添加剂对农作物秸秆混合青贮发酵品质的影响

为了研究绿汁发酵液和乳酸菌对农作物秸秆混合青贮品质的影响,试验选用乳酸菌制剂、稀释5倍绿汁发酵液、稀释20倍的绿汁发酵液作为试验因素,用量分别为0.5 L/t、2.5 L/t、2.5 L/t。60 d后对开封的青贮饲料进行感官鉴定和实验室鉴定。结果表明:添加不同稀释度的绿汁发酵液或乳酸菌制剂显著地降低了青贮饲料的pH值以及乙酸、丁酸、氨态氮含量,显著提高了乳酸、粗蛋白、可溶性碳水化合物的含量,中性洗涤纤维和酸性洗涤纤维含量差异不显著。总之,试验三处理均显著提高青贮品质,三处理之间差异不显著。在生产中推荐使用稀释5～20倍的绿汁发酵液。     

转基因农作物及其副产品饲料化的营养价值与安全性研究综述

近年来,转基因农作物及其副产品以其独有的优势在世界粮食和饲料资源中扮演了越来越重要的角色。但到目前为止,人们对于转基因作物的安全性仍然没有一个定论。围绕转基因农作物及其副产品用作食品及饲料的安全性问题,各国学者作了大量研究。本文综述了近年来转基因农作物及其副产品的安全性问题由来及其用作动物饲料时与非转基因作物相比的安全性和饲喂价值差异等方面的一些研究进展,并对未来转基因农作物饲用安全性的研究方向提出了作者的观点。     

利用无人机遥感技术提取农作物植被覆盖度方法研究

基于无人机的遥感信息获取技术已广泛应用在农业领域。无人机遥感平台获取农作物信息技术具有高时效、高分辨率、低成本、快速、准确等特点,是目前精准农业中农田信息获取的重要手段之一。利用无人机遥感技术获取可见光影像,以棉花、花生和玉米为研究对象,选取不同的植被指数进行可见光图像阈值分割,结合研究区域可见光影像监督分类结果,确定3种作物提取植被覆盖度方法。试验结果表明,利用无人机可见光图像植被指数阈值分类方法,可以有效提取作物植被覆盖度。该方法对于棉花、花生和玉米3种作物植被覆盖信息的提取精度较高。     

The critical period for weed control in three corn (Zea mays L.) types

Knowledge of the crop-weed competition period is vital for designing effective weed management strategies in crop production systems. Field studies were conducted at the Agricultural Research Institute, Kahramanmaras, Turkey in 2013 and 2014 to determine the critical period for weed control (CPWC) in three corn (Zea mays L.) types (field corn, popcorn, and sweet corn). A four parameter log-logistic model described the relationship between relative crop yield to both increasing duration of weed interference and length of weed-free periods. The relative yield of corn was influenced by duration of weed-infested or weed-free period, regardless of corn types. Increasing periods of weed interference significantly reduced corn yields in both years. In field corn, the CPWC ranged from 175 to 788 growing degree days (GDD) in 2013 which corresponded to V2–V12 growth stages, and 165–655 GDD (V1–V10 growth stages) in 2014 based on the 5% acceptable yield loss (AYL) level. In popcorn, the CPWC ranged from 92 to 615 GDD (VE–V10 growth stages) in 2013 and 110–678 GDD (V1–V10 growth stages) in 2014. In sweet corn, the CPWC ranged from 203 to 611 GDD in 2013 (V2–V10 growth stages) and 182–632 GDD (V2–V10 growth stages) in 2014. The practical implication of this study is that weed management should be initiated around V1 stage and maintained weed-free up to V12 stage in all corn types to prevent yield losses greater than 5%. These findings could help corn producers improve the cost effectiveness and efficacy of their weed management programs.     

