Segregation of herring larvae from inshore and offshore spawning grounds in the north-western North Sea — Implications for stock structure

Herring larvae hatching from spawning sites around the Scottish coast are dispersed by water currents during the weeks following hatching. Hydrographic data, observations on the distribution of caesium-137 and measurements of current velocities by moored meters and drifting buoys, suggest that larvae from offshore spawning sites around the north of Scotland should be more rapidly dispersed than those hatching in inshore areas. This has been confirmed by direct observations on the advection of herring larvae in different regions of the north western North Sea. The conclusion is that larvae hatching in inshore areas, especially in the Moray Firth, are most likely to contribute to nearby juvenile populations, whereas larvae from offshore spawning sites should be widely dispersed over the North Sea.Tagging and parasitology investigations have shown that adult herring spawning in the north-western North Sea have been widely dispersed in the North Sea and adjacent waters as juveniles (six months — one and a half years old). However, a high proportion of adult fish caught at inshore spawning sites and in the Moray Firth were found to have been recruited from more local areas. Taken together with the observations on larval drift, these observations suggest that the stock structure of herring in the northern North Sea may in part be a consequence of the physical oceanography of the area.     

Effect of Plastic Mulch on Squash (Cucurbita pepo L.): Germination, Root Distribution, and Soil Temperature under Trickle Irrigation in the Jordan Valley

An experiment with squash ( Cucurbita pepo L.) was conducted at the University of Jordan Research Station, located in the Jordan Valley in Jordan during the 1984 and 1985/86 seasons. Its objectives were to determine the effects of different plastic mulch using drip irrigation on soil temperature, root growth distribution, and production dates, Earliness in picking dates under mulch was obtained during the relatively warm 1985/86 season, where picking started 13 days earlier under mulch. Root weights, secondary root lengths, and horizontal root distribution were not significantly different between treatments, during each season. Tap roots were not significantly different between treatments during the 1984 season, yet those under transparent mulch were significantly higher (5% level) from those under bare soil conditions, during the 1985/86 season. Density of plant canopy influenced mulching effect on soil temperature. High plant canopy under mulch prevented solar radiation from increasing soil temperature. Whereas, higher soil temperature was obtained under non-mulched conditions when compared to the mulched ones. This was most probably due to relatively low vegetative cover.     

Physiological Analysis of Yield Variation in Mungbean (Vigna radiata [Roxb.] Wilczek)

Two mungbean varieties, Guj-1 and PIMS-1 differing in their productivity potential, were examined to investigate their photosynthetic system at various stages of growth in relation to yield with two different dates of sowing. Vertical leaves were found to be beneficial. On the other hand, excessive leaf area during the later stages of growth may be detrimental to yield. Lower LAD at seedling stage and overall high NAR values may be reflected in higher grain yield. NAR declined as season progressed and this, in turn, may be related with increase in LAI. The grain yield was considerably more at the first date of sowing as compared to second date of sowing, the effect was being more pronounced in var. PIMS-1 . Various environmental factors recorded at two different dates of sowing and at various stages of growth indicated that these factors may have influenced the yield potential at two different dates of sowing.     

长江中游地区双季稻安全生产日期的变化

安全生产日期是品种和种植方式选择、温光资源高效利用和生产季节安全的重要基础。本文以长江中游地区47个气象台站的逐日日平均温度资料为基础,分析了近50年(1960-2009)该地区50%和80%保证率的双季稻各安全生产期。发现生产中常用的80%保证率安全生产日期,后25年(1985-2009)较前25年(1960-1984)早稻覆膜旱育秧安全播种期推迟了3 d,早稻露地水育秧安全播种期提前了3 d,早稻安全移栽期提前了4 d,杂交晚籼稻安全齐穗期提前了3 d,常规晚籼稻安全齐穗期推迟了1 d,晚籼稻安全成熟期基本没有变化,早稻覆膜旱育秧条件下的双季稻安全生产季节天数缩短了4 d,早稻露地水育秧条件下的双季稻安全生产季节天数延长了1 d。本文列出了后25年各气象台站80%保证率的安全生产日期,按就近指导原则可以作为各地双季稻生产季节安排、品种和种植方式选择的依据。对比东北、华北、黄淮等地区,长江中游地区的气候及安全生产日期变化并不显著。除早稻露地水育秧安全播种期、早稻安全移栽期明显提前,有利于早稻提早播种、增加产量潜力外,其他安全生产日期的变化并不利于延长生长季节和增加产量潜力,其中晚稻安全齐穗期还略有提前。因此,从生产安全性的角度,该地区不能盲目地推广直播稻,机插稻也应重视安全生产日期的问题,搞好品种选择和播期安排。     

Immigration and settlement pattern of Paralichthys dentatus and P. lethostigma in an estuarine nursery ground,North Carolina,U.S.A.

