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1.
不同生物质炭输入水平下旱作农田温室气体排放研究 总被引：4，自引：0，他引：4
在陇中黄土高原干旱半干旱区,采用小区定位试验,对不同生物质炭输入水平下春小麦农田土壤温室气体(CO_2、N_2O和CH_4)的排放通量进行全生育期连续观测,并分析其影响因子。结果表明:6个生物质炭输入水平处理下[0 t·hm~(-2)(CK)、10 t·hm~(-2)、20 t·hm~(-2)、30 t·hm~(-2)、40 t·hm~(-2)、50 t·hm~(-2)],旱作农田土壤在春小麦全生育期内均表现为CH_4弱源、N_2O源和CO_2源。全生育期各处理CH_4平均排放通量依次为:0.005 7 mg·m~(-2)·h~(-1)、0.0047 mg·m~(-2)·h~(-1)、0.003 6 mg·m~(-2)·h~(-1)、0.003 3 mg·m~(-2)·h~(-1)、0.002 7 mg·m~(-2)·h~(-1)和0.000 4 mg·m~(-2)·h~(-1),N_2O平均排放通量依次为:0.230 5 mg·m~(-2)·h~(-1)、0.144 1 mg·m~(-2)·h~(-1)、0.135 3 mg·m~(-2)·h~(-1)、0.098 9 mg·m~(-2)·h~(-1)、0.125 0 mg·m~(-2)·h~(-1)和0.151 3mg·m~(-2)·h~(-1),CO_2平均排放通量依次为:0.449 2μmol·m~(-2)·s~(-1)、0.447 0μmol·m~(-2)·s~(-1)、0.430 3μmol·m~(-2)·s~(-1)、0.391 4μmol·m~(-2)·s~(-1)、0.408 0μmol·m~(-2)·s~(-1)和0.416 4μmol·m~(-2)·s~(-1)。土壤CH_4排放通量随生物质炭输入量的增加而减小;当生物质炭输入量小于30 t·hm~(-2)时,土壤N_2O、CO_2排放通量随其输入量增加而显著减小,但当其输入量超过30 t·hm~(-2)时,N_2O、CO_2排放通量则呈显著增大趋势。各处理在5~15 cm土层平均土壤温度差异显著(P0.05),在5~10 cm土层平均土壤含水量差异显著(P0.05),土壤温度及含水量受生物质炭影响明显;且CK处理不同土层的土壤温度及含水量波动最大,生物质炭输入可在一定程度上降低不同土层土壤的水热变化幅度;N_2O、CO_2排放通量与10~15 cm土层土壤温度呈显著性负相关,与20~25 cm土壤温度呈显著性正相关;CH_4平均排放通量与5~10 cm土层土壤温度呈显著性负相关,与其含水量呈显著性正相关;N_2O平均排放通量与15~20 cm土层土壤温度呈显著性正相关;CH_4、N_2O、CO_2平均排放通量与0~5 cm土层土壤水分呈显著性负相关。生物质炭的输入能够减小温室气体的排放,且会因其输入量的不同而异,因此适量应用生物质炭有利于旱作农田生育期内增汇减排。 相似文献
2.
