不同种植密度对夏玉米‘郑单1002’抗倒性及机收籽粒性能的影响

为明确国审玉米品种‘郑单1002’在黄淮海区域的适宜种植密度以及种植密度与抗倒伏及机收指标的关系。采用大田不同密度单因素随机区组试验设计,分析玉米产量性状、抗倒伏能力以及机收指标。结果表明,种植密度75000 株/hm2条件下产量水平最高(11211.52 kg/hm2),随着密度增加,倒伏发生率增加,各节间长呈增加趋势,第3、4 及穗下节间长增加明显,高密度（97500 株/hm2）较低密度（60000 株/hm2）分别增加了27.67%、18.29%、4.36%,差异均达到显著水平。基部第3 节间和穗下节间抗倒伏能力随种植密度增加呈下降趋势。基部第3 节间抗折力、压碎强度下降幅度大于穗下节间,高密度（97500 株/hm2）较低密度（60000 株/hm2）抗折力分别减少了52.50%、32.34%,压碎强度分别减少了56.26%、17.73%。机收籽粒落穗率、落籽率和籽粒破损率均呈上升趋势。从产量、倒伏率和机收指标分析结果来看,‘郑单1002’玉米品种在黄淮海区域适宜密度为67500~75000株/hm2。     

乙矮合剂对不同密度夏玉米茎秆抗倒伏能力及产量的影响

以中单909和浚单20为试验材料,研究乙矮合剂对不同密度夏玉米茎秆形态建成、抗折力、抗倒伏指数及产量的影响。结果表明,随密度增加,株高、穗位高、重心高度、节间长度、倒伏率呈升高趋势,而节间粗度、单位长度节间干重、抗折力及抗倒伏指数呈降低趋势,这些变化品种间存在差异。乙矮合剂处理显著降低株高、穗位高、重心高度,缩短节间长度、增加节间直径和单位长度节间干重,抗折力和抗倒伏指数提高,倒伏率降低;较高密度下(≥7.5万株/hm2),中单909和浚单20较各自对照增产幅度分别为3.77%~8.15%和6.73%~68.94%。综上所述,采用合理的种植密度并结合喷施乙矮合剂,能够提高抗倒伏能力和产量,可作为华北夏玉米区高产栽培的重要技术措施。     

不同种植密度对桥玉8号的叶面积指数和机收籽粒质量的影响

旨在掌握适宜河南省各地夏播种植的机收玉米品种‘桥玉8号’的最佳种植密度，本研究采用大田单因素随机区组试验设计，分析了不同种植密度对其叶面积指数、倒伏率、抗倒能力、机收指标和产量的影响。结果表明‘桥玉8号’整个生育期叶面积指数呈先增后减的单峰变化趋势，在抽雄期达到峰值。随着种植密度的增加，倒伏率升高，地上第3节间的茎粗变细、穿刺强度下降，机收籽粒的落籽率、籽粒破碎率也随之增加，而杂质率无明显变化规律。从产量、倒伏率、机收含水量和机收指标方面分析来看，‘桥玉8号’适宜的种植密度为8.25~9.00万株/hm2。本研究结果可为适宜机收玉米品种高产栽培提供合理的种植密度和良好的机收质量依据。     

群体密度对玉米茎秆农艺性状、力学特性和产量的影响

针对山西省雨养区春玉米倒伏引起的减产问题,选用玉米品种郑单958和晋单86为材料,设5.25万、6.00万、6.75万、7.50万和8.25万株/hm~2 5个密度处理,分析玉米茎秆抗倒力学和农艺性状的变化特点及其与产量和倒伏率的关系,明确影响玉米产量和倒伏率的主要茎秆节间因素。结果表明,随群体密度的增加,郑单958茎秆各节间长度和直径均先增加后降低,且在密度7.50万株/hm~2时最大;晋单86茎秆各节间长度显著增加,直径显著降低。随群体密度增加,茎秆各节间干重、单位茎长干重、硬皮穿刺强度、弯曲能力均先增加后降低,郑单958密度7.50万株/hm~2时最大,晋单86密度6.00万株/hm~2时最大,且晋单86在密度6.00万株/hm~2处理与其他处理间差异均显著。相关分析表明,硬皮穿刺强度和弯曲能力与节间长度呈显著或极显著负相关,与节间干重和单位茎长干重呈极显著正相关;产量与节间干重、单位茎长干重、硬皮穿刺强度和弯曲性能呈显著或极显著正相关;倒伏率与第3节间直径、节间干重、单位茎长干重、茎秆硬皮穿刺强度和弯曲能力呈显著或极显著负相关。郑单958和晋单86产量分别以密度7.50万、6.00万株/hm~2处理最高,分别较其他密度处理提高8%~26%、20%~30%。     

