Determination of Festuca filiformis seedbank characteristics,seedling emergence and herbicide susceptibility to aid management in lowbush blueberry (Vaccinium angustifolium)

Festuca filiformis is a common perennial grass in lowbush blueberry fields, but little is known about the general biology, seedbank characteristics, seedling recruitment or susceptibility of seedlings to currently registered herbicides. The objectives of this research were to determine (i) the presence of F. filiformis seedbanks in lowbush blueberry fields, (ii) whether F. filiformis seedbanks accumulate near the soil surface in lowbush blueberry fields, (iii) the dormancy status of fresh F. filiformis seeds, (iv) the temporal patterns of seedling recruitment in established F. filiformis populations, (v) whether F. filiformis has a vernalisation requirement for flowering in lowbush blueberry and (vi) susceptibility of F. filiformis seedlings to various herbicides currently registered in lowbush blueberry. Festuca filiformis formed a seedbank in lowbush blueberry fields, with an average of 1660 ± 272–5680 ± 1409 seedlings m^?2 emerging from soil cores collected from two infested fields. Most seeds were located at the soil surface, providing opportunities for seedbank management through predation or burning. Fresh seeds lacked dormancy and readily germinated, although germination was reduced by dark conditions. New seedlings emerged in spring and autumn and required vernalisation to flower. Seedlings were susceptible to several currently registered herbicides in lowbush blueberry, although mortality rates were highest in plants treated with glufosinate, flumioxazin, glufosinate + flumioxazin and terbacil. Growers should avoid movement of seeds on machinery, and additional research should be conducted to determine the effects of registered herbicides on F. filiformis seedling recruitment under field conditions in lowbush blueberry.     

Root physiological traits and cold hardiness of alfalfa grown alone or mix-sowed with meadow fescue

Cold hardiness is important for alfalfa (Medicago sativa L.) grown in northeast China. We investigated overwintering for three alfalfa grown alone or mix-sowed with meadow fescue. During the overwinter stage of the year from October 2013 to April 2014, five physiological and biochemical indexes and overwintering rate were investigated under natural conditions. The results showed that no matter either singly sowed or mix-sowed plants, physiological traits such as soluble sugar, soluble protein, and free proline of the alfalfa roots increased as the temperature decreased at the end of autumn, and decreased when the air temperature increased in the spring. The malondialdehyde content and peroxidase activity of all the treatments showed the trend of up–down–up during the whole overwintering stage. Investigation of the overwintering rate and using the membership function method combined with correlation analyses revealed that the order of the cold resistance of the selected alfalfa cultivars was as follows: Gongnong1?+?meadow fescue?>?Gongnong1?>?Wega7F?+?meadow fescue?>?Wega7F?>?WL319HQ?+?meadow fescue?>?WL319HQ. These results indicated that the cold resistance of alfalfa mix-sowed with the meadow fescue was higher than that of alfalfa that was singly sown.     

高温胁迫下高羊茅草坪草生理特性研究

从美国引进的39个高羊茅草坪草种分成了5个生态类型,在1999—2000年从每类中找出一个具有典型性状的草种,测定其周年草坪坪质表现、根系活力、叶片可溶性糖含量变化,同时测定各类草种在高温胁迫下保护酶活性与质膜透性的变化。结果表明,根系活力及可溶性糖含量在一定程度上影响着草坪坪质的周年变化。同时,草坪草叶片MDA含量的增长率和草坪草叶片的质膜透性增长率具有显著的正相关效应。在40℃高温胁迫下,草坪草叶片SOD与POD相对活性和MDA含量的增长率及PMP增长率具有显著的负相关效应,5个草种对高温的抗性能力大小顺序是:Gooden>Regi ment>Tomahawk>SR-8210>Brandy。在此基础上,最后对草坪草抗性的准确快速检测方法进行了讨论。     

紫花地丁对2种草坪草的化感潜力初探

采用室内生物测定法研究紫花地丁(Viola yedoensis)水浸提液、腐解液对草地早熟禾(Poa pratensis)和高羊茅(Festuca arundinacea)2种草坪草的化感潜力,以初步探讨其化感作用,为杂草地草坪建坪草种选择提供依据。结果表明:紫花地丁水浸提液对2种草坪草种子萌发和幼苗生长的综合效应有显著抑制作用,且具有浓度效应;腐解液对草地早熟禾种子萌发和幼苗生长的综合效应有显著抑制作用,而对高羊茅种子萌发和幼苗生长的综合效应表现出"低促高抑"的趋势。以水浸提液对草地早熟禾和高羊茅的抑制作用最明显;紫花地丁对草地早熟禾的化感抑制作用大于对高羊茅的抑制作用。高羊茅比草地早熟禾适合在紫花地丁为主要杂草的土地建坪。     

