红鳞蒲桃开花物候特性研究

对红鳞蒲桃种群的花期物候，单株、单个花序、单花的开花动态进行系统的观测研究，详细测量并记录花部构件，同时调查红鳞蒲桃种群的同花期植物。结果表明：红鳞蒲桃种群的花期物候为8月1日～9月15日（2008年），持续时间46d；单株花期从23d到33d不等；单花序的花期情况较为复杂，总体表现为花朵数越多，该花序持续时间越长，但也有个别情况出现，在开花中期花序持续时间长，开花后期花序持续时间最短，开花前期花序持续时间介于两者之间；在整个种群花期内单花平均开花时间约5．2d，种群开花前期单花的持续时间约为6．7d，开花中期约为4．7d，末花期约为4．3d，种群开花前期单花的持续时间显著大于种群中后期的持续时间。红鳞蒲桃种群的同花期植物隶属于16科21属22种。     

Germination ecology of seeds of the annual weeds Capsella bursa-pastoris and Descurainia sophia originating from high northern latitudes

Low temperatures may inhibit dormancy break in seeds of winter annuals, therefore it was hypothesized that seeds of Capsella bursa‐pastoris and Descurainia sophia that mature at high latitudes in late summer–early autumn would not germinate until they had been exposed to high summer temperatures. Consequently, germination would be delayed until the second autumn. Most freshly matured seeds of both species collected in August and September in southern Sweden were dormant. After 3 weeks of burial at simulated August (20/10°C) and September (15/6°C) temperatures, 28 and 27%, respectively, of the C. bursa‐pastoris and 56 and 59%, respectively, of the D. sophia seeds germinated in light at 15/6°C. In contrast, in germination phenology studies conducted in Sweden, only a few seeds of either species germinated during the first autumn following dispersal. However, there was a peak of germination of both species the following spring, demonstrating that dormancy was lost during exposure to the low habitat temperatures between late summer and early autumn and spring. Nearly 100% of the seeds of both species subjected to simulated annual seasonal temperature changes were viable after 30.5 months of burial. In the burial study, exhumed seeds of C. bursa‐pastoris were capable of germinating to 98–100% in light at the simulated spring–autumn temperature regime (15/6°C) in both spring and autumn, while those of D. sophia did so only in autumn. In early spring, however, seeds of D. sophia germinated to 17–50% at 15/6°C. Thus, most seeds of these two annual weeds that mature in late summer do not germinate in the first autumn, but they may do so the following spring or in some subsequent autumn or spring.     

Phenotypic Changes in Grain Sorghum Over the Last Five Decades

Sorghum [Sorghum bicolor (L.) Moench] is a drought‐tolerant crop, and its productivity in rain fed environments has increased since the 1950s. This increase is due to changes in agronomic practices and hybrid improvement. The objective of this study was to determine what aspects of grain sorghum morphology, physiology and water use have changed with hybrid improvement and might have contributed to this yield increase. A 2‐year greenhouse experiment was conducted with one hybrid from each of the past five decades. The hybrids were studied in well‐watered and pre‐ and post‐flowering water deficit conditions. Total water use, transpiration, stomatal conductance and photosynthesis were measured during the growing period. Biomass and biomass components were measured at harvest. There was no consistent change in the leaf physiological parameters resulting from hybrid advancement. In contrast, total water use increased in rate of 8.5 cm³ kg soil^?1 year^?1 from old to new hybrids in the well‐watered treatments. Root biomass also increased in rate of 0.2 g plant^?1 year^?1. Leaf biomass and panicle length also was greater for the newest compared with the older hybrids. Hybrid advancement was related to increase in panicle length but decrease in peduncle length. Results indicated that hybrid development programmes created hybrids with improved drought avoidance, due to better root density of newly released hybrids, or hybrids with better resource use which ultimately increased yield under rain fed conditions.     

