干旱条件下土壤盐分对大豆生长及光合作用的影响

以盆栽大豆为材料,设置不同程度的土壤盐分(NaCl)、干旱及旱盐组合处理,然后测定各处理大豆植株的株高、生物量、光合作用指标以及植株的水分状况和Na~+、K~+含量,探索干旱条件下土壤盐分对大豆生长的影响及可能机制。结果表明:干旱和盐胁迫均可导致大豆叶片的净光合速率降低和生长量的减少,干旱还导致光合机构的严重损伤。但是,干旱和适量土壤盐分(100~150 mmol·L~(-1)NaCl)组合处理的大豆植株,其生长量、净光合速率和PSⅡ最大光化学效率都显著高于单一干旱处理。同时,旱盐组合处理的大豆叶片RWC、Na~+含量也高于单一干旱处理,水势和渗透势低于后者,且叶片Na~+含量与其渗透势降低显著相关。综合分析表明,在干旱条件下,土壤适量NaCl的存在使大豆能够吸收和积累更多Na~+等盐离子作为渗透调节物质,来降低渗透势、提高吸水能力,以改善植株的水分状况和光合性能,保持植株较高的生长速率,即土壤中适量盐分(NaCl)的存在可减轻干旱对大豆的负效应。     

大豆抗旱种质的鉴定及其与根系的关系

从辽宁省主要推广品种中选出20份优异种质资源,依据株高、叶面积指数、茎、叶生物量为指标,采用平均隶属函数值方法鉴定了大豆苗期耐旱性.结果从供试材料中共筛选出大豆生长前期较强耐旱型(2级)品种2个,干旱较敏感型(4级)品种3个,中间型(3级)品种15个.大豆的平均耐旱隶属函数值与干旱胁迫下的相对根表面积、相对根生物量分别...     

不同降雨条件对不同耐旱型大豆根系的影响

为了明确耐旱型大豆根构型的特异性,田间条件下,以不同耐旱型大豆为研究对象,探讨不同降雨条件对大豆根系特性的影响。结果表明:干旱胁迫降低了各时期大豆植株的根和地上部生物量;同一地点,R2和R4期取样,辽豆14的根和地上部生物量高于辽豆21。随着生育进程的推进,根冠比值逐渐增大;一般而言,V4~R4期,干旱胁迫提高了植株的根冠比。苗期干旱胁迫显著提高了大豆根长,但结荚期和鼓粒期干旱胁迫均降低了大豆根长、根表面积。大豆根长占比以细根为主,平均根直径≤2.5 mm的根长比例均在90%以上。根表面积占比也主要以细根为主,但大豆根体积分配比例较高的却主要是根系直径2.5 mm的粗根。研究结果进一步丰富了耐旱基因型大豆根器官应答干旱胁迫的理论知识,对大豆抗旱生产栽培具有重要的理论价值和实践意义。     

植物木质部水势对叶片延伸和渗透调节的影响

本实验在良好灌水、土壤缓慢干旱7d以及在干旱周期过程中通过给根部加压来维持高的叶片木质部水势条件下,测定了小麦和羽扇豆的叶片延伸速率和完全膨压下的渗透压。尽管随着土壤含水量的降低完全膨压下渗透压以及渗透调节的程度可能增加,但随着土壤干旱木质部水势高的并不能阻止叶片延伸速率的降低。随着土【壤含水量降低,具有较高木质部水势的叶与木质部水势降低的叶片相比,其延伸速率降低得更多,渗透调节的程度更大。小麦和羽扇豆叶片的渗透调节与叶延伸速率的降低呈线性相关。     

大豆种质的耐旱性鉴定及耐旱指标筛选

干旱是影响大豆产量的重要因素之一,建立相对稳定的耐旱鉴定方法、发掘耐旱品种是大豆耐旱育种的前提。基于前期对87份大豆材料耐旱性的初步鉴定结果以及对其中30份大豆材料耐旱等级划分重复鉴定的基础上,选取了代表性大豆材料12份,对分别反映萎蔫情况、叶片相对含水量、生长状况的10个耐旱相关指标进行测定。结果表明:与对照相比,干旱胁迫下大豆的叶片相对含水量降低,叶片相对电导率升高,大部分材料的生长受到抑制,生物量降低,根冠比增加,以上指标在不同材料间均存在显著差异(P0.05)。萎蔫天数的遗传率为93%,是简单、直观、稳定的耐旱鉴定指标。相关性分析表明:萎蔫等级、叶片相对电导率分别与萎蔫天数呈极显著负相关,叶片相对含水量、根相对干重分别与萎蔫天数呈极显著正相关,且这些指标具有较高的遗传率(73%~89%),亦可作为耐旱鉴定的指标。筛选到的PI595843、科丰1号、五河齐黄豆等耐旱种质可为大豆耐旱育种提供材料基础。     