紫花地丁水浸提液对草地早熟禾和高羊茅的化感作用研究

以紫花地丁为材料,采用室内生物测定法研究紫花地丁水浸提液对草地早熟禾和高羊茅种子萌发、幼苗生长及生理指标的化感作用,并采用气相色谱-质谱(GC-MS)联用技术对紫花地丁水浸提液化学成分进行了分析.结果表明:紫花地丁水浸提液对草地早熟禾和高羊茅种子萌发、幼苗生长和生理均有明显的化感作用,其作用程度与草坪草种类和水浸提液浓度有关.各浓度紫花地丁水浸提液对草地早熟禾和高羊茅发芽指标均有显著的抑制作用,最大种子发芽抑制率分别达到100％和97.16％;对草地早熟禾根长、苗高和单株重均表现出抑制作用,低浓度水浸提液对高羊茅苗高和单株重表现为促进作用;对草地早熟禾和高羊茅幼苗SOD、POD、CAT活性以及MDA含量均表现出促进作用,对可溶性蛋白含量表现为抑制作用.紫花地丁水浸提液中鉴定出28种化合物,主要成分是2,3-二氢苯并呋喃(8.83％)、4-羟基-3,5,6-三甲基-4-(3-氧代-1-丁烯基)-2-环己烯-1-酮(5.79％)、4-(3-羟丁基)-3,5,5-三甲基-2-环己烯-1-酮(4.32％)、3-氧代-β-紫罗兰酮(4.10％)和松酒(2.67％)等.     

Simulating bimodal tall fescue growth with a degree‐day‐based process‐oriented plant model

Plant growth simulation models have a temperature response function driving development, with a base temperature and an optimum temperature defined. Such models function well when plant development rate shows a continuous change throughout the growing season. This approach becomes more complex as it is extended to cool‐season perennial grasses with a dormant period and bimodal growth curves. The objective of this study was to develop such a bimodal growth model for tall fescue (Schedonorus arundinaceus (Schreb.) Dumort) in the Midwest USA based on multiyear measurement trials. Functions for bimodal growth were incorporated into the ALMANAC model and applied to tall fescue using published tall fescue yields for a variety of sites and soils. Fields of cultivars “Kentucky 31” and “BarOptima Plus E34” were divided into paddocks and sampled weekly for dry‐matter accumulation. These biomass estimates were used to derive weekly growth values by differences between sequential weekly samplings. The measured values were compared to a single tall fescue simulation each year on one soil. Using these results, the ALMANAC model was modified and tested against mean reported tall fescue yields for 11 sites, with one to three soils per site. When we introduced midsummer dormancy into ALMANAC, we assumed dormancy began on the longest day of the year and lasted until the photoperiod was 0.68 hr shorter than the longest. ALMANAC simulated previously reported tall fescue yields well across the range of sites. Thus, ALMANAC shows great promise to simulate bimodal growth in this common cool‐season grass.     

4个高羊茅品种幼苗期抗旱性比较研究

本试验以4个不同品种的高羊茅为材料,在幼苗期对其进行5种不同水势(0MPa、-0.3MPa、-0.6MPa、-0.9MPa、-1.2MPa)的PEG-6000人工模拟干旱胁迫,从丙二醛(MDA)、脯氨酸(Pro)和类胡萝卜素(Car)含量以及抗氧化保护酶活性等几个生理生化指标着手,对其抗旱性进行了对比研究.试验数据表明,随着干旱胁迫的加剧,高羊茅幼苗叶片中MDA、Pro和Car含量呈上升趋势;超氧化物歧化酶(SOD)活性呈先降后升的趋势,而过氧化物酶(POD)活性呈先升后降的趋势.同时发现,高羊茅幼苗期的耐旱极限范围可能在-0.9MPa水势左右.最后利用综合聚类分析法得出这4个高羊茅品种的抗旱性强弱为:贝克的抗旱性较强,家园的抗旱性较弱,火凤凰和爱瑞3的抗旱性一般.     

