种植密度对川中丘区夏玉米冠层结构、干物质积累及产量的影响

通过设置4.50×104、5.25×104、6.00×104、6.75×104、7.50×104株·hm~(-2)(分别用T1、T2、T3、T4、T5表示)5个密度,研究种植密度对玉米冠层结构、干物质积累及产量的影响,为川中丘区夏玉米高产栽培提供理论依据和技术支撑。结果表明:随种植密度增加,玉米叶面积指数显著增加,茎粗、茎叶夹角和透光率显著降低;密度每增加1×104株·hm~(-2),茎粗分别降低1.4 mm(2015年)和1.3 mm(2016年),穗下、穗上第1叶夹角分别降低3.601°、1.440°,吐丝期和灌浆中期底层透光率分别降低3.73%和2.82%;玉米单株干物质积累随种植密度增加显著降低,T5较T1在成熟期分别降低37.13%(2015年)、25.95%(2016年);而群体干物质随种植密度呈增加趋势,2016年T5较T1在吐丝后7天、成熟期分别增加了26.72%、23.41%;玉米产量随种植密度呈先增后降的变化趋势,在密度为6.00×104株·hm~(-2)下产量最高;该密度下玉米群体和个体功能达到协同增益,玉米产量构成(有效穗数、穗粒数和千粒重)协调,是产量提高的主要原因。     

密度、种植方式和品种对夏玉米群体发育特征的影响

在豫北高产灌区的生产条件下,以郑单958和浚单20为试验材料,研究了不同密度和种植方式对夏玉米群体发育特征的影响。结果表明:密度和种植方式对两个品种的株高、茎粗、穗位、叶面积指数(LAI)、叶绿素含量、干物质积累量、穗部性状、籽粒产量和经济系数的影响达到极显著水平。郑单958在宽窄行种植方式和90000株/hm2的密度下产量最高,达到14236.97kg/hm2,浚单20在宽窄行种植方式和82500株/hm2的密度下产量最高,达到13333.51kg/hm2。     

密度与氮肥对关中灌区夏玉米(Zea mays L.)群体光合生理指标的影响

合理的密度是玉米构建良好群体结构、优化群体光合生理功能的基础,适宜的氮肥施用量是玉米进行光合生产的营养物质保障.运用作物群体生理学的方法,采用二次饱和D试验设计,研究了关中灌区夏玉米密度与氮肥耦合和群体光合生理指标的关系及其效应,明确了在关中灌区夏播条件下,在45000～75000株/hm2的密度范围内,密度与玉米籽粒产量、总干物质积累量(DMA)、吐丝期叶面积指数(MLAI)、总光合势(LAD)、平均作物生长率(CGR)为正相关,在45000～60000株/hm2的密度范围内,密度与玉米叶片平均净同化率(NAR)为正相关,而在60000～75000株/hm2的密度范围内,密度与玉米NAR为负相关;在氮素施用量≤600.0 kg/hm2的范围内,氮素施用量与玉米籽粒产量、DMA、CGR为正相关,在氮素施用量≤260.55 kg/hm2的范围内,氮素施用量与玉米MLAI、LAD为正相关,与玉米NAR为负相关,而在氮素施用量260.55～600.0kg/hm2的范围内,氮素施用量与玉米MLAI、LAD为负相关,与玉米NAR为正相关.密度对其影响较大的指标为:籽粒产量、DMA、LAD、CGR和MLAI , 影响较小的指标为:NAR;氮肥对其影响较大的指标为:DMA、CGR、籽粒产量、NAR,影响较小的指标为:LAD和MLAI .对籽粒产量和群体生理指标的综合影响效应,密度显著大于氮肥,玉米生产中,尤其要重视合理密植.通过对回归模型的解析,筛选确定了陕单8806玉米在关中灌区夏播中,实现高产的密度与氮肥耦合优化技术方案:合理密度为61713～66177株/hm2,适宜纯氮施用量为309.88～569.02kg/hm2.     