马蔺的花部构造及开花授粉生物学特性

对马蔺的花部特征、开花动态、授粉特性及传粉媒介等进行了研究,运用多种处理方式,对马蔺的传粉机制进行测定。结果表明:自然条件下,马蔺5～6月开花,群体花期约40d,盛花期约25d,单花花期约58h。马蔺的繁育系统属于异交,部分自交亲和,自然传粉需要借助传粉媒介,虫媒传粉是其传粉方式之一。     

甘肃多儿国家级自然保护区维管植物区系分析

基于野外实地考察、植物标本的采集与鉴定以及结合文献研究的方法,分析了多儿保护区维管植物区系的物种组成和分布区类型。结果表明,该区维管植物共115科469属1323种,包括蕨类植物14科25属61种,裸子植物4科8属25种,被子植物97科436属1237种。多儿保护区维管植物区系优势现象明显,≥20种的优势科共879种,占该区维管植物总种数的66.44%;小属和单种属成分比例较大,占该区维管植物总属数的95.31%,总种数的75.51%。科级水平上,热带科（30.43%）稍多于温带科（26.96%）;属级水平上,温带科（72.49%）明显高于热带科（13.01%）;种级水平上,中国特有种有545种,其中538种与周边省份所共有,体现了该区系明显的过渡性和交汇性。该保护区维管植物区系地理成分复杂多样,属的分布有15个分布型和5个变型,温带地理成分占绝对优势,尤其以北温带分布为主。该区珍稀濒危野生植物较多,被列入保护名录有37种;一些古老、孑遗植物在该保护区具有良好的原始类群分布。本研究进一步完善了多儿保护区维管植物区系特征,为以后了解该保护区生物多样性提供可靠依据。     

Optimising cutting method and timing for the control of Abutilon theophrasti seed production

Abutilon theophrasti (velvetleaf) is a widespread and problematic annual weed. Greenhouse and field experiments were conducted to investigate the effects of different cutting methods on the viability of A. theophrasti seeds. Three cutting methods were assessed: (1) Entire plant cut and dried (EPD)—plants were cut at soil level and dried with capsules attached on the greenhouse bench or soil surface for 4 weeks; (2) capsules detached and dried (CD)—capsules were removed from plants and dried for 4 weeks; and (3) capsules detached and tested while fresh (CF)—a control treatment. Before drying, the developmental stage (stage one, dark green; stage two, light green; stage three, yellowish-green; or stage four, black with the slightly open capsule) and age (days after flowering, DAF) of each capsule was recorded. Seed viability was measured immediately in the CF treatment and after the 4-week drying period in the EPD and CD treatments. No seeds in the EPD and CD treatments were viable when harvested at the first developmental stage (1–8 DAF) in either experiment, but 100% of seeds in the CF treatment in the field were viable when harvested at 8 DAF. In both greenhouse and field experiments, seeds attained full viability at earlier harvest ages in CF than in EPD or CD treatments, suggesting that seeds might become viable relatively early in development but lose viability if allowed to dry. These findings could be applied to optimise late-season mechanical control of A. theophrasti.     

无土栽培适宜葡萄品种的筛选研究初报

以87-1、京蜜、红地球、夏黑和金手指葡萄为试材,珍珠岩作为基质,Hoagland改良式营养液循环方式提供水分和养分,连续三年研究了设施无土栽培条件下不同葡萄品种生长发育的差异。结果表明,87-1、京蜜葡萄果实成花枝率均达到85%以上,结果系数达到1.50,可以满足生产的需要。夏黑和金手指的成花枝率分别为61.35%和36.38%,夏黑的结果系数仅为1.32,均显著低于87-1和京蜜。红地球葡萄在无土栽培条件下基本不能成花。果实产量方面,87-1葡萄的亩产超过2400kg,京蜜葡萄也超过1500kg,能够满足生产的要求。金手指葡萄亩产1245.51kg,夏黑葡萄出现严重的落花落果,亩产仅为796.95kg。果实品质方面,金手指、夏黑和京蜜葡萄的可溶性固形物含量均超过17%,可溶性总糖含量均超过15%,基本上可以满足生产要求。87-1由于产量过高,品质降低。因此,无土栽培87-1葡萄必须控制产量,参照京蜜葡萄以1500kg/亩左右为宜。综上所述,初步认为87-1和京蜜是适合无土栽培的葡萄品种,生产需要配合合理负载,亩产以1500kg为宜。金手指和夏黑葡萄需要继续调整营养液配方和管理方法,红地球不适合无土栽培生产。     

