长期施肥对红壤旱地玉米生物量及养分吸收的影响

基于江西进贤旱地长期施肥定位试验田,研究不同施肥模式下玉米不同器官的生物量、养分吸收与分配及其与土壤养分的关系。结果表明:(1)长期施用化肥导致土壤pH值下降,不合理施肥使土壤养分含量有不同程度的下降,有机无机肥配施能有效缓解土壤酸化,显著提高土壤有机碳和有效养分含量。(2)与对照相比,N处理降低了玉米籽粒、穗轴、秸秆和根茬的生物量,而均衡施肥(NPK、2NPK)及有机肥处理(NPKOM、OM)使玉米籽粒增产1.1～2.9倍,并提高了其他器官的生物量。土壤酸碱度、有机质及N、P养分对玉米籽粒的产量影响显著,土壤K养分对玉米生物量影响相对较小。(3)玉米对N的吸收主要集中在籽粒和秸秆,分别占总吸N量的41.8%～61.3%和30.3%～48.4%,P在籽粒中的吸收量高达61.8%～73.9%,K的吸收主要集中在秸秆,占总吸K量的51.4%～67.9%。有机无机肥配施模式则显著促进了作物各器官对养分的吸收和提高作物产量。作物养分的收获指数为P>N>K。

不同灌溉方式对玉米生物量的影响

[目的]为了研究节水灌溉方式对玉米产量及构成的影响。[方法]2012年在武威荒漠生态与农业气象试验站设计了滴灌、喷灌、漫灌大田试验,并调查玉米整个生育期内的作物生长高度、叶面积指数、株子粒重等指标。[结果]滴灌条件下生物量高于喷灌和漫灌,拔节时差异最明显,滴灌比喷灌重48%、比漫灌重109%;滴灌叶面积指数最高,喷灌次之;在成熟期,滴灌、喷灌株高均较漫灌高22 cm;滴灌和喷灌百粒重分别重于漫灌11.88%、9.95%;滴灌、喷灌株子粒重分别重于漫灌24.8%、21.1%;滴灌理论产量大于喷灌22.59%,大于漫灌35.62%,喷灌大于漫灌10.63%;滴灌实际产量大于喷灌1.68%,大于漫灌6.52%,喷灌大于漫灌4.76%。[结论]3种灌溉技术条件下,滴灌效果最好,喷灌次之。

河套灌区不同强度低温冷害对玉米生物量累积和产量的影响

深入揭示不同发育期、不同强度和持续日数的低温冷害对玉米生物量累积和产量的影响,对农业防灾减灾具有重要意义。本文以河套灌区玉米低温冷害为研究对象,在对WOFOST模型进行参数校准的基础上,通过数值模拟试验方法,对模型在研究区域上的适应性进行了分析、检验,同时探讨了不同发育阶段出现不同强度和持续日数低温对玉米贮存器官生物量累积和产量的影响。结果表明:在玉米出苗-灌浆期中的每个发育期发生低温时,玉米贮存器官生物量累积和产量对低温强度和持续日数的响应程度基本一致;当降温强度不同、持续日数相同时,灌浆期低温对玉米产量和贮存器官生物量累积的影响最大;当降温强度相同,持续日数不同时,低温持续日数1 d,玉米拔节至抽雄期发生的低温对贮存器官生物量和产量的影响最大,低温持续日数大于3 d时,玉米灌浆期发生的低温对贮存器官生物量和产量的影响最大;发生时段不同时,出苗至拔节期发生的低温,玉米产量和贮存器官生物量随低温持续日数增加而减少,但持续日数相同,不同低温强度对其影响差别不大;其他发育阶段随着低温强度加大,持续日数增加,玉米产量和贮存器官生物量减少。本文结果较好地反映了研究区低温冷害对玉米生长影响的实际情况,可为当地农业生产决策提供科学依据。

