碳(TOC)以及水溶性物质(WSS)、胡敏酸(HA)、可提取腐殖酸(HE)及胡敏素(Hu)组分碳含量(C_(WSS)、C_(HA)、C_(HE)和C_(Hu))的影响,并分析胡富比(C_(HA)/C_(FA))、HA碱溶液E_4/E_6的变化。结果表明:(1)无论玉米单作或是间作紫花苜蓿,配施200kg/hm~2氮均可在玉米灌浆期充分抑制TOC的矿化分解,使TOC含量为6.69和6.93 g/kg,显著高于其他处理;(2)玉米单作或是间作结合140 kg/hm~2施氮量均可显著提高玉米灌浆期的C_(Hu),在此施氮水平下,TOC中CHE比例也可得到显著提高;(3)玉米单作结合较高施氮水平(200和225 kg/hm~2)、玉米间作结合较低施氮水平(140和175kg/hm~2)均有利于FA向HA的转化,改善腐殖质品质,尤其在玉米抽雄期和灌浆期,玉米单作结合200 kg/hm~2施氮量能够较好促进HA形成,使C_(HA)达到1.85和1.74 g/kg,显著高于其他处理,在该施氮影响下,玉米间作紫花苜蓿更易促进HA分子的芳构化程度。     

Amelioration strategies for saline soils: a review

Soil salinization is one of the major causes of declining agricultural productivity in many arid and semiarid regions of the world. Excessive salt concentrations in soils, in most cases, cannot be reduced with time by routine irrigation and crop management practices. Such situations demand soil amelioration. Various means used to ameliorate saline soils include: (a) movement of excess soluble salts from upper to lower soil depths via leaching, which may be accomplished by continuous ponding, intermittent ponding, or sprinkling; (b) surface flushing of salts from soils that contain salt crusts at the surface, a shallow watertable, or a highly impermeable profile; (c) biological reduction of salts by harvest of high‐salt accumulating aerial plant parts, in areas with negligible irrigation water or rainfall available for leaching; and (d) amelioration of saline soils under cropping and leaching. Among these methods, cropping in conjunction with leaching has been found as the most successful and sustainable way to ameliorate saline soils. Cropping during leaching or between leachings causes an increase in salt‐leaching efficiency because a decrease in soil water content occurs under unsaturated water flow conditions with a concurrent decrease in large pore bypass and drainage volume. Consequently, anaerobic conditions in soil may occur during leaching that can affect crop growth. Thus, in addition to the existing salt‐tolerant crop genotypes, research is needed to seek out or develop genotypes with increased tolerances to salinity and hypoxia. Since salt leaching is interacted by many factors, evaluation of the traditional concepts such as the leaching requirement (LR), the leaching fraction (LF) and the salt balance index (SBI) demands incorporation of a rapid, efficient and economical way of monitoring changes in soil salinity during amelioration. Besides this, numerous models that have been developed for simulating movement and reactions of salts in soils need evaluation under actual field conditions. Copyright © 2000 John Wiley & Sons, Ltd.     

Inoculant effects on alfalfa nodulation

Abstract

Alfalfa (Medicago sativa L.) does not grow as well as it used to in areas of Canada and northwestern United States. Affected plants have nitrogen (N)‐deficiency symptoms, few or no nodules, and respond to N fertilizer. For lack of a good explanation, such plants are called “sick”;.

Six commercial inoculant products were tested with alfalfa grown on cores of eight soils in which alfalfa establishment and stand duration have been problems, to determine if inoculant quality influenced development of any sick‐alfalfa symptoms. Percentages of nodulated plants ranged from 35 to 82 after 5 to 8 weeks’ growth, and corresponded closely with estimated rhizobia numbers in the products. Dry forage yields were not closely related to percentage nodulation, however, because of residual soil N levels that supported seedling growth. Inoculant products containing inadequate numbers of rhizobia to promptly and effectively nodulate plants resulted in poor nodulation that may lead to establishment failure or sparse, weak stands.

Contribution from the Central Oregon Exp. Stn. and Dep. of Microbiology, Oregon Agric. Exp. Stn. Journal Article No. 4910.     

管理调控措施对土壤盐分分布和作物体内盐分离子吸收的作用

通过盆栽试验 ,研究了不同管理调控措施包括施肥、灌溉、应用化学改良剂对盐渍土壤盐分分布和作物体内盐分离子吸收和分布的作用机制。结果表明 ,施用化学肥料可增大土壤电导率 ;灌水量增加可降低土壤电导率 ;施用改良剂CaSO4早期可引起土壤表层电导率升高 ,但到作物生长中、后期已与不施改良剂的相近。施肥、灌溉改善了作物生长条件 ,提高了作物的抗盐害能力。灌溉总量 375mm、三天一次的灌溉方式在降低土体盐分浓度、抑制土壤碱化方面优于两天一次的灌溉方式。大麦具有将Na 截留在茎中 ,从而减少Na 对叶片伤害的功能。大麦茎和叶中的Cl-含量都高于K 和Na 含量 ,显示较多的Cl-通过根部向地上部运输。在增加植株中K 含量、降低Na 含量 ,减轻植株盐分离子胁迫方面改良剂表现出良好的调控效果     