化学调控对高密条件下玉米抗倒性能的影响

增加种植密度作为玉米产量提升的重要途径,同时会带来群体郁闭、倒伏等问题,又在一定程度上制约着产量提高。为了探明高密群体不同化学调控方式对玉米茎秆抗倒伏性状的影响,选用近年来表现较好的高产潜力品种‘迪卡159’作为试验材料,设8.5×10~4、9.5×10~4、10.5×10~4株/hm~2 3个种植密度和8展叶1次化控(T1)、7+8展叶2次化控(T2)以及清水对照(CK) 3个试验处理,测定了茎秆农艺性状和抗倒力学性状,结果表明,化学调控降低了玉米植株的株高、穗位高、基部节间长和第2～5节位的节间干物质重,增加了基部第3～5节位的节间周长和第1～5节位的单位节间长干物质重,以上变化在不同化控处理间存在差异。8.5×10~4～9.5×10~4株/hm~2时,一次化控可取得较好的调控效果,10.5×10~4株/hm~2时则需两次化控才能取得明显的调控效果。茎秆抗倒力学性状与农艺性状密切相关,逐步回归分析表明,在化控条件下,单位节间长干物质重对茎秆穿刺强度及压折强度的影响最大,可以作为植株化控抗倒伏效果检验的重要农艺指标。     

种植密度对贵州春玉米茎秆抗倒伏性能及籽粒产量的影响

为了明确密植条件下春玉米茎秆特性和产量的变化及其相互关系,为贵州春玉米密植高产提供理论依据和实践指导。以贵州广泛种植的玉米品种先玉1171和新中玉801为材料,设置3.0、4.5、6.0、7.5、9.0和10.5万株hm-26个密度,于2018—2019年开展田间试验,研究种植密度对春玉米茎秆形态特征和力学特性、空秆率、倒伏率和产量的影响。结果表明:(1)春玉米株高和穗位高随密度增加先增高后降低;增密后第3节长增幅最大,第3节单位茎长干重、穿刺强度和抗折力,第7节茎粗、干重和横截面积下降幅度最大;密度对茎秆横截面扁率影响不显著。品种之间比较,先玉1171节间长,第3、5节的节间干重和第3节穿刺强度显著高于新中玉801,第7节干重、节间粗、单位茎长干重、节间横截面积、横截面扁率和抗折力显著低于新中玉801。(2)倒伏率和空秆率随密度增加而增大,增密后先玉1171倒伏率显著高于新中玉801,空秆率显著低于新中玉801。(3)产量随密度增加先增加后降低,先玉1171和新中玉801分别在9.3万株hm^-2和8.6万株hm^-2时产量最高。增密后先玉1171比新中玉801增产10.28%,有效穗数和穗粒数更高。(4)相关和多元回归分析表明,株高、穗位高与倒伏率显著正相关,节间粗和单位茎长干物质对玉米茎秆抗折力的正向影响显著。产量与茎秆性状密切相关,株高对产量的正向影响最大。可见,不同春玉米茎秆抗倒伏性能和籽粒产量对密度的响应有差异,新中玉801增密后茎秆节间短而粗,单位茎长干重较大,抗倒伏能力较强。而先玉1171由于在高密度下空秆率比新中玉801低,有较高的有效穗数和穗粒数,因此高密度下产量更高。综合考虑茎秆性状和产量,先玉1171和新中玉801在贵州适宜密度分别为9.0万株hm^-2和8.5万株hm^-2。     