Immigration and settlement pattern of 0-group summer flounder (Paralichthys dentatus) and southern flounder (P. lethostigma) in an estuarine nursery are described. Flounders entering the estuary were transforming larvae. Despite their sympatric occurrence during larval immigration, the two species were found concentrated in different habitats. Sampling along transects within the estuary indicated that newly settled southern flounder were concentrated on tidal flats towards the head of the estuary while greatest numbers of summer flounder were captured on tidal flats in the middle reach of the system. Logistic regression analysis of presence/absence data indicated that salinity affected the distribution of southern flounder while substrate type was an important factor affecting the distribution of summer flounder. Numbers of both species on tidal flats declined in the spring, southern flounder appeared to move upstream to oligohaline riverine habitat and summer flounder appeared to move to high salinity salt marsh habitat. The segregated distribution apparent in juveniles is largely established during the immigration period. Differences in settling behaviour and subsequent movement and/or differential mortality occurring during settlement, appear important in determining the observed distribution of juvenile summer and southern flounder.     

A Comparison of Methods Used to Determine Biomass on Naturalized Swards

An experiment was conducted in 2000 to compare simple visual estimate, sward height and rising plate meter (RPM) methods for determining forage biomass in mixed-species, naturalized, rotationally grazed dairy and beef pastures. Measurements were taken pre- and post-grazing on 10 sampling dates at the dairy pasture, and post-grazing at 13 sampling dates at the beef pasture. For each sampling date, the effectiveness of each method for estimating the actual biomass from a quadrat was evaluated using regression analysis. The results for the visual estimate method were not consistent, with non-linear relationships occurring early and late in the season. While the meter stick was most effective in the dairy pasture, the RPM was most effective in the beef pasture. Species composition and structural characteristics of the stand were important factors affecting accuracy of biomass estimation. Equations developed for each method and site using data from all dates had low R²-adjusted values, and were unreliable predictors of biomass. The results from individual sites and dates were extremely variable, with no single method effective in all circumstances. To estimate forage biomass in mixed-species, naturalized pastures, standard quadrat harvesting remains the most reliable method, provided that enough quadrats are clipped to adequately represent a given area.     

泥鳅的人工繁殖与苗种培育初步研究

为了寻找泥鳅繁殖的最佳催产剂配比、催产温度及苗种培育开口饵料的最佳选择。通过注射不同的催产药物,在不同的水温下进行人工催产,苗种培育过程中选择不同的开口饵料进行投喂。本次试验研究发现：雌鳅的怀卵量跟性成熟度成正比,即性成熟度越高其怀卵量也越高,成熟系数为24%的雌鱼绝对怀卵量相对怀卵量分别为62142和990粒而成熟系数为9%的雌鱼仅为18207和367粒。不同的催产药物对泥鳅催产的效果不同,促黄体生成素释放激素类似物(LRH-A2)相对比绒毛膜促性腺激素(HCG）效果好,使用绒毛膜促性腺激素,受精率78.84%,而使用促黄体生成素释放激素类似物(LRH-A2),受精率为83.04%。上述2种激素按照一定比例(LRH-A2 5μg∕尾,HCG100 IU∕尾)可提高催产效果,受精率可达89.17%。在一定的温度范围内,温度越高泥鳅的催产效果越好。水温在(30±0.5)℃之间是泥鳅人工催产的最适水温,效应时间6~8 h,催产率为93.33%,受精率为89.26%。在苗种的培育过程中开口饵料是至关重要的,用轮虫（以萼花臂尾轮虫、角突臂尾轮虫为主）作为泥鳅仔鱼的开口饵料,其仔鱼成活率最高,成活率为93.3%,其他依次为卤虫幼体、微粒子配合饲料、蛋黄。合理搭配开口饵料能够促进仔鱼的生长,投喂蛋黄+轮虫的泥鳅仔鱼生长速度明显高于其他单独投喂的3组,投喂蛋黄+轮虫的鳅苗,其生长速度是单独投喂蛋黄的1.21倍,是单独投喂轮虫的1.04倍,是单独投喂卤虫幼体的1.11倍。     

