不同坡面草被格局下的侵蚀产沙量及其连通性指数表征

为探寻植被格局的定量表征参数,并建立其与侵蚀产沙的关系,深入揭示植被格局阻蚀减沙作用机制,该研究采用室内人工模拟降雨试验,以40%盖度的高羊茅草被坡面为研究对象,探讨了不同坡度（5°、15°和25°）和植被分布格局（裸地、带状横坡、带状顺坡、块状镶嵌、点状均匀格局）下的坡面侵蚀产沙过程变化,并分析了不同草被格局下平均汇流路径长度指数（Mean Flow Length Index,MFLI）、连通性指数（Index of Connectivity,IC）变化及其同坡度和土壤侵蚀量的关系。结果表明：带状顺坡、点状均匀、块状镶嵌和带状横坡的草被坡面平均侵蚀量分别较裸地减小42.9%、55.7%、62.4%和78.0%,带状横坡的阻蚀减沙作用最优。不同草被格局坡面间的MFLI和IC总体也与平均侵蚀量的差异关系一致,从小到大依次为：带状横坡、块状镶嵌、点状均匀、带状顺坡、裸地。MFLI和IC可分别与坡度结合用于模拟评价不同草被格局坡面的侵蚀产沙,决定系数（R2）达0.84以上。其中,IC与坡度的协同性更佳、依赖性更小,是表征植被格局对坡面侵蚀产沙影响的较佳参数。结果可为快速优选水土保持型植被格局、促进生态脆弱区林草植被格局优化和提质增效提供依据。     

牧草种植对黄河三角洲盐碱土壤改良效果的动态监测及综合评价

为揭示牧草种植改良盐碱地的效果,更好地开发利用后备土地资源。以黄河三角洲滨海盐碱地为研究对象,采用小区试验、野外取样、室内测试相结合的方法,研究了高丹草、甜高粱和墨西哥玉米3种一年生牧草在1个生长期内对黄河三角洲盐碱地土壤物理、化学和酶活性改良效果的动态变化,并依据土壤质量指数综合评价了改良效果。结果表明:(1)土壤含水量、pH和电导率随生长时间增加呈下降趋势,高丹草和墨西哥玉米在生长旺盛期对土壤pH的降低效果最明显,甜高粱在收获期降低pH的效果最好。3种牧草土壤电导率较CK均显著降低,对20—40 cm土层的降低效果优于0—20 cm土层,其中墨西哥玉米效果最好。(2)种植不同牧草对土壤养分含量有明显改善,其中土壤有机质、速效氮、速效磷含量有显著提升,但对土壤速效钾含量影响不大。(3)3种牧草在不同生长期内对土壤酶活性的影响不同,在生长旺盛期土壤酶活性最强,均显著增强土壤过氧化氢酶、蔗糖酶和脲酶的活性,其中甜高粱对过氧化氢酶和蔗糖酶活性影响最大。(4)不同牧草对盐碱土壤改良指标的贡献值存在差异,综合土壤理化性质、养分含量和土壤酶活性作为土壤评价指标,种植不同牧草后土壤质量从高到低依次为甜高粱＞高丹草＞墨西哥玉米＞CK。研究结果可为黄河三角洲地区盐碱地的植物修复技术和筛选及引进国内外具有高效生态经济效益的耐盐植物提供理论依据和重要参考。     

智能田间除草机器人发展现状研究

智能田间除草机器人是当代农业发展现代化、精细化、智能化的重要体现,对国家社会发展、环境保护等方面有着重要意义。为明确智能除草机器人关键技术与装备当前研究现状,从除草方式、苗草识别定位和智能导航方式等方面,总结梳理典型除草机器人的研究现状及作业方式;综述智能导航、苗草识别、除草执行系统关键技术的重要意义及研究进展;结合除草机器人具有作业环境复杂多变性、作业对象娇嫩性、使用对象特殊性、作业季节性的研究特点,指出当前关键技术的现存问题并阐释组合导航技术、复杂田间环境图像处理技术及杂草分类、株间除草末端执行机构研发及机械结构优化是未来发展趋势。     