Emergence and performance of volunteer oilseed rape (Brassica napus) in different crops

Volunteer oilseed rape (OSR, Brassica napus L.) causes various agronomic problems in crop rotations and can contribute to gene dispersal by pollen and by seed admixture. A 4-year field experiment (2008–2011) was set up in south-west Germany to investigate the performance of volunteers derived from two OSR cultivars with different levels of seed dormancy. Volunteers of a high-dormancy (HD) and a low-dormancy (LD) OSR cultivar were deliberately generated by spreading 10,000 seeds m⁻² on a field in August 2008 and 2009. Four different crops were grown on that area in the first year following the seed rain: winter wheat (Triticum aestivum L.), winter turnip rape (Brassica rapa L.), spring barley (Hordeum vulgare L.) and field pea (Pisum sativum L.). In the second year, maize (Zea mays L.) was sown uniformly across all plots. Numbers of OSR seedlings emerging in early autumn shortly after seed rain were not connected with the size of the soil seed bank in early spring of the following year. The seeds of the HD-cultivar formed a much greater soil seed bank (up to 14% of the initially spread seed number) compared with the LD-cultivar (up to 1.3%) in the soil layer of 0 to 30 cm in early spring 2009 and 2010). Across all crops, considerably more volunteers of the HD-cultivar than of the LD-cultivar were present at several survey dates in the first year following seed rain. The highest number of volunteers originated from the HD-cultivar with up to 11 volunteers m⁻² in winter turnip rape compared with a maximum of 0.48 plants m⁻² in the other crops. Cultivar-specific differences in volunteer density were observed as well in maize two years after OSR seed rain. Flowering and seed setting volunteers were only present in 2010 and the flowering time was crucially overlapping with that of sown winter OSR. The reproductive ability (seeds produced m⁻²) of the LD-volunteers was five times lower in winter turnip rape than of the HD-volunteer; a similar trend was observed for the OSR volunteers in the other host crops.Strategies to definitely reduce unwanted effects of OSR volunteers, such as gene flow, should include the use of LD-cultivars with a low potential to form a soil seed bank, particularly if selective herbicides are not available, for instance in broad-leaved crops, or if the volunteers are herbicide-tolerant.     

Modelling early growth under different sowing conditions: A tool to predict variations in intercrop early stages

Early growth is a critical phase of the crop cycle, which lasts from emergence to the beginning of competition between plants and is sensitive to sowing conditions and species characteristics. Providing tools to improve the management of this critical phase in intercrops is a challenge for agroecology as these cropping systems are the subject of renewed interest for their ability to maintain yields while requiring fewer inputs. The aim of the present study was to investigate variations in early growth under different sowing conditions in different species with contrasted seed and seedling characteristics (seed mass, hypogeal or epigeal emergence, and legume and non-legume species), especially species used as intercrops. Experiments were carried out in glasshouses using different sowing depths and levels of mineral nutrition, first for each species separately, then in mixed sowings. In the first set of experiments, biomass at emergence and relative growth rate after emergence were measured and then modelled as a function of seed mass, mineral nutrition, and time to emergence. Predictive equations were tested by comparing simulations with biomass measured in the second set of experiments, for two intercrops grown under varied sowing conditions. Finally, simulations were run to analyse variations in the early growth of two intercrops (durum wheat/pea or alfalfa) under a wider range of sowing conditions (seed mass, sowing depth, and with or without mineral nutrition). Biomass at emergence was positively correlated with seed mass, and in epigeal species, was also negatively impacted by time to emergence. Relative growth rate was highly stimulated by mineral nutrition whereas its response to time to emergence varied among species. The amount of seminal reserves at emergence (in hypogeal species) and the cotyledon specific mass (in epigeal species) were correlated with the establishment of the relative growth rate. When evaluated, the model was shown to satisfactorily predict the early growth of two intercrops. Used as a simulation tool, the model indicated that all the sowing techniques tested can have a major influence on total biomass and on the proportion of each component species when competition begins. This model can thus contribute to the management of sowing techniques for sole as well as combined crops whose effects are difficult to predict and are also difficult to analyse from field experiments alone because of the number of possible combinations and interactions.     

Evaluation on the High Yielding,Stability and Comprehensive Performances of Check Cultivars in National Cotton Regional Trials in the Yangtze River Valley

