秸秆全量还田下晚稻季翻耕对双季稻田温室气体排放和产量的影响

翻耕有利于秸秆还田,为了探究秸秆全量还田下不同耕作措施对双季稻产量和温室气化排放的影响,在晚稻季设置浅旋耕和翻耕2个处理,采用静态暗箱–气相色谱法连续监测当季晚稻和第2年早稻季稻田温室气体排放,以阐明秸秆全量还田下晚稻季翻耕对稻田甲烷（CH₄）和氧化亚氮（N₂O）排放及产量的影响。与浅旋耕处理相比,晚稻季翻耕显著降低了当季晚稻CH₄累积排放量（19.04%）、综合温室效应（19.19%）和温室气体排放强度（22.02%）,而对N₂O累积排放量无显著影响。晚稻季翻耕对第2年早稻季稻田温室气体排放无显著影响。可见,翻耕的减排效应只体现在当季。此外,浅旋耕和翻耕处理对当季晚稻和第2年早稻产量及其构成均无显著影响。短期来看,秸秆全量还田下晚稻季翻耕有利于协同实现双季稻稳产和稻田温室气体减排。     

双季稻区不同土壤耕作模式对水稻干物质积累及产量的影响

为探明双季稻区不同土壤耕作模式下双季水稻干物质积累及产量的变化,以紫云英-双季稻大田定位试验为平台(设双季水稻翻耕+秸秆还田(CT)、双季水稻旋耕+秸秆还田(RT)、双季水稻免耕+秸秆还田(NT)、双季水稻旋耕+秸秆不还田(RTO,对照)4种土壤耕作处理),于2016-2017年取样,应用常规试验方法系统分析了不同处理条件下早稻和晚稻干物质积累及产量的变化。结果表明,早稻和晚稻各个主要生育期,各处理水稻LAI大小顺序均表现为CTRTNTRTO。早稻和晚稻各个主要生育期,水稻植株的群体根系和地上部总干质量及茎、叶、穗群体干质量均表现为CTRTNTRTO。早稻和晚稻齐穗期和成熟期,根系干质量占总干质量的比例均表现为CTRTNTRTO;齐穗期和成熟期,茎的比例均以RTO处理最高;苗期和分蘖期,叶比例均以NT和RTO处理最大,CT处理最小;早稻和晚稻的成熟期,穗的比例分别以RT和NT处理最大。不同处理早稻和晚稻产量大小顺序均表现为CTRTNTRTO,2个不同年份CT、RT和NT处理早稻产量分别比RTO处理增加733.3,534.1,300.5 kg/hm~2和731.1,556.9,276.2 kg/hm~2;晚稻产量分别比RTO处理增加582.5,399.8,282.9 kg/hm~2和717.6,558.9,345.1 kg/hm~2。总的来说,土壤翻耕和旋耕结合秸秆还田的综合措施水稻干物质总量大而且分配合理,有利于改善产量构成因素,增加水稻产量。     

绿肥轮作对早稻生长动态及氮素吸收利用的影响

综合评价南方稻区不同冬季绿肥种植下水稻对氮素的吸收利用特性,为水稻高产栽培中氮肥的合理运筹和水稻氮素营养性状改良提供依据。比较不同冬季绿肥紫云英、油菜、黑麦草及混播绿肥对后作水稻产量、生长动态及氮素吸收利用的变化。结果表明：（1）处理紫云英—早稻—晚稻(MV-R-R)的早稻产量分别比黑麦草—早稻—晚稻(RG-R-R)、油菜—早稻—晚稻(RP-R-R)、混播绿肥—早稻—晚稻(MS-R-R)高6.61%、3.29%及0.78%。（2）在分蘖期、孕穗期、抽穗期和成熟期植株含氮率均是处理MV-RR达到最大,较其他处理平均分别高9.68%、19.72%、6.23%和8.66%。在分蘖期、孕穗期、抽穗期和成熟期植株吸氮量均是处理MV-R-R最高,处理RP-R-R最低。（3）处理MV-R-R在分蘖期至孕穗期、孕穗期至抽穗期及抽穗期至成熟期各处理的吸收量较其他处理平均分别高出21.81%、68.73%和286.5%,且绿肥轮作条件下水稻氮素阶段吸收量及其占总吸收量的比例均以抽穗至成熟期最小,最大值所处的生育阶段则是分蘖前。因此,MV-R-R处理具有较高的增产潜力,有利于提高氮肥利用效率,改善稻田氮素循环。     

