以作物残茬为生物篱在裸露农田营建防风带技术的研究

根据农田防护林等生物篱网防治农田风蚀的原理,把作物残茬作为生物篱间隔插入马铃薯裸露农田,形成以残茬为生物篱的农田防护篱网,可以解决北方旱作马铃薯生产基地农田严重风蚀问题,核心技术是利用残茬把连片的裸露农田间隔分成宽7.2m以下的带田,形成留茬带与裸露带间作的农田,不仅使留茬带的风蚀量降低80%以上,其裸露带的风蚀量也降低50%以上,取得防治马铃薯裸露农田的风蚀沙化,保护和提高耕地质量的实效。总结提出在北方旱作区采用麦类/油菜等条播作物留茬与马铃薯等根茎类作物间作轮作营建裸露农田防风篱网的保护性耕作技术。     

带状留茬间作对防治干旱地区农田风蚀沙化的生态效应

对内蒙古阴山北麓旱农区不同类型耕地土壤风蚀及其影响因素的野外观察与室内分析,揭示了该地区风蚀气候侵蚀力的特点及风蚀作用对农田生态环境的主要危害。观察研究了粮草、糖薯和灌草带状间作及其残茬覆盖度对减轻农田土壤风蚀的作用,指出在农田防护林不完善的阴山北 麓旱农区,采用带状留茬间作轮作具有良好生态效应,可以有效地控制农田风蚀沙化,减轻风蚀危害,进而明确了不同类型退化农田应采用的带状留茬间作轮作方式与增产增收配套技术措施。     

农牧交错带粮草带状间作防风蚀保土效应的研究

在内蒙古阴山北麓地区的中部,年降水量平均只有280～350mm.由于冬春季地表大部分裸露,风蚀沙化已相当严重,因此应控制耕作,鼓励农民种草,耕作种植模式应以粮草带状间作为主.试验结果表明该模式可有效增加地表粗糙度,比对照裸地平均降低近地面5cm风速31.6%,风蚀量平均降低79.4%;减缓地表风蚀粗化,＞1mm的砾石为对照裸地的25%;生物量达3773kg/hm2,是天然草场的5.7倍.同时具有轮作培肥土壤的的作用,是适应当地条件的有效、简单、经济可行的防风蚀方法.     

河北坝上农牧交错区不同下垫面土壤风蚀特征研究

针对河北坝上农牧交错区不同下垫面土壤,采用“陷阱捕捉”与埋设风蚀盘的方法进行了风蚀特征的野外监测。监测表明坝上不同下垫面类型的风蚀量存在显著差异。以耕翻地为对照,在滩地上莜麦留茬地的风蚀量减少了9.1%,而玉米留茬地、免耕菜地的风蚀量则比对照分别增加了123.71%和229.07%。在梁地上莜麦留茬地、草地、林地的风蚀量分别比对照减少14.76%、68.67%和82.23%。在滩地与梁地两种地貌上,莜麦留茬地与耕翻地的风蚀量差异都不显著。地表的粗糙度和植被盖度是影响土壤风蚀量的重要因素。     

科尔沁沙地4种作物根茬抗风蚀效果风洞试验研究

摘 要：利用野外风洞设备,以翻耕地为对照,对科尔沁沙地东部农田的4种不同作物茬地抗风蚀效果进行了测试,对风蚀主要影响因子进行了分析。试验结果表明：作物留茬可显著提高地表抗风蚀能力;在相同风速条件下,抗风蚀能力大小依次为燕麦茬地>玉米茬地>向日葵茬地>绿豆茬地>翻耕地;与翻耕地相比,燕麦茬地、玉米茬地、向日葵茬地和绿豆茬地的起动风速分别抬高了53.3% 、17.8% 、11.1%、 8.9%。本试验表明,风蚀量与土壤地表覆盖度、土壤0～5cm表层含水量、地表粗糙度、土壤容重、土壤坚实度呈负相关关系,其中与前三者呈显著高度负相关关系。采用免耕留茬措施可以有效地抑制农田土壤风蚀,有利于防治农田荒漠化。     