基于SPOT-5遥感影像估算玉米成熟期地上生物量及其碳氮累积量

通过构建基于SPOT-5光谱参数的玉米成熟期地上生物量、碳氮累积量的遥感估算模型,为耕地生产力估测、农田生态保护和碳氮循环研究提供依据。利用皮尔逊相关分析法分析玉米成熟期地上生物量、碳氮累积量与同期14个预选光谱参数之间的相关性,筛选出适宜的光谱参数;通过回归分析,比较得出最优遥感估算模型。在构建的14个光谱参数中,土壤校正植被指数(SAVI)与玉米成熟期地上生物量和碳累积量均呈显著的正相关,相关系数分别达到0.831和0.846,因此以SAVI为底数的幂函数模型估算生物量和碳累积量的拟合效果最好,决定系数(R2)分别达到0.698和0.722,在0.01水平下的F检验均呈显著性;与氮累积量相关性最强的是由近红外波段和绿波段构建的比值指数(R3/R1),相关系数达到0.844;从而以R3/R1为自变量的线性模型对氮累积量拟合效果最佳,决定系数(R2)达到0.713,在0.01水平下的F检验呈显著性。因此,利用SPOT-5的土壤校正植被指数(SAVI)、近红外波段和绿波段的比值指数(R3/R1)构建的遥感模型来估算玉米成熟期生物量、碳氮累积量是可行的。

生物炭对岩溶区玉米生长、土壤CO_2及岩溶作用的影响

为研究生物炭对岩溶区玉米生长、土壤CO2体积分数和排放速率及岩溶作用的影响,通过野外盆栽试验,将蔗渣生物炭分别以土壤质量分数为0%(CK)、0.5%(T1)、1%(T2)、2%(T3)和5%(T4)添加到石灰土中,并栽培玉米。测定玉米生育期中土壤CO2体积分数和排放速率、土壤淋溶水中Ca2+和3HCO?质量分数;并测试玉米收割后土壤有机碳质量分数和容重及玉米生物量。结果表明,添加生物炭增加土壤有机碳质量分数,显著降低了土壤容重;2%和5%生物炭添加显著增加了玉米秸秆干重、玉米棒干重和玉米根干重;在玉米苗期,5%生物炭添加显著增加了土壤CO2体积分数和排放速率;在玉米拔节期、抽穗期和成熟期,2%和5%生物炭添加显著增加了土壤CO2体积分数、排放速率以及在此期间收集的土壤淋溶水Ca2+和3HCO?质量分数。由此可见,蔗渣生物炭作为岩溶区石灰土改良剂,在一定程度上改良石灰土性质,促进了玉米生长,提高了岩溶区土壤CO2的体积分数和排放速率,加快了岩溶作用。

生物炭添加对降低盐滩地有害离子及促进玉米生长效果研究

黄河三角洲盐渍化土壤改良是农作物产量提升的主要途径之一。为了解生物炭施用对降低盐滩地有害盐分离子浓度和促进玉米生长效果的影响,通过田间试验,研究秸秆还田、秸秆还田加化肥施用和不同类型低剂量(3 g·kg^(-1))生物炭(棉秆炭、芦苇炭和玉米芯生物炭)添加对盐渍土有害盐离子、电导率、钠吸附比对玉米生长效果的影响。结果表明,生物炭的添加可降低土壤溶液中有害盐分离子浓度、电导率、钠吸附比(SAR),提升玉米地下和地上生物量。以芦苇炭施用(3 g·kg^(-1))降盐效果最为明显,土壤溶液中Na^(+)浓度较对照降低了76%,土壤电导率降低了33%,土壤钠吸附比(SAR)降低了52%。以玉米芯生物炭施用(3 g·kg^(-1))对降低土壤钠吸附比和电导率最为显著,分别较对照降低了58%和45%,土壤溶液中Na^(+)浓度较对照降低了47%,并且玉米芯生物炭施用对提升玉米地上和地下生物量显著,分别较秸秆还田增加了12.19倍和6.78倍。生物炭添加可以降低土壤溶液中的Na^(+)、钠吸附比和电导率,提升K^(+)浓度缓解盐的胁迫,提高玉米的耐盐性进而提升玉米的生物量。

