摄食水平对黄颡鱼氮和能量收支的影响

在25℃、自然光照条件下,测定黄颡鱼在摄食水平为1/3饱食、2/3饱食和饱食时的氮和能量收支.结果显示,摄食水平对黄颡鱼的氮收支和能量收支均有显著影响,随着摄食水平的提高,生长氮和生长能的比例显著提高,排泄氮、粪氮和代谢能的比例显著下降,但在饱食2/3和饱食水平时,生长氮、生长能、排泄氮和代谢能比例差异都不显著.     

早实核桃幼树施肥效果研究

试验设置N、P、B 3种肥料9种不同施肥处理,研究不同施肥处理对早实核桃产量和对不同枝类的单枝结果量和产量比例的影响。结果表明:N、P、B 3种肥料的不同配比对核桃产量有很大的影响,P肥是影响干果重和核仁重的主要肥料,低水平的P肥处理的干果重和核仁重都明显低于其他处理;P、B肥是影响长、中、短结果枝产量比例的主要肥料。施肥处理8(N3P3B2K)的肥料配比效果最好。     

冷凉灌区马铃薯施肥量与种植密度对马铃薯生长及产量的影响

为了明确不同施肥量(复合肥)和种植密度对冷凉灌区马铃薯生长的影响。试验以‘冀张薯12号’为供试品种,开展施肥量与种植密度二因素试验,设3个施肥量(600、1100、1600 kg/hm²)与4个种植密度(5.25万、6万、6.75万、7.5万株/hm²),研究不同施肥量与种植密度对马铃薯生长、产量与水分利用效率的影响。结果表明：增加施肥量能延缓马铃薯生育期,提高种植密度能缩短生育期;随施肥量增大,马铃薯株高、茎粗、叶面积指数及叶片SPAD值均显著增大;随种植密度增加,马铃薯株高、茎粗、叶面积指数及叶片SPAD值与产量均表现为先增后减趋势,施肥量与种植密度对马铃薯株高、SPAD值与产量的影响顺序为施肥量>密度;随施肥量和群体种植密度的增加,马铃薯大薯产量、大薯数、产量、水分利用效率均呈先增后减的变化趋势,产量要素之间呈极显著正相关关系,其中,以处理F₂D₃的马铃薯产量与水分利用效率最大。通过二元二次回归分析表明,当施肥量达到1065.366 kg/hm²,种植密度达到6.7...     

不同施肥模式下的稻-克氏原螯虾田块水体菌群初探

为研究不同施肥模式对稻田养殖克氏原螯虾(Procambarus clarkii)田块水体细菌的影响,通过采用Illumina高通量测序技术针对施用化肥(CF)、有机肥(OF)和有机肥加腐熟鸡粪(OM)等3种施肥模式的水体细菌进行检测。高通量测序结果显示在3种不同施肥模式下的稻田中主要细菌门类均为变形菌门(Proteobacteria)、放线菌门(Actinobacteria)、拟杆菌门(Bacteroidetes)、蓝藻门(Cyanobacteria)和厚壁菌门(Firmicutes)。主要优势菌属为Sporichthyaceae hgcl_clade、Limnohabitans、Polynucleobacter、Alpinimonas、Comamonadacea和Hydrogenophaga。在3种模式中,施用有机肥的田块细菌丰度显著高于施用化肥和有机肥加腐熟鸡粪的田块,细菌物种多样性显著高于施用有机肥加腐熟鸡粪田块,与施用化肥田块差异不显著。结果表明在施用有机肥模式下,水体微生物具有更好的多样性,生态系统更加稳定。有机肥与腐熟鸡粪配施虽然会降低水体细菌的物种多样性,但是腐熟鸡粪与有机肥配施会大大降低蓝藻细菌的丰度。聚类分析结果显示有机肥组与有机肥加腐熟鸡粪组水体细菌群落相似度更高。对稻田水体细菌与水体理化因子关联分析发现,对水体细菌影响最主要的环境因子是溶氧、总氮、pH和总磷。研究结果为不同施肥处理对稻田水体生态环境的影响以及为稻田综合种养施肥模式优化提供理论依据。     

One-time fertilization at first flowering improves lint yield and dry matter partitioning in late planted short-season cotton

Cotton producers have substantially reduced their inputs(labor, nutrients, and management) mainly by adopting a shortseason cropping management that is characterized by late sowing, high density, and reduced fertilization with one-time application at the first bloom stage without lint yield reduction. However, it has been hypothesized that one-time fertilization at an earlier growth stage could be a more effective and economic management practice. A two-year field experiment was conducted by applying five fertilizer one-time fertilization at 0(FT1), 5(FT2), 10(FT3), 15(FT4), and 20(FT5) days after the first flower appeared in the field and one three-split fertilizer application taken as the conventional control(FT6), making six treatments altogether. Cotton growth period, biomass accumulation, yield, and its formation were quantified. The results showed that the one-time fertilization did not affect the cotton growth progress as compared to FT6, however, the total crop cycles for FT3–FT5 were 3 days shorter. FT1 produced the highest cotton lint yield(1 396 kg ha–1), which was similar to the FT6 but higher than the other treatments, and could be attributed to more bolls per unit area and higher lint percentage. Cotton yield was positively correlated with cotton plant biomass accumulated. FT1 had both the highest average(VT)(193.7 kg ha–1 d–1) and the highest maximum(VM)(220.9 kg ha–1 d–1) rates during the fast biomass accumulation period. These results suggest that one-time fertilizer application at the first flower stage might be an adjustment that is more effective than at first bloom, and allowed for easier decision making for application date due to non counting of plants with flowers is needed.     