Cry1Ah蛋白通过三级食物链对龟纹瓢虫幼虫的影响

使用生物测定方法评价了Cry1Ah蛋白和食料对龟纹瓢虫幼虫的影响.研究结果表明,用1.0和10.0μg·g1的Cry1Ah蛋白处理下的棉铃虫饲喂龟纹瓢虫后,其存活率、幼虫虫体质量、幼虫发育时间和化蛹率均没有影响,但龟纹瓢虫体内某些酶活力有所改变,这种改变并未显著影响幼虫的生长发育.用蚜虫饲喂的龟纹瓢虫存活率、虫体质量和化蛹率显著高于棉铃虫处理,差异达显著水平;幼虫发育时间前者显著短于后者.研究结果表明食料的不同对龟纹瓢虫的影响远远大于Cry1Ah蛋白对其的影响.     

Effects of Shading Densities on the Agronomic and Physiological Characters of Two Sugarbeet Cultivars

This study was carried out at the Agricultural Experiment Station of King Saud University near Riyadh (26° N, 46° E) during the 1984/85 season to study the effect of shading densities on the agronomic and growth parameters of sugarbeet. Two cultivars were grown under three shading nets with densities of 37, 50 and 70 % in addition to the control (0 % shading = normal sunlight condition).
The results indicated that shading affected the growth and the weight of sugarbeet plants and the effects were function of shading density. Root weights were drastically reduced by increasing shading density, whereas top weights were less affected.
Increasing shading density resulted in a significant increase in specific leaf area, leaf area ratio while it decreased leaf area index, root weight ration, net assimilation rate and crop growth rate for both cultivars. The interaction between shading densities and sampling dates was significant for most of the studied characters, while that between cultivars and shading densities was significant for root weight and crop growth rates only.     

不同寄主植物对斜纹夜蛾生长发育、繁殖及飞行的影响

 试验研究表明,取食不同食物斜纹夜蛾幼虫的发育历期、存活率、蛹重和成虫的羽化率有显著的差别。取食人工饲料的幼虫发育历期最短(18.11 d),其次为取食甘蓝和大豆(20.13 d和20.45 d)。取食人工饲料幼虫存活率达91.80%,显著高于取食棉花(75.47%)、甘蓝(\{73.68%\})和大豆(72.22%)的处理。幼虫取食人工饲料、甘蓝、棉花和大豆的成虫寿命和产卵前期没有显著性差别,但成虫的产卵期、产卵量和卵的发育历期有显著不同。取食人工饲料成虫的飞行能力显著高于取食甘蓝的处理,而以取食大豆和棉花处理的飞行能力最差。鉴于较差的幼期营养条件并不导致成虫飞翔能力的增加,斜纹夜蛾的远距离迁飞是成虫对羽化后所处不良环境的行为反应。     

Characterization of fall and spring plantings of Galician cabbage germplasm for agronomic, nutritional, and sensory traits

Twenty one landraces of cabbage (Brassica oleracea var. capitata L.) and two of Tronchuda cabbage (B. oleracea var. tronchuda Bailey) from Galicia (north–western Spain) along with five commercial hybrids of cabbage and one commercial variety of Tronchuda cabbage were evaluated in this study in two planting dates, autumn/winter for an early harvest and spring/summer for a late harvest. Data were recorded on morphologic, agronomic, nutritional, and sensory traits. The objectives were to assess the characteristics of the Galician cabbage landraces and to compare their agronomic value with that of the commercial hybrids available in local markets, at two planting dates. Four cabbage landraces and the two Tronchuda cabbage landraces showed no head formation. At the autumn/winter season, commercial hybrids showed poor adaptation, with more plants lost after transplanting, less early vigor, and yield than the head forming landraces. However, for characters related to crop uniformity (head appearance, days to harvest, and synchrony of production), commercial hybrids did better than landraces. Regarding the sensory and nutritional values, in the autumn/winter season, accessions were tenderer, sweeter, had a better flavour, and showed higher levels of crude protein and less of crude fibre than in the spring/summer season. Landraces had higher calcium contents compared to commercial varieties. Local landraces MBG-BRS0425, MBG-BRS0452, MBG-BRS0536, and MBG-BRS0537 stood out for the most interesting traits in the autumn/winter season growing period and they could be included in breeding programs to obtain hybrids suitable to grow in this planting period.     