双季稻区冬季覆盖作物残茬还田对稻田甲烷和氧化亚氮排放的影响

研究冬季不同覆盖作物还田后稻田的甲烷(CH₄)和氧化亚氮(N₂O)排放特征,对合理利用冬闲稻田,发展冬季覆盖作物,以及科学评价不同种植模式具有重要意义。本研究采用静态箱-气相色谱法,对冬季不同覆盖作物处理(免耕直播黑麦草-双季稻、免耕直播紫云英-双季稻、翻耕移栽油菜-双季稻、翻耕稻草覆盖马铃薯-双季稻和冬闲-双季稻)的稻田进行监测,以分析不同覆盖作物残茬还田对稻田CH₄和N₂O排放的影响。结果表明,冬季覆盖作物还田后,各处理早、晚稻田CH₄排放量均明显高于冬闲-双季稻(对照)。早稻田CH₄排放量最高的为翻耕稻草覆盖马铃薯-双季稻和免耕直播黑麦草-双季稻,分别达20.713 g m^-2和16.068 g m^-2;晚稻田CH₄排放量最高的为翻耕稻草覆盖马铃薯-双季稻和翻耕移栽油菜-双季稻,分别为60.421 g m^-2和48.666 g m^-2。各处理早、晚稻田N₂O总排放量均显著高于冬闲-双季稻,免耕直播黑麦草-双季稻、免耕直播紫云英-双季稻、翻耕移栽油菜-双季稻和翻耕稻草覆盖马铃薯-双季稻处理的早稻田N₂O总排放量分别比对照增加265.00%、320.00%、275.00%和65.00%,晚稻田分别比对照增加157.89%、113.16%、134.21%和42.11%。稻田CH₄和N₂O综合温室效应总和表现为翻耕稻草覆盖马铃薯-双季稻>翻耕移栽油菜-双季稻>免耕直播黑麦草-双季稻>免耕直播紫云英-双季稻>冬闲-双季稻,冬季覆盖作物还田明显提高稻田CH₄和N₂O排放。     

不同混作方式绿肥替代部分基施化学氮肥对双季稻产量形成特性的影响

为探索化学氮肥减量配施条件下双季稻田较优的绿肥混作方式,以早稻品种中早39和晚稻品种泰优390为材料,于2016-2017年采用定位试验研究了不同绿肥混作方式(紫云英单作,AS;紫云英与满园花混作,AR;紫云英与黑麦草混作,AL;紫云英与满园花与黑麦草混作,ARL;冬闲处理,CK)与氮肥减量配施对双季早、晚稻产量形成特性的影响。结果表明:各绿肥还田处理绿肥替代化肥氮比例,2016年为28. 98%～39. 68%,2017年为30. 55%～39. 47%,以AS处理较大,AL处理最低。绿肥替代部分基施化肥对水稻分蘖动态无显著影响,但各绿肥还田处理均有较好的增产效果,不同模式间差异明显,2016年早、晚稻均以AS处理增产效果最好(分别较CK增产7. 3%和8. 5%),其次是AR处理(分别较CK增产6. 0%和7. 1%); 2017年早、晚稻均以AR处理增产效果最好(分别较CK增产7. 2%和5. 5%),其次是AS处理(分别较CK增产5. 5%和4. 7%)。绿肥替代部分基施化肥有利于提高水稻灌浆期叶面积指数、叶片SPAD值与干物质积累量,进而提高有效穗数和结实率;各处理在年际间有一定差异,但一般以AS和AR处理表现较好。可见,绿肥替代部分基施化学氮肥有利于提高双季稻产量,且以紫云英单作和紫云英+满园花混作效果较好。     

