CO2浓度升高对不同水分养分条件下小麦幼苗生长的影响

设置了5个氮素浓度梯度(N0、N1、N2、N3、N4)、3个PEG(P0、P1、P2)浓度梯度以及2个CO2浓度(370±50μmol·mol-1;700±50μmol·mol-1)水平的盆栽试验,探究了小麦幼苗生长、物质积累与分配以及植株水分条件的变化规律。结果表明:小麦幼苗株高、地上部干重、根干重、生物量以及叶水势的最大值以及高浓度CO2的最大刺激作用均出现在处理N1P0;而根长和根冠比的最大值分别出现在处理N0P0和N1P2,高浓度CO2的最大刺激值也分别出现在处理N0P0和N1P2;适宜养分条件下,高浓度CO2能够最大限度地促进小麦幼苗的生长,同时高浓度CO2通过提高小麦幼苗叶水势,一定程度上缓解了低浓度PEG胁迫的不利影响。因此,未来CO2浓度升高将对水肥条件好的小麦产生促进作用,可缓解轻度水分不足的不利影响,而对严重干旱胁迫下小麦的生长作用不明显。     

钙离子浓度对NaCl胁迫下嫁接黄瓜幼苗光合与荧光特性的影响

针对宁夏设施土壤盐渍化严重,作物盐害加剧等问题,以嫁接黄瓜幼苗为试验材料,研究100 mmol·L~(-1)NaCl处理下,施用不同浓度CaCl_2对嫁接黄瓜幼苗光合和荧光特性的影响。结果表明:随着胁迫时间的延长,不同钙离子浓度处理下黄瓜幼苗叶片净光合速率(Pn)、气孔导度(Gs)均降低,蒸腾速率(Tr)、胞间CO_2浓度(Ci)先下降后升高,10 mmol·L~(-1)Ca~(2+)处理显著增加了植株的水分利用率;处理第11天,除10 mmol·L~(-1)Ca~(2+)处理外,其他处理初始荧光均呈上升趋势,10 mmol·L~(-1)Ca~(2+)处理的Fo值最低,仅为787.4,最大荧光(Fm)较高,仅次于CK,施入10mmol·L~(-1)Ca~(2+)可显著增加最大光化学效率(Fv/Fm),分别为其他5个Ca~(2+)浓度处理的17.69、1.33、1.66、2.82倍与1.22倍;当处理第11天,各处理qP值均出现上升的趋势,10 mmol·L~(-1)Ca~(2+)处理的q P为0.677且接近于CK,经不同浓度CaCl_2处理后,各处理间非光化学猝灭系数(qN)差异不显著,10 mmol·L~(-1)Ca~(2+)处理的光合电子传递速率(ETR)显著高于其他处理。综上所述,施用10 mmol·L~(-1)Ca~(2+)可显著缓解盐分对黄瓜幼苗的伤害,提高其耐盐性。     

黑麦草幼苗对NaHCO3胁迫的生理响应

采用营养液砂培方法,研究了不同浓度NaHCO3(0、50、100、150 mmol/L和200 mmol/L)胁迫对黑麦草幼苗生长、活性氧代谢和渗透溶质积累的影响。结果表明:(1)随着NaHCO3浓度增加,黑麦草幼苗鲜、干重呈降低趋势,叶片超氧阴离子(O2.)、过氧化氢(H2O2)、丙二醛(MDA)和Na+含量不断升高,过氧化氢酶(CAT)、过氧化物酶(POD)活性和抗坏血酸(AsA)、谷胱甘肽(GSH)、K+含量及K+/Na+持续下降,超氧化物歧化酶(SOD)和抗坏血酸过氧化物酶(APX)活性呈先升后降变化,液泡膜H+-ATPase和H+-PPase活性在NaHCO3浓度为50～150 mmol/L时高于对照,NaHCO3浓度为200 mmol/L时低于对照。(2)碱胁迫降低了幼苗叶片中可溶性蛋白质和游离氨基酸的含量,提高了可溶性糖和脯氨酸的含量。表明活性氧代谢和Na+、K+平衡失调及积累有机溶质进行渗透调节需更多能耗等可能是碱胁迫下黑麦草幼苗生长受抑的重要因素。     