Long-term fertilization leads to specific PLFA finger-prints in Chinese Hapludults soil

Soil microbes play essential roles in the biogeochemical processes of organic carbon and nutrient cycling. Many studies have reported various short-term effects of fertilization on soil microbes. However, less is known about the effects of longterm fertilization regimes on the rhizosphere. Therefore, the objective of this study was to explore how the soil microbial communities in the rhizosphere respond to different long-term fertilization strategies. Based on a 21-year field treatment experiment in Guizhou, China, we extracted phospholipid fatty acids(PLFAs) to determine the microbial community structure in both the non-rhizosphere(NR) and rhizosphere(R). Six treatments were included: no fertilizer(CK), mineral nitrogen fertilizer(N), N with potassium(NK), phosphorus with K(PK), NPK, and NPK combined with manure(MNPK). The results showed that total PLFAs under unbalanced mineral fertilization(N, NK and PK) were decreased by 45% on average in the NR compared with CK, whereas MNPK increased fungi and G~– bacteria abundance significantly in both the NR(by 33 and 23%) and R(by 15 and 20%), respectively. In addition, all microbial groups in the R under these treatments(N, NK and PK) were significantly increased relative to those in the NR, except for the ratio of F/B and G~+/G~–, which might be due to the high nutrient availability in the R. Soil pH and SOC significantly regulated the soil microbial community and structure, explaining 51 and 20% of the variation in the NR, respectively. However, the rhizosphere microbial community structure was only significantly affected by soil pH(31%). We concluded that the soil microbial community in the NR was more strongly affected by long-term fertilization than that in the R due to the rhizosphere effect in the agricultural ecosystem. Rhizosphere nutrient conditions and buffering capacity could help microbial communities resist the change from the long-term fertilization.     

配方施肥改善米老排容器苗生长指标

为筛选米老排容器苗最佳施肥组合,采用L₁₆ (4 ⁵)正交试验设计和等量施肥法,研究N、P和K肥3因素对米老排容器苗苗高、地径、生物量以及养分利用的影响。研究结果表明：不同施肥组合处理对米老排容器苗苗高、地径、总生物量等指标均有着显著影响,配方施肥对米老排容器苗的生长发育具有明显促进作用;3种肥料对米老排容器苗苗高生长的影响效应均是N>P>K,其施肥最优组合是N₁P₃K₂（每株施N、P和K分别为50、50、60 mg）,对地径生长和生物量积累影响效应均为N>K>P,施肥最优组合分别是N₁P₄K₂（每株施N、P和K分别为50、60、60 mg）和N₁P₄K₁（每株施N、P和K分别为50、60、45 mg）;合理的配方施肥能有效提高米老排苗木的养分利用效率。综合苗木各指标看,米老排容器苗最优施肥配方是：N₁P₄K₁（每株施N、P和K分别为50、60、45 mg）。     

不同限水条件下施肥方式对小麦产量构成因素的影响

为了提高水分和肥料的利用效率,2015~2016年进行了限水条件下施肥方式对产量构成因素影响的试验。结果表明:底施三元素复合肥+春季浇2水(拔节水+开花水)的产量最高;在相同水分或肥力条件下对穗数的影响较小,穗粒数、不孕小穗数随着水肥条件的不同变化较大,说明在小麦生产中水分和养分是制约小麦生产的主要因素。     

不同追肥次数和用量对番茄产量及品质的影响

为推行减量施肥,提高肥料利用率,研究了不同施肥措施对连续种植的番茄产量及品质的影响。结果表明:优化施肥处理在保证不减产的情况下,节肥效果显著,与传统施肥处理(T1)相比,优化施肥各处理(T2—T5)每667 m~2施用化肥纯养分总量分别减少44.8、44.8、65.6、3.2 kg,节肥47.0%、47.0%、68.8%、3.4%,T4处理节肥效果最佳;在高肥力地力水平下,追肥用量减半完全可以保证作物所需养分,其中T3产量最高,表明在优化施肥的基础上增加追肥次数,少量多次追肥更利于作物生长;T3提高了番茄维生素C含量,降低了番茄的硝酸盐含量。综上,化肥减量对连续种植的番茄产量没有明显影响,但显著提高了番茄的品质,以T3即化肥底施减量50%配施40%有机肥且适当增加追肥次数处理的效果最好。     

基于MODIS TVDI和模糊数学方法的藏北地区旱情等级遥感监测

为了实现对藏北区域范围内春夏旱情的动态连续监测,基于温度植被干旱指数(TVDI)和模糊数学方法建立了遥感干旱的划分标准,研究时段为1980-2017年。首先利用MODIS产品数据计算TVDI,然后根据气象干旱等级监测结果,采用模糊数学法建立基于MODIS TVDI的干旱等级划分标准,并对监测结果进行精度验证,最后分析了近年来藏北地区旱情的时空变化特征。得到的主要结论:①基于归一化植被指数(NDVI)和增强植被指数(EVI)计算得到的温度植被干旱指数TVDIN和TVDIE,均与20 cm实测土壤水分含量在0.05的水平达到显著相关,TVDIE的决定系数更高;②基于TVDIE将旱情划分为无旱、轻旱、中旱、重旱、特旱5个等级,其中,据此标准获得的藏北地区旱情等级与气象干旱等级监测结果大体一致;③近年来藏北地区旱情整体不太严重,且总体趋缓,其中,2009年最严重,发生中旱及以上旱情的区域面积达24%,年内旱情在6月最严重。就旱情的空间分布特征而言,研究区西南部和中部干旱比较严重,北部和东南部相对较轻。研究成果可为藏北地区干旱监测提供数据支撑,遥感干旱等级的划分方法可为其他地区的干旱研究提供参考。