紫云英协同秸秆还田下氮钾减施对双季稻产量及光合特性的影响

为探究化肥氮钾减施配合紫云英秸秆还田对双季稻产量与光合特性的影响。通过田间小区试验,以常规化肥处理(100%化肥)为对照,研究紫云英协同晚稻秸秆还田下早稻减施20%,30%,40%化肥氮和同时减施40%化肥钾对双季稻产量、幼穗分化期倒三叶叶片净光合速率(Pn)、气孔导度(Gs)、胞间CO_2浓度(Ci)、蒸腾速率(Tr)、叶绿素含量(SPAD)及早晚稻收获期土壤理化性质的影响。结果表明:不同氮肥减施比例下紫云英协同晚稻秸秆还田均能增强水稻光合作用,提高土壤肥力,增加水稻年产量,且以减施30%化肥氮、40%化肥钾处理(T4)效果较好。与常规施肥处理相比,T4的水稻年产量增加4.5%,早稻稻谷增产6.8%,倒三叶叶片Pn、Gs、Tr和SPAD值分别降低7.8%,23.9%,21.0%,9.5%,Ci提高19.5%;其晚稻稻谷增产2.0%,倒三叶叶片Pn、Gs、Tr和SPAD值分别提高27.0%,55.3%,14.8%,13.4%,Ci降低1.6%;早晚稻收获期土壤碱解氮、有效磷、速效钾和有机质含量均有提高。研究结果,对指导双季稻田紫云英协同晚稻秸秆还田下化肥氮钾减施、水稻增产和地力提升有重要意义。     

施石灰和秸秆还田对清洁的酸性稻田籽粒镉含量的影响

为了探究清洁的酸性稻田施用石灰对双季稻籽粒镉(Cd)含量的影响,本研究在清洁的酸性稻田(土壤pH 5.2,土壤总Cd含量0.2 mg/kg)上开展田间定位试验,并测定籽粒镉含量,设置4个处理,分别是(1)对照,不施石灰,秸秆不还田;(2)施石灰,秸秆不还田;(3)每季秸秆全量还田,不施石灰;(4)秸秆还田配施石灰。结果表明:除2020年晚稻季外,施石灰显著降低了早、晚稻糙米Cd含量,秸秆还田对糙米Cd含量无显著影响。二者仅对2020年早稻糙米Cd含量有显著互作效应。在秸秆还田条件下,施石灰使2020年早稻糙米Cd含量降低61.0%;在秸秆不还田条件下,降幅为38.0%。施石灰显著降低了2019年早、晚稻精米Cd含量。秸秆还田仅显著增加了2020年晚稻精米Cd含量。二者对2020年晚稻精米Cd含量有显著互作效应。在秸秆还田条件下,施石灰使2020年晚稻季精米Cd含量降低38.1%;而在秸秆不还田条件下,降幅为4.2%。因此,在清洁的酸化红壤性双季稻田上,施石灰不仅可以有效减少稻米的Cd含量,而且能够降低秸秆还田导致的Cd污染风险,有利于保障稻米质量安全。     

周年秸秆还田量对南方双季稻生长及产量的影响

为探究适合南方双季稻高产稳产的秸秆还田量,连续2年(2016—2017)通过大田试验研究不同秸秆还田量对早稻和晚稻分蘖、株高、干物质积累量及产量构成的影响。试验设置5个不同比例秸秆还田量：CK：秸秆不还田;S1：25%早、晚稻秸秆量还田;S2：50%早、晚稻秸秆量还田;S3：75%早、晚稻秸秆量还田;S4：100%早、晚稻秸秆量还田。结果表明：全量秸秆还田抑制早稻分蘖而显著促进晚稻分蘖,25%、50%及75%量还田对早、晚稻生长前期的分蘖促进效果不显著,在中后期促进作用显现;75%量还田及全量还田较CK显著促进晚稻株高增长,平均提高了8.15 cm;不同秸秆还田量较不还田处理均提高了早、晚稻成熟期的干物质累积量,且半量还田在早稻季差异达显著性水平(P<0.05),较CK提高了8.0%,50%、75%及100%量还田在晚稻季差异达显著性水平,平均提高了13.3%,但不同还田量之间差异不显著(P>0.05);早、晚稻产量在不同秸秆还田量下均高于秸秆不还田,半量还田促进早稻产量方面的效果最显著,与不还田处理相比差异达显著水平(P<0.05),增产6.92%;50%、75%及100%量还田较CK均显著提高了晚稻产量(P<0.05),增产幅度分别5.33%、7.50%和8.23%,不同秸秆还田量间在促进早、晚稻增产方面的效果差异不显著(P<0.05)。研究结果显示,短期看,在南方双季稻生产中,半量早稻和晚稻秸秆均还田对提高早稻产量效果最优,而全量还田对晚稻最优,而秸秆还田对水稻产量的长期效应如何,还需要进行长期定位试验研究。     