种植密度对夏玉米产量和源库特性的影响

以高产玉米品种郑单958(ZD958)和登海661(DH661)为试验材料,在4个不同区域(山东农业大学、汶口、兖州和莱州)设置22500、45000、67500、90000和112500株.hm-25个种植密度,研究了种植密度对夏玉米产量及源库特性的影响.结果表明:两品种在112500株.hm-2密度条件下玉米籽粒产量和生物产量最高,分别为19132和36965kg.hm-2,与22500和67500株.hm-2密度相比,籽粒产量分别增加了72%和48%,生物产量分别增加了152%和112%.两品种单株叶面积、最大花丝数、穗粒数和千粒重随密度增大而减小,但叶面积指数随密度增大而显著提高.收获指数与粒叶比随密度增大而显著减小,当密度超过67500株.hm-2时差异不显著,表明高密度条件下玉米通过增加群体库来提高产量.     

东北雨养区黑色地膜和种植密度对玉米田间地温和产量的影响

在不同颜色地膜覆盖和种植密度条件下地温和作物产量将发生改变,为了研究其变化规律,2016年在沈阳农业大学水利学院试验场开展了玉米覆膜种植田间试验,设置了3种种植方式(裸地、透明地膜和黑色地膜覆盖)和3个种植密度(60000、75000和90000株·hm~(-2))的田间试验,对玉米田间地温和产量进行了对比研究。结果表明:不同处理下田间0~25 cm深度平均地温的日变化呈现正态分布规律,总体上,透明地膜地温高于黑色地膜和裸地,低密度处理地温高于高密度处理;裸地种植条件下,玉米产量随密度的提高先增加后减小,覆膜处理下产量随着种植密度的增加而增加;黑膜处理下的玉米产量高于透明地膜和裸地,黑膜覆盖处理、密度为90000株·hm~(-2)的组合产量达到最大,为14264.6kg·hm~(-2);产量与抽穗期的地温相关性最大,且表现为负相关关系。本文研究结果对提高东北雨养区玉米产量具有指导意义。     

不同群体结构夏玉米灌浆期光合特征和产量变化

大田试验以夏玉米为试料,采用裂裂区试验设计,密度设计包含75000、90000\,105000株/hm² 3个密度作为主区,每个密度处理包括: ①等行距60 cm×单株留苗,②等行距60 cm×双株三角留苗,③宽窄行距(宽行70 cm + 窄行距50 cm)×单株留苗和 ④宽窄行距×双株三角留苗共12种方式进行处理,测定光合及叶绿素荧光参数。研究不同群体结构对夏玉米灌浆期群体光合特性的影响。结果表明,在吐丝期,随着种植密度的增加,群体光合速率提高;蜡熟期以90000株/hm²最高,种植方式上表现为宽窄行大于等行距种植,双株留苗种植方式大于单株种植方式,差异均达到显著水平;随着种植密度的提高,群体内3个层次叶片最大光能转换效率(Fv/Fm)、光化学猝灭系数(qP)逐渐降低,种植方式基本表现为宽窄行大于等行距,留苗方式表现为双株大于单株。试验条件下,以90000株/hm²,宽窄行,双株三角留苗产量最高。     

密度和种植方式对夏玉米酶活性和产量的影响

在豫北灌区的生产条件下,以郑单958和浚单20为试验材料,研究了不同密度和种植方式对夏玉米碳氮关键酶的影响。结果表明:生育后期夏玉米叶片硝酸还原酶(NR)、谷氨酰胺合成酶(GS)和籽粒蔗糖磷酸合成酶(SPS)、蔗糖合成酶(SS)活性均呈先升高后降低的变化趋势,叶片NR和GS活性峰值出现在吐丝期,籽粒SPS和SS活性峰值出现在灌浆后15d。基因型、密度和种植方式对夏玉米生育后期叶片NR、GS和籽粒SPS、SS活性均有显著影响,而3因素间总体上没有显著的互作效应。郑单958生育后期叶片NR、GS和籽粒SPS、SS活性均显著高于浚单20,分别提高5.02%、7.40%、6.25%和4.43%。在6.75—9.00万株hm2的范围内,随着密度的增大,夏玉米生育后期叶片NR、GS和籽粒SPS、SS活性显著降低。与60cm等行距种植方式相比,80cm-40cm宽窄行种植方式下夏玉米生育后期叶片NR、GS和籽粒SPS、SS活性均显著提高,分别提高6.23%、9.25%、6.87%和2.84%。在采用宽窄行种植、密度为8.25万株hm2时,产量最高。     

