Northeast Institute of Geography and Agroecology, Chinese Academy Of Sciences
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Soil Nutrient Variance by Slope Position in a Mollisol Farmland Area of Northeast China
No full textIn order to generate scientifically-based comparative information to improve fertilization efficiency and reduce nutrient loss, 610 samples of 122 soil profiles were collected at the 0-60 cm depth to compare soil nutrient contents including soil organic matter (SOM), total nitrogen (TN), total phosphorus (TP), available phosphorus (AP), and available potassium (AK) among different slope positions in a Mollisol farmland area of Northeast China. The contents of SOM and TN typically decreased with increased soil depth at back and bottom slope. Soil loss and deposition tended to decrease SOM and TN at the 0-20 cm soil depth on both the back slope and the slope bottom. The TP firstly decreased from 0-20 cm to 30-40 cm, and then not constantly increased at the back slope and the bottom slope. Due to the characteristics of soil nutrients and crop absorption, the contents of both AP and AK were typically the highest at the summit, followed by the slope bottom and the back slope in the 0-20 cm layer. Generally, in order to sustain the high soil productivity and protect the environment, attention should be paid to soil conservation on back slope; in addition, additional N and P fertilizer is necessary on the back slope
Effects of Wetland Utilization Change on Spatial Distribution of Soil Nematodes in Heihe River Basin, Northwest China
No full textThe first account of the effects of wetland reclamation on soil nematode assemblages were provided, three sites in Heihe River Basin of Northwest China, that is grass wetland (GW), Tamarix chinensis wetland (TW) and crop wetland (CW) treatments, were compared. Results showed that the majority of soil nematodes were presented in the 0-20 cm soil layers in CW treatments, followed by in the 20-40 cm and 40-60 cm layers in GW treatments. Plant-feeding nametodes were the most abundant trophic groups in each treatment, where GW (91.0%) > TW (88.1%) > CW (53.5%). Generic richness (GR) was lower in the TW (16) than that in GW (23) and CW (25). The combination of enrichment index (EI) and structure index (SI) showed that the soil food web in GW was more structured, and those in TW was stressed, while the enrichment soil food web was presented in the CW treatment. Several ecological indices which reflected soil community structure, diversity, Shannon-Weaver diversity (H'), Evenness (J'), Richness (GR) and modified maturity index (MMI) were found to be effective for assessing the response of soil namatode communities to soil of saline wetland reclamation. Furthermore, saline wetland reclamation also exerted great influence on the soil physical and chemical properties (pH, Electric conductivity (EC), Total organic carbon (TOC), Total nitrogen (Total-N) and Nitrate Nitrogen (N-NO_3~-)). These results indicated that the wetland reclamation had significantly effects on soil nematode community structure and soil properties in this study
养分添加对三江平原沼泽化草甸植物群落组成和地上生物量的影响
No full text三江平原是人类农业开垦活动最为强烈的区域之一,农业施肥已经显著增加了该地区自然沼泽湿地氮和磷的输入量,这将会深刻影响到湿地生态系统的结构和功能。通过3年的氮和磷添加试验,研究了养分富集对三江平原沼泽化草甸植物群落物种组成、多样性和地上生物量的影响。结果表明:与对照相比,氮添加(N,6 g N·m~(-2)·a~(-1))显著增加了禾本科植物的优势度,降低莎草科植物的优势度,导致物种多样性下降,但提高了植物群落地上生物量;而磷添加(P,1.2 g P·m~(-2)·a~(-1))降低了禾本科植物的优势度,增加了莎草科植物的优势度,但对植物群落物种多样性和地上生物量均没有造成显著的影响;氮、磷同时添加(N+P)虽然对植物多样性和地上生物量的影响没有产生显著的交互作用,但增强了小叶章在群落中的优势地位,降低了植物群落的物种多样性,提高了植物地上生物量。本研究表明,在三江平原沼泽化草甸中,养分富集将显著改变植物群落组成和地上净初级生产力,而且氮素和磷素富集影响并不一致
青藏地区中草药浸提液诱导瓜列当和向日葵列当种子萌发的研究
No full text本试验采用甲醇和蒸馏水浸提法,从69种青藏地区传统中草药中筛选具有诱导瓜列当(Phelipanche Aegyptiaca Pers.)和向日葵列当(Orobanche Cumana Wallr.)种子萌发作用的植物,旨在通过寻找稳定的种子萌发刺激物质来为根寄生杂草列当防除提供依据。结果表明:1)供试材料中,16种中草药的甲醇或蒸馏水浸提液诱导瓜列当种子的萌发率≥20%,21种中草药的甲醇或蒸馏水浸提液诱导向日葵列当种子的萌发率≥20%;2)其中,黄花蒿、雪参、鸡血藤、青兰、甘松和独一味6种中草药诱导2种列当的发芽率均高于20%,表明上述中草药种含有较高活性或较高浓度的列当种子萌发诱导物质,上述6种中草药可作为列当诱捕作物或列当种子萌发刺激物的潜在供体而应用于列当的生物防除
1975~2014年巴尔喀什湖水体面积的变化