紫云英翻压量对豫南地区单季稻养分吸收和水稻产量的影响

依托长期种植翻压紫云英定位试验，探讨豫南稻田在翻压紫云英作绿肥的情况下对后茬作物水稻养分吸收、养分利用效率及产量等方面的影响，并由此确定紫云英鲜草的最佳翻压量。试验设置CK(不施肥)、CF(常规施化肥)以及紫云英鲜草翻压量分别为22.5,30.0,37.5,45.0,52.5,60.0 t/hm²,共8个处理。结果表明，与CK相比，常规施化肥和翻压紫云英处理分别增加稻谷产量21.72%和19.23%～29.20%(P<0.05)。在所有紫云英翻压处理中，紫云英翻压量为52.5 t/hm²时，稻谷氮、磷、钾含量和养分吸收量最高，但继续增加翻压量，稻谷养分含量和养分吸收量显著降低(P<0.05)。紫云英翻压量为37.5～60.0 t/hm²时，水稻地上部氮磷钾素累积量显著高于CK(P<0.05)。与CF相比，紫云英翻压22.5～37.5 t/hm²显著提高水稻磷、钾素养分利用效率及磷、钾素偏生产力(P<0.05)。因此，在豫南地区，长期紫云英翻压22.5～37.5 t/hm     

红壤稻田不同轮作方式对水稻生长发育的影响

17年34季水稻不同轮作方式的长期定位试验，研究禾本科、豆科、十字花科绿肥翻压还田对水稻生长发育的影响，结果证明：1．绿肥处理能提高水稻产量。双季稻总产平均为10423.kg/hm2，比双季稻冬闲处理增产2383.5kg/hm2，增幅30.0％。2．油菜处理能促进水稻提早成熟。生育期比双季稻绿肥处理提前36d。而且水稻空秕率低，早稻比双季稻冬闲处理低14.6％。     

长期施肥条件下我国南方双季稻产量的变化趋势

系统分析我国南方双季典型稻区福建省白沙、江西省进贤、江西省南昌及湖南省望城4个水稻长期施肥试验资料,研究化肥N、P、K (氮、磷、钾)的不同组合(NP, NK, NPK)、化肥配施有机肥(NPKM)及不施肥(CK)各处理水稻的产量差异、变化趋势。结果显示,不同施肥条件下各试验点上水稻产量差异大,试验期内各施肥处理较CK的总增产率分别为NPKM 84.3%、NPK 68.1%、NP 42.9%和NK 39.9%,其中NPKM总体上显著高于NPK。长期配施NPK或NPKM肥产量较稳定或呈上升趋势,尤其是晚稻,而仅施NK均呈下降或极显著下降趋势(周年变化幅度为-103~ -201 kg hm^-2 yr^-1),其他施肥处理晚稻产量相对稳定。不同试验点间施磷量较高(52 kg hm^-2 yr^-1)的南昌点产量相对稳定,而施磷量较低(24 kg hm^-2 yr^-1)的白沙点各处理均呈显著下降趋势。本试验条件下,施肥投入不足又特别是施磷肥量低或不施磷为早稻产量下降的主要驱动因素。合理施用NPK肥,配合有机肥,为推荐的施肥模式,为了使试验点双季稻产量稳定且不呈下降趋势,需年施纯磷50.0~63.9 kg hm^-2, 且适当偏重于早稻季。     