部分根区灌溉与合理密植对旱区棉花产量和水分生产率的影响

为揭示部分根区灌溉与合理密植在棉花产量和水分生产率上的互作效应及其生理学机制,探索旱区节水灌溉植棉的新途径,在内蒙古自治区西部大田条件下,采用两因子试验设计研究了灌溉方式(常规灌溉、亏缺灌溉、部分根区灌溉)和种植密度(13.5万、18.0万、22.5万株·hm^-2)对棉花生长发育、产量、水分生产率和相关生理指标的影响.结果表明: 灌溉方式和种植密度及其互作对棉花生物产量、籽棉产量、产量结构和收获指数有显著影响.常规灌溉条件下,提高密度能显著提高生物产量和单位面积铃数,但铃重和收获指数显著降低,高密度与中等密度下的经济产量相当,并显著高于低密度处理;部分根区灌溉可显著提高棉花叶片中脱落酸(ABA)含量,并显著降低吲哚乙酸(IAA)含量,促进同化物向生殖器官的分配,提高收获指数.随着种植密度的提高,部分根区灌溉下单位面积铃数增加、铃重基本不变,高密度较中、低密度籽棉分别增产6.7%和11.5%.高密度下,部分根区灌溉与常规灌溉的籽棉产量相当,霜前花率提高22.5%,节水30%,水分生产率提高49.3%.种植密度对主茎功能叶光合速率没有显著影响,灌溉方式对光合速率有显著影响,亏缺灌溉显著降低了主茎功能叶的光合速率,而部分根区灌溉的叶片光合速率与常规灌溉相当.部分根区灌溉灌水侧根系茉莉酸(JA)含量和水通道蛋白基因(PIP)表达量显著高于常规灌溉,表明部分根区灌溉下,JA作为信号分子参与了灌水侧根系水分吸收的调控,PIP基因上调表达,根系吸水能力增强,保障了地上部叶片的水分平衡,进而维持了较高的光合速率.部分根区灌溉配合适当密植(22.5万株·hm^-2)是旱区节水植棉的重要技术途径.     

牛膝不同密度群体光合速率与干物质积累和品质的关系

在大田条件下,探讨不同种植密度(A,500 000;B,330 000;C,250 000;D 200 000株/hm2)与牛膝的群体光合速率、干物质积累、产量及多糖含量之间的关系.结果表明:群体光合速率B处理较高,各群体日变化在开花期均呈双峰型,籽盛期均为单峰型;单株根干重和单位面积根产量的拟合均呈Logistic曲线变化;不同密度处理单株根干重增加速率为D>C>B>A,而单位面积根产量增加速率为B>C>D>A;密度与产量呈负相关,与多糖呈正相关;各处理群体光合速率与产量呈显著正相关,与多糖含量在开花和籽末期呈负相关.综合分析显示,330 000株/hm2为牛膝最佳种植密度;密度对牛膝产量和多糖含量影响较大,适当地提高籽粒期群体光合速率有利于提高牛膝产量和质量.     