多效唑和PVA 对轻度干旱下多年生黑麦草幼苗抗旱性的影响

轻度干旱下,对聚乙烯醇(Polyvinyl alcohol,PVA)浸种预处理的多年生黑麦草(Lolium perenne L.)品种'旋风'的幼苗叶面喷施不同剂量(150、300、450 mg/m2)的多效唑,探讨PVA浸种及叶面喷施多效唑处理对多年生黑麦草生长及幼苗抗旱性的影响.结果表明:与对照相比,2%PVA浸种的多年生黑麦草成苗率提高0.13倍(P＜0.01),叶片相对含水量提高0.03倍(P＜0.05);2%PVA漫种 叶面喷施150 mg/m2多效唑处理的多年生黑麦草叶片相对合水量增加0.04倍,SOD、POD和CAT活性分别提高0.40、0.44和0.17倍,MDA含量降低51.58%.植株生长高度降低42.57%,差异均显著(P＜0.05),且比单独喷施多效唑、单一2%PVA漫种的抗旱效果显著;2%PVA浸种处理下,300～450 mg/m2多效唑缓解轻度干旱对黑麦草的胁迫作用明显或显著降低.综合效应表明,2%PVA浸种预处理 叶面喷施150 mg/m2多效唑处理能有效减轻水分匮乏对幼苗的胁迫并廷缓植株生长,处理效果最佳.     

氮素水平和形态对小麦幼苗叶最小导度的影响

叶最小导度反映了叶片气孔关闭后残余蒸腾的大小,因而是植物抗旱性的一个重要方面。采用水培试验,研究了不同氮素浓度(低氮:2 mmol/L;高氮:15 mmol/L)和形态(硝态氮、铵态氮和硝酸铵)对小麦叶最小导度的影响,试图揭示氮素营养影响植物抗旱性的生理机制。结果表明:铵态氮和硝态氮处理高氮的叶最小导度低于低氮,但硝酸铵处理两个氮水平下的叶最小导度无差异;氮素形态对叶最小导度无显著影响。氮浓度对与叶最小导度有关的形态和生理特征无影响,氮素形态对比叶片重、绒毛密度、蜡质含量和蜡质晶体形态结构和气孔特性亦无显著影响,对叶含水量有显著影响,铵态氮处理叶含水量低于硝态氮和硝酸铵处理。相关分析表明,叶最小导度与比叶片重呈显著正相关。本研究结果说明比叶片重的差异是导致不同处理最小导度不同的重要原因,氮素形态并未通过影响叶最小导度而对植物的抗旱性产生影响。     

不同浓度外源玉米黄质对低温弱光胁迫下辣椒幼苗的缓解效应

针对冬春季节西北地区设施栽培辣椒生产过程中出现的低温弱光逆境问题,本研究以低温敏感型辣椒品种‘航椒2号’为试材,开展不同浓度外源玉米黄质对低温弱光胁迫下辣椒幼苗缓解效应的研究。辣椒幼苗通过连续4d叶面喷施0（CK）、20（T1）、50（T2）、100（T3） mg·L^-1的玉米黄质溶液预处理,后置于人工气候箱模拟低温弱光胁迫处理7 d,测定辣椒幼苗生长、光合和抗氧化酶相关生理指标。研究发现不同浓度外源玉米黄质预处理均对低温弱光条件下辣椒幼苗的胁迫有明显的缓解作用,其中以T2处理效果最佳。与CK相比,T2处理株高和茎粗分别增加5.52%和17.09%;叶片光合色素含量及净光合速率（P_n）、气孔导度（G_s）、蒸腾速率（T_r）均显著提高;渗透调节物质可溶性糖和可溶性蛋白分别增加22.35%和19.58%;抗氧化酶SOD和CAT分别增加19.23%和381.55%。此外,T2处理显著降低了超氧阴离子、丙二醛（MDA）含量和相对电导率。表明50 mg·L^-1的外源玉米黄质能有效缓解低温弱...     

不同种植模式对玉米幼苗某些生理特性及产量的影响

在大田条件下,研究了常规、覆膜、覆草不同种植模式、不同氮素水平对玉米幼苗某些生理特性及产量的影响。结果表明,不同种植模式明显影响了幼苗干物质的积累,无论施肥与否,覆膜种植模式下,玉米生物量最高。生理指标测定结果显示,覆膜种植叶片叶绿素含量最高,光合速率最高,但蒸腾速率最小。叶片耐脱水力测定结果表明,叶片耐脱水力均随施肥量的增加而增强;在相同氮素水平下,覆膜种植的叶片耐脱水力最强,其次是覆草,而常规种植最弱。不论施肥与否,覆膜种植条件下玉米产量最高,其次是覆草,常规种植产量最低。     

Fungicide seed treatments to improve seedling emergence of perennial ryegrass Lolium perenne and the effect of different cultivars and soils

