Comparison of maize,permanent cup plant and a perennial grass mixture with regard to soil and water protection

Agricultural production of biogas maize (Zea mays L.) causes hazards to aquatic ecosystems through high levels of nitrogen (N) inputs. Newly introduced and already established perennial crops such as the cup plant (Silphium perfoliatum L.) and perennial grass mixtures offer the possibility of more environmentally friendly agricultural bioenergy production. The objectives of this field study were to quantify and compare soil mineral N, water infiltration, water runoff, soil erosion and N leaching under maize, permanent cup plant, and a perennial grass mixture. The study was conducted from October 2016 to March 2019 in Braunschweig, Germany. Plots with cup plant and grass mixture exhibited lower mineral N contents than maize, especially between 30 and 90 cm soil depth. Soil water infiltration was significantly different between the three crops. The grass mixture had the highest infiltration rates (6.2 mm/min averaged across 3 years), followed by cup plant (3.6 mm/min) and maize (0.9 mm/min). During wet periods, higher N leaching was found for maize (up to 42 kg N ha^?1 year^?1) than for cup plant (up to 5 kg N ha^?1 year^?1) or the grass mixture (up to 11 kg N ha^?1 year^?1). While runoff and erosion for cup plant and the grass mixture were negligible during the study period, considerable amounts of runoff water and eroded sediment of up to 1.5 Mg ha^?1 year^?1 were collected from the maize plots despite the near flat terrain of the experimental field. Overall, permanent cup plant proved suitable as a component for energy cropping systems to reduce the risk of N leaching and soil erosion, which is particularly important for the preventive flood protection in view of the more frequent occurrence of high intensity rainfall under climate change conditions.     

Land suitability for energy crops under scenarios of climate change and land‐use

Bioenergy is expected to play a critical role in climate change mitigation. Most integrated assessment models assume an expansion of agricultural land for cultivation of energy crops. This study examines the suitability of land for growing a range of energy crops on areas that are not required for food production, accounting for climate change impacts and conservation requirements. A global fuzzy logic model is employed to ascertain the suitable cropping areas for a number of sugar, starch and oil crops, energy grasses and short rotation tree species that could be grown specifically for energy. Two climate change scenarios are modelled (RCP2.6 and RCP8.5), along with two scenarios representing the land which cannot be used for energy crops due to forest and biodiversity conservation, food agriculture and urban areas. Results indicate that 40% of the global area currently suitable for energy crops overlaps with food land and 31% overlaps with forested or protected areas, highlighting hotspots of potential land competition risks. Approximately 18.8 million km² is suitable for energy crops, to some degree, and does not overlap with protected, forested, urban or food agricultural land. Under the climate change scenario RCP8.5, this increases to 19.6 million km² by the end of the century. Broadly, climate change is projected to decrease suitable areas in southern regions and increase them in northern regions, most notably for grass crops in Russia and China, indicating that potential production areas will shift northwards which could potentially affect domestic use and trade of biomass significantly. The majority of the land which becomes suitable is in current grasslands and is just marginally or moderately suitable. This study therefore highlights the vital importance of further studies examining the carbon and ecosystem balance of this potential land‐use change, energy crop yields in sub‐optimal soil and climatic conditions and potential impacts on livelihoods.     

全球生物产业发展现状及政策启示

生物经济时代正在引发人类新一波技术和产业革命,并已成为了全球主要发达国家和新兴经济体抢占的制高点。文中从生物医药产业、转基因作物种植产业、生物能源产业以及生物基化学品产业4个角度分析了全球生物产业发展的时空特征,概括总结了全球生物产业发展的主要特点,并进一步针对我国生物产业发展中存在的瓶颈问题提出政策建议,对我国生物经济的未来发展具有指导意义。     

甜荞果皮开裂类型及其对籽粒早期萌发性状的影响

甜荞是我国传统的药食同源植物,籽粒是甜荞的重要贮藏器官,籽粒果皮的开裂类型及其开裂行为影响种子的萌发性状。该研究以5份甜荞为材料,进行果皮裂口的建模与分型,并通过纸床发芽法,检测种子的发芽率、胚根及下胚轴长度。结果表明:(1)甜荞籽粒果皮开裂主要包括纵向完全开裂型、种孔端部半开裂型、种脊中部半开裂型、种脐端部半开裂型和横裂型等5种类型;(2)开裂型籽粒比完整型萌发时间提早约12 h;(3)开裂型籽粒早期萌发率均高于相应的果皮完整型,但48 h后,完整型籽粒的萌发率超过果皮开裂型;(4)开裂型籽粒胚根及下胚轴的早期增长速度比完整型快,但果皮开裂型籽粒胚根与下胚轴增长比值显著小于果皮完整型;(5)不同开裂类型的萌发率从大到小依次为种孔端部半开裂型、纵向完全开裂型、种脐端部半开裂型、种脊中部半开裂型、横裂型,而种子霉烂率从大到小依次为种脐端部半开裂型、纵向完全开裂型、种脊中部半开裂型、种孔端部半开裂型、横裂型。果皮开裂虽然可以提高甜荞种子早期的萌发率,促进胚根及下胚轴早期的伸长速度,但会降低甜荞整体的萌发率以及胚根/下胚轴增长比值,种子霉烂率显著增加,不利于田间壮苗与全苗的形成。     