高粱抗旱机理及保苗技术

高梁对干旱具有广泛的适应性,在干旱条件下,通过加强水分的吸收和减少水分的散失来抵御干旱逆境,高粱叶片细胞在低水分下保持较高的膨压是其抵御干旱逆境的机制之一。高粱可在玉米、小麦和大豆不能忍耐的干旱条件下,获得一定产量。抗旱播种方法大体可分为三类。在水资源严重短缺的干旱和半干旱地区应大力发展耐旱和抗旱的高粱。     

不同嫁接方式下大豆对干旱胁迫的响应

为明确大豆地上和地下部分对干旱胁迫的响应及对产量的影响，以用于大豆抗旱改良，利用耐旱型品种 辽豆14与干旱敏感型品种辽豆21进行相互嫁接，采用盆栽试验，在结荚期进行水分胁迫处理（土壤含水量保持在 田间持水量的50%）13 d后，测定大豆叶片相关生理指标和各器官生物量。结果表明，水分胁迫使辽豆21自身嫁接 植株叶片的叶色值、叶面积、PSII 系统光化学量子产量Y（II），调节性能量热耗散Y（NPQ）、最大电子传递速率 ETRmax、半饱和光强下最小饱和光强Ik显著降低，非调节性能量热耗散Y（NO）显著提高。无论以哪个品种为砧木， 与辽豆21相比，辽豆14作为接穗始终具有较高的叶色值、叶面积、Y（II），Y（NPQ）、ETRmax和Ik，从而获得较高的植 株生物量。另外，干旱条件下，辽豆14作为砧木具有较高的根系活力，能使辽豆21接穗的叶面积、Y（II），Y（NPQ）、 ETRmax和Ik显著提高，最终获得荚重的增加。由此说明，大豆PSII性能和物质生产能力主要由地上部叶片特性决 定，但干旱下大豆的生长也会受到根系生理活性的影响。     

茶树叶水势,萎蔫系数与耐旱力的关系

本文研讨了“七五”以来新育成的浙农１２１等６个茶树良种叶水势和萎蔫系数与耐旱力的关系,结果表明,不同供水水平,不同茶树品种叶水势与萎蔫系数的变化趋势大体一致;高湿,中湿条件下,叶水势变化小,低湿条件下,叶水势明显,下降幅度大;叶水势高,萎蔫系数低的茶树品种,耐旱力较强。     

不同土壤水分条件下吲哚丁酸钾对大豆根系形态建成及生理代谢的影响

为了研究吲哚丁酸钾（IBA-K）在减轻干旱对大豆根系的伤害中的作用,以垦丰16（干旱敏感型）和合丰50（耐旱型）为材料,采用盆栽法研究IBA-K拌种对两个品种大豆在正常供水、干旱和复水条件下根系形态建成及生理代谢的影响。结果表明,与正常供水相比,干旱胁迫抑制了大豆根系的生长发育,而IBA-K处理后,大豆根系干物质积累量、形态建成、抗氧化酶活性和渗透调节物质含量在不同土壤水分条件下均高于其干旱对照,膜受损程度减轻。IBA-K处理下,大豆根系SOD活性、POD活性、可溶性糖和脯氨酸含量在干旱条件下均显著高于其干旱对照;MDA含量、相对电导率显著低于其干旱对照。IBA-K处理下的两个品种大豆根表面积、根平均直径、根体积、POD活性和CAT活性在复水条件下分别高于其干旱对照,均未达到显著性差异。复水后,IBA-K处理下的垦丰16根干重和总根长分别较其干旱对照显著增加了3.13%和24.51%,合丰50根干重和总根长较其干旱对照未达到显著性差异。IBA-K处理下的合丰50相对电导率和MDA含量分别较其干旱对照显著降低11.80%和15.09%,SOD活性和可溶性糖含量分别较其干旱对照显著增加14.90%和3.94%,垦丰16相对电导率、MDA含量、SOD活性和可溶性糖含量较其干旱对照未达到显著性差异。IBA-K处理下的两个品种大豆根系脯氨酸含量分别较其干旱对照显著增加了10.62%和10.70%。IBA-K处理和不同土壤水分处理对两个品种大豆根系形态和生理指标存在显著或极显著影响,二者间的交互作用无明显调控作用。综上,IBA-K通过提高根系干物质积累量、抗氧化酶活性和渗透调节物质含量,降低MDA含量和相对电导率,减轻干旱胁迫对苗期大豆根系的伤害。     

