不同栽培年限黄花倒水莲产量与品质分析

为确定黄花倒水莲的适宜采收期，该研究采用国标等方法对1～5年生黄花倒水莲根系形态特征、生物量、药用成分、营养成分和矿质元素进行了分析。结果表明：(1)根系形态(根幅、基径及一级根径)和根生物量在前2年增长缓慢，第2～3年增长迅速，第3年后趋于平缓。(2)不同药用成分含量在不同栽培年限间存在显著差异，其中粗多糖在第1年含量最高，皂苷类化合物在第2年含量最高，黄酮类化合物在第4年含量最高。(3)矿质元素含量受栽培年限影响较复杂，Ca、Mg、Mn、Cu含量在第3年累积至最多，Fe含量逐年降低，Pb含量与Fe含量变化规律相反。(4)粗蛋白含量呈现先增加后降低的趋势，总灰分含量与粗脂肪含量呈逐年降低趋势。(5)黄花倒水莲在第3年达到高产量，4～5年生黄花倒水莲根中大多品质指标均处于最低值，第3年为黄花倒水莲较为理想的采收期。该研究阐明了黄花倒水莲在不同栽培年限根系的产量指标及品质指标积累动态变化规律，揭示了黄花倒水莲的最佳采收期，为黄花倒水莲高产优质栽培提供了技术指导。     

广东省草地贪夜蛾冬季发生特征及周年繁殖区域研究

广东省是草地贪夜蛾入侵我国的桥头堡和主要的北迁虫源地之一,明确该虫在广东省的冬季发生特征及越冬存活情况,对广东省乃至全国草地贪夜蛾的预测预报及源头治理意义重大。为准确掌握广东省草地贪夜蛾的周年繁殖区范围及冬季发生为害情况,2020年1-3月在粤东、粤西、粤北及珠三角地区,利用成虫性诱、挖土查蛹、幼虫密度及植株为害率普查等方法,分析广东省草地贪夜蛾冬前、冬后种群发生为害情况及冬季发生特征。调查结果表明:(1)广东省冬玉米种植区主要分布在湛江、茂名、阳江、惠州等地,冬玉米种植区均发现草地贪夜蛾幼虫为害,主要为害冬玉米,极少为害甘蔗;(2)不同地区冬种玉米上草地贪夜蛾的发生程度差异较大,湛江、茂名、阳江发生为害较为严重,平均为害率30%左右,而珠三角及粤东地区发生较轻,为害率低于10%;较冬前调查,冬后草地贪夜蛾发生量和为害程度出现不同程度的下降;(3)广东省大部分地区的冬种玉米田和空闲地均可持续诱捕到草地贪夜蛾成虫,而挖土调查发现草地贪夜蛾蛹密度较低。本调查明确了草地贪夜蛾在北回归线以南的冬玉米区可以周年繁殖,无明显的滞育越冬现象,粤西茂名、阳江以南至雷州半岛一带为典型冬种玉米区,草地贪夜蛾发生为害较为严重,珠三角及粤东大部分地区草地贪夜蛾种群数量相对较低,调查结果为广东省乃至全国草地贪夜蛾的早期预警和精准防控提供了重要参考。     

The food and feeding relationships of larval and 0+ year juvenile fishes in lowland rivers and connected waterbodies. II. Prey selection and the influence of gape

The relative importance of taxa- and size-specific prey selection, and the influence of gape on the prey consumed by the larvae and 0+ year juveniles of four fish species were investigated in 'main river', 'marina' and 'pond' macrohabitats in the lower River Trent, England. A general sequence of ontogenetic shifts in food consumption was reflected in the electivity indices of particular prey taxa, partly due to the restrictions imposed by the gape of 0+ year fishes. Certain taxa, however, were consistently selected over others, irrespective of size, suggesting that taxa-specific, as well as size-specific, prey characteristics may be important in the selection process. There were significant, positive relationships between maximum prey (zooplankton) length and maximum gape height for larvae, but not for 0+ year juveniles. The majority of fishes, however, consumed prey substantially smaller than the maximum theoretically possible inferred from their gape. The greater size ranges of zooplankton in connected waterbodies compared with main river channels provide suitable prey for a range of developmental steps and fish species, and may, thus, enhance recruitment success.     

Laying date,body mass and tick infestation of nestling tropical Roseate Terns Sterna dougallii predict fledging success,first‐year survival and age at first return to the natal colony