羌塘国家自然保护区植被生长季NDVI时空变化及其对气候变化的响应

为详细了解羌塘国家级自然保护区生长季NDVI时空特征及其对气候变化的响应,使用MODIS传感器的生长季归一化植被指数(NDVI),计算2000—2020年羌塘国家级自然保护区各功能区生长季NDVI变化趋势和稳定性,结合中国第一代大气和陆面再分析产品(CRA/LAND)研究NDVI对气候变化的响应。结果表明：（1）保护区多年植被生长季NDVI均值为0.02~0.55,平均值为0.138,呈现由东南向西北逐渐减小的空间分布特征。（2）保护区86.39%的面积区域植被生长季（6—9月）NDVI呈缓慢上升趋势,并且大部分区域达到显著水平(P<0.05),剩余13.61%的面积区域植被生长季NDVI处于下降趋势,其中只有极少部分区域达到显著性水平(P<0.05);总体植被状况随时间变化呈变好趋势。（3）2000年以来保护区的生长季NDVI稳定性较差,NDVI≤0.1的大部分区域处于较低稳定度,较低稳定度和中等稳定度面积之和占整个研究区域面积的86.66%。（4）保护区在植被生长季气候趋向于“暖湿化”;气温与降水量对保护区生长季NDVI都有重要的正向影响。研究结论能为气候变化背景下该区域植被生态保护提供一定科学依据。     

抗性棉铃虫在转基因棉花上某些生命参数的研究

用室内转Bt基因棉叶汰选的低抗种群及同源对照种群,测定对田间不同生育期转基因抗虫棉叶及常规棉叶的反应.结果表明,抗性和敏感种群在常规棉叶上,幼虫存活率、化蛹率、幼虫历期及蛹重等指标均无显著差异,但抗性种群的每雌产卵量降低.抗性种群在转基因棉花上存活随棉花不同生育期的变化而出现差异.在7月下旬、8月下旬开始接虫的两代,第10天幼虫存活率,抗性种群比敏感种群提高;而在6月下旬开始接虫,抗性种群与敏感种群一样均不能化蛹,抗性种群化蛹率的提高仅在棉花生长后期(8月下旬开始接虫).比较敏感种群,抗性种群在转基因棉花上幼虫存活率提高,但存活幼虫生长缓慢,幼虫历期延长,蛹重明显减轻.结果表明,低水平抗性种群虽然对转基因棉花有一定适应性,但在转基因棉花上仍然生长发育不正常.     

Diallel analysis of sooty stripe resistance in sorghum

Sooty stripe [Ramulispora sorghi (Ellis and Everhart) Olive and Lefebre] is a widespread foliar disease of sorghum [Sorghum bicolor (L.) Moench] in West Africa, responsible for grain yield losses up to 46%. We studied the inheritance of sooty stripe resistance in a 9 × 9 sorghum F₂-population diallel grown together with parent lines and checks in1996 under natural disease pressure at two locations in Mali. The percentage of infected leaf area was determined twice over a two-week interval during the season. At the second evaluation, the mean sooty stripe severity amounted to 13% infected leaf area at Samanko and 12% at Cinzana. The frequency distribution of the entries was approximately normal for the mean disease severity, averaged across assessment dates and locations, pointing to the involvement of multiple genes. With the data combined across the two locations, genetic differences among lines and among F₂ populations were highly significant. Genotype × location interaction variances were also significant but much smaller than the genetic variances. Broad-sense heritability estimates were 0.92 for lines and 0.94 for the F₂ populations, for the mean percentage infected leaf area across the two assessment dates. General combining ability effects (GCA) determined most of the differences among the F₂ populations. Specific combining ability effects (SCA), and the interactions of GCA or SCA with locations were also significant but less important. Line performance per se was highly correlated with GCA. Because of the high heritability and predominance of additive effects, prospects are good for the genetic improvement of resistance to sooty stripe in sorghum in Mali, using simple pedigree or recurrent selection procedures. This revised version was published online in August 2006 with corrections to the Cover Date.     