密度与氮肥对关中灌区夏玉米（Zea mays L.）群体光合生理指标的影响

合理的密度是玉米构建良好群体结构、优化群体光合生理功能的基础,适宜的氮肥施用量是玉米进行光合生产的营养物质保障。运用作物群体生理学的方法,采用二次饱和D试验设计,研究了关中灌区夏玉米密度与氮肥耦合和群体光合生理指标的关系及其效应,明确了在关中灌区夏播条件下,在45000～75000株/hm2的密度范围内,密度与玉米籽粒产量、总干物质积累量（DMA）、吐丝期叶面积指数（MLAI）、总光合势（LAD）、平均作物生长率（CGR）为正相关,在45000～60000株/hm2的密度范围内,密度与玉米叶片平均净同化率（NAR）为正相关,而在60000～75000株/hm2的密度范围内,密度与玉米NAR为负相关;在氮素施用量≤600.0 kg/hm2的范围内,氮素施用量与玉米籽粒产量、DMA、CGR为正相关,在氮素施用量≤260.55 kg/hm2的范围内,氮素施用量与玉米MLAI、LAD为正相关,与玉米NAR为负相关,而在氮素施用量260.55～600.0kg/hm2的范围内,氮素施用量与玉米MLAI、LAD为负相关,与玉米NAR为正相关。密度对其影响较大的指标为:籽粒产量、DMA、LAD、CGR和MLAI , 影响较小的指标为:NAR;氮肥对其影响较大的指标为:DMA、CGR、籽粒产量、NAR,影响较小的指标为:LAD和MLAI 。对籽粒产量和群体生理指标的综合影响效应,密度显著大于氮肥,玉米生产中,尤其要重视合理密植。通过对回归模型的解析,筛选确定了陕单8806玉米在关中灌区夏播中,实现高产的密度与氮肥耦合优化技术方案:合理密度为61713～66177株/hm2,适宜纯氮施用量为309.88～569.02kg/hm2。     

Y-chromosome Data and Tribal Affiliations of Allenopithecus and Miopithecus

The phylogeny of Old World monkeys has remained unresolved in part because of a lack of resolution in the Cercopithecinae. Competing morphological hypotheses have had Allen's swamp monkey (Allenopithecus nigroviridis) and the talapoins (Miopithecus spp.) as basal branches of either the tribe Cercopithecini or the tribe Papionini. Previous molecular analyses have not adequately addressed the issue. To better understand the evolutionary history of these primates, we sequenced and subjected to phylogenetic analysis 3.1 kb of 2 loci (TSPY and SRY) from the non-recombining portion of the Y-chromosome. Individuals from the genera Allenopithecus, Miopithecus, Erythrocebus, Chlorocebus, and Cercopithecus were surveyed and their sequences compared with those previously published for the Papionini and Colobinae. The results suggest Allenopithecus and Miopithecus are more closely related to the Cercopithecini than Papionini. Our data also support the hypothesis that within the Cercopithecini, Erythrocebus and Chlorocebus share a close evolutionary relationship, distinct from the other members of the tribe.     

Nystatin and killer toxin sensitivity of free and immobilizedSaccharomyces cerevisiae

The inhibitory effect of nystatin and killer toxin on the growth of free and covalently-immobilizedSaccharomyces cerevisiae cells was studied. The resistance of immobilized cells to both agents was accompanied by increased amounts of phospholipids and sterols. The possible relationship between these changes in the membrane composition and the transduction of a signal across the cytoplasmic membrane is discussed.     

The hernandez and fernandez genes of Drosophila specify eye and antenna

The formation of different structures in Drosophila depends on the combined activities of selector genes and signaling pathways. For instance, the antenna requires the selector gene homothorax, which distinguishes between the leg and the antenna and can specify distal antenna if expressed ectopically. Similarly, the eye is formed by a group of "eye-specifying" genes, among them eyeless, which can direct eye development ectopically. We report here the characterization of the hernandez and fernandez genes, expressed in the antennal and eye primordia of the eye-antenna imaginal disc. The predicted proteins encoded by these two genes have 27% common amino acids and include a Pipsqueak domain. Reduced expression of either hernandez or fernandez mildly affects antenna and eye development, while the inactivation of both genes partially transforms distal antenna into leg. Ectopic expression of either of the two genes results in two different phenotypes: it can form distal antenna, activating genes like homothorax, spineless, and spalt, and it can promote eye development and activates eyeless. Reciprocally, eyeless can induce hernandez and fernandez expression, and homothorax and spineless can activate both hernandez and fernandez when ectopically expressed. The formation of eye by these genes seems to require Notch signaling, since the induction of ectopic eyes and the activation of eyeless by the hernandez gene are suppressed when the Notch function is compromised. Our results show that the hernandez and fernandez genes are required for antennal and eye development and are also able to specify eye or antenna ectopically.     