Seeds of perennial ryegrass Lolium perenne treated with four fungicides, benomyl, captan, iprodione and metalaxyl, used singly and in all combinations were sown in soil in pots. The soil was maintained at a low moisture content to predispose the seedlings to pre-emergence infection by soil-borne fungi. Thirteen of the fifteen fungicide treatments significantly increased seedling emergence and all but one contained benomyl and/or captan. In another pot experiment, a combination of benomyl and captan was tested against four similar treatments, carbendazim+captan, thiabendazole+captan, thiabendazole+metalaxyl and thiabendazole+thiram and also drazoxolon. Only benomyl+captan and drazoxolon did not increase seedling emergence significantly. A natural infection of the seedlings by powdery mildew Erysiphe graminis was reduced significantly by all treatments except thiabendazole+thiram and drazoxolon. Only car-bendazim+captan significantly increased the dry weight of seedlings per pot 98 days after sowing. Benomyl+captan seed treatment significantly increased seedling emergence in 9 of 16 soils collected from widespread sites. One perennial ryegrass cultivar, Parcour, was used in the above experiments and in a comparison with 12 other diploid cultivars its response to benomyl seed treatment was about mid-range.     

Effects of fungicides on Drechslera spp. and leaf surface filamentous saprophytic fungi on Lolium perenne

Small plots of Lolium perenne were treated between February and September 1979 with benomyl, triadimefon and chlorothalonil and the incidence and relative abundance of sporulating filamentous fungi measured on distinct lesions and senescent areas of leaves.
Benomyl reduced the levels of most saprophytes but increased the levels of the two Drechslera species present. Triadimefon reduced levels of Drechslera species but allowed an increase in levels of Phoma and Epicoccum and in the number of naturally senescing leaves devoid of obvious filamentous fungal growth. In chlorothalonil-treated plots, levels of all filamentous fungi except Epicoccum were reduced and, by controlling Drechslera species, the number of healthy leaves increased.     

Cytology of the host-pathogen interactions between Lolium perenne and Drechslera dictyoides

The interactions between Drechslera dictyoides and Lolium perenne resulting in the development of the net blotch lesion were examined using light and electron microscopy. Following appressorium formation a reorganization of the network of cytoplasmic strands in underlying epidermal cells resulted in the accumulation of cytoplasm and the migration of the nucleus towards the appressorium. Successful penetration was followed by extensive colonization of the invaded epidermal cell. Abortive penetration attempts often resulted in the formation of hyphae within the epidermal cell wall. During lesion development, advancing hyphae came into contact with unmodified host cells which responded with the production of wall appositions. Hyphae were sparsely distributed within the developing lesions and their sparingly branched, predominantly linear pattern of growth resulted in the formation of discrete net lesions. Prior to the commencement of sporulation, the density of hyphae increased and the invasion of moribund cells of the senescent host tissue was observed.     

进境苇状羊茅和多年生黑麦草种子携带内生真菌带菌率的研究

苇状羊茅内生真菌和多年生黑麦草内生真菌曾给一些国家的畜牧业造成巨大损失.为防止内生真菌随进境草籽传入我国并在中国扩散危害,我们对该2种进境草籽内生真菌的带菌率进行了研究.首先通过分离培养,得到了苇状羊茅内生真菌和黑麦草内生真菌,然后采用染色法对1998年以来收集到的从天津口岸进境的部分苇状羊茅和黑麦草种子进行了初步检验,经检验,37份苇状羊茅样品中有18个品种带菌,34份多年生黑麦草样品中14个品种带菌,带菌率最高可达86.7%.早熟禾、剪股颖等其它禾本科草籽目前尚未发现带有内生真菌.     

The effect of asulam on two Lolium perenne swards containing Rumex obtusifolius

The effects of asulam applied in September 1970 at 0.55, 1.12 and 2.24 kg a.i./ha on Rumex obtusifolius (L.), Lolium perenne (L.), Other grasses and Trifolium repens (L.) growing in two swards in Wales were investigated. Good short-term control of Rumex was achieved by all rates of asulum although regeneration was occurring by the spring following treatment. Dry matter yields of L. perenne were slightly lowered by 2.24 kg a.i./ha 6 weeks after spraying but production in the spring following treatment was substantially greater than on untreated plots. Poa trivialis (L.) and Agrostis stolonifera (L.) were substantially reduced but invasion of the bare spaces by P. trivialis and P. annua (L.) seedlings tended to mask the success of this control. No harmful effects on T. repens were recorded.     