坡缕石对甘南高原紫花苜蓿生物学特性的影响

本试验采用田间单因素随机区组设计,研究了加施坡缕石对紫花苜蓿生物学特性的影响。结果表明:坡缕石用量750 kg·hm^-2~3 000 kg·hm^-2下,均能提高紫花苜蓿的产量和品质,3 000 kg·hm^-2时产量最高、植株最高,且较对照极显著增产41.72%(p<0.01),粗蛋白质、赖氨酸含量也最高,品质最优。这一研究结果在紫花苜蓿栽培中科学合理的将N、P、K肥料与坡缕石配施是提供了科学依据。     

紫花苜蓿耐逆诱变和转基因研究进展

本文简述了紫花苜蓿耐逆性状遗传基础研究,并综述了利用生物技术和诱变技术改良紫花苜蓿耐逆性的研究进展,旨在为紫花苜蓿的耐逆育种提供参考。     

毛乌素沙地杨树防护林内紫花苜蓿蒸散耗水规律的研究

本文利用验证后的Penman-Monteith模型,计算了内蒙古毛乌素沙地新疆杨防护林内紫花苜蓿的蒸散耗水,结果表明：(1)通过Penman-Monteith模型计算得到的蒸散量与涡度相关法实测值平均相对误差为14.73%(R²=0.84),说明利用Penman-Monteith模型计算林草复合模式内牧草蒸散量是可行的;(2)不同生育期内紫花苜蓿蒸散量差别较大,具体表现为：返青－分枝阶段、现蕾－开花阶段蒸散量较小,分别为5.03 mm和44.95 mm;分枝－现蕾、开花－结荚阶段蒸散量较大,分别为71.10 mm和101.74 mm;其中耗水最大的生育期为开花－结荚阶段,占整个生育期总耗水量的45.66%。在空间上表现为：随着距主防护林带距离增加,紫花苜蓿蒸散量逐渐增大,最大蒸散量出现在距离林带约115 m处(约7倍树高),为234.41 mm,之后,受另一侧防护林的影响,蒸散量逐渐减少。整个生育期防护林内紫花苜蓿总蒸散量为222.83 mm,对照地紫花苜蓿蒸散量为269.02 mm,与对照相比,防护林内紫花苜蓿比林外蒸散量降低了17.2%。防护林内和对照紫花苜蓿生物量干重分别为3287.28 kg/hm²和2959.93 kg/hm²,林内比对照增产11.1%。     

苜蓿接种根瘤菌和施肥对铁尾矿砂基质改良效果的影响

采用裂区试验设计方法,以铁尾矿砂为生长基质进行紫花苜蓿(Medicago sativa L.)盆栽试验,探讨了紫花苜蓿接种不同根瘤菌菌株和施肥水平对紫花苜蓿生长的影响,以筛选出明显促进紫花苜蓿生长的根瘤菌菌株与施肥水平的最佳组合。在最佳组合条件下,研究了紫花苜蓿连续种植2a后铁尾矿基质理化性质和生物学特性的变化。结果表明:(1)接种根瘤菌明显促进了紫花苜蓿根瘤重、根鲜重、地上部鲜重、株高的提高,其中以接种菌株17676的效果明显。(2)施肥对紫花苜蓿的生长有显著的促进作用。随着施肥水平的提高,紫花苜蓿的各项生长指标均逐渐增大,在5%施肥水平时最高,并且在5%施肥水平时紫花苜蓿地上部鲜重和株高与2.5%和1%2个施肥水平间差异显著。2.5%施肥水平下,紫花苜蓿根瘤重最大,但与5%施肥水平差异不显著。表明5%施肥水平对促进紫花苜蓿生长的效果最佳。(3)与对照(裸尾矿砂)相比,在5%施肥水平条件下,种植接种17676菌株的紫花苜蓿后,铁尾矿砂基质的理化性质和生物学特性均有了极为明显的改善(P0.01)。其中,容重显著下降,田间持水量和总孔隙度明显提高,pH值显著下降并接近中性,有机质和速效养分(碱解氮、速效磷、速效钾)含量显著提高,基质中的细菌、真菌和放线菌的数量以及土壤酶(过氧化氢酶、脲酶、蔗糖酶、磷酸酶和纤维素酶)活性明显提高。(4)与播种当年相比,种植紫花苜蓿2a的铁尾矿砂基质的理化性质和生物学特性均有不同程度的改善。其中,除了细菌和真菌数量以及有机质和碱解氮含量的提高效果不明显外,其他各项指标均达到了显著水平。表明5%有机肥水平条件下种植接种17676菌株的紫花苜蓿对铁尾矿砂基质的改良效果显著,紫花苜蓿种植年限对铁尾矿砂基质的改良效果也有重要作用。     