Variations in vernalization requirements among ecotypes of Festuca hallii

Plains rough fescue (Festuca hallii [Vasey] Piper) is an important forage grass species in the Northern Great Plains of Canada. Its seed is in demand for forage production and habitat restoration, but erratic seed production limits supply. A comprehensive understanding of factors influencing flowering and seed production in this species is needed. This study evaluated the morphological and phenological variation among six ecotypes of F. hallii from Saskatchewan and Manitoba. Seeds were germinated, and seedlings were grown in the field and then transplanted to a greenhouse in November. Plants not flowering in the greenhouse were vernalized under 5°C and 8-h light for 11 weeks. In a separate experiment, plants were subjected to temperature regimes of 15/5°C, 10/0°C and 5/−5°C with day-length treatments of 12 h, 8 h and a gradually changing daylength from 12 to 8 h respectively. This study demonstrated the existence of considerable variation in morphological and phenological characteristics, and in growth and vernalization requirements among ecotypes of F. hallii. Vernalization requirements were not met for the ecotype from the Moist Mixed Grassland Ecoregion when it was grown under common conditions, whereas ecotypes from other ecoregions were vernalized in at least one of the 2 years in the field experiment. Northern ecotypes tended to flower earlier after artificial vernalization treatments. Overall, 15/5 to 5/−5°C d per night temperature regimes with photoperiods between 12 and 8 h were effective in inducing flowering. The seed source of F. hallii should be regarded as an important consideration affecting its use, both for habitat restoration and for forage production.     

Field Evaluation of Cocksfoot,Tall Fescue and Phalaris for Dry Marginal Environments of South‐Eastern Australia. 1. Establishment and Herbage Production

Newly developed candidate cultivars of cocksfoot (Dactylis glomerata L.), phalaris (Phalaris aquatica L.) and tall fescue (Festuca arundinacea Schreb. = syn. L. arundinaceum (Schreb) Darbysh.) were evaluated over four years for persistence and productivity against current commercial cultivars in small plots at five locations selected for lower and less reliable rainfall and difficult soils (low pH and high Al) in south‐eastern Australia known to be marginally too dry for these grass species. The five locations were ‐ representing summer dominant rainfall, Inverell, in northern New South Wales (NSW); ‐ representing uniform rainfall; Trungley Hall, (medium rainfall), and Beckom (lower rainfall) both in southern NSW; and; representing a winter dominant pattern ‐ Eversley, (higher rainfall), and Bealiba, (lower rainfall), in central Victoria. The objective was to determine if the new candidate cultivars were more likely to persist and to be productive than current commercial cultivars. The study showed that most phalaris and cocksfoot treatments were highly productive in high rainfall years at one or both sites in southern NSW. However, all treatments had become much less productive by the end of the experimental period due to plant loss under hot, dry conditions in the final summer. At Bealiba in central Victoria, cocksfoot was the most productive species with several cocksfoot treatments of both subsp. hispanica and subsp. glomerata still present at the final harvest despite a hot and dry final summer‐autumn. Tall fescue was the most productive species in the two higher rainfall environments (Inverell, Eversley) although most treatments of all species performed well at those sites. Continental tall fescues were more productive on average than Mediterranean tall fescues at the strongly acidic Eversley site. As a result of this work, two of the new cocksfoot candidates (Moroccan Fine and AVH48 Selection) and one of the tall fescue candidates (Summer Active 1) have been licensed for commercial development and release.     

高羊茅腐解物的自毒作用初探

为探明高羊茅草坪逐年退化现象是否与化感作用有关，在室内用生物测定方法测定了高羊茅腐解物对高羊茅自身的化感作用，并探讨了相关的作用机制。结果表明，高羊茅腐解液能抑制高羊茅种子的萌发和幼苗生长，且腐解液质量浓度越大，抑制作用越明显。在腐解液质量浓度为0.06 g/mL时，其对高羊茅种子发芽率、发芽势、发芽指数、活力指数、根长、苗高、单株鲜质量的抑制率分别达58.64%、81.68%、73.34%、81.63%、37.86%、41.13%、30.43%。随着高羊茅腐解液质量浓度的增加，其幼苗SOD活性先升后降；POD活性与空白对照差异不显著；CAT活性先升后降，在高质量浓度时，与空白对照的差异达到显著水平；膜脂过氧化产物MDA含量持续升高；可溶性蛋白含量下降。可见，高羊茅残体腐解是其草坪逐年退化的原因之一。