京郊农田不同植被的土壤风蚀模数比较

为了研究京郊地区农田植被土壤风蚀变化规律,提出京郊防尘的农作制度,笔者采用野外风洞原位测试方法定量评价北京周边不同植被冬春季节的土壤风蚀状况。结果表明：植被覆盖在冬春季可以明显降低农田土壤风蚀量,5种植被均表现为100 cm的土壤风蚀模数略大于20 cm的。在风速20 m/s的条件下,3月中旬冬小麦、小黑麦的农田抗风蚀能力＞紫花苜蓿＞油菜、菠菜;小黑麦和冬小麦分别在20 cm和100 cm处地表抗风蚀能力强。4月中旬菠菜的农田抗风蚀能力＞油菜＞紫花苜蓿＞冬小麦、小黑麦、小黑麦和冬小麦分别在20 cm地和100 cm抗风蚀能力最弱。翻耕地比免耕地风蚀模数高,其中留根茬翻耕地最高,立秆免耕最低;3月份秸秆粉碎免耕风蚀模数大于留根茬免耕,4月份则相反。不同植被下土壤风蚀模数与土壤含水量呈负相关,且随着土层的增加相关系数逐渐降低;不同秸秆残茬处理下土壤风蚀模数与5~10 cm土层含水量和土壤覆盖度相关性较高,且均呈负相关。一年两作区越冬作物能提高土壤抗风蚀力;春玉米区立秆免耕抗风蚀里最强,免耕和秸秆还田等也均能提高土壤抗风蚀力。     

花生与绿肥轮作对土壤含水量和土壤肥力的影响

探讨在冬春裸地上种植绿肥对后茬作物春花生养分含量、土壤含水量和土壤肥力的影响,为山东地区春花生等冬闲田建立一种合理的轮作方式提供理论依据。在田间试验条件下,设置了春花生—冬闲田、夏花生—冬小麦、春花生—二月兰和春花生—毛叶苕子4种轮作处理。结果表明：种植二月兰和毛叶苕子绿肥作物,可促进后茬作物花生氮磷钾养分增加,二月兰增加程度高于毛叶苕子。种植二月兰和毛叶苕子绿肥作物,可提高后茬作物花生土壤含水量和土壤肥力,在0～20 cm土层中,2021年,与春花生—冬闲田相比,春花生—二月兰、春花生—毛叶苕子土壤相对含水量分别升高了4.70%、6.14%,在20～40、40～60 cm土层中也表现出相似趋势,2022年与2021年相比,表现出相似规律;与春花生—冬闲田相比,春花生—二月兰处理有机质、碱解氮、有效磷和速效钾含量平均增加了5.71%、8.98%、7.22%和7.72%,春花生—毛叶苕子处理有机质、碱解氮含量平均增加了4.54%、14.91%。可以利用春花生种植期间的冬春裸地种植一季冬绿肥,促进后茬作物养分积累量增加,改善土壤肥力。     

不同轮作方式下蚕豆节约氮对玉米产量的影响

为了评价在中国西南地区广为采用的蚕豆—玉米轮作种植体系中前茬种植蚕豆所增加的土壤氮的供给量对后茬玉米生长的影响,设计了田间二因素试验,分别在不施氮、N75kg/hm^2、N150kg/hm^2、N300kg/hm^2四个氮水平条件下,比较前茬小麦单作、蚕豆单作和小麦/蚕豆间作处理条件下轮作玉米的产量。数据表明,在不施氮（N0）和75kg/hm^2（N1）处理时,与前茬小麦单作相比,前茬单作蚕豆和小麦/蚕豆间作处理显著提高了后茬玉米棒子的产量,前茬蚕豆单作时后茬玉米棒子产量提高了21%和33%,而前茬小麦/蚕豆间作时分别提高了7%和30%,因此在外源氮供应低时蚕豆节约氮对下茬玉米的生物有效性高,从而生物固氮残留提供的氮营养增加;但随施氮量的增加,前作不同种植方式下后作玉米产量间差异不显著,表明随施氮量增加蚕豆节约氮对下茬玉米的生物有效性降低。研究认为在蚕豆-玉米轮作体系中进行氮养分资源管理时,要综合考虑轮作方式和施氮水平,以求得经济和环境效益的统一。     

丘陵沟壑区山坡地草粮带状间轮作水土保持效应的研究

本文依据我们1983～1986年4年中,在大田试验所取得的发生径流总次数、年均径流泥沙量、侵蚀模数、年均每平方公里泥水量、2米土层贮水量等资料,进行了主成分分析和相似性聚类分析,获得了比较满意的结果:认为上述5个指标在水土保持效应分析中须同等使用,不可互相代替;对不同间套作的效应进行了初步的比较。黄土高原是世界上水土流失最强烈的地区,黄土高原丘陵沟壑区则尤其强烈。由于严重的水土流失,显著的降低了土壤肥力。如陕北本来分布有大面积较肥沃的黑垆土,由于长期严重的水土侵蚀,非但表土流失,甚至连沉积层也常流失殆尽,致使母质裸露,成为幼年的黄绵土,其肥力同黄土母质相差无几,亩产粮食仅几十斤。形成了愈低产愈扩大耕地面积,愈扩大耕地面积愈低产的恶性循环。本试验的目的是,通过在25～30°之间的坡耕地实行草粮带状间轮作,由于草带的合理布设,减少甚至防止水土流失,把粮食作物种在经过生物培肥的草茬上,以提高粮食作物的单产;通过人工种植优质牧草,促进舍饲养牛、兔等养殖业的发展。本文就是依据我们草粮带状间轮作试验1983～1986年4年所取得的水土保持方面的资料,论述草粮带状间轮作的水土保持效应。     