苗期大豆根系及地上部性状与耐旱性的关系

选用耐旱性较强的野生大豆SNWS0048和综合性状优良但不耐旱的育成品种晋大73为亲本,构建回交自交系(BIL)群体。连续2 a在人工控制环境下,检测不同水分条件下该大豆群体的苗期根系及地上部性状,采用相关及通径分析研究了大豆根系及地上部性状与耐旱性的关系,同时探讨了这些性状的遗传特性。结果表明:在干旱胁迫下株高、茎重、根长和根重均有所下降,根冠比有所升高。干旱胁迫下的耐旱系数与所有性状呈正相关,其中与主根长、根重、根冠比极显著相关,与茎重显著相关,与株高相关不显著。通径分析进一步表明正常供水条件下根干重对大豆耐旱性有重要影响,而干旱胁迫条件下根冠比对大豆耐旱性的影响较大。     

Nitrogen Fixation Establishment during Initial Growth of Grain Legume Species

Atmospheric nitrogen fixation as a result of the symbiosis between bacteria and legume species, can result in major advantages in providing host plants with organic nitrogen. The objective of the present study was to evaluate the physiological potential during early seedling development for initiation of nodulation and nitrogen fixation activity of four grain legumes species: soybean [Glycine max (L.)], cowpea [Vigna unguiculate (L.) Walp], common bean [Phaseolus vulgaris (L.)], and peanut [Arachis hypogaea (L.)]. Seedlings were grown on a hydroponic solution so that nodule development could be readily observed until about 3 weeks after germination. Nodules developed in all cases. Acetylene reduction activity (ARA) by soybean and cowpea was also found early in seedling development. In contrast, peanut and common bean showed little or no development of ARA during seedling development. The results provided insight into differences in physiological potential among grain legumes in establishing symbiotic nitrogen fixation during crop establishment. These results indicate those species/cultivars that are candidates for readily establishing nitrogen fixation activity during the seedling stage of plant development.     

大豆GmFDL06基因抗干旱及耐盐性研究

bZIP转录因子在植物防卫反应和逆境胁迫应答过程中起着十分重要的作用,大豆GmFDL06是bZIP转录因子家族A组成员,其表达水平受PEG和高盐胁迫影响。本研究分析了GmFDL06转基因大豆苗期的抗干旱和耐盐性。PEG和盐处理后GmFDL06转基因植株的相对植株高度(RPH)和相对植株干重(RSDW)显著高于非转基因大豆东农50。在盐胁迫下,GmFDL06转基因植株比东农50伤害程度低,并且GmFDL06过表达减少了Na~+离子积累,降低了盐胁迫带来的伤害,且过表达GmFDL06促进了下游逆境胁迫基因的表达。这些研究结果表明GmFDL06参与大豆非生物胁迫反应,并有潜力改善大豆的干旱和盐胁迫耐受性,为大豆抗逆基因的研究及抗逆大豆材料的筛选提供了依据。     

Studies on Mechanisms of Dehydration Postponement in Cassava Leaves under Short-term Soil Water Deficits

Abstract

Cassava (Manihot esculenta Crantz) can produce a high crop yield even in an environment with irregular rains. This is mainly attributed to its abilities to maintain leaf area under drought conditions and rapidly regrow after rain. In this study, we investigated the mechanism of leaf maintenance under water deficits through measurement of photosynthetic rate and water potential changes in leaves. The cassava plants were grown in pots and exposed to water deficits, and the diurnal changes in water potentials, rates of photosynthesis and transpiration and stomatal conductance were measured. The relationship between leaf water potential (ψW) and photosynthetic rate with decreasing soil water, and osmotic adjustment were also investigated. With respect to water supply in leaves, the movement of water in plants was measured using stem heat balance. Under water deficits, photosynthesis occurred only in the early morning. The water loss was reduced by stomatal closure in the mid-day. This was attributed to the complete closure of the stornata during the decrease in ψW to a range between –1.0 and –1.4 MPa. Furthermore, the firm stomatal closure is caused by the consistency of osmotic potential under decreases in soil water, i.e., to a lack of osmotic adjustment. Water stored in the pith parenchyma of stem flowed into leaves in the morning. From these results, we conclude that cassava can consistently maintain an adequate water level in leaves via water storage and the sensitivity of stornata to water deficits, thereby avoiding leaf dehydration.     