不同耕作措施下旱作农田土壤团聚体中有机碳和全氮分布特征 总被引：17，自引：3，他引：17
以连续进行12年的保护性耕作长期定位试验为研究对象,探索了传统耕作(T)、传统耕作+秸秆还田(TS)、免耕不覆盖(NT)、免耕+秸秆覆盖(NTS)4种耕作措施对陇中黄土高原旱作农田豌豆-小麦双序列轮作系统的土壤团聚体中有机碳和全氮分布特征的影响。结果表明:各处理均以≥0.25 mm团聚体为优势团聚体,且≥0.25 mm团聚体含量随土层深度增加而增加,而其他粒径团聚体含量随土层深度的变化并无明显规律。较之T处理,TS、NT、NTS处理均可提升≥0.25 mm团聚体含量和平均重量直径,NTS处理提升效果最明显。TS、NT、NTS处理土壤有机碳和全氮含量均高于T处理,其中TS、NTS处理显著高于T处理,NTS处理高于TS处理;各处理土壤有机碳和全氮含量均随土层增加而减小。较之T处理,NT、TS、NTS处理可不同程度提高各粒径团聚体中有机碳和全氮含量,NTS处理的含量最高;各粒径团聚体中有机碳和全氮含量均随土层深度增加而减小;同时,团聚体中有机碳和全氮含量随粒径减小而增加。2~5 mm和0.25~2 mm和≥5 mm团聚体含量与相应粒径团聚体有机碳含量呈极显著正相关、极显著正相关和极显著负相关;0.25~2 mm和≥5 mm团聚体含量与相应级别团聚体全氮含量分别呈极显著正相关和显著负相关。T处理不同粒径团聚体有机碳和全氮贡献率按其大小排序均为(0.25 mm)(≥5 mm)(0.25~2 mm)(2~5 mm),其他3种耕作措施各粒径团聚体有机碳和全氮贡献率在各土层中的排序各有不同,并无明显规律。 相似文献
3.
Joseph Akwasi Manu-Aduening Bright Boakye Peprah Adelaide Agyeman 《Journal of Crop Science and Biotechnology》2013,16(1):23-28
Availability of genetic diversity is important in selecting suitable cultivars for crop improvement. Progenies of crosses between 19 farmer-preferred cassava landraces and Cassava Mosaic Disease (CMD)-resistant cultivar TME 11 were evaluated and compared with their maternal parents to assess their genetic variability and genetic gains based on CMD tolerance, some growth variables and root yield. The combined analysis of variance for the traits showed significant genotypic differences amongst the progenies and the parents. Apart from a few instances, the differences in replications and years were also significant. Genetic variability components showed high heritability ranging from 92.3 to 99.6% and moderately high genetic gains of 54.1 to 99.6% for the parental cultivars. Apart from canopy spread and plant height, heritability and genetic gains of the progenies were slightly lower than the parents indicating high variability within families of the progenies. The phenotypic coefficient of variation was slightly greater than genotypic coefficient of variation indicating minimal influence of environment on the genotypes. For most of the characters evaluated, the mean performance of the progenies was higher than their corresponding parental lines. Although the genotypes differed significantly (P < 0.001) for all traits evaluated, cultivars such as Afebankye, Bosome nsia, Cedi bankye, 262 Debor, Kwadaso 25, Nkaakom 57 and Sisipe were found to constitute a pool of germplasm with adequate variability. The negative correlation between CMD incidence and other traits evaluated showed significant progress made in the breeding program. 相似文献
4.
Context
Despite decades of research, there is an intense debate about the consistency of the hump-shaped pattern describing the relationship between diversity and disturbance as predicted by the intermediate disturbance hypothesis (IDH). Previous meta-analyses have not explicitly considered interactive effects of disturbance frequency and intensity of disturbance on plant species diversity in terrestrial landscapes.Objective
We conducted meta-analyses to test the applicability of IDH by simultaneously examining the relationship between species richness, disturbance frequency (quantified as time since last disturbance as originally proposed) and intensity of disturbance in forest landscapes.Methods
The effects of disturbance frequency, intensity, and their interaction on species richness was evaluated using a mixed-effects model.Results
We found that species richness peaks at intermediate frequency after both high and intermediate disturbance intensities, but the richness-frequency relationship differed between intensity classes.Conclusions
Our study highlights the need to measure multiple disturbance components that could help reconcile conflicting empirical results on the effect of disturbance on plant species diversity.5.