低温胁迫下的夏玉米苗期高光谱特征

本文以盆栽试验的方法,通过对低温下不同氮磷钾营养水平下的夏玉米苗期光谱曲线及其玉米生物量和苗期植株体内氮磷钾含量的对应分析,结果表明:(1)不同氮磷钾营养水平下,低温玉米苗期叶片光谱反射曲线在形状和趋势上基本相同,绿峰出现在550nm处、红端位于720nm左右、近红外反射平台出现在760～930nm。玉米苗期不同氮磷钾处理情况下没有“红移”和“蓝移”现象。(2)近红外区的叶片光谱反射率均可用来评价玉米的氮磷钾营养状况,而可见光区的叶片光谱反射率对玉米的氮、钾营养状况评价的可靠性高,对磷营养状况评价的可靠性相对较低。(3)在红光680nm 处,氮、磷处理下的玉米生物量与其叶片光谱反射率达到高度相关,其相关系数分别为0.92和0.85,但钾处理下的玉米生物量与其叶片光谱反射率没有明显的相关性。(4)玉米苗期植株体内氮磷含量与其叶片光谱反射率在红光、近红外反射平台区存在较高的相关性,玉米叶片光谱反射率与N含量在720nm左右其相关系数可达到-0.63,与P含量在近红外770～790nm相关系数达0.63。因此可用红光、近红外区的光谱反射率来诊断玉米植株体内氮磷含量。K含量与叶片光谱反射率在400nm左右相关性较强,相关系数达0.71,因此可用紫光波段400nm处的光谱反射值来诊断植株体内钾含量。(5)根据氮磷钾?

有机肥等氮替代化肥对玉米产量和氮素吸收利用效率的影响

有机肥替施部分化肥是实现我国化肥零增长并保持作物高产稳产的重要途径之一。以等养分条件为基础,研究不同比例有机肥等氮替代基施化肥对玉米产量以及氮素吸收利用的影响,为云南红壤坡耕地有机肥的合理利用及玉米施肥结构的调整提供科学依据。通过田间小区试验,分别设置不施肥处理(CK)、施用100%化肥处理(NPK)及4个基施有机肥等氮替代化肥处理,替代率分别为10%(T_(1)),20%(T_(2)),30%(T_(3)),40%(T_(4)),分析玉米产量、吸氮量以及氮肥利用率等指标在不同施肥处理下的变化情况。结果表明:与NPK处理相比,不同比例有机肥替代化肥的处理能在一定程度上提高玉米籽粒、秸秆生物量,玉米籽粒产量提高达6.07%~19.53%,秸秆生物量提高达2.16%~21.76%,且有机肥替代30%的化肥处理下的玉米籽粒产量和秸秆生物量最高,分别达到7653 kg/hm^(2),16530 kg/hm^(2),较其他施肥处理有一定的显著性;有机肥替代化肥的处理均提高了玉米籽粒和秸秆的吸氮量,各施肥处理下的玉米地上部氮素平均积累量从大到小依次为T_(3)(292 kg/hm^(2))>T_(2)(248 kg/hm^(2))>T_(1)(212 kg/hm^(2))>T_(4)(203 kg/hm^(2))>NPK(176 kg/hm^(2))>CK(52 kg/hm^(2)),T_(3)处理较NPK,T_(1),T_(2),T_(4)处理下的玉米地上部分吸氮量分别提高了39.90%,27.37%,15.01%,30.38%;与NPK处理相比,有机肥替代化肥的处理均提高了氮肥偏生产力、氮肥贡献率、氮肥表观利用率、氮肥的农学利用率,提高比例分别为5.00%~21.80%,2.44%~9.48%,20.48%~94.02%,7.54%~32.86%,且T_(3)处理下的各氮素利用率指标均显著高于其他施肥处理。综上,有机肥与化肥配施可提高玉米的籽粒产量和生物产量,且提高玉米的吸氮量及氮素利用效率,且以有机肥等氮替代30%基施化肥的配施效果最好,可作为云南红壤坡耕地玉米增产和氮肥增效的合理施肥模式。

Quantifying biochemical variables of corn by hyperspectral reflectance at leaf scale