不同生育期脱水对稻米镉含量的影响

为进一步探究水分管理对稻米镉含量的影响,以6 个早稻品种、4 个晚稻品种为研究材料,通过盆栽试验研究了不同生育期脱水（分蘖期脱水,T1;孕穗期脱水,T2;抽穗期脱水,T3;乳熟期脱水,T4;蜡熟期脱水,T5;全生育期淹水,CK）对稻米镉含量的影响。结果表明：脱水处理、品种及二者交互效应对稻米镉含量的影响均达到极显著水平(P＜0.01),不同处理间精米镉含量的大小顺序为T3＞T1＞T2＞T4＞T5＞CK,W2（‘C两优7 号’）、W12（‘湘晚籼13 号’）、W8（‘金优59’）3 个品种的耐镉特性及稳定性较好,适合一般污染区大面积种植。精米镉含量在水稻品种类型之间存在极显著差异(P＜0.01),其含量由高到低为超级杂交稻、常规稻、杂交稻;生育类型不存在主效应。     

冬种黑麦草对6种稻田土壤微生物量碳、氮的影响

利用氯仿熏蒸浸提法研究了南方双季稻区6种母质发育的土壤种植黑麦草(Lolium multiflroum Lam.)作为冬季覆盖作物对土壤微生物量碳、氮周年动态的影响。结果表明：土壤类型对微生物量碳、氮影响显著（P＜0.05)。其中板页岩土壤微生物量碳含量最高,为450.8mg kg-1;河沙泥微生物量最低,为60.8 mg kg-1,由大到小排列为：板页岩＞紫土＞花岗岩＞红壤＞石灰岩＞河沙泥。不同取样时期内土壤微生物性状有显著差异（P＜0.05),种植黑麦草各处理比对照（冬闲）显著提高了土壤有机质含量和微生物量碳、氮。所有处理表现出相似的微生物量周年变化趋势：水稻成熟期高于分蘖期（P＜0.05),晚稻生长季节大于早稻季节。土壤微生物量受土壤类型、土壤营养元素含量和种植制度的综合影响,微生物活动与作物生长有关。冬季种植黑麦草可显著提高土壤有机质含量和微生物量（P＜0.05),在有机质分解快、有效养分含量低的土壤中效果更显著。     

Rice reproductive growth duration increased despite of negative impacts of climate warming across China during 1981–2009

Changes in rice phenology during 1981–2009 were investigated using observed phenological data from hundreds of agro-meteorological stations across China. Spatiotemporal changes of rice phenology across China, as well as the relations to temperature, day length and cultivars shifts were analyzed and presented. We found that major rice phenological dates generally advanced while rice growing period changed diversely for different rice cultivation systems in different agro-ecological zones. Length of vegetative growth period (VGP) increased at 59 (67.0%) stations for single-rice, however, decreased at 36 (54.5%) and 35 (51.5%) stations for early-rice, and late-rice, respectively. Length of reproductive growth period (RGP) increased at 71 (70.3%) and 49 (55.7%) stations for single-rice and early-rice, respectively, however, decreased at 46 (54.8%) stations for late-rice. The changes were ascribed to the combined effects of changes in temperature, photoperiod and cultivar thermal characteristics. Increase in temperature had negative impacts on the lengths of VGP and RGP. Day length slightly counterbalanced the roles of temperature in affecting the duration of VGP. Furthermore, we found that during 1981–2009 cultivars with longer growth duration of VGP were adopted for single-rice, but cultivars with shorter growth duration of VGP were adopted for early-rice and late-rice. Cultivars with longer growth durations of RGP were adopted for single-rice and early-rice, as well as late-rice at the middle and lower reaches of Yangtze River. However, in the southwestern China and southern China, cultivars with shorter or almost same growth duration of RGP were adopted for late rice.     