群体密度对玉米茎秆抗倒力学和农艺性状的影响

适当增加种植密度是提高玉米产量的重要途径之一,而倒伏是玉米增加群体密度的主要限制因素。2005—2006年以茎秆抗倒伏性不同的3个品种（稀植大穗型品种京科519、耐密抗倒型品种登海3719和当地主栽品种农大108）为材料,设3.0、5.25、7.5、9.25、12.0万株 hm^-2 5个密度处理,研究了种植密度对茎秆的抗倒力学和农艺性状的影响。结果表明,随着群体密度的增加,茎秆的压碎强度（SCS）和外皮穿刺强度（RPS）以及节间直径、干重（DW）、干物质百分比、单位茎长干物质重(RDWL)显著降低,而节间长度有所增加,以上这些变化在供试品种间存在着明显的差异;茎秆抗倒力学性状随群体密度呈指数曲线（y = ae^bx）变化。茎秆抗倒力学性状与农艺性状密切相关。节间伸长慢且节间变细可能是耐密品种在高密度群体下的适应性表现,而节间干物质积累、尤其高位节间的干物质积累较高的品种抗倒伏能力强。在玉米抽雄前1周茎秆第4节间以上干物质百分比大于7.5%,单位茎长干物质重（RDWL）高于0.2 g cm^-1时较为抗倒。逐步回归分析表明,单位茎长干物质对茎秆压碎强度（SCS）和外皮穿刺强度（RPS）的正向影响最大,可以作为玉米抗倒伏品种选择的重要农艺指标。     

三江平原不同玉米品种茎秆特性比较与抗倒伏品种筛选

为明确三江平原抗倒伏玉米品种的茎秆特性,筛选出优良的抗倒伏玉米品种,本研究以‘L38P05’、‘先玉1219’、‘德美亚3’、‘A6565’、‘C2235’、‘J6518’、‘迪卡556’、‘P5697’、‘中单859’和‘垦沃6’10个玉米品种为试验材料,比较不同玉米品种的倒伏情况、产量表现和茎秆形态特征、力学特性及其与倒伏的相关性。结果表明,玉米的株高、穗位高、穗高系数、节间抗折断力与倒伏率无显著相关关系,不适宜作为评价玉米植株抗倒伏能力的形态指标和力学指标;基部节间的茎粗系数、穿刺强度、压碎强度可作为抗倒伏玉米品种筛选的依据,测定第2～第4节间更有意义。该区域正常年份下,基部2～5节间平均穿刺强度80 N/mm2以上和第2～第4节间平均压碎强度390 N/mm2以上的玉米品种具有较强的抗倒伏潜力。综合各品种的倒伏情况、茎秆性状和产量,筛选出适合三江平原机械化种植的优良抗倒伏玉米品种为‘德美亚3’、‘先玉1219’、‘C2235’和‘迪卡556’。     

叶面喷施5-氨基乙酰丙酸对不同密度春玉米生长特性和产量的影响

为探讨5-氨基乙酰丙酸（5-aminolevulinic acid,ALA）对不同密度春玉米生长发育和产量的影响,以中单909为材料,在玉米9展叶时期叶面喷施100mg/L ALA,以喷施等量清水为对照,在大田条件下研究ALA对不同密度春玉米群体（45 000、75 000、105 000株/hm ²）的作用效果。结果表明：ALA处理下,玉米45 000和75 000株/hm ²密度群体产量分别比对照增加9.7%和4.9%,75 000株/hm ²密度群体千粒重和收获期单株干物质积累量分别增加3.7%和4.3%,花后叶面积指数平均增加6.8%,SPAD值比对照分别平均增加2.5%,净光合速率平均比对照高15.7%。综上所述,ALA处理改善了大田玉米的群体结构,延缓了叶片衰老进程,提高了地上部分干物质积累量,进而提高了玉米单产水平,因此可作为东北春玉米高产稳产的技术措施。     

种植密度对‘桥玉8号’叶面积指数和机收籽粒质量的影响

旨在掌握适宜河南省各地夏播种植的机收玉米品种‘桥玉8号’的最佳种植密度,本研究采用大田单因素随机区组试验设计,分析了不同种植密度对其叶面积指数、倒伏率、抗倒能力、机收指标和产量的影响。结果表明‘桥玉8号’整个生育期叶面积指数呈先增后减的单峰变化趋势,在抽雄期达到峰值。随着种植密度的增加,倒伏率升高,地上第3节间的茎粗变细、穿刺强度下降,机收籽粒的落籽率、籽粒破碎率也随之增加,而杂质率无明显变化规律。从产量、倒伏率、机收含水量和机收指标方面分析来看,‘桥玉8号’适宜的种植密度为8.25万~9.00万株/hm~2。     

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.