The cotton aphid (Aphis gossypii) is one of the major pests of okra. Eleven okra varieties collected from farmers' fields in Cameroon and four aphid-resistant accessions from The World Vegetable Center (AVRDC, Asian Vegetable Research and Development Center) were evaluated from October 2012 to March 2013, and another seven aphid-resistant accessions from AVRDC were evaluated from March to July 2013 at AVRDC's Nkolbisson station, Yaoundé, Cameroon. Accessions selected from these trials were screened in an advanced confirmatory screening in autumn (October–December) 2013 in Shanhua, Taiwan. Results showed that none of the farmers' landraces were resistant to aphids. Two accessions (VI041210 and VI033824) with the lowest aphid populations had the highest trichome density. Analysis of various phytochemicals in selected okra accessions revealed that higher nitrogen and potassium levels made the okra accessions susceptible to aphids during the reproductive stage of the plants. Similarly, the total phenol content was lower in moderately resistant accessions during their reproductive stage. Aphid feeding induced an increase in phenols, and to a lesser extent, tannins. Accessions VI041210 and VI033824 could be incorporated into an integrated pest management strategy to enhance productivity of okra. 相似文献
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7.
不同生物质炭输入水平下旱作农田温室气体排放日变化研究 总被引：1，自引：0，他引：1
在陇中黄土高原干旱半干旱区,采用小区定位试验,对不同生物质炭水平(0 t·hm~(-2)、10 t·hm~(-2)、20 t·hm~(-2)、30 t·hm~(-2)、40 t·hm~(-2)、50 t·hm~(-2))下农田土壤温室气体(CO_2、N_2O和CH_4)的日排放通量及其影响因子进行连续观测,并确定1 d中不同生物质炭处理水平下的最佳观测时间。结果表明:6个生物质炭输入水平处理下,春小麦地土壤CH_4、N_2O和CO_2通量变化趋势与气温日变化轨迹大体一致,均表现为白天排放量大于夜间,并在4:00—5:00时,出现对CH_4通量的吸收峰,以及N_2O与CO_2的排放低谷;全天内各处理CH_4平均排放通量依次为:10.14mg·m~(-2)·h~(-1)、7.82mg·m~(-2)·h~(-1)、6.57mg·m~(-2)·h~(-1)、-0.10mg·m~(-2)·h~(-1)、1.05mg·m~(-2)·h~(-1)和2.89mg·m~(-2)·h~(-1),N_2O平均排放通量依次为:288.79mg·m~(-2)·h~(-1)、201.78mg·m~(-2)·h~(-1)、157.14mg·m~(-2)·h~(-1)、112.06mg·m~(-2)·h~(-1)、154.60mg·m~(-2)·h~(-1)和164.02mg·m~(-2)·h~(-1),CO_2平均排放通量依次为:85.44 mg·m~(-2)·h~(-1)、80.91 mg·m~(-2)·h~(-1)、76.49 mg·m~(-2)·h~(-1)、65.29 mg·m~(-2)·h~(-1)、67.19 mg·m~(-2)·h~(-1)和69.10 mg·m~(-2)·h~(-1);当生物质炭输入量小于30 t·hm~(-2)时,土壤CH_4、N_2O、CO_2排放通量随其输入量增加而显著减小,但当其输入量超过30 t·hm~(-2)时,3种温室气体排放通量则呈显著增大趋势;当生物质炭输入水平为30 t·hm~(-2)时,春小麦土壤全天表现为CH_4的吸收汇,其余各水平处理下的土壤表现为CH_4的弱排放源;6种处理水平下,全天春小麦地土壤表现为N_2O、CO_2的排放源。0~5 cm的土壤温度及水分(y)与生物质炭输入量(x)回归方程分别为y=-0.017 6x+16.585(R~2=0.302 6,r=-0.55,P0.05)和y=0.056 5x+13.626(R~2=0.815 1,r=0.903,P0.05),生物质炭输入量与0~5 cm的土壤水分呈显著正相关关系;无生物质炭输入处理下3种温室气体的吸收或排放通量与地表温度及5 cm地温均呈显著正相关关系,其他各处理也表现出不同程度的正相关关系。因此,当生物质炭输入水平为30 t·hm~(-2)时,更有利于CH_4、N_2O和CO_2 3种温室气体的增汇减排;生物质炭输入水平差异引起的土壤温度及水分差异可能是不同生物质炭处理CH_4、N_2O和CO_2日排放通量产生差异的主要原因;由矫正系数及最佳时段温室气体排放量与累积排放量回归分析可得,3种温室气体的最佳同期观测时间为8:00—9:00。 相似文献
8.
