基于检索1950-2016年发表在中国知网、Google Scholar、Web of Science等数据库的文章,筛选出关于我国退耕还草工程与土壤有机碳的文献123篇(126个研究地点)。基于筛选文献,提取了农田和恢复草地的土壤有机碳含量、土壤有效养分含量、...基于检索1950-2016年发表在中国知网、Google Scholar、Web of Science等数据库的文章,筛选出关于我国退耕还草工程与土壤有机碳的文献123篇(126个研究地点)。基于筛选文献,提取了农田和恢复草地的土壤有机碳含量、土壤有效养分含量、恢复时间和气候等数据735条,旨在探究我国退耕还草工程对土壤有机碳含量的影响及其主导因素。结果表明:1)农田恢复为草地后,土壤有机碳含量呈先下降后上升趋势(时间拐点约为第6年),整体上退耕还草工程使土壤有机碳含量提高了19.8%。2)土壤有机碳的正响应随土壤深度增加而减弱,且深度超过1 m时其正响应不明显。3)土壤有效氮是影响土壤有机碳恢复的主要因素,而土壤有效磷和植物功能群对其影响不大。4)沿着增加的水分梯度,土壤有机碳的恢复效果由负变正,转变阈值为25.15 (干旱指数)。总体而言,我国退耕还草工程对土壤有机碳含量的影响为正效应,此效应受环境梯度和恢复时间的共同影响。本研究能够为我国土地利用变化背景下土壤碳库管理的相关决策提供科学依据。展开更多
Salt and drought limit the range of applications of perennial ryegrass(Lolium perenne L.), which is one of the important turf and forage grasses. Previous studies have suggested that pyrroline-5-carboxylate reductase(...Salt and drought limit the range of applications of perennial ryegrass(Lolium perenne L.), which is one of the important turf and forage grasses. Previous studies have suggested that pyrroline-5-carboxylate reductase(P5CR) might play a central role in proline accumulation in plants that are responsive to stresses. In the present study, the Lolium perenne L. pyrroline-5-carboxylate reductase(LpP 5CR) gene was cloned from leaves of the cultivar ‘Derby' using the RACE technique. The full-length LpP 5CR gene was 1 047 bp in length, which comprised an open reading frame(ORF) of 840 bp in size. Sequence alignment revealed that the putative Lp P5 CR had a 94.3% similarity to Ta P5 CR. q RT-PCR displayed that the mR NA levels of the LpP 5CR gene were almost the same as that in the roots, stems, and leaves of perennial ryegrass seedlings subjected to normal condition or NaC l treatment for 1 h. Moreover, the transcription level of LpP 5CR was up- or down- regulated with Na Cl, polyethylene glycol(PEG), cold, or abscisic acid(ABA) treatment for 3 to 48 h. In addition, confocal microscopy localized the GFP-Lp P5 CR fusion protein to the cytoplasm of onion epidermal cells. These findings suggest that LpP 5CR encodes a cytoplasmic P5 CR protein that plays an important role in the response of perennial ryegrass to various stresses.展开更多
基金The National High Technology Research and Development Program of China(Grant No.2011AA100209)Jilin Provincial Department of Education(Grant No.2013-23)supported this study
文摘Salt and drought limit the range of applications of perennial ryegrass(Lolium perenne L.), which is one of the important turf and forage grasses. Previous studies have suggested that pyrroline-5-carboxylate reductase(P5CR) might play a central role in proline accumulation in plants that are responsive to stresses. In the present study, the Lolium perenne L. pyrroline-5-carboxylate reductase(LpP 5CR) gene was cloned from leaves of the cultivar ‘Derby' using the RACE technique. The full-length LpP 5CR gene was 1 047 bp in length, which comprised an open reading frame(ORF) of 840 bp in size. Sequence alignment revealed that the putative Lp P5 CR had a 94.3% similarity to Ta P5 CR. q RT-PCR displayed that the mR NA levels of the LpP 5CR gene were almost the same as that in the roots, stems, and leaves of perennial ryegrass seedlings subjected to normal condition or NaC l treatment for 1 h. Moreover, the transcription level of LpP 5CR was up- or down- regulated with Na Cl, polyethylene glycol(PEG), cold, or abscisic acid(ABA) treatment for 3 to 48 h. In addition, confocal microscopy localized the GFP-Lp P5 CR fusion protein to the cytoplasm of onion epidermal cells. These findings suggest that LpP 5CR encodes a cytoplasmic P5 CR protein that plays an important role in the response of perennial ryegrass to various stresses.