覆膜方式对旱作农田土壤水热状况及向日葵产量的影响

为探究地膜覆盖对旱作农田土壤水热状况、向日葵产量及减轻土壤风蚀效果的影响,通过大区试验对不同覆膜方式和覆膜时间处理的土壤温度、水分,向日葵生长状况、产量及土壤风蚀量进行了监测。结果表明,土壤温度表现为春季全覆膜秋季半覆膜春季半覆膜、全覆膜处理半覆膜处理、垄上覆膜测定点垄沟覆膜测定点;与春季半覆膜相比,春季全覆膜和秋季半覆膜全生育期累积地温分别增加了71.70℃和55.42℃,出苗时间分别提前了3d和1d,开花时间分别提前2d和1d,花期分别延长3d和1d,子实空秕率分别降低8.44和7.05个百分点,增产率分别为19.82%和9.84%,作物耗水量分别降低了5.82%和8.11%,水分利用效率分别提高2.70和0.73kg/(hm~2·mm);秋季半覆膜可降低土壤风蚀量,与大面积裸露农田相比可以降低土壤风蚀量73.87%左右,而且有利于增加冬春雨雪的储集,减少地表蒸发。试验认为春季全覆膜和秋季半覆膜具有提高土壤温度、增加土壤贮水量、促进向日葵提前出苗和开花并延长花期、增加向日葵产量和水分利用效率等作用,秋季半覆膜还具有减轻土壤风蚀的良好效果。     

Biological Activity and Quantification of Suspected Allelochemicals from Alfalfa Plant Parts

Autotoxicity restricts reseeding of alfalfa (Medicago sativa L.) after alfalfa until autotoxic chemical(s) breaks down or is dispersed into external environments. A series of aqueous extracts from leaves, stems, roots and seeds of alfalfa ‘Vernal’ were bioassayed against alfalfa seedlings of the same cultivar to determine their autotoxicity. The highest inhibition was found in the extracts from the leaves. Extracts at 40 g dry tissue l^?1 from alfalfa leaves were 15.4, 17.5 and 28.7 times more toxic to alfalfa root growth than were those from roots, stems and seeds, respectively. A high‐performance liquid chromatography (HPLC) analysis with nine standard compounds showed that the concentrations and compositions of allelopathic compounds depended on the plant parts. In leaf extracts that showed the most inhibitory effect on root growth, the highest amounts of allelochemicals were detected. Among nine phenolic compounds assayed for their phytotoxicity on root growth of alfalfa, coumarin, trans‐cinnamic acid and o‐coumaric acid at 10^?3 m were most inhibitory. The type and amount of causative allelochemicals found in alfalfa plant parts were highly correlated with the results of the bioassay, indicating that the autotoxic effects of alfalfa plant parts significantly differed.     

Changes in Seed Yield and Quality with Maturity in Onion (Allium cepa L., cv. 'Early Cream Gold')

Development of onion (Allium cepa L., cv. ‘Early Cream Gold’) seed under cool climate conditions in Tasmania, Australia occurred over a longer duration than previously reported, but similar patterns of change in yield components were recorded. In contrast to previous studies, umbel moisture content declined from 85 to 67 % over 57 days while seed moisture content decreased from 85 to 31 %. Seed yield continued to increase over the duration of crop development, with increasing seed weight compensating for seed loss resulting from capsule dehiscence in the later stages of maturation. Germination percentage was high and did not vary significantly from 53 to 77 days after full bloom (DAF), but mean germination time declined and uniformity of germination increased significantly over the same time period. The percentage abnormal seedlings declined with later harvest date, resulting in highest seed quality at 77 DAF. The results of this study suggest that the decision to harvest cool climate onion seed crops before capsule dehiscence will result in a loss of potential seed yield and quality.     