盐胁迫下AM真菌对紫花苜蓿生长及生理特征的影响

利用盆栽试验研究了NaCl胁迫条件下AM真菌对紫花苜蓿(Medicago sativa L.)植株生长及生理特征的影响。结果显示:随土中加入NaCl浓度增高(0%,0.5%,1.0%),与未接菌紫花苜蓿相比,接种AM真菌显著(P<0.05)促进紫花苜蓿生长,并使其可溶性糖、可溶性蛋白及根系脯氨酸累积量增加。1.0%NaCl接种AM真菌处理下根系鲜重(28.1 mg)为0%NaCl未接种下的1.27倍;不同盐处理接种AM真菌植株丙二醛含量均低于对照株;1.0%NaCl浓度下接种AM菌植株叶片及根系脯氨酸含量分别为对照株的0.82,1.41倍。表明AM真菌在胁迫环境下不仅可促进植株生长发育及渗透调节物质的积累,还可维持植物体丙二醛含量较低水平,降低植株遭受盐胁迫,推测叶片与根系脯氨酸对ABA依赖程度不同而导致其脯氨酸含量不同。     

田间越冬期不同根型苜蓿根系的生理生化特性

以根茎型清水苜蓿、直根型陇东苜蓿、根蘖型甘农2号杂花苜蓿和野生黄花苜蓿为试验材料,在田间条件下,测定3类根型的4个苜蓿品种(材料)在秋末至翌年初春根系脯氨酸、丙二醛、可溶性糖及可溶性蛋白质含量、过氧化氢酶和超氧化物歧化酶活性6项指标的变化,以研究不同根型苜蓿品种(材料)对低温的适应性.结果表明,4个苜蓿品种(材料)其脯...     

Fertilization Capacity of Aquatic Plants Used as Soil Amendments in the Coastal Sandy Area of Central Vietnam

In Central Vietnam, and more especially in Thua Thien Hue Province, aquatic plants are used empirically by some farmers as an external source of organic matter to improve fertility of sandy soils. The fertilization capacities of aquatic plant species [Najas indica (Willid.) Cham., Najas minor All., Vallisneria spiralis L. (Michx.) Torr., Hydrilla verticillata (L.f.) Royle, Potamogetum malaianus Miq., Myriophyllum spicatum L., Enteromorpha flexuosa (Wulfen) J. Agardh, Rhizoclonium kerneri Stockmayer, and Eichhornia crassipes (Mart) Solms] were assessed from a pot trial including soils amended with aquatic plants (5 g dry matter kg^?1 soil) and soils supplied with increasing rates of urea nitrogen (N) fertilizers. Rice (Oryza sativa L.) at a vegetative stage was used as a convenient bio‐extractor. The fertilization capacity of aquatic plant amendments was calculated from aboveground biomass and from N accumulated in shoots as compared to treatments receiving only inorganic N fertilizers. Najas indica (Willid.) Cham. and Hydrilla verticillata (L.f.) Royle showed the greatest fertilization capacity, equivalent to 170–180 mg urea‐N kg^?1 soil as estimated from biomass yield, whereas a lesser fertilization capacity, equivalent to less than 100 mg urea‐N kg^?1 soil, was observed for Myriophyllum spicatum L., Enteromorpha flexuosa (Wulfen) J. Agardh, Rhizoclonium kerneri Stockmayer, and Eichhornia crassipes (Mart) Solms. This study provides quantitative data on the fertilization capacity of aquatic plants found in the coastal area of central Vietnam, which can improve this empirical practice and alleviate local agro‐environmental constraints related to the lack of organic matter in farming systems.     

基于典范对应分析的干旱区春季盐渍化特征研究

运用常规统计学和典范对应分析方法,对干旱区盐渍土土壤全盐量(TS)、盐分离子组成、碱化度(ESP)、pH、电导率(EC)的空间分布特征进行了分析。结果表明,该区土壤为重度至轻度盐化,不同层次土壤中,Na+与Cl-、Ca2+与Mg2+保持较好的关联性。TS的空间分布,在0～50 cm全剖面上主要受控于Cl-、HCO3-和Na+离子;分层与全剖面的情况略有不同,Cl-、Na+在各个土层仍为主要控制离子。ESP在全剖面上其空间分布受环境因子的影响较小,0～10 cm土层主要受Na+与Cl-离子的制约;10～30 cm土层内主要受HCO3-离子的制约;30～50 cm土层未表现控制因子。pH在全剖面上受盐分离子的影响较小,分布较为均匀,表层受离子影响很小,在10～30 cm、30～50 cm土层内受HCO3-离子的影响微弱。EC在全剖面上的空间分布受控于Ca2+、Mg2+离子,30～50 cm土层主要受K+离子的控制,其他土层与全剖面相同。