To further develop the methods to remotely sense the biochemical content of plant canopies,we report the results of an experiment to estimate the concentrations of three biochemical variables of corn,i.e.,nitrogen(N),crude fat(EE) and crude fiber(CF) concentrations,by spectral reflectance and the first derivative reflectance at fresh leaf scale. The correlations between spectral reflectance and the first derivative transformation and three biochemical variables were analyzed,and a set of estimation models were established using curve-fitting analyses. Coefficient of determination(R2),root mean square error(RMSE) and relative error of prediction(REP) of estimation models were calculated for the model quality evaluations,and the possible opti-mum estimation models of three biochemical variables were proposed,with R2 being 0.891,0.698 and 0.480 for the estimation models of N,EE and CF concentrations,respectively. The results also indicate that using the first derivative reflectance was better than using raw spectral reflectance for all three biochemical variables estimation,and that the first derivative reflectances at 759 nm,1954 nm and 2370 nm were most suitable to develop the estimation models of N,EE and CF concentrations,respectively. In addition,the high correlation coefficients of the theoretical and the measured biochemical parameters were obtained,especially for nitrogen(r=0.948).

Impact of Nitrogen Fertilization on the Oil, Protein, Starch, and Ethanol Yield of Corn （Zea mays L,） Grown for Biofuel Production

Nitrogen fertilization is one of the greatest challenges associated with the production of biofuel from corn grain. The objective of this research was to determine the effect of N fertilization on the content and yield of oil, protein, and starch in corn grain. The project was done in Southeast Missouri （USA）, from 2007 to 2009 in a silt loam soil. Corn grain contains 3.8-4.2% oil, 6.7%-8.9% protein, 68.0%-70.4% extractable starch, and 76.0%-77.7% total starch. The total starch yield ranged from 2.8 to 7.8 mg.ha1 whereas the extractable starch varied between 2.5 to 7.1 mg-ha1. As the N rate went up, the oil and starch content of the grain decreased, whereas the protein content and the protein, starch, and oil yields increased, reaching their maximum at the N rate corresponding to 179.0 kg N.ha~. The potential ethanol yield varied between 616.2 and 7,035.1 L-ha1 depending on the method of conversion of the starch into ethanol, the year and the N rate （P 〈 0.0001）. The negative correlation between N fertilization rate and starch content suggested that when farmers add too much N to their soil to increase grain yield, they reduce the starch content in those grains, and consequently the conversion into bioethanol. Therefore, for biofuel production to be beneficial for both farmers and the power plant owners, an agreement needs to be made with regard to the use of fertilizers.

Effect of Transgenic Corn Cultivation and Sampling Location on Feeding Habits of Collembola

Transgenic corn was modified to combat lepidopteran pests, herbicide and other deteriorate environmental factors. However, fewer studies concerned the effects of transgenic corn cultivation on the soil Collembola in black soil region in China. In Jilin black soil region, a six treatments study including three corn varieties （transgenic corn, control and local variety） and two sampling locations （in rizhosphere and in between plants） were deployed to study the effect of transgenic corn cultivation and sampling location on densities, species richness and community structure of Collembola. We found that root biomass was marginally decreased in transgenic corn and control variety when compared to local variety. Collembola significantly affected by sampling location treatments. Densities and species richness of collembolans significantly decreased in ＂between plants＂ than in ＂rizhosphere＂. Densities of Collembola were impacted by corn varieties. In the whole growing season, densities of Collembola significantly decreased in control than in local variety. Collembolans in transgenic variety only slightly decreased in ＂jointing stage＂ than local variety. Collembolans adversely affected in ＂between plants＂ when compared to ＂in rhizosphere＂ in ＂seeding stage＂ but not other stages. These variations of collembolans were in lines with the trend of corn root biomass. It is indicated that Collembola variations could be caused by food resources （root biomass） but not corn varieties （transgenic, control and local）.