Development and function of Pisolithus and Scleroderma ectomycorrhizas formed in vivo with Allocasuarina,Casuarina and Eucalyptus

The effect of inoculating seedlings of Eucalyptus grandis, Allocasuarina littoralis and Casuarina equisetifolia with two isolates of Pisolithus and two isolates of Scleroderma from under eucalypts was examined in a glasshouse trial. Ectomycorrhizas formed extensively on Eucalyptus (23–46% fine roots ectomycorrhizal) and Allocasuarina (18–51% fine roots ectomycorrhizal). On Casuarina, the fungi were either unable to colonize the rhizosphere (one isolate of Pisolithus), or sheathed roots, resembling ectomycorrhizas, formed on 1–2% of the fine roots. Colonization of roots by one isolate of Scleroderma resulted in the death of Casuarina seedlings. Inoculation with fungi increased shoot dry weight by up to a factor of 32 (Eucalyptus), 4 (Allocasuarina) and 3 (Casuarina). Ectomycorrhizas formed in associations with Eucalyptus and Allocasuarina had fully differentiated mantles and Hartig nets in which the host and fungal cells were linked by an extensive fibrillar matrix. Sheathed roots in Casuarina lacked a Hartig net, and the epidermis showed a hypersensitive reaction resulting in wall thickening and cell death. The sheaths are described as mantles since the density and arrangement of the hyphae in the sheaths was similar to that in mantles of the eucalypt ectomycorrhizas. The intercellular carbohydrate matrix was not produced in the Casuarina mantle in association with Pisolithus, hence the mantle was not cemented to the root. These structures differ from poorly compatible associations described previously for Pisolithus and Eucalyptus. The anatomical data indicate that ectomycorrhizal assessment based on surface morphological features may be misleading in ecological studies because compatible and incompatible associations may not be distinguishable.     

Ovule and seed anatomy ofCistaceae and relatedMalvanae

Ovule and especially seed anatomy of eight species ofCochlospermaceae, Bixaceae, Cistaceae, Monotoideae, Pakaraimaeoideae (two subfamilies ofDipterocarpaceae), andSarcolaenaceae were investigated. All representatives show a bixoid chalazal region in the seed as probable exclusive synapomorphy among angiosperms. The palisade layer of the exotegmen is curved inwards at its proximal end and forms a dome-shaped structure. A plug of hypostase tissue with an annulus/core structure fits into this dome. Moreover, two additional tissue types in the hypostase can be found in some representatives of the group. These and other micromorphological, wood anatomical, and floral morphological characters, indicate that the taxa form a monophyletic group close toMalvales s. str. The form of the starch grains in the endosperm is compared and is described for the first time forPakaraimaea (Dipterocarpaceae) andLeptolaena (Sarcolaenaceae). The position ofDiegodendron close toBixa and the presumably more distant positions ofMuntingia andNeuradaceae are discussed.     

Molecular identification and differentiation of Brevibacterium species and strains

Amplified ribosomal DNA restriction enzyme analysis (ARDRA), pulsed field gel electrophoresis (PFGE) and ribotyping were used to differentiate among 24 strains of Brevibacterium linens, Brevibacterium casei and Brevibacterium epidermidis obtained from type culture collections or isolated from various smear ripened cheeses. ARDRA was applied to the 16S rDNA. B. linens was shown to be a quite heterogenic group with 2 to at least 4 copies of rrn operons per strain with aberrant nucleotide sequences. AccI gave genus specific restriction patterns and was used to separate Brevibacterium from Corynebacterium species. The expected species specificity of TaqI applied to B. linens type culture strains, but not to all strains isolated from cheese. By AvaI restriction, B. casei and B. linens were differentiated from B. epidermidis and the orange pigmented Arthrobacter casei, a new species of coryneform bacteria; by XmnI restriction, B. linens and B. epidermidis were differentiated from B. casei. One of 4 B. linens genotypes could not be distinguished from B. casei by this method. Here, the typical orange B. linens pigments were used for classification, which was confirmed by partial sequencing of the 16S rDNA.     