纳帕海沼泽化草甸不同季节土壤真菌群落结构与理化性质的关系

为阐明纳帕海湿地沼泽化草甸土壤真菌群落结构的季节变化规律及其与理化性质的关系,采用稀释培养结合形态鉴定比较,分析旱季和雨季土壤真菌群落结构的季节变化,并探讨其与土壤理化性质的相互关系。结果表明：（1）土壤有机质、全氮、速效氮、速效钾和速效磷在0~20 cm土层为雨季>旱季;20~40 cm土层除全氮外,为旱季>雨季。土壤容重和自然含水率在0~20 cm土层和20~40 cm土层为雨季>旱季。（2）旱季和雨季土壤真菌多样性均具有明显季节变化,0~20 cm土层除均匀度指数JSW外,真菌数量、多样性指数H'和丰富度指数DMA为旱季>雨季。20~40 cm土层,多样性指数H'和丰富度指数DMA为旱季>雨季,真菌数量和均匀度指数JSW为雨季>旱季。（3）经形态鉴定,旱季和雨季分别分离到12 属和11 属真菌,群落结构组成相似性极高,但也表现出一定差异性。曲霉属和腐霉属同为旱季和雨季沼泽化草甸的优势类群;枝孢菌属和壳囊孢属是旱季特有属,链孢菌属是雨季特有属。（4）经Pearson 相关性分析：在旱季和雨季,土壤有机质、全氮、速效氮、速效钾、速效磷、容重和自然含水率与土壤真菌群落结构组成相关性大。不同季节土壤真菌多样性和群落组成有明显的季节变化特征,土壤理化性质与真菌群落结构组成密切相关,为研究真菌群落对纳帕海湿地生态系统的影响提供参考依据。     

Root and Shoot Growth of Maize (Zea mays) as Affected by Incorporation of Crotalaria juncea and Tithonia diversifolia as Green Manures

Crop establishment, determined by shoot and root growth during early growth is a vital component in procuring desired plant populations and high yields in rainfed tropical smallholder farming systems, where green manures help maintain soil fertility and sustainability. As green manure incorporation could affect early seedling growth, studies were conduced in a plant house using soils from fields, to evaluate the impact of incorporating two popular tropical green manures (Crotalaria juncea and Tithonia diversifolia) into soil under rainfed field conditions over 3 years, on selected physico‐chemical properties of the soils and on establishment and early shoot and root growth of maize (Zea mays), with and without inorganic fertilizers. In a given year, green manure was grown in one season while maize was grown in the other. A soil that did not receive green manures but was left fallow during the period of green manure cultivation was used as the control treatment. The incorporation of green manures over the 3 years showed trends of increasing soil physical properties, and also the available nitrogen, phosphorus and potassium contents. Incorporation of Crotalaria, with its higher nitrogen content, promoted shoot growth, while Tithonia induced the development of an extended root system. The use of inorganic fertilizers stimulated the beneficial impact of the green manures in promoting shoot and root growth. The use of green manures, especially Tithonia, promoted the development of seminal and nodal roots of maize seedlings, both in the form of length and thickness (based on root surface area) and root length densities, which could assist in successful crop establishment and resource utilization, rather than primary roots. The benefits of using green manures, especially Tithonia, in promoting root growth and Crotalaria in shoot development of maize seedlings even without inorganic fertilizers is presented.     

Effects of green manure herbage management and its digestate from biogas production on barley yield,N recovery,soil structure and earthworm populations

In repeatedly mown and mulched green manure leys, the mulched herbage contains substantial amounts of nitrogen (N), which may only slightly contribute to the following crops’ nutrient demand. The objective of the present work was to evaluate the effect of alternative strategies for green manure management on the yield and N recovery of a subsequent spring barley crop, and their short term effects on soil structure and earthworm populations. A field trial was run from 2008 to 2011 at four sites with contrasting soils under cold climate conditions. We compared several options for on-site herbage management and the application of anaerobically digested green manure herbage. Depending on the site, removal of green manure herbage reduced the barley grain yield by 0% to 33% compared to leaving it on-site. Applying digestate, containing 45% of the N in harvested herbage, as fertilizer for barley gave the same yields as when all herbage was mulched the preceding season. Overall, the apparent N recovery was enhanced from 7% when all herbage was mulched, to 16% when returned as digestate. A positive effect on earthworm density and biomass was seen after one season of retaining mulch material, rather than removing it. Digestate did not affect the earthworm population, but contributed to higher soil aggregate stability. In conclusion, for spring barley production after green manure ley, the digestate strategy increased N recovery and reduced the risk of N losses. The yield of the succeeding barley crop yield was reduced when N in herbage was not returned as mulch or digestate.     