发芽蚕豆与发芽豌豆对草鱼生长和肉质影响的比较

为研究发芽蚕豆与发芽豌豆对草鱼生长性能和肌肉品质的影响,分别以普通配合饲料、发芽蚕豆和发芽豌豆投喂体质量为(1056.1±30.3)g的草鱼(Ctenopharyngodon idella),养殖周期为84 d。结果显示:与投喂普通配合饲料的草鱼相比,发芽蚕豆与发芽豌豆均显著降低了草鱼的体质量增长,增大了饲料系数(P<0.05);同时,草鱼肌肉的失水率下降,硬度与咀嚼性显著提高,肌纤维密度增大、肌肉胶原蛋白含量增加,肌肉与皮肤中Ⅰ型胶原蛋白基因COL1A1和COL1A2 mRNA的表达量也显著提高(P<0.05);发芽蚕豆组草鱼的体质量增长、肌肉硬度与咀嚼性、肌纤维密度以及肌肉胶原蛋白含量显著高于发芽豌豆组(P<0.05)。结果表明:投喂发芽蚕豆与发芽豌豆,虽然降低了草鱼的生长性能,但能够改善草鱼的肌肉品质,并且投喂发芽蚕豆的效果优于发芽豌豆。     

Performance and environmental effects of forage production on sandy soils. IV. Impact of slurry application, mineral N fertilizer and grass understorey on yield and nitrogen surplus of maize for silage

A field experiment was conducted from 1998 to 2001 to measure the performance and environmental effects of a maize crop (Zea mais L.) in a continuous production system with and without a grass understorey (Lolium perenne L.), with varied N inputs. The experiment was located on a sandy soil in northern Germany and comprised all combinations of slurry application rate (0, 20, 40 m³ ha^?1) and mineral N fertilizer (0, 50, 100, 150 kg N ha^?1). Understorey treatments included maize with and without perennial ryegrass. Net energy (NEL) yield of maize increased with mineral N application rate but reached a plateau at high rates. Increase in yield of dry matter because of mineral N fertilizer was lower with increased slurry application rate. Neither slurry and mineral N application nor a grass understorey affected NEL concentration of maize, whereas crude protein (CP) concentration increased with increase in application of slurry and mineral N fertilizer. Nitrogen supply by slurry or mineral fertilizer had no effect on the amount of N in the grass understorey after the harvest of maize. The average amount of N bound annually in the understorey was 60 kg N ha^?1. The reduced biomass of the understorey because of enhanced maize competition was compensated for by an increased CP concentration in the grass. The grass understorey affected the NEL yield of maize negatively only at very low levels of N input but increased the N surplus at all levels.     

Selecting for nutrient use efficiency within forage grass species: I. Development of a screening system

One means of achieving increased forage grass production on infertile soils is to select plant genotypes which grow efficiently at low levels of available nutrients. This requires methods to identify variability in individual plant nutrient response from among large populations of plants grown under controlled environmental conditions.

A compact, containerized system, partially developed for growing large numbers of forage grass seedlings for use in automatic machine transplanter research, was adapted as the basis for such a screening technique. Three trials were made with 100‐plant samples of a kleingrass‐75 (Panicum coloratum L.) population to test the utility of the system. Results of these trials showed that differences in nutrient use efficiency (= reciprocal of nutrient concentration in the plant tissue, or milligrams dry matter produced per milligram nutrient absorbed) among the grass plants could be effectively identified by using the system in conjunction with laboratory analysis of the material grown. Plants could be maintained in vigorous condition during several harvest periods, and those selections that were retained could be easily transplanted for further propagation and evaluation.     

Does genetic diversity of grass improve yield,digestibility, and resistance to weeds,pests and disease infection?

ABSTRACT

Intraspecies genetic level diversity has the potential to improve ecosystem functions and services, similar to that by species-level diversity. Although yield, pollination, and pest and disease control have been enhanced by crop genetic diversity, mixing multiple cultivars of grass within a species in an agricultural field have not been fully tested by farmers.