稻茬冬小麦氮肥吸收、残留和损失特性

为推进稻茬小麦氮肥合理施用,采取田间¹⁵N示踪技术研究了施氮量(0、150、225、300 kg·hm^-2,分别表示为N₀、N₁₅₀、N₂₂₅、N₃₀₀)对氮肥回收、残留、损失和籽粒产量的影响。结果表明: 随施氮量增加,小麦植株不同来源氮素积累量显著增加,氮肥回收率则显著下降。基肥氮以越冬至拔节期在植株中的积累量最高,追肥氮以拔节至开花期积累量最高;成熟期各处理追肥氮在植株中的积累量均高于基肥氮,N₁₅₀处理植株中土壤氮的积累量高于肥料氮,N₂₂₅、N₃₀₀处理呈相反趋势。随施氮量增加,成熟期0～100 cm土层氮肥残留量显著增加,肥料氮在60～100 cm土层残留比例逐渐升高。小麦全生育期氮肥损失量和损失率均随施氮量增加而增加,基肥氮损失量以播种至越冬期最高,追肥氮损失量以拔节至开花期最高。综合考虑籽粒产量,N₂₂₅处理可作为稻茬小麦氮肥推荐用量,相应的籽粒产量为6735 kg·hm^-2,氮肥回收率、土壤残留率和损失率分别为42.6%、34.0%和23.3%。     

喷施脱水剂对不同熟期夏玉米脱水特性和籽粒品质的影响

目前,我国种植的夏玉米品种收获时籽粒含水率过高,限制了玉米机械粒收技术的发展。喷施脱水剂可以调控作物籽粒灌浆生理过程,降低收获时的籽粒含水率。本试验研究了喷施脱水剂对不同熟期夏玉米品种脱水过程、收获期籽粒含水率和籽粒品质的调控作用。结果表明: 喷施脱水剂减少了玉米各器官的干物质积累量,促进了植株向籽粒中的干物质转移,提高了收获指数,而且对籽粒品质没有显著影响。相关性分析显示,籽粒脱水速率与各器官脱水速率呈正相关,喷施脱水剂后籽粒脱水速率与茎鞘脱水速率呈极显著正相关。喷施脱水剂在产量没有显著降低的前提下提高了总脱水速率,缩短了开花期至生理成熟期的时间,增加了生理成熟期到收获的时间,有利于后期籽粒含水率的进一步降低,为玉米机械粒收提供了更大的可能性。不同熟期夏玉米品种喷施脱水剂进行机械粒收的经济效益与机械穗收相比没有显著差异,中晚熟品种的经济效益高于早熟品种。因此,收获前合理喷施脱水剂可以作为玉米机收籽粒的一种可行性配套技术。     

Seed longevity of maize conserved under germplasm bank conditions for up to 60 years

Background and AimsThe long-term conservation of seeds of plant genetic resources is of key importance for food security and preservation of agrobiodiversity. Nevertheless, there is scarce information available about seed longevity of many crops under germplasm bank conditions.MethodsThrough germination experiments as well as the analysis of historical monitoring data, we studied the decline in viability manifested by 1000 maize (Zea mays subsp. mays) seed accessions conserved for an average of 48 years at the CIMMYT germplasm bank, the largest maize seedbank in the world, under two cold storage conditions: an active (–3 °C; intended for seed distribution) and a base conservation chamber (–15 °C; for long-term conservation).Key ResultsSeed lots stored in the active chamber had a significantly lower and more variable seed germination, averaging 81.4 %, as compared with the seed lots conserved in the base chamber, averaging 92.1 %. The average seed viability detected in this study was higher in comparison with that found in other seed longevity studies on maize conserved under similar conditions. A significant difference was detected in seed germination and longevity estimates (e.g. p₈₅ and p₅₀) among accessions. Correlating seed longevity with seed traits and passport data, grain type showed the strongest correlation, with flint varieties being longer lived than floury and dent types.ConclusionsThe more rapid loss of seed viability detected in the active chamber suggests that the seed conservation approach, based on the storage of the same seed accessions in two chambers with different temperatures, might be counterproductive for overall long-term conservation and that base conditions should be applied in both. The significant differences detected in seed longevity among accessions underscores that different viability monitoring and regeneration intervals should be applied to groups of accessions showing different longevity profiles.