Flooding of vegetable crop fields along the Yangtze River basin in China has been an annual occurrence; therefore the cultivation of tolerant varieties has become one of the most promising control strategies. Our objective was to investigate the inheritance of waterlogging tolerance of cucumber at the early stage of growth with two cucumber parents consisting of PW0832 (tolerant) and PW0801 (susceptible). In 2006, 4-weeks-old potted plants of P1, P2, F1, F2, B1 and B2 generations were subjected to one week waterlogged stress, control plants were not flooded. The simple additive model explained the variations of tolerance score (TOL) adventitious root formation (ARF) and waterlogged root dry weight (RDW) while the additive-dominance model explained the control treatment of RDW. Non-allelic interactions were detected for waterlogged vine length (VLH) and root length (RLH). Complementary epistasis occurred in waterlogged VLH while additive × additive, additive × dominance and dominance × dominance epistastic effects were significant for waterlogged RLH. Transgressive segregation was also observed in most of the traits in the F2 generation indicating some alleles are dispersed in the parents used in this study. The estimates of narrow-sense heritabilities for TOL and ARF were moderately high. Backcross of F1 to both parents in ARF, waterlogged SDW and waterlogged RDW showed good convergence of genes in the B2. These results suggest that it should be possible to develop varieties with high levels of tolerance by selecting transgressive segregants in this cross. 相似文献
9.
种植模式对旱地玉米光合特性和产量的影响 总被引：4，自引：0，他引：4
为进一步优化陇中半干旱区玉米高产栽培技术,提高有限水土资源利用效率,2014—2015年采用田间试验,研究了玉米马铃薯间作和单作下全膜沟垄作、全膜平作和露地平作对玉米抽雄期光合速率(Pn)、蒸腾速率(Tr)、气孔导度(Gs)、胞间CO_2浓度(Ci)及子粒产量的影响。结果表明:(1)不同种植模式下玉米抽雄期叶片Pn和Tr的日变化均呈先升后降的单峰曲线,峰值出现在中午12∶00左右,全膜沟垄作高于平作和露地,间作高于单作;全膜沟垄作玉米间作马铃薯下的玉米Pn、Tr和Gs均最高。(2)全膜沟垄作、全膜平作和露地平作的玉米间作马铃薯,土地当量比(LER)均大于1,以全膜沟垄作玉米间作马铃薯优势最为突出,其间作下玉米子粒产量为5 451.35kg·hm~(-2),较露地间作提高了66.00%,特别是在降水量偏少的年份,增产效果更明显。因此,在陇中雨养农业区进一步提高玉米产量和水土资源利用效率,引入间作是可行的,全膜沟垄作玉米间作马铃薯是较佳的种植模式。 相似文献
10.
在陇中黄土高原干旱半干旱区,采用小区定位试验与室内盆栽模拟试验相结合的方法,对不同生物质炭输入水平下旱作黄绵土N_2O的日排放通量及其影响因子进行连续观测,并确定1天中不同生物质炭处理水平下的最佳观测时间。结果表明:6个生物质炭输入水平处理下(0、10、20、30、40、50 t·hm~(-2)),旱作黄绵土全天表现为N_2O的排放源;无生物质炭添加处理的N_2O排放通量均显著高于其他各处理,随输入水平增加呈U型变化规律,当生物质炭输入水平为30 t·hm~(-2)时,更有利于N_2O气体的增汇减排;各处理N_2O日总排放通量均在白天所占比例最高;温度是环境因子相对稳定条件下N_2O气体排放的主要影响因子,N_2O的排放与地表温度及10 cm土层地温呈不同程度的正相关关系;10 cm土层地温与生物质炭输入量呈显著正相关关系;N_2O气体的最佳同期观测时间为8∶00—9∶00。 相似文献