Mixed Planting with Legumes Modified the Water Source and Water Use of Pearl Millet

Abstract

In semi-arid areas, pearl millet is an important staple food crop that is traditionally intercropped with cowpea. This study evaluated the water competition between pearl millet and cowpea using deuterated water. At vegetative stage, pearl millet biomass production was lower in the pearl millet-cowpea (PM-CP) combination than in the pearl millet-pigeon pea (PM-PP) and pearl millet-bambara nut (PM-BN) combinations. PM-CP used more water than PM-PP and PM-BN under well-watered conditions; however, all combinations used similar amounts of water under dry conditions. The biomass production, photosynthetic rates, transpiration rates, and midday leaf water potential of pearl millet at early flowering stage were not significantly reduced by mixed planting with cowpea sown two weeks later as compared with single planted pearl millet. When pearl millet and cowpea were sown at the same time, mix planting significantly increased the recovery rates of recently irrigated heavy water in pearl millet, but not in cowpea in both vegetative and early flowering stages. Midday leaf water potential and transpiration rates in pearl millet were lowered by mixed planting but those in cowpea were not. These indicate that the water source of pearl millet is shifted to the recently irrigated and easily accessible water. By contrast, when cowpea was sown two weeks later than pearl millet, this trend was not observed. These results provide new evidence on water competition in the PM-CP intercropping system; cowpea has higher ability to acquire existing soil water than pearl millet when both crops are sown at the same time.     

云南间作大豆耐荫性综合评价及鉴定指标筛选

      本文旨在探讨不同基因型大豆品种的耐荫特性，筛选出耐荫性鉴定指标，建立可用于耐荫性评价的数学模型。以44个大豆品种（系）为试验材料，在玉米-大豆间作下创设的自然荫蔽条件开展耐荫性鉴定，净种大豆作为对照。在各参试材料植株成熟期调查10个主要形态性状和产量性状，以各指标的耐荫系数为基础，采用多元统计方法对大豆的耐荫性进行综合评价。结果表明：与对照相比，受荫蔽胁迫后，参试材料的各性状变化趋势及幅度不同，各指标间都有不同程度的相关性，部分性状间相关性达到显著或极显著水平。通过主成分分析，将10个单项指标转换为4个相互独立的综合指标，代表了全部数据79.77%信息量。利用隶属函数法计算综合耐荫评价值（D），并对其进行系统聚类，将44个大豆品种（系）按照耐荫性强弱分为了强耐荫、中等耐荫和弱耐荫3大类。通过逐步回归建立了大豆耐荫性评价数学模型，并筛选出株高、主茎节数、有效分枝数、单株荚数、单株粒数、单株产量、每荚粒数和倒伏8个性状可作为云南省间作大豆耐荫性鉴定指标     

Amendment of soil with African marigold and sunn hemp for management of Meloidogyne incognita in selected legumes

Field experiments were conducted in 2008 and 2009 in the tropical rainforest zone of Nigeria to investigate the effects of amendment of soil with seedlings of African marigold (Tagetes erecta) and sunn hemp (Crotalaria juncea) incorporated singly in plots on Meloidogyne incognita and yield of cowpea and soybean. The experimental field, which was naturally free of plant-parasitic nematodes, was inoculated with chopped roots of M. incognita race 2-infected Celosia argentea roots and planted to tomato to increase M. incognita population at the site.Eight week-old marigold seedlings were incorporated in cowpea or soybean field and eight week-old sunn hemp seedlings were also incorporated in cowpea or soybean field. At the ends of the experiments, M. incognita population densities were significantly higher in control plots than those of the plots amended with marigold or sunn hemp with correspondingly higher grain yield in the amended plots in both cowpea and soybean fields in both years. A significantly higher population of the nematode and consequently, lower yield was associated with cultivar Ife Brown than cultivar Ife Bimpe of cowpea for each treatment whereas in soybean cultivars, the pattern was not definite. Also twelve seedlings of marigold or sunn hemp per plot incorporated into the soil produced significantly higher grain yield in cultivar Ife Brown of cowpea and cultivar TGX 1440 of soybean compared to six seedlings per plot. The results of this study suggest that incorporating marigold or sunn hemp in M. incognita-infected cowpea or soybean field has potentials to suppress M. incognita population and reduce nematode damage on yield of the associated leguminous crops.     