甘蔗苗期大螟幼虫空间格局的地统计学分析

为明确大螟幼虫在甘蔗苗期的空间格局,2012年在云南省农业科学院甘蔗研究所科研示范基地开展了甘蔗苗期大螟为害枯心苗调查,并应用地统计学方法进行空间格局分析。结果表明：新植蔗虫口密度（1.07头/点）明显低于宿根蔗（1.91头/点）,新植蔗变异系数、峰度和偏度均较宿根蔗大,表明大螟在宿根蔗较新植蔗发生重,且新植蔗田较宿根蔗田有更高的聚集度。在半变异函数理论模型模拟方面,新植蔗田在4个方向均为球形模型,宿根蔗田在45°和90°方向为球形模型、0°方向为高斯模型、135°方向属随机分布,表明大螟幼虫整体上呈聚集分布,但新植蔗田聚集度较宿根蔗田高。在相关性方面,新植蔗田和宿根蔗田均在0°和45°方向上有中等的空间相关性,相关距离宿根蔗明显大于新植蔗,表明宿根蔗田的大螟幼虫空间相关性较新植蔗田强。通过Kriging插值模拟图可清晰看出,新植蔗大螟幼虫在蔗田边缘发生严重,虫源主要来自周边蔗田,宿根蔗大螟幼虫在田间的螟虫发生点多且均匀,虫源主要来自自身蔗田。     

Increased utilization of lengthening growing season and warming temperatures by adjusting sowing dates and cultivar selection for spring maize in Northeast China

Global warming has lengthened the theoretical growing season of spring maize in Northeast China (NEC), and the temperatures during the growing season have increased. In practise, crop producers adjust sowing dates and alternate crop cultivars to take advantage of the lengthening growing season and increasing temperatures. In this study, we used crop data and daily weather data for 1981–2007 at five locations in NEC to quantify the utilization of the lengthening growing season and increasing temperatures by adjusting sowing dates and cultivar selection for spring maize production. If these two positive factors are not fully utilized, then it is important to know the potential impacts of these climatic trends on spring maize grain yields. The results show that in NEC, both the actual and theoretical growing seasons are lengthening, i.e., the sowing dates have been advanced and the maturity dates have been delayed. The actual sowing dates are 1–8 days later and the actual maturity dates are 6–22 days earlier than the theoretical perspective. Advancing sowing dates and changing cultivars led to 0–5 days and 6–26 days extension of the growing season. For the potential thermal time (TT), adjusting the sowing dates decreased the unutilized TT before sowing, while the cultivar selection increased the utilized TT and decreased the unutilized TT after maturity. On average, the unutilized heating resource before sowing is less than that after the maturity date (0.3–1.9% vs. 2.1–7.8%). During 1981–2007, for per day extension of the growing season, the spring maize grain yield increased by 75.2 kg ha⁻¹. The spring maize grain yields have increased by 7.1–57.2% when both early sowing and changing cultivars during 1981–2007. In particular, adjusting the sowing dates increased the grain yield by 1.1–7.3%, which was far less than the increase effect (6.5–43.7%) from switching to late maturing cultivars. Therefore, selecting late maturing cultivars is an important technique to improve maize grain yields in NEC under the global warming context. Nevertheless, if the currently unutilized TT were fully explored, the local spring maize grain yield would have increased by 12.0–38.4%.     

1960—2019年海河平原地区夏玉米生长季高温特征分析

夏玉米生长季高温频发给夏玉米生产带来极大的不确定性。为系统分析海河平原地区夏玉米生长季高温年际和年内分布规律,本研究基于研究区26个气象站点1960—2019年逐日最高气温数据,以35℃作为夏玉米高温阈值,从高温事件个数和持续天数、生长季高温日数和高温度日4个方面展开研究。研究结果表明,4个高温指标在空间上都呈现出由东北部沿海地区向西南内陆地区增高的趋势。1960—2019年间夏玉米生长季高温指标的年际变化存在1972、1996年2个明显的突变点,将这60年分割成高温较强—较弱—较强3个时期;6月中旬—7月上旬发生高温的日数最多,占6—9月高温日数总和的69.8%,而6月下旬—7月下旬各旬的高温日数年际变化与生长季高温年际变化规律最为接近,是影响生长季高温变化的主要时段。研究结果对于全面掌握研究区夏玉米生长季高温时空分布特征、指导夏玉米生产具有一定的意义。     