蓝莓不同品种花芽形成过程中内源激素变化

采用酶联免疫吸附测定法测定5个蓝莓品种在花芽形成期间花芽中4种内源激素含量,研究内源激素对蓝莓花芽分化的影响,为人工调控蓝莓花芽分化奠定理论基础。研究结果表明,5个蓝莓品种在花芽形成过程中,花芽中GAs和ZR含量呈先升高后下降,再升高的变化趋势,在花芽分化初期达到最大值,之后一直保持在较低水平;IAA含量呈先下降后升高的趋势,在花芽分化中期达到最小值,之后含量迅速上升;ABA含量呈先下降后升高,再下降的趋势,在花芽分化末期达到最大值。在花芽形成过程中,5个蓝莓品种花芽中ABA/GAs比值均表现为先下降后升高;ZR/GAs和ZR/IAA的变化趋势相同,均呈先升高后下降的‘M’形变化;ABA/IAA的变化趋势与ZR/GAs相反。     

Foliar lifespan,phenology and seasonal dynamics of the invasive shrub Schinus terebinthifolia

Schinus terebinthifolia is a dioecious tree native to South America that has become an invasive weed in Florida, southern California, southern Arizona, Texas and Hawaii and has been naturalised in over 20 countries. Biological control is considered a viable long-term control option for S. terebinthifolia because release from natural enemies appears to be at least partly responsible for its success in Florida. We examined leaf phenology of S. terebinthifolia over a period of 15 months at five sites in central and southern Florida to provide information that may help in predicting the impacts of potential biocontrol agents for this weed. We documented leaf lifespan, the seasonality of leaf development and abscission and the survivorship of leaves that emerged during either spring, summer or autumn. Average leaf lifespan was >4.5 months at all sites, and leaf phenology followed the seasons closely. Although S. terebinthifolia possesses leaves throughout the year, leaf production was greatest from April to September, and most leaves were abscised in February and March. Spring- and summer-emerging leaves were also longer-lived than leaves produced during autumn. These results suggest that leaves of S. terebinthifolia would be most vulnerable to herbivory during the spring and summer months when newly growing leaf tissue is most plentiful. Biocontrol agents capable of damaging these tissues during spring/summer might be an effective means of controlling this invasive weed.     

Water availability affects nectar sugar production and insect visitation of the cup plant Silphium perfoliatum L. (Asteraceae)

The perennial cup plant (Silphium perfoliatum L.) is considered as an alternative feedstock to maize for biogas plants. Due to its ecological advantages of an extensive management and function as food resource for pollinators, it can be grown in Ecological Focus Areas (EFAs) since 2018. However, studies at the Julius Kühn-Institute in Braunschweig (Germany) showed that the assumed advantage of the cup plant of a high drought tolerance could not be confirmed regarding aspects of crop production and yield. We complemented this experiment by assessing how different soil moisture conditions affect the production of floral resources and insect visitation. In 2014, we sampled three irrigated and three rainfed plots of the cup plant. We quantified the nectar volume and sugar mass per inflorescence, the number of inflorescences per plant and calculated the total nectar sugar production. We further counted insect visitation on the inflorescences. Due to reduced numbers of inflorescences per plant and an earlier harvest, the estimated nectar sugar production was 58 kg/ha regarding irrigated and 20 kg/ha regarding rainfed plots. Honeybee visitation per inflorescence was about twice as high in the irrigated plots. Furthermore, the early harvest is a disadvantage for wild pollinators with a late activity period.