不同气候年型下耕作覆盖对宁南旱区土壤水热及马铃薯产量的影响

为探讨宁夏南部地区不同气候年型下耕作结合覆盖措施对旱作农田土壤水分、温度和马铃薯产量形成的影响,于2014—2016年设置不同耕作(免耕、深松、翻耕)和覆盖(不覆盖、玉米秸秆、塑料地膜)双因素裂区定位试验。结果表明,地膜覆盖对0~25 cm土壤温度有增温效应,秸秆覆盖有降温效应;2014年(正常年)免耕秸秆覆盖降低马铃薯苗期至块茎膨大期土壤温度效果最佳,较翻耕不覆盖显著显著降低3.5℃。秸秆覆盖下0~200cm层土壤贮水量最高;深松、免耕土壤贮水量均高于翻耕;深松秸秆覆盖增加苗期至块茎膨大期土壤贮水量效果最佳,较翻耕不覆盖在正常年和高温年分别显著增加15.80%、20.77%。在正常年免耕地膜覆盖出苗率最高,较翻耕不覆盖显著增加24.12%;在高温年免耕秸秆覆盖出苗率最高,较翻耕不覆盖显著增加19.32%。将马铃薯地上部生物量进行Logistic生长模拟后发现,在正常年免耕秸秆覆盖快速生长持续期和干物质最大积累参数最高,干物质最大积累速率较翻耕不覆盖显著增加15.80%,在高温年深松秸秆覆盖快速生长持续期和干物质最大积累速率最高,干物质最大积累速率较翻耕不覆盖显著增加24.28%。所有处理中,在正常年免耕秸秆覆盖马铃薯产量最高,较翻耕不覆盖显著增加51.82%,在高温年深松秸秆覆盖产量最高,较翻耕不覆盖显著增加62.08%。正常年块茎形成期的土壤水分、温度对马铃薯产量形成的影响最大,而高温年现蕾期的土壤水分、温度对马铃薯产量形成的影响最大。可见,深松或免耕结合秸秆覆盖能改善宁南旱区土壤水热环境,促进马铃薯生长发育,进而实现作物显著增产。

深松覆盖模式对宁南地区雨养马铃薯水分利用效率的影响

针对宁南旱区年际降水变率大、马铃薯产量和降水利用率低等问题,连续3a秋作物收获后分别采用深松覆盖秸秆、深松覆盖地膜、深松不覆盖3种深松覆盖模式,以传统翻耕不覆盖为对照,研究不同深松覆盖模式对休闲期和生育期土壤水分、马铃薯干物质累积、产量和水分利用效率的影响。结果表明,深松覆盖模式可改善休闲期土壤水分状况,以深松覆秸秆处理效果最佳,0−200cm层平均土壤含水量较对照显著增加6.41%。与对照相比,深松覆秸秆和深松覆地膜处理下休闲期0−200cm层平均土壤蓄水量和降水补给率分别显著提高49.85%、121.85%和46.82%、83.73%。深松覆盖模式可改善马铃薯生育期0−200cm层土壤含水量,调控不同生育阶段耗水量。深松覆秸秆处理对生育前期(播种后0~60d)60−100cm层土壤保水效果显著,而对照处理该阶段耗水量最高,深松覆地膜处理次之,而深松覆秸秆处理最低;深松覆秸秆处理对生育中期(播种后60~120d)0−60cm(2016年)和140−200cm(2015年)层土壤保水效果较好,而深松覆地膜处理生育中期耗水量最高,深松覆秸秆处理次之,对照处理最低;深松覆秸秆处理对生育后期(播种后120~150d)0−40cm层土壤蓄水效果最佳,其阶段耗水量也最高,深松覆地膜处理次之,对照处理最低。深松覆盖模式下马铃薯地上部和地下部干物质累积量均显著高于对照,生育前期以深松覆地膜处理效果较好,而生育中后期以深松覆秸秆处理具有显著促进作用。深松覆盖模式能显著提高马铃薯产量和水分利用效率,以深松覆秸秆处理最高,平均分别较对照显著提高49.33%、43.80%。可见,休闲期深松覆盖可改善休闲期土壤水分状况,有利于提高生育期土壤水分含量,调控马铃薯阶段耗水量,从而增加马铃薯干物质累积,实现作物的高产和水分高效利用,以深松覆盖秸秆处理效果最佳。

A new gain-of-function OsGS2/GRF4 allele generated by CRISPR/Cas9 genome editing increases rice grain size and yield

Grain size is one of the most important factors affecting rice grain quality and yield,and attracts great attention from molecular biologists and breeders.In this study,we engineered a CRISPR/Cas9 system targeting the miR396 recognition site of the rice GS2 gene,which encodes growth-regulating factor 4(OsGRF4)and regulates multiple agronomic traits including grain size,grain quality,nitrogen use efficiency,abiotic stress response,and seed shattering.In contrast to most previous genome editing efforts in which indel mutations were chosen to obtain null mutants,a mutant named GS2^(E) carrying an in-frame 6-bp deletion and 1-bp substitution within the miR396-targeted sequence was identified.GS2^(E) plants showed increased expression of GS2 in consistent with impaired repression by miR396.As expected,the gain-of-function GS2^(E) mutant exhibited multiple beneficial traits including increased grain size and yield and bigger grain length/width ratio.Thousand grain weight and grain yield per plant of GS2^(E) plants were increased by 23.5%and 10.4%,respectively.These improved traits were passed to hybrids in a semidominant way,suggesting that the new GS2^(E) allele has great potential in rice improvement.Taken together,we report new GS2 germplasm and describe a novel gene-editing strategy that can be widely employed to improve grain size and yield in rice.This trait-improvement strategy could be applied to other genes containing miRNA target sites,in particular the conserved miR396-GRF/GIF module that governs plant growth,development and environmental response.

