孝感市蔬菜产业现状、存在问题及对策

孝感市是湖北省三大蔬菜主产区之一,具有发展蔬菜产业的有利条件,产业发展迅速,但仍存在现代化水平不高、组织化程度低、抵御市场风险能力弱等一系列问题,通过调查研究,提出了发展蔬菜生产的几点对策。     

燕麦散黑穗病菌冬孢子萌发条件研究

为明确燕麦散黑穗病菌(Ustilago avenae)冬孢子在自然生境中的萌发条件,研究了疏亲水界面、不同温度、湿度、光照时间、pH、碳源和氮源对冬孢子萌发的影响。结果表明,亲水界面促进冬孢子萌发,在水琼脂培养基上萌发率最高;冬孢子萌发的最适温度为20~25℃,温度过高或过低均抑制其萌发。冬孢子对湿度要求较高,RH≥90%时才可萌发,且萌发率较低。光照对冬孢子萌发的影响不明显,酸性条件有利于冬孢子萌发,最适pH为4~7,葡萄糖和蛋白胨可促进冬孢子萌发。     

Economic effects of proposed changes in living conditions for laying hens under the National Organic Program

In this paper, we estimate the costs and benefits of implementing the proposed National Organic Program for laying hens compared with alternatives. For the regulatory proposals under option 2, the regulatory cost will be zero because most producers are already in compliance with the proposed regulation. The anticipated benefits of this regulation will be zero as well, because the current market prices already reflect consumers’ willingness to pay for the existing animal welfare conditions. For the regulatory proposals under option 3, before market adjustments, the average regulatory burden for the entire organic egg industry will amount to $0.09 per dozen eggs, with extreme variations between $0 for small operations and $2.30 per dozen for large operations. If we rely on the average price of organic eggs, $2.69 per dozen, and assume a maximum estimated benefit associated with improved animal welfare conditions, that consumers would be willing to pay of about 30% above the current market price, the estimated benefit of regulation amounts to $0.81 per dozen eggs. Based on the findings, we conclude that option 2 is welfare neutral and could be easily adopted because it already has been adopted by representative producers. For option 3, the benefit-cost ratio is larger than 1, which indicates that the proposal passes the benefit-cost ratio test. The obtained result, however, has to be interpreted with serious reservation because of the differential effect that the proposed regulation would have on different industry participants. Under option 3, the effect of the proposed changes on small organic egg producers is negligible because most small producers are operating under conditions similar to the proposed living standards. However, costs will increase substantially for large organic egg producers and likely cause a substantial number of producers to exit organic production and switch to conventional production, which would cause a substantial decline in the prices of conventional eggs and organic feed in the short run.     

Synchronicity in southern hemisphere squid stocks and the influence of the Southern Oscillation and Trans Polar Index

Squid are short lived, with highly labile populations that respond rapidly to changes in environmental conditions. This makes them a good model for studying the response of recruitment processes to environmental signals. This study examines the influence of the Southern Oscillation Index (SOI) and Trans Polar Index (TPI) on the environment and abundance of six species of commercially important squid from the southern hemisphere, all linked to major current systems connected by the Antarctic Circumpolar Current: Dosidicus gigas (Southeast Pacific), Loligo vulgaris reynaudii (Southeast Atlantic), Nototodarus sloanii, N. gouldi (Southwest Pacific), Illex argentinus and L. gahi (Southwest Atlantic). All fisheries displayed a high level of inter‐annual variability and a degree of synchronicity was seen to occur in the abundance of the three Pacific species. The SOI signal was reflected in the environment of each fishery, particularly in Pacific regions. Both indices are correlated with squid abundance, particularly during the early life history stages (SOI) and adult stages (TPI), suggesting some degree of latitudinal separation, with juveniles potentially influenced by environmental variability at lower latitudes and adults at higher latitudes.     

Sardine and anchovy regime fluctuations of abundance in four regions of the world oceans: a workshop report

Regimes of high abundance of sardine (Sardinops sagax and Sardina pilchardus) have alternated with regimes of high abundance of anchovy (Engraulis spp.) in each of the five regions of the world where these taxa co-occur and have been extensively fished. When one taxon has been plentiful, the other has usually been at a reduced level of abundance, and vice versa. Changes in the four heavily fished regions that support S. sagax–the Japanese, Californian, Humboldt, and Benguela systems–from a regime dominated by one taxon to a high level of abundance of the other have occurred more or less simultaneously. In the Pacific Ocean, sardines have tended to increase during periods of increasing global air and sea temperatures and anchovies to decrease. The Japanese system is dominated by sardines to a greater extent than the other systems, and sardines off Japan appear to increase as the Kuroshio Current cools. At the eastern edge of the Pacific Ocean, sardines colonize cooler areas during periods of warming. The Benguela system is out of phase with the three Pacific systems. The four systems all appeared to be in a state of flux in the 1980s. Increased abundance of the subdominant taxon is often one of the first signs of change. Sardines are relatively sedentary in refuge areas when scarce but change behavior to become highly migratory and colonize cooler areas when abundant. Anchovies, by contrast, expand around a fixed geographic center.     