微生物菌肥作用下荒漠土壤微生物群落结构和功能研究

为了探究施用微滴灌生物菌肥后对土壤的影响,笔者以经过微滴灌菌肥处理、种植棉花的荒漠土壤为研究对象,采用常规的稀释平板法和Biolog-Eco微平板反应系统研究了4种不同浓度的微生物菌剂(A、R、G、K)对荒漠土壤微生物群落结构及功能多样性的影响。结果表明,各处理组的土壤中的微生物数量关系为：细菌＞真菌＞放线菌;相比对照组,处理组AWCD提高了3.7%~25.6%,并且AWCD、Shannon指数(H’)、Simpson指数(D)与有机质、全氮、可溶性磷、全钾等的含量呈现显著的正相关;不同种类的微生物菌肥影响了不同土壤中微生物群落间的代谢特征,通过主成分分析表明碳水化合物类碳源是这种变化重要指示指标。本试验结果可为微滴灌微生物肥料的使用效果以及荒漠土壤微生物群落结构评价提供一定的参考。     

元阳梯田核心区周边森林群落植物多样性研究

为了了解元阳梯田核心区周边植被群落物种、结构特征及多样性,揭示元阳梯田核心区周边森林群落结构及多样性特征,为元阳梯田核心区周边森林群落进行合理保护和利用提供依据,笔者通过样方法对元阳梯田核心区周边森林群落进行野外调查,利用物种丰富度指数、Shannon-Wiener指数、Simpson指数、Pielon均匀度指数、生态优势度等多样性指数,对森林群落植物多样性进行研究。结果表明：（1）草本层植物种类91种,灌木层67种、乔木层42种。草本层多样性最大,其Shannon-Wiener指数和Simpson指数分别为0.82、0.98、均匀度指数为0.18;灌木层多样性最小,Shannon-Wiener指数和Simpson指数分别为0.32、0.87、均匀度指数为0.08;（2）14个群落中,鸭公树-木荷群落多样性最大,其Shannon-Wiener指数和Simpson指数分别为1.38、0.92,均匀度指数为0.36;云南松群落多样性最小,Shannon-Wiener指数和Simpson指数分别为0.42、0.37,均匀度指数为0.16。不同群落类型间的多样性大小次序为：阔叶林群落>人工林群落>草地群落>针叶林群落;（3）多样性指数随海拔梯度变化,呈先增大后减小的变化趋势,其最大值出现在1850 m,体现了“中度膨胀“的垂直分布格局。     

Yield variation of double-rice in response to climate change in Southern China

Food security is a major concern in China due to increasing nutritional demands, limited resources, and a changing and uncertain climate. Rice (Oryza sativa L.) plays an important role in food security, whilst its yield is greatly influenced by climate change. Thus, it is critical to quantify changes in rice yield, determine the potential climatic conditions affecting yield variation, and identify strategies to counter the effects of climate change. Historical double-rice yields and climatic variables were analyzed in the major double-rice region of Southern China. Yield varied nonlinearly in most provinces, fluctuated more for late-rice, and exhibited stagnation in 1980–2012. During the growth stages, the mean temperature (T_mean) increased significantly at 75.1% of the stations examined (P < 0.05), while high inter-annual variation in precipitation (Prec) and radiation (Rad) decreased for 64.2% and 62.2% of stations. The joint effects of the three climatic variables increased yields of early- and late- rice by 0.51% and 2.83%, respectively. Climatic variation accounted for 40.04% and 29.72% of yield variability for early- and late-rice, respectively. Thus, double-rice production in Southern China is strongly affected by inter-annual climatic variation, requiring resilient farming practices to adapt to climate change and consequently enhance food security.