秸秆还田配施氮肥对东北春玉米光合性能和产量的影响

秸秆还田配施氮肥是解决旱作农田"耕层变浅"、"土壤紧实"、"有效耕层土壤减少"问题的重要措施之一,在旱作农业生产中具有重要意义。为探明秸秆深翻还田配施氮肥对东北春玉米光合性能和产量的影响,本研究于2014—2015年在辽宁铁岭设置S0F0(秸秆0 kg hm~(–2)+纯NPK 0 kg hm~(–2))、SN0(秸秆9000 kg hm~(–2)+纯N 0 kg hm~(–2)+纯P 112.5 kg hm~(–2)+纯K 90 kg hm~(–2))、SN1(秸秆9000 kg hm~(–2)+纯N 112.5 kg hm~(–2)+纯P 112.5 kg hm~(–2)+纯K 90 kg hm~(–2))、S0N2(秸秆0 kg hm~(–2)+纯N 225 kg hm~(–2)+纯P 112.5 kg hm~(–2)+纯K 90 kg hm~(–2),当地传统种植方式,CK)、SN2(秸秆9000kg hm~(–2)+纯N 225 kg hm~(–2)+纯P 112.5 kg hm~(–2)+纯K 90 kg hm~(–2))、SN3(秸秆9000 kg hm~(–2)+纯N 337.5 kg hm~(–2)+纯P 112.5kg hm~(–2)+纯K 90 kg hm~(–2))6个处理开展了研究。结果表明,秸秆还田配施氮肥对春玉米籽粒产量和生物产量影响显著,秸秆还田9000 kg hm~(–2)和配施氮肥225 kg hm~(–2)处理的籽粒产量最高,比秸秆不还田和施氮量225 kg hm~(–2)处理(CK)2年平均增产6.33%,增产的主要原因是百粒重和行粒数的显著提高和秃尖的显著降低;玉米籽粒产量并未随着施氮量的增加而持续增加;相同施氮量条件下,秸秆还田比秸秆不还田2年平均群体生物产量增加2.95%。秸秆还田配施氮肥能够增加春玉米株高、茎粗、叶面积,提高叶绿素含量和光合作用,相同施氮量条件下,秸秆还田比秸秆不还田处理2年平均灌浆期叶面积增加2.71%,光合速率提高4.80%。综合分析认为,秸秆还田9000 kg hm~(–2)和配施氮肥225kg hm~(–2)是辽北棕壤区春玉米生产比较理想的还田和施肥模式,在该区域农业发展中具有一定的应用价值。     

秸秆还田配施氮肥对春玉米水氮利用效率的影响

为了探明秸秆还田配施氮肥对春玉米水氮利用效率的影响,2014-2015年在辽宁铁岭设置了秸秆0.0 kg/hm~2+纯NPK 0.0 kg/hm~2(S0F0)、秸秆9 000 kg/hm~2+纯N 0.0 kg/hm~2+纯P 112.5 kg/hm~2+纯K 90.0kg/hm~2(SN0)、秸秆9 000 kg/hm~2+纯N 112.5 kg/hm~2+纯P 112.5 kg/hm~2+纯K 90.0 kg/hm~2(SN1),秸秆0.0 kg/hm~2+纯N 225.0 kg/hm~2+纯P 112.5 kg/hm~2+纯K 90.0 kg/hm~2(S0N2)(CK),秸秆9 000 kg/hm~2+纯N225.0 kg/hm~2+纯P 112.5 kg/hm~2+纯K 90.0 kg/hm~2(SN2),秸秆9 000 kg/hm~2+纯N 337.5 kg/hm~2+纯P 112.5kg/hm~2+纯K 90.0 kg/hm~2(SN3)6个处理开展了研究。结果表明,秸秆还田配施氮肥对春玉米产量、氮肥农学利用率影响明显。全量还田9 000 kg/hm~2和配施氮肥225.0 kg/hm~2产量最高,相同施氮条件下,2年秸秆还田比秸秆不还田增产1.10%~11.56%,增加的主要原因是百粒质量和行粒数的显著提高和秃尖的显著降低,但产量并未随着施氮量的增加而持续增加;秸秆还田配施氮肥春玉米干物质最大生长速率(Cm)和干物质最大积累量(Wm)均随着施氮量的增加而增加,秸秆未还田和不施氮肥春玉米干物质最大生长速率时间(tm)出现延后,这在一定程度上导致了干物质积累量的减少;秸秆还田配施氮肥对土壤水库起到了扩蓄增容作用,提高春玉米水分利用效率,相同施氮量条件下,秸秆还田比秸秆不还田有一定程度的提高,但并未达到显著差异(P0.05);秸秆还田配施氮肥能够提高氮肥农学利用率,提高土壤有机质含量,但速效养分增加并不明显。秸秆还田量9 000 kg/hm~2和配施氮肥225.0 kg/hm~2是辽北棕壤区比较理想的还田方式,在该区域农业发展中具有一定的应用价值。     