Seasonal dynamics and impact factors of urban forest CO2 concentration in Harbin,China

CO2 concentrations in different plant communities （larch, birch, lilac, and grassland） were measured during the growing season in the Heilongjiang Forest Botanical Garden to study diurnal variation, seasonal and annual dynamics and factors that impact CO2 concentration in different spaces. CO2 concentration in different communities in green lands had an obvious diurnal variation, chronically decreasing, and temperature influenced the lilac area and the grassland. Seasonally, CO2 was lowest in the larch green land （344.03 ±23.03 μmol/mol） and highest in the grassland （360.13 ± 22.43 μmol/mol）. The overall trend in CO2 concentration was autumn 〉 spring 〉 summer; temperature is the main factor controlling variation in CO2 concentrations during the growing season; the CO2 concentration at the larch, birch, lilac, and grassland types of sites was negatively correlated with land surface temperature and air temperature, and the CO2 concentration at the larch and birch sites was positively correlated with atmospheric pressure. Without any obvious annual change law, further study and observation are needed.

Short-term effects of fire disturbance on CH4 emission from forested wetlands in the Xiaoxing’an Mountains, Northeast China

Using static chamber gas chromatography, we determined the seasonal dynamics, controlling factors, and distribution patterns of forest swamp CH4 levels and related environmental factors (temperature, water level) after fire disturbance in the Xiaoxing’an Mountains. The results showed the following: during the growing season, the annual CH4 emission distribution ranged from - 0.001 ± 0.012 to 22.373 ± 3.650 mg m^-2 h^-1;mild fire caused the swamp CH4 emission flux of tussock, shrub, Alnus sibirica and birch swamp to increase by 56.0–524.7%;at low water levels, temperature had a significant influence on the swamp type, and the correlation between the methane emission flux and temperature was significantly strengthened;after a fire disturbance, methane emissions from all types of marsh were highest in summer and second highest in autumn, with a weak absorption in spring;and along the water environment gradient of the transition zone, the CH4 emission flux presented a decreasing trend in its spatial distribution pattern.

宁南旱区耕作覆盖对马铃薯产量及土壤水热特征的影响

为探究耕作覆盖对土壤水热及旱作马铃薯产量的影响,连续2年在宁南旱区不同耕作深度结合覆盖模式下开展了研究工作。结果表明:耕作深度、覆盖材料对马铃薯播种期0~100 cm土层土壤贮水量有极显著影响,而二者交互作用无显著影响;2019年土壤贮水量以深松30 cm覆盖地膜处理最高,2020年以深松40 cm覆盖秸秆处理较高,分别较翻耕15 cm不覆盖处理(对照)显著提高16.9%和33.4%;耕作深度、覆盖材料可显著影响马铃薯关键生育期土壤贮水量;同一耕作深度下土壤贮水量以秸秆、地膜覆盖处理效果较好,同一覆盖材料下以深松30~40 cm处理最佳。覆盖材料、耕作深度与覆盖材料二者交互作用对播种-现蕾期0~25 cm土层土壤有效积温影响显著;同一耕作深度下覆盖地膜处理土壤有效积温平均较不覆盖处理显著增加9.3%,而覆盖秸秆处理较不覆盖处理显著降低18.7%;2019和2020年各处理全生育期土壤有效积温分别以深松30 cm和深松40 cm覆盖地膜处理最高。2019年马铃薯总产量和经济效益以深松30 cm覆盖秸秆处理较高,分别较对照显著提高84.6%和107.9%;2020年以深松40 cm覆盖秸秆处理最佳,分别较对照显著提高81.7%和105.7%。耕作深度、覆盖材料对作物水热利用效率均有显著影响,水分利用效率以深松30~40 cm覆盖秸秆处理较高,而积温利用效率不同耕作深度结合秸秆覆盖各处理均较翻对照显著提高。相关分析表明,块茎形成期的土壤水分和有效积温对马铃薯总产量的形成至关重要,而全生育期土壤水分对总产量的影响高于土壤有效积温。可见,深松30~40 cm覆盖秸秆处理可改善土壤水热状况,实现马铃薯增产增收和水热资源的高效利用,在宁南半干旱区马铃薯生产中有一定的应用推广价值。

Understanding the role of tungsten on Pt/CeO_(2)for vinyl chloride catalytic combustion

Spherical CeO_(2)synthesized by the hydrothermal process was used as support to prepare Pt/WO_(3)/CeO_(2),and the effects of tungsten(W)contents on activity,stability and polychlorinated by-products were investigated to understand the role of W for vinyl chloride(VC)catalytic oxidation.The introduction of12 wt%W to Pt/CeO_(2)(P12 WC)exhibits the highest catalytic activity with 90%conversion of VC at 250℃,meanwhile the stability improves and the polychlorinated by-products in the tail gas significantly decrease due to the removal of dissociated Cl species in the formation of HCl.The beneficial effects of W on Pt/CeO_(2)are closely related to the chemical state of Pt,redox and surface acid sites distribution.The doped W not only makes Pt disperse evenly on the support with the high valence,but also weakens the interaction between Pt and CeO_(2)by the formation of Pt-O-W and Pt-O-W-O-Ce species,which facilitates oxygen mobility.In addition,the modification of W species also significantly increases the surface acidity amount and changes the distribution of acid sites.