[Objective] This study was to analyze the high yielding, stability, adaptabil-ity and main characteristics of check cultivars in national cotton regional trials in the Yangtze River Val ey in 2000-2013, with the aim to provide theoretical basis for the reasonable selection of check cultivars for cotton regional trials. [Method] GGE biplot analysis method was used to carry out the intensive analysis and comprehensive comparisons on the performances and differences of the 9 major characters of check cultivars, namely, lint cotton yield , stability, and other main traits including bol weight, bol number, lint percentage, fiber length, fiber strength, micronaire val-ue, plant height and seed index. [Result] Ezamian 10 was suitable in the majority of cotton planting regions in the Yangtze River Val ey, with the best high yielding abili-ty and perfect yield stability. The yielding ability of Xiangzamian 8 ranked the sec-ond, but its stability was the poorest. Xiangzamian 8 was of the specific adaptive cultivar with relatively good performance in high yielding but the poorest stability. The suitable planting areas of Xiangzamian 8 were limited to the cotton planting re-gion around Dongting Lake in Hunan province, Poyang Lake in Jiangxi Province, the Coastal region in Jiangsu Province and Wuhan district in Hubei Province. Xi-angzamian 2 performanced poorer in both yielding and stability, while Simian 3 ranked first in stability but the last in yielding ability. The dominant character of Xi-angzamian 8 and Xiangzamian 2 were high cotton plants and big bol s. Simian 3 performanced super in lint percentage and fiber length. Ezamian 10 was strong in cotton bol formation ability, lint cotton yielding, fiber strength and seed size, as wel as high micronaire value. [Conclusion] The outstanding performance of Ezamian 10 in high and stable yield in the Yangtze River Val ey in recent years has effectively promoted the high yielding ability of candidate varieties in cotton regional trials in the area.     

Population dynamics and interactions between plant parasitic and non-parasitic nematodes: An empirical analysis

Non-linear regression models were used to estimate the effect of own and other taxa previous population levels, nitrogen application, and crop rotation on population dynamics of Mononchidae, Dorylaimidae, microbivorous (Rhabditidae), lance (Hoplolaimus galeatus), spiral (Helicotylencus dihystera), stubby root (Paratrichodorus minor), lesion (Pratylenchus zeae), and cotton root-knot (Meloigogyne incognita) nematodes using data from the Cullars rotation, which is the oldest soil fertility experiment in the Southern United States. Because field experimental data was used, a spatial component was included as populations in one plot were proved to be related to the population level of their neighbors. Own previous levels were found to be very important for all eight groups of nematodes (all groups’ current population relied heavily on its own previous population value) and all the groups had an interaction effect with at least one other group. Lesion and cotton root-knot nematodes were found to be competitive while Mononchidae, Dorylaimidae, microbivorous and lance nematodes were non-competitive. All the populations showed high seasonality patterns having lower populations during winter, to then remain steady until September–October when there is a significant increase in the population of cotton root-knot, Dorylaimidae, microbivorous, and lesion nematodes. Nitrogen had a positive effect on Mononchidae, microbivorous, spiral, and cotton root-knot nematodes. The use of clover after cotton in the rotation crop program proved to be significantly better in reducing plant parasitic nematodes compared to other treatments.     

Drought Tolerance Screening Under Controlled Conditions Predicts Ranking of Water‐Limited Yield of Field‐Grown Soybean Genotypes

Drought is a major limitation to crop yields worldwide. Screening for soybean yield under water deficit is often a bottleneck in breeding programmes. We assessed the validity of a standardized drought tolerance screening method to predict water‐limited field performance of soybean in NW Argentina. First, to determine the phenological period when yield of glasshouse‐grown plants was more sensitive to water deficit, we applied treatments during 21 days in V₇, R₃ or R₅ stages, being the period from R₅ to R₆ the most critical for yield. Afterwards, two glasshouse experiments were carried out to quantify the tolerance of either eight or four genotypes, respectively, by applying a controlled water deficit of constant intensity during the critical period. Finally, yield data obtained in field trials in Argentina across several locations and seasons classified according to rainfall were analysed. Drought Susceptibility Index was calculated for each experiment and for field data, and rankings of tolerance were similar in all cases. This standardized method, which can be automated for high‐throughput phenotyping, could represent a useful tool in breeding programmes for identifying soybean cultivars with improved performance under drought conditions.     

宁夏引黄灌区草坪型多年生黑麦草种子生产性能研究

在宁夏引黄灌区对６个草坪型多年生黑麦草品种的种子生产性能进行了研究。结果表明，不同品种间种子产量差异极显著（Ｐ〈０．０１），由高到低依次为Ｒｅｇａｌ〉Ｔａｒｇｅｔ〉Ｍｕｌｌｉｇａｎ〉Ｄｅｒｂｙ〉ＡＰＭ〉Ｓｅｖｉｌｌｅ，种子产量分别为１３８９．４、１２７９．９、１０７１．５、１０５１．７、６５２．６ｋｇ／ｈｍ＾２。因此认为，在宁夏平原灌溉条件下，多年生黑麦草种子生产以选用Ｒｅｇａｌ、Ｔａｒｇｅｔ最好