Temperature conditions in the Argentine chub mackerel (Scomber japonicus) fishing ground: implications for fishery management

We describe the seasonal migrations of Argentine chub mackerel ( Scomber japonicus ) into the fishing ground in relation to sea surface temperature conditions and analyse the temperature evolution during the fishing season on the basis of 1955–97 time-series. The upper temperature limit for the presence of schools was around 19°C. At higher values, most schools leave coastal waters (< 50 m) for the shelf. An inverse relationship was observed between catches per unit of effort (CPUE) of the inshore fishery and sea surface temperature. The highest standardized CPUE values corresponded to temperatures lower than 19°C. Above this temperature, the probability of obtaining a standardized CPUE higher than 1 was extremely low, and the standard deviations were minimal. The economic benefit from catches was also analysed through the different months of the fishing season. It was found that the mean benefit corresponding to temperatures lower than 19°C exceeded approximately 15 times that obtained at higher temperatures. A simple fishing strategy was proposed to the commercial fleet in order to improve the economic benefit of the catches. The migratory pattern followed by mackerel during the spawning period was also analysed in relationship to other environmental factors like food availability. Zooplankton composition, size structure and abundance in coastal and shelf waters are described, and their implications for feeding ecology of larvae and adults of the species are discussed.     

Estimating theoretical radiation‐use efficiency for kale crops

Establishing the radiation‐use efficiency (RUE) of forage brassica crops will aid our understanding of their photosynthetic performance. The concept of RUE has been developed for cereals and legumes, but there is limited information for forage brassica crops. Three experiments defining the influence of different sowing dates on ‘Gruner’ kale (Brassica oleracea acephala L.) dry matter production were conducted at Hastings (Hawkes Bay) and Lincoln (Canterbury) in New Zealand between 2002 and 2009. These trials were also evaluated for radiation interception and RUE. Delayed sowing increased RUE in two out of three experiments across sites: from 1·93 g MJ^?1 photosynthetically active radiation (PAR) for December‐sown crops to 2·72 g MJ^?1 PAR (P < 0·001) for January‐sown crops at Hastings and from 1·50 for September‐sown crops to 2·00 g MJ^?1 PAR (P < 0·001) for November‐sown crops at Lincoln. The different sowing dates and years of experimentation provided a range of mean temperatures (from 13 to 16°C) during the vegetative period. Across years and sowing dates, RUE was strongly correlated with mean temperature (R² = 0·81) and sowing date (R² = 0·64), but weakly correlated with season length (R² = 0·11) and dry matter (R² = 0·002). There was also a strong correlation (R² = 0·83) between sowing date and mean temperature. The increase in RUE with delayed sowing was therefore mainly attributed to increased mean temperatures. Radiation‐use efficiency increased at about 0·41 g MJ^?1 for each 1°C increase from 13 to 16°C.     

低温下硅对春小麦种子萌发及抗氧化和渗透调节系统的影响

为了解硅缓解低温胁迫春小麦种子萌发的作用,以春小麦品种龙麦26和克旱16为材料,分析了低温条件下硅酸钠处理后春小麦种子萌发、渗透调节物质含量和保护酶活性的变化。结果表明,低温条件下硅酸钠处理后,春小麦种子萌发显著受到促进,发芽率、发芽势、发芽指数和活力指数提高,其中以1.0mmol·L-1硅酸钠处理效果最好;小麦种子α-淀粉酶、超氧化物歧化酶、过氧化物酶活性以及可溶性糖含量显著提高,丙二醛含量、外渗电导率和脯氨酸含量显著降低。说明外源硅可缓解低温对春小麦种子萌发产生的影响。     

白砂糖干燥与冷却机理及影响

砂糖的含水量、装包温度和仓储条件对其贮存保质具有重要影响。本文从白砂糖的含水分特性、干燥机理和生产过程环节等对白砂糖干燥与冷却的影响进行深入分析。由于结晶过程的包裹现象,砂糖含水分可分为表面和内部水分,白砂糖干燥过程只能去除前者。生产过程中煮糖、分蜜操作对内部水分含量有影响。贮存过程的内部水分的扩散是砂糖降质的根本原因,而装包温度和贮存条件是影响内部水分扩散的外在条件。     

2000—2019年黄土高原地区土壤保持时空变化及影响因素分析

为揭示全球气候变化背景下黄土高原的生态建设成效,以土壤保持量为评估指标,应用美国修正通用土壤流失方程,评估了黄土高原土壤保持服务功能以及植被、气象等因素对其影响,分析了2000年以来植被和气候变化影响下黄土高原土壤保持量时空动态变化特征。结果表明:2000—2019年黄土高原土壤保持量平均值为109.5 t/hm²,并呈增加趋势,平均每年增加2.0 t/hm²,空间分布黄土高原中部和东部土壤保持量增加较明显。2000年以来黄土高原地区植被NPP呈增加趋势,年平均值为330.5 gC/m²,且平均每年增加7.2 gC/m²; 2000年以来植被覆盖度年平均值为29.2%,且以平均每年0.52%的趋势增加。黄土高原地区2000年以来气温和降水量均显著增加,平均年降水量为469.1 mm,且呈增加趋势,平均每年增加3.1 mm,年平均气温为10.2℃,平均每年增加0.03℃。黄土高原生态恢复措施加强,加之区域“暖湿化”有利气候条件,促进了区域生态建设成效显现,成为黄土高原生态恢复、功能提升的重要因素之一。