Both intrinsic and extrinsic factors recorded at individual nests can predict offspring fitness and survival but few studies have examined these effects in the tropics. We recorded nestling survival, post‐fledging survival and age at first return of Roseate Terns breeding at Aride Island, Seychelles, over a 12‐year period (1998–2009). Nest data recorded at the egg, nestling and fledging stages were collected during six breeding seasons (1998, 2001–2005) and a capture‐mark‐recapture dataset of six cohorts of fledglings was obtained from 2001–2009. Logistic regression models were used to assess the predictive effect of reproductive variables on fledging success, while multistate capture‐mark‐recapture models were used to estimate post‐fledging survival and return–recruitment probabilities to the natal site. Nestling survival probability increased with earliness of laying and was negatively affected by tick infestation during the growth period (0–23 days). Fledging probability was also positively related to chick body condition, whereas other pre‐fledging reproductive parameters such as clutch size and egg size were not influential. A multistate modelling of age‐specific survival and return–recruitment (transition) rates found that first‐year survival differed between cohorts and was also negatively affected by tick infestation. Annual survival stabilized from age 2 onwards at 0.83 ± 0.02. Transition rates were positively related to body condition at fledging, with heavier individuals returning for the first time to the natal colony at a younger age compared with lighter individuals. These results highlight the importance of local conditions encountered by tropical seabirds during the breeding season in shaping demographic parameters.     

拓扑预测阀值ξi的确定及广西八角丰歉年预测

本文将灰色系统理论中拓扑预测的阀值ξi从一常量延伸为一变量,使拓扑预测的功能得到拓广,并利用拓广后的方法对广西八角产量的大小年作了预测,并获得较高的精度。     

Reproductive biology of four large riverine fishes (Cyprinidae) in a man-made lake,Orange River,South Africa

The reproductive biology ofBarbus holubi, B. kimberleyensis, Labeo capensis andL. umbratus was examined in a large reservoir on the Orange River, South Africa. The findings are integrated into the existing knowledge on largeBarbus andLabeo species, which coexist in most river systems in Africa and Asia.LargeBarbus spawn on gravel beds within the river channel during floods in spring or summer. In continuously flowing regulated rivers, time of spawning is governed by water temperatures. They have moderate fecundity; large eggs, incubation time of several days and the larvae are initially immobile with large yolk sacs. In the impoundment, they spawn in the inflowing regulated river withB. kimberleyensis spawning four to six weeks later than the more cold-tolerantB. holubi, the dominant largeBarbus. Survival is generally good and the juveniles disperse throughout the lake, but unseasonal release of cold water from an upstream impoundment may cause poor reproductive success.In contrast,Labeo species generally spawn on newly flooded ground, usually leaving the main river channel. Spawning may or may not be preceded by a longitudinal migration. Labeos are relatively fecund with small (30%Barbus size) eggs which hatch quickly and the larvae swim in bursts up into the water column before sinking down again.L. capensis does not require a longitudinal spawning migration and breeds throughout the lake, depending on local conditions. Large temporal variation in gonadal development within the population can result in more than one spawning. Dispersal within the lake is poor.L. umbratus uses larger inflowing tributaries for spawning thanL. capensis and its juveniles have a much greater power of dispersal. Early dependence on external feeding and undependable occurrence of conditions for spawning and juvenile feeding makes for variable reproductive success.     

陇东黄土旱塬作物组合系统农田耗水规律研究

本文根据１９８８－１９９１年陇东黄土旱塬作物组合模式（即作物轮作与复种模式）田间试验土壤水分测定资料,对作物组合系统中主要组分作物田间耗水量及其构成特征、变异规律及农田土壤水分的利用程度进行了研究,并探讨了不同作物组合系统的田间耗水量及其构成特征。结果表明,不同作物组合系统的田间耗水量及其构成特征存在明显差异;作物田间耗水量是一个动态变量,因作物种类、降水年型等不同而异,并与生育期有效降水量呈显著正相关;来自播前土壤有效储水的土壤供水量对秋播作物冬小麦和冬油菜生育期水分不足有重要补偿作用,是维持其较高的生产稳定性的关键原因;无论丰水年还是欠水年,冬小麦、玉米、谷子和马铃薯４种主要作物在农田水分利用程度上均存在一定差异。     

Within‐and among‐year germination in Sonoran Desert winter annuals: bet hedging and predictive germination in a variable environment

In variable environments, organisms must have strategies to ensure fitness as conditions change. For plants, germination can time emergence with favourable conditions for later growth and reproduction (predictive germination), spread the risk of unfavourable conditions (bet hedging) or both (integrated strategies). Here we explored the adaptive value of within‐ and among‐year germination timing for 12 species of Sonoran Desert winter annual plants. We parameterised models with long‐term demographic data to predict optimal germination fractions and compared them to observed germination. At both temporal scales we found that bet hedging is beneficial and that predicted optimal strategies corresponded well with observed germination. We also found substantial fitness benefits to varying germination timing, suggesting some degree of predictive germination in nature. However, predictive germination was imperfect, calling for some degree of bet hedging. Together, our results suggest that desert winter annuals have integrated strategies combining both predictive plasticity and bet hedging.     

Occurrence of the parasite Glugea hertwigi in young‐of‐the‐year smelt in Lake Tuusulanjärvi

Young‐of‐the‐year smelt Osmerus eperlanus in Lake Tuusulanjärvi were examined for Glugea hertwigi cysts. Cysts were visible on smelt in the beginning of August and showed a peak at the end of August. Glugea hertwigi may cause mortality among the most heavily infected young‐of‐the‐year smelts.