大豆抗旱性研究进展

大豆是人类优质蛋白质和食用油脂的重要来源。大豆生长期需水量多,是对缺水最敏感的豆类作物。干旱严重影响大豆产量和品质。抗旱大豆品种在干旱和半干旱地区的大豆生产中起着重要的作用。从干旱对大豆的影响机理、大豆抗旱机制、常用的抗旱性研究方法以及大豆抗旱性评价方法4个方面概述了大豆抗旱性的研究进展。     

Drought tolerance and yield increase of soybean resulting from improved symbiotic N2 fixation

Drought is by far the most important environmental factor contributing to crop yield loss, especially in soybean [Glycine max (L.) Merr.] where symbiotic fixation of atmospheric nitrogen (N₂) is sensitive to even modest soil water deficits. Decline of N₂ fixation with soil drying causes yield reductions due to inadequate N for protein production, which is the critical seed product. In this paper, we present a combined physiological and breeding research effort to develop soybean lines that have diminished sensitivity of N₂ fixation to drought. A preliminary physiological screen was used to identify lines that potentially expressed N₂ fixation drought tolerance. One hundred progeny lines derived from a cross between Jackson, a cultivar proven to have N₂ fixation tolerance to drought, and KS4895, a high-yielding line, were tested in the screen. Seventeen lines were identified for subsequent yield trials in moderate- and low-yielding rainfed environments. Two lines, found to have higher yields than commercial checks in these environments were then tested in the greenhouse for their N₂ fixation activity in drying soil. Nitrogen fixation activity was found to persist at lower soil water contents than exhibited by the sensitive parent. These two soybean lines offer a genetic resource for increased yields under rainfed conditions as a result of decreased sensitivity of N₂ fixation to water deficit.     

Pearl Millet Developed Deep Roots and Changed Water Sources by Competition with Intercropped Cowpea in the Semiarid Environment of Northern Namibia

abstract

The practice of intercropping pearl millet with cowpea is widespread among subsistence farmers in northern Namibia. In this region, the scarce and erratic rainfall may enhance competition for the limited soil water between intercropped plants. Trials were conducted on a field of the University of Namibia (on-station) and on a farmer’s field (off-station) to determine the effects of competition between pearl millet and cowpea on the water sources and plant growth of each crop. The deuterium analysis showed that pearl millet, intercropped with cowpea, significantly increased its dependence on the recently supplied labeled irrigation water. Intercropped cowpea also showed an increased trend of the dependence but it was not statistically significant. At the university field, intercropped pearl millet showed higher dependence on the irrigation water than monocropped pearl millet. At the farmer’s field, the dependence of intercropped pearl millet on the irrigation water was low in the pearl millet-dominant zone. In contrast, the dependence on the irrigation water was high in the cowpea-dominant zone, indicating that the dependence on the irrigation water changes according to the size of the pearl millet canopy. The water sources of cowpea did not show a significant difference at either pearl millet-dominant or cowpea-dominant zone, indicating a stable water uptake trend under competitive conditions. Competition with cowpea significantly increased the root-weight density of intercropped pearl millet in the deep soil layers, but decreased that in the shallow layers. The root-weight density of intercropped cowpea, however, was reduced in most of the soil layers. In conclusion, cowpea has a higher ability to acquire existing soil water, forcing pearl millet to develop deep roots and shift to the surface irrigation water.     

大豆芽期和苗期耐盐性评价指标筛选

大豆耐盐性是决定盐碱地大豆产量的关键因素之一。为探究不同盐浓度对大豆芽期、苗期生长发育的影响,评价不同大豆品种对不同盐浓度的耐受能力,以合豆3号、徐豆14、中黄55和临豆10号大豆品种为材料,在芽期,设置50,75和100 mmol·L~(-1)的盐溶液处理,苗期设置100,200和250 mmol·L~(-1)盐浓度处理。记录大豆芽期生长指标和苗期形态生理指标,并以各指标耐盐指数隶属函数值、总隶属函数值为依据,对4个大豆品种芽期和苗期耐盐性进行比较及聚类分析。结果表明:芽期主根长、下胚轴长、根干重、含水量、鲜重、根鲜重、活力指数耐盐指数的隶属函数值与总耐盐指数隶属函数值的相关性均达到极显著水平,苗期根干重、根鲜重、MDA含量、株高的耐盐指数与总耐盐指数隶属函数值的相关性均达到显著水平。在不同时期和不同品种的盐耐受分析中,不同生育时期的大豆耐受性表现不同;芽期4个大豆品种耐盐程度大致相同。苗期徐豆14、临豆10号耐盐性较强,中黄55耐盐性中等,合豆3号耐盐性较弱。在耐盐指标筛选分析中,下胚轴长、根干重、含水量、鲜生物量、根鲜重和主根长的耐盐指数可作为大豆芽期耐盐鉴定指标,而MDA含量和株高的耐盐指数则可以作为大豆苗期耐盐鉴定指标。