Sugarbeet yield response to competition from Sinapis arvensis or Lolium perenne growing at three different distances from the beet and removed at various times during early growth

A sugarbeet field experiment was conducted in 1999 and 2000 to measure beet yield where Sinapis arvensis or Lolium perenne were growing in the crop row at 2, 4 or 8 cm from the beet plants. The weeds were removed by cutting once in the growing season in either late May, mid‐June or early July. The number of neighbouring beet plants to every target beet plant was recorded. Projected leaf cover of a subset of the data with non‐cut weeds was analysed by using image analysis to investigate whether this could be used to predict beet yield loss early in the growing season. Increasing the distance between beet and weed from 2 to 8 cm increased the beet yield significantly by an average of 20%, regardless of weed species. The dry weight of non‐cut and re‐growing weeds at harvest time decreased when cutting was postponed to the period between mid‐June and early July. The number of neighbours described a sigmoidal yield decline of the single beet plants. Results from image analysis showed that approximately 33 g of beet yield was lost in October/November for each per cent relative projected leaf cover of the weeds in May, despite variation in growing conditions. The results are discussed in relation to potentials for robotic in‐row weed control.     

Paraquat tolerant Lolium perenne L.: effects of paraquat on germinating seedlings

A cultivar of Lolium perenne L. (Causeway) selected for tolerance to foliar-applied paraquat was shown also to be tolerant at seed germination and establishment. When seeds were germinated in paraquat solutions (1, 3, 9, 27 ppm), Causeway was more than ten times as tolerant as a normal cultivar of L. perenne. When germination and survival were studied in a soil which had been sprayed with paraquat (0.0, 0.3, 0.9, 2.7 kg/ha) before sowing, Causeway was nearly three times as tolerant as a normal cultivar. Holcus lanatus L. was about equal to normal L. perenne, but Poa trivialis L. was less tolerant. Phytotoxicity was greater in a 10.5% organic than a 4.8% organic soil. It is concluded that the mechanism of paraquat tolerance operates in the non-photosynthetic tissues of germinating seedlings as well as in the photosynthetic tissues of older plants, although the degree of tolerance varies according to the mode and stage of application of the herbicide. There might be advantages in using a paraquat tolerant cultivar of L. perenne when direct drilling grass after sward destruction by paraquat.     

Response of ten cultivars of Lolium perenne to the ectoparasitic nematode Tylenchorhynchus dubius

The interaction between 10 cultivars ofLolium perenne andTylenchorhynchus dubius was studied to investigate the incidence of tolerance and resistance to ectoparasitic nematodes inL. perenne.Differences in tolerance were small; the nematode treatments yielded 67 to 76% of the dry shoot mass of the controls. Cultivars with a low leaf weight ratio and a low transpiration coefficient tended to have a somewhat better tolerance. Differences in resistance occurred, but resistance is of minor importance to reduce damage in theL. perenne/T. dubius host-parasite system.Samenvatting Om na te gaan of inLolium perenne tolerantie en resistentie t.a.v. ectoparasitaire nematoden voorkomt, werd de interactie tussen 10 cultivars vanL. perenne en de ectoparasitaire nematodeTylenchorhynchus dubius onderzocht.De verschillen in tolerantie bleken gering. Cultivars met een lage spruit/wortel-verhouding en een lage transpiratiecoëfficiënt waren in het algemeen wat toleranter. Er werden verschillen in resistentie gevonden, maar voor het verminderen van schade in het waardplant/parasiet-systeemL. perenne/T. dubius is resistentie van, weinig belang.     

Effects of nitrogen and potassium fertilizer application on Drechslera spp. and Puccinia coronata on perennial ryegrass (Lolium perenne) foliage

In a field experiment nitrogen (N) fertilizer was applied to small plots of perennial ryegrass ( Lolium perenne ) at rates equivalent to 0, 200, 400 and 600 kg N/ha/yr at each of two levels of potassium (K) 0 and 200 kg K/ha/yr. Plots were cut at 6-week intervals during 1977–79 and dry matter yield was determined. Water-soluble carbohydrate and N content of the foliage were measured at three harvests in 1977. The incidence and severity of Drechslera spp. were assessed at and between harvests; attack by Puccinia coronata was assessed each autumn. Most foliar damage was caused by Drechslera spp. This was increased by N application which also altered the relative proportions of the Drechslera spp. present. K application had no apparent effect on disease incidence. Puccinia coronata was more prevalent on older leaves and on one occasion its incidence was increased by N application.