Quantification of CrylAb Toxin in Bt Maize for Ostrinia nubilalis （Lep.： Crambidae） Bioassay

Two variants of diet composition were prepared to evaluate the susceptibility of ECBs to CrylAb toxin as follows： 1） 38-0600 Stonefly Heliothis Diet mixed with purified CrylAb protein and 2） 38-0600 Stonefly Heliothis Diet mixed with lyophylized leaves of Bt maize MON 810-YieldGard. A method of sample preparation and extraction of Bt toxin for reproducible ELISA quantification were optimized. The qualitative DAS-ELISA kit from Agdia was optimized for use in quantitative analysis of Cry lAb toxin. The mortality of ECB larvae from the laboratory strain on the diet with CrylAb toxin did not differ significantly from the mortality on the diet with Bt maize leaves with the same rate of Cry lAb toxin. Similarly, the mortality of the ECB larvae from the field population on the diet with Bt maize leaves did not differ significantly from the mortality of ECB larvae from the laboratory strain on the same type of diet. Therefore, the incorporation of Bt maize leaves into the diet did not influence the efficacy of CrylAb toxin against ECBs. Using this method, a susceptibility of one field population of ECBs from the Czech Republic to CrylAb toxin was determined （LC50 of 2.16 μg of Cry 1Ab g^-1 of diet）.

Productivity of Soil Fertilised with Fermented Calliandra, Gliricidia and Leucaena Browses and Maize Forage

Fermented Callliandra, Gliricidia and Leucaena browses and maize material （milk stage） were applied to the soil to determine their effect on soil productivity. Hopi Red Dye Amaranthus （Amaranthus cruentus） was used as the test crop. Its DM yield was determined. The browse materials had higher total N and narrower C：N ratio than the maize material. Calliandra material had higher levels of insoluble fiber （ADF）, fiber bound N （ADFN） and lignin. Application of the browse and maize materials raised C, N, and C：N ratio of the soil in which they were applied compared to the control soil. The treated soils maintained higher levels of C and N and a narrower C：N ratio up to the third crop. Amaranthus DM yield was highest （P 〈 0.05） with browse treatments. Treatment with maize material did not have DM yield advantage over the control soil. Treatments with browse materials could have given higher yields because the materials had more N and fermentation could not only have increased the proportion of soluble N, but also degradability of the materials, thus making the N and other nutrients in the fermented materials available for plant growth. DM yield was highest （P 〈_ 0.05） with the first and third crops but lowest （P 〈 0.05） with the second crop. Plant growth in the second crop could have coincided with high demand for the N by the soil micro-organisms decomposing the added materials. During the third crop, decomposition of the readily degradable components of the added materials could have been complete and the N became available for plant growth. DM yield dropped （P 〈 0.05） with the fourth crop as the available N could have been depleted from the soil for plant growth.

Long-term variability of root production in bioenergy crops from ingrowth core measurements

Aims Long-term determination of root biomass production upon land-use conversion to biofuel crops is rare.To assess land-use legacy influences on belowground biomass accumulation,we converted 22-year-old Conservation Reserve Program(CRP)grasslands and 50+-year-old agricultural(AGR)lands to corn(C),switchgrass(Sw)and restored prairie(Pr)biofuel crops.We maintained one CRP grassland as a reference(Ref).We hypothesized that land-use history and crop type have significant effects on root density,with perennial crops on CRP grasslands having a higher root biomass productivity,while corn grown on former agricultural lands produce the lowest root biomass.Methods The ingrowth core method was used to determine in situ ingrowth root biomass,alongside measurements of aboveground net primary productivity(ANPP).Ancillary measurements,including air temperature,growing season length and precipitation were used to examine their influences on root biomass production.Important Findings Root biomass productivity was the highest in unconverted CRP grassland(1716 g m?2 yr?1)and lowest in corn fields(526 g m?2 yr?1).All perennial sites converted from CRP and AGR lands had lower root biomass and ANPP in the first year of planting but peaked in 2011 for switchgrass and a year later for restored prairies.Ecosystem stability was higher in restored prairies(AGR-Pr:4.3±0.11;CRP-Pr:4.1±0.10),with all monocultures exhibiting a lower stability.Root biomass production was positively related to ANPP(R2=0.40).Overall,attention should be given to root biomass accumulation in large-scale biofuel production as it is a major source of carbon sequestration.