We, therefore, tested whether multiple ecosystem functions are increased in a grass mixture of multiple cultivars compared to monoculture and whether this relationship differs with soil fertility. We performed monocultures of four Orchard Grass cultivars and a mixture of these cultivars with and without fertilizer application and examined the aboveground net primary productivity (ANPP), their stability, dry matter digestibility, and resistance to weed, pest, and disease. We found significant differences between cultivars in the second yield and disease lesion area on the leaf, but not between mixed culture and monoculture. Moreover, no significant difference was found in the first and third yields in terms of stability, dry matter digestibility, and leaf damage by insects, although the number of leaves damaged by insects for mixed culture was less than half of that on average for monoculture. Although genetic diversity is not always an important driver of ecological processes due to fluctuation among plots, it may play a role in pest control of agricultural land in the long term.     

植草带对红壤坡耕地面源污染物输出的削减效果

为探讨植草带对红壤坡耕地面源污染输出的削减效果,以植草带和裸露红壤坡面作对照,根据野外观测数据拟定降雨强度和N,P等面源污染物浓度,室内模拟产流产沙及N,P输出过程.结果表明,雨强越小,植草带的减流和减沙效果越明显;在同一雨强条件下,植草带的减沙效果比减流效果明显.与裸地比较,植草带对全N的削减率随雨强和全N输入量增大而逐渐减小;在20 mm/h和35 mm/h雨强条件下,植草带对全P的削减率随着全P输入量的增大而增大,在同一全P输入浓度条件下削减率随雨强增大而逐渐减小;在50 mm/h雨强条件下,植草带径流中全N输出量大于裸地对照.     

Investigating soil physical properties and yield response in a grassland field using a dual‐sensor penetrometer and EM38

Precision‐farming applications are mainly based on site‐specific information of soil properties at the field scale. For this purpose, a number of novel sensor techniques have been developed but not intensively tested under different field conditions. This study presents a combined application of a self‐developed dual‐sensor vertical penetrometer (DVP) for measuring volumetric soil water content (VSWC) and cone index (CI), and an EM38 for soil apparent electrical conductivity (EC_a) in a pasture (1.4 ha). To verify the feasibility of the DVP for interpreting the depth‐specific information in the field, not only the soil physical properties and their geographical coordinates were measured, but also geo‐referenced yield data were collected. We found that the yield pattern was quite similar to the soil water‐content pattern of each layer (layer‐1: 5–15 cm; layer‐2: 15–25 cm, layer‐3: 25–35 cm) and EC_a pattern. Using the map‐based comparisons in conjunction with the statistical analyses, the effect of each measured soil physical property (VSWC, CI, and EC_a) on the yield was investigated. The regression between the yield and VSWC at each layer fitted a quadratic equation (R² = 0.515 at 5–15 cm; R² = 0.623, at 15–25 cm; R² = 0.406 at 25–35 cm). The negative correlation between yield and CI at each layer fitted a linear model with R² ≥ 0.510.     

稻田稗属杂草致病菌的分离与鉴定

稗草Echinochloa crus-galli作为稻田难以防除的恶性杂草,严重影响水稻产量。为发掘具有防治稻田稗草潜力的生防菌,本研究从江苏、广西、贵州三省采集感病稗草,采用组织分离法获得10株对稗草致病性较强的优势菌株。通过观察优势病原菌的形态特征,结合rDNA-ITS、GAPDH、EF-1α基因片段序列分析确定10株菌分别为新月弯孢Culvularia lunata、尖角突脐蠕孢Exserohilum monoceras、禾长蠕孢菌Setosphaeria rostrata、稻平脐蠕孢Bipolaris oryzae、梭形突脐蠕孢Exserohilum fusiforme、澳大利亚弯孢Curvularia australiensis、双色平脐蠕孢Bipolaris bicolor、高粱附球菌Epicoccum sorghinum、亚隔孢壳属Didymella americana和亚隔孢壳属Didymella pinodella。该研究丰富了稗草病原菌生物资源,为进一步开发稻田生物除草剂提供了新材料。