Location of a high-lysine gene and the DDT-resistance gene on barley chromosome 7

Summary The high-lysine gene in Risø mutant 1508 conditions an increased lysine content in the endosperm via a changed protein composition, a decreased seed size, and several other characters of the seed. The designation lys3a, lys3b, and lys3c, is proposed for the allelic high-lysine genes in three Risø mutants, nos 1508, 18, and 19. Linkage studies with translocations locate the lys3 locus in the centromere region of chromosome 7. A linkage study involving the loci lys3 and ddt (resistance to DDT) together with the marker loci fs (fragile stem), s (short rachilla hairs), and r (smooth awn) show that the order of the five loci on chromosome 7 from the long to the short chromosome arm is r, s, fs, lys3, ddt. The distance from locus r to locus ddt is about 100 centimorgans.     

A note on the origin of Kalanchoë x vadensis Boom & Zeilinga (Crassulaceae)

Summary K x vadensis is a hybrid of K. blossfeldiana and K. marmorata obtained after doubling the number of chromosomes.     

Simultaneous Determination of Four Phenolic Acids in Radix Salviae Miltiorrhizae Formula Granules by QAMS

[Objectives]This study aimed to establish a QAMS(quantitative analysis of multi-components by single-marker)method for simultaneous determination of four phenol...     

Avoidance of leaf rust fungi in wild relatives of cultivated cereals

Summary Avoidance of rust fungi that was based on poor appressorium induction was previously found in Hordeum chilense. In the present study 95 accessions of Triticeae were screened for avoidance of Puccinia hordei. The percentage of appressorium formation per germinated spore ranged from 6 to 90%. On none of the 41 accessions of Aegilops, Agropyron, Elymus, Secale, Thinopyrum or Triticum studied was the rate of appressorium formation lower than 25%. Lower rates of appressorium formation were, however, found on accessions of wild barley species Hordeum brachyantherum, H. marinum, H. parodii and H. secalinum. Its implications in cereal breeding are discussed.     

Variation in forage grasses as hosts of the root-knot nematode Meloidogyne naasi (Franklin) and selection for resistance in ryegrass

Summary Reactions of 13 grasses to Meloidogyne naasi varied with species; ryegrasses, fescues and their hybrids were generally susceptible and cocksfoot and timothy resistant. Marked variation in host resistance levels occurred between genotypes within cultivars.Selection of single plants, followed by tests on replicate tillers, identified resistant and susceptible genotypes in both Italian and perennial ryegrass cultivars. Resistant plants had few nematode-induced galls and fewer females and eggs than susceptibles. There was more or less continuous variation, with many genotypes intermediate between extremes of resistance and susceptibility. Selected resistant and susceptible genotypes are of use in assessing variation in nematode populations and as controls for breeding and selection programmes.     

Present status and future strategy in breeding faba beans (Vicia Faba L.) for resistance to biotic and abiotic stresses

Progress is being made, mainly by ICARDA but also elsewhere, in breeding for resistance to Botrytis, AScochyta, Uromyces, and Orobanche; and some lines have resistance to more than one pathogen. The strategy is to extend multiple resistance but also to seek new and durable forms of resistance. Internationally coordinated programs are needed to maintain the momentum of this work.Tolerance of abiotic stresses leads to types suited to dry or cold environments rather than broad adaptability, but in this cross-pollinated species, the more hybrid vigor expressed by a cultivar, the more it is likely to tolerate various stresses.     

Water Extraction Process of Chinese Herbal Compound Man Gan Ning

[Objectives]To optimize the water extraction process of Chinese Herbal Compound Man Gan Ning and establish a method for its extraction and content determination...     

Current and future strategies in breeding lentil for resistance to biotic and abiotic stresses

Lentil production is limited by lack of moisture and unfavorable temperatures throughout its distribution. Waterlogging and salinity are only locally important. Progress has been made in breeding for tolerance to drought through selection for an appropriate phenology and increased water use efficiency and in breeding for winter hardiness through selection for cold tolerance.The diseases rust, vascular wilt, and Ascochyta blight, caused by Uromyces viciae-fabae, Fusarium oxysporum f. sp. lentis, and Ascochyta fabae f. sp. lentis, respectively, are the key fungal pathogens of lentil. Cultivars with resistance to rust and Ascochyta blight have been released in several countries and resistant sources to vascular wilt are being exploited. Sources of resistance to several other fungal and viral diseases of regional importance are known. In contrast, although the pea leaf weevil (Sitona spp.) and the parasitic weed broomrape (Orobanche spp.), and to a lesser extent the cyst nematode (Heterodera ciceri), are significant yield reducers of lentil, no sources of resistance to these biotic stresses have been found. Directions for future research in lentil on both biotic and abiotic stresses are discussed.