Cause and Consequence in Maize Planting Dates in Germany

An important part of agricultural adaptation is the timing of crop sowing dates, affecting yields and the level of risk incurred during a particular season. Cold stress is especially relevant in maize, Zea mays L., so that the timing of planting in the spring is a tactical response to short‐term weather, but is also subject to strategic planning with regard to longer‐term climate. Both factors compare the potential implications of cold stress to the additional yield obtainable through earlier planting. New cultivars suited to growing conditions in Europe and generally increasing spring temperatures have enabled earlier planting, but it is still dependent on short‐term weather during the planting period. In the context of field‐level decision‐making, a panel regression is used to estimate the relationship between weekly local temperature and precipitation and planting dates at specific sites throughout Germany. Next, localised weather data and planting behaviour are linked to yields at the district (Landkreis) level to show the effects of planting date on yield. Based on these relationships optimal planting dates are explored with some associated costs and benefits. Results show a trend towards earlier planting that follows observed increasing spring temperatures and the availability of more cold‐tolerant cultivars but this advance is buffered by the increasing severity of minimum temperatures during a critical period. Earlier planting potentially increases yield but this is offset by additional management costs and risk. A robust and simple depiction of farmer behaviour in climatic, technological and economic context can help to understand trends in crop management and productivity that effect agricultural landscapes.     

Increasing the rate of ripening of date palm fruit (Phoenix dactylifera L.) cv. Helali by preharvest and postharvest treatments

‘Helali’ is a late season date palm cultivar. At the mature (Bisir) stage, the fruit are astringent as a result of high contents of soluble tannins, and removal of tannins is necessary for the fruit to be edible. During the harvesting season, only 30–40% of the total fruit might normally ripen (Rutab stage) on the tree and the remaining fruit fail to ripen. This study showed that bunch bagging with different materials such as black or blue polyethylene bags, white ‘agrlsafe’ (polypropylene fleece) and paper bags during the growing season significantly increased the rate of fruit ripening and increased Rutab yield per bunch. In this respect, black and blue polyethylene bags were the most effective followed by ‘agrlsafe’ and paper bags. Preharvest ethrel application significantly increased Rutab fruit yield per bunch compared to the controls. There were no significant differences in Rutab yield per bunch between sprays or injection of ethrel into the bunch peduncle. Postharvest dipping of fruit at the Bisir stage in ethrel at 4.2 ml/l and abscisic acid at 1.0 mM significantly enhanced ripening, compared to the controls. However, ABG-3168 (an ethylene blocker) application at 3.33 g/l significantly inhibited ripening, suggesting a role for ethylene in the ripening process. Ethanol vapor significantly hastened ripening of Bisir fruit over 10 days at ambient conditions in desiccators. The response of immature fruit (according to fruit density and TSS) to ethanol vapor was much greater than mature ones. Also, immersion of fruit in water for 10 h significantly increased fruit ripening compared to the controls, but to a lesser extent. It is concluded that ‘Helali’ date ripening could be hastened by bunch bagging during growth, or by exposing the Bisir fruit to ethanol vapor following harvest. Neither treatment showed any negative impact on the overall quality characteristics of ripe fruit, suggesting that they may be practical tools for increasing the ripening rate of Bisir ‘Helali’ dates.     

Genotype-environment relationships for repening time in blackberries and prospects for breeding an early ripening cultivar for Scotland

Summary When grown in Scotland, eight blackberry cultivars of diverse origin showed considerable variation in the dates when their first fruits ripened. These dates were determined in part by variation in the date of their first open flower and in part by variation in the number of days required from flowering to ripening. Genotype x environment interactions were important for both components, but especially for the second, where they could be attributed to heterogeneity of regressions against the environmental means. Temperature was considered the important environmental factor determining the number of days required from flowering to repening, and accumulated heat units successfully quantified the differences between cultivars for this component: cultivars required similar numbers of heat units in each season and there were no interaction effects. Heat units were not useful for study of flowering dates, however.The implications for breeding early ripening cultivars for Scotland are discussed.