No full text以1975年、1980年和1985年的Landsat MSS影像、1990年、1995年、2000年和2010年的Landsat TM影像、2005年的Landsat ETM+影像、2014年的Landsat OLI影像为数据源,根据水体的光谱特征,利用波段比值法(绿波段/短波红外波段),进行水体信息提取,得到了9个时期的巴尔喀什湖水体面积及其变化趋势,并综合分析了其主要影响因素。研究结果表明,1975~2014年巴尔喀什湖面积呈波动减少,并与水位变化趋势基本一致;1975~1990年期间,巴尔喀什湖水体面积急剧减少,变化速率为-48.4 km~2/a,与水位降低了0.9 m;1990~2005年期间,巴尔喀什湖水体面积波动变化,但增加幅度很小,仅增加了0.36%;2005~2014年期间,巴尔喀什湖水体面积以每年10.1 km~2的速度缓慢减少,水位也发生小幅度下降。巴尔喀什湖水体面积不受同期年平均气温和年降水量的影响,其主要受水库调节入湖水量的影响
环境筛选和扩散限制在地表和地下螨群落物种共存中的调控作用
No full text识别扩散限制和环境筛选在群落物种共存中的相对作用,是土壤动物群落物种共存机制研究的重要内容,然而少有针对地表和地下土壤动物群落的探讨。在三江平原农田生态系统,设置一个50 m×50 m的空间尺度,探讨环境筛选和扩散限制对地表和地下土壤螨群落物种共存的调控作用。基于Moran 特征向量图(MEMs)和变差分解的方法来区分环境筛选和扩散限制的调控作用; 采用偏Mantel 检验进一步分析环境距离和空间距离的相对贡献; 使用RDA 分析环境因子对螨群落物种组成的解释能力。变差分解结果表明,空间变量对地表、地下和地表-地下土壤螨群落具有较大的显著方差解释量,而环境变量和空间环境结构的解释量相对较小且不显著; 偏Mantel 检验没有发现环境距离或空间距离的显著贡献; RDA 分析表明土壤pH 值、大豆株高和土壤含水量对土壤螨群落具有显著的解释能力,说明环境变量对螨群落物种组成的重要作用。研究表明,在三江平原农田生态系统,地表和地下土壤螨群落物种共存主要受到扩散限制的调控作用,同时环境筛选的调控作用也不容忽视
Altered amino acid profile of arbuscular mycorrhizal maize plants under low temperature stress
No full textWe investigated the effect of arbuscular mycorrhiza (AM) on amino acid concentration and composition of maize plants under low-temperature stress. The AM plants had higher amino acid concentrations than the non-AM pants. The concentrations of Thr, Lys, Gly, Ala, His, and Ile of the AM plants were higher than non-AM plants. The results show that low-temperature stress decreased the concentrations of amino acids and altered their composition
Functional conservation and diversification of the soybean maturity gene E1 and its homologs in legumes
No full textGene regulatory networks involved in flowering time and photoperiodic responses in legumes remain unknown. Although the major maturity gene E1 has been successfully deciphered in soybean, knowledge on the functional conservation of this gene is limited to a certain extent to E1 homologs in legumes. The ectopic expression of Phvul.009G204600 (PvE1L), an E1 homolog from common bean, delayed the onset of flowering in soybean. By contrast, the ectopic expression of Medtr2g058520 (MtE1L) from Medicago truncatula did not affect the flowering of soybean. Characterization of the late-flowering mte1l mutant indicated that MtE1L promoted flowering in Medicago truncatula. Moreover, all transgenic E1, PvE1L and MtE1L soybean lines exhibited phenotypic changes in terms of plant height. Transgenic E1 or PvE1L plants were taller than the wild-type, whereas transgenic MtE1L plants produced dwarf phenotype with few nodes and short internode. Thus, functional conservation and diversification of E1 family genes from legumes in the regulation of flowering and plant growth may be associated with lineage specification and genomic duplication
Long-term effect of residue return and fertilization on microbial biomass and community composition of a clay loam soil
No full textA field study was carried out to examine the response of microbial communities of a clay loam soil to long-term (30 years) effects of residue return and fertilization. The experimental design was a split-plot arrangement of treatments, consisting of three residue treatments (crop residues returned at rates of 0, 2500 and 5000 kg/ha) in combination with eight fertilization treatments (control, no fertilizer; N, mineral nitrogen (N) fertilizer; P, mineral phosphorus (P) fertilizer; K, mineral potassium (K) fertilizer; NP, mineral NP fertilizer; NK, mineral NK fertilizer; PK, mineral PK fertilizer; and NPK, mineral NPK fertilizer). Soil microbial communities were characterized by phospholipid fatty acid analysis. Results indicated that the more crop residues were returned, the lower ratio of fungi to bacteria was observed. However, soil microbial biomass was only found to be significantly higher in plots with residues returned at a rate of 5000 kg/ha but not 2500 kg/ha. This suggested there was a threshold for microbial biomass to increase under residue return for the clay loam soil studied. The fertilization effect on soil microbial biomass gradually decreased with increases in the amount of crop residues returned. A significant composition change was observed under N fertilization. Structural equation modelling indicated that soil microbial communities were influenced directly by residue return and indirectly by residue-induced change in ratio of carbon to N and fertilization-induced change in soil pH