Amino acids and sugars in nectar,and their putative evolutionary significance

Individual amino acids and sugars from flower nectar of 32 plant species with different pollination systems were quantified and compared. Data show that there is no correlation between sugar and amino acid concentration. Furthermore there is no correlation between composition and concentration of amino acids and evolutionary advancement, nor any direct relation with pollination systems. However, higher sugar concentrations are often linked with more advanced morphological characters. Nectars from pierced or damaged flowers or nectars contaminated with pollen exhibit modifications and increases in amino acid composition. The presence of proline probably indicates such pollen contamination. Most pollinating animals depend on flower nectar in their energetic requirements, yet innumerable alternative amino acid and protein sources exist. Future research has to consider the relationship between nutritional requirements of pollinating animals and dependence on flower nectars.Dedicated to Prof. Dr.L. van der Pijl, Den Haag, in honour of his 80th birthday.     

Theoretical Study of Antagonists and Inhibitors of Mammalian Adenosine Deaminase: I. Adenosine and Its Aza- and Deazaanalogues

Aza- and deazaanalogues of adenosine, including their 1-protonated forms (except for that of 1-deazaadenosine), were studied by computer computation to find a relationship between their molecular structures and substrate properties for the mammalian adenosine deaminase. The atomic charge distribution and maps of the electrostatic potential around their van der Waals molecular surface were calculated for these compounds using the ab initio STO-3G method. The conformational studies are carried out by the MM⁺ method of molecular mechanics. The mechanism that determines the substrate selectivity of mammalian adenosine deaminase is discussed.     

Cyclooxygenase inhibitory and antioxidant cyanidin glycosides in cherries and berries

Anthocyanins from tart cherries, Prunus cerasus L. (Rosaceae) cv. Balaton and Montmorency; sweet cherries, Prunus avium L. (Rosaceae); bilberries, Vaccinum myrtillus L. (Ericaceae); blackberries, Rubus sp. (Rosaceae); blueberries var. Jersey, Vaccinium corymbosum L. (Ericaceae); cranberries var. Early Black, Vaccinium macrocarpon Ait. (Ericaceae); elderberries, Sambucus canadensis (Caprifoliaceae); raspberries, Rubus idaeus (Rosaceae); and strawberries var. Honeoye, Fragaria x ananassa Duch. (Rosaceae), were investigated for cyclooxygenase inhibitory and antioxidant activities. The presence and levels of cyanidin-3-glucosylrutinoside 1 and cyanidin-3-rutinoside 2 were determined in the fruits using HPLC. The antioxidant activity of anthocyanins from cherries was comparable to the commercial antioxidants, tert-butylhydroquinone, butylated hydroxytoluene and butylated hydroxyanisole, and superior to vitamin E, at a test concentration of 125 microg/ml. Anthocyanins from raspberries and sweet cherries demonstrated 45% and 47% cyclooxygenase-I and cyclooxygenase-II inhibitory activities, respectively, when assayed at 125 microg/ml. The cyclooxygenase inhibitory activities of anthocyanins from these fruits were comparable to those of ibuprofen and naproxen at 10 microM concentrations. Anthocyanins 1 and 2 are present in both cherries and raspberry. The yields of pure anthocyanins 1 and 2 in 100 g Balaton and Montmorency tart cherries, sweet cherries and raspberries were 21, 16.5; 11, 5; 4.95, 21; and 4.65, 13.5 mg, respectively. Fresh blackberries and strawberries contained only anthocyanin 2 in yields of 24 and 22.5 mg/100 g, respectively. Anthocyanins 1 and 2 were not found in bilberries, blueberries, cranberries or elderberries.