灌水量对北疆棉花增效缩节胺化学封顶效应的影响

【目的】在不同灌水量条件下研究增效缩节胺(1,1-dimethyl-piperidinium chloride,缓释型水乳剂,简称DPC+)对棉花化学封顶的效应,为完善新疆棉花化学封顶技术提供依据。【方法】以早熟陆地棉品种新陆早53号为材料,设置不同的灌水量(3000,4800,6600 m3·hm~(-2))和DPC+剂量(450,750,1050 m L·hm~(-2)),测定棉花农艺性状、生理特性及产量和品质等指标。【结果】棉花株高和单株果枝数随DPC+剂量的增加而下降,低(450m L·hm~(-2))、中(750 m L·hm~(-2))、高剂量(1050 m L·hm~(-2))DPC+处理的株高和单株果枝分别比人工打顶增加9.4cm和4.8个,6.2 cm和3.9个,2.2 cm和2.6个。中等灌水量(4800 m3·hm~(-2))下棉花产量最高,比低灌水量(3000m3·hm~(-2))处理增产20%左右,比高灌水量(6600 m3·hm~(-2))处理增产5%左右。低、中、高灌水量下,分别以低、中、高剂量DPC+的产量最高,一般较人工打顶提高5%~10%。低灌水量下低剂量DPC+处理主要依靠较大的群体生物量获得相对较高的产量,高灌水量下高剂量DPC+处理主要依靠较高的产量器官干物质分配率获得相对较高的产量,而中等灌水量下中等剂量DPC+处理的产量在所有处理中最高,得益于比较适宜的冠层生产能力和合理的干物质分配能力。【结论】灌水量需要与DPC+剂量互相配合,在增加群体物质生产能力的同时保障营养生长和生殖生长协调,这是提高棉花DPC+化学封顶技术成功率的关键途径之一。     

控失肥与普通化肥对夏玉米养分积累与生长发育的影响

为了比较研究控失肥和普通化肥对夏玉米养分累积与生长发育的影响,于2014-2015年在河北农业大学辛集试验站进行了大田试验。采用玉米杂交种郑单958为试材,测定了不同时期玉米形态和生理性状及其养分吸收效率。结果表明:在施入相同养分含量(N 144 kg/hm~2,P2O572 kg/hm~2,K2O 72 kg/hm~2)的控失肥和普通肥料后,玉米生长发育、干物质积累和营养元素累积量均发生了显著的变化,控失肥处理玉米产量显著高于普通肥料。与普通肥料相比,控失肥可提高玉米千粒质量、干物质和产量分别为12.3%,12.8%和6.9%;控失肥处理的器官营养元素含量高于对照肥料。控失肥处理提高了玉米灌浆期叶面积指数和光合强度。同时,控失肥处理增加了基部茎秆粗度和抗穿刺强度,抗倒伏性大为提高。控失肥作为一种新型肥料将对提高玉米产量、提高施肥效益和保护资源环境起到重要作用。     

秸秆还田与优化施氮对稻田土壤碳氮含量及产量的影响

针对滨海盐碱地稻田土壤有机质较低、氮肥投入过量,采用田间微区试验研究了秸秆还田与优化施氮对稻田土壤全氮、铵态氮、硝态氮、有机碳、可溶性有机碳、微生物碳氮含量及水稻生长特征的影响。设秸秆还田与氮肥两因素,3个碳(秸秆还田)水平:C0:无秸秆还田; C1:秸秆还田4 500 kg/hm~2; C2:秸秆还田9 000 kg/hm~2; 2个氮水平:N1:255 kg/hm~2(优化施氮); N2:400 kg/hm~2(农民传统施氮)。结果表明,与C0、C1处理相比,C2处理时土壤有机碳含量分别增加了100. 46%,28. 06%;分蘖期时C2N2处理土壤全氮含量最高,而成熟期C1N1处理土壤全氮含量最高;秸秆还田与优化氮肥显著增加了DOC(可溶性有机碳)含量,分蘖期与成熟期土壤铵态氮、硝态氮含量均以C1N1最高,分蘖期与成熟期时,与未秸秆还田相比,土壤微生物量碳、氮含量显著增加,且C1N1、C1N2处理含量最高;秸秆还田量4 500 kg/hm~2与氮肥施用量255 kg/hm~2处理可有效增加水稻二次枝梗数、千粒质量、结实率及水稻产量,且高于其余处理。与农民传统施肥管理(C0N2)相比,秸秆还田与优化施氮(C1N1)处理水稻产量提高19. 02%,且显著提高滨海盐碱地稻田土壤碳氮含量。     

长江流域大麦后直播棉集中成铃与高产协同表达群体株型特征

【目的】研究品种和氮肥运筹对麦后直播棉成铃、产量和株型影响,明确长江流域棉花集中成铃与高产协同表达群体株型特征。【方法】采用大田试验,2014年和2015年前茬均为大麦,2014年以国欣12-1、宜机棉、鲁棉研36为供试品种,设计2种氮肥用量水平(45 kg·hm~(-2)、150 kg·hm~(-2));2015年进一步以国欣12-1为材料,设置2个缓释肥纯氮用量(150 kg·hm~(-2)、225 kg·hm~(-2))和2种运筹(苗肥和花肥质量比分别为70%∶30%和100%∶0)处理,并以常规施肥(纯氮150 kg·hm~(-2))和不施肥为对照。【结果】2014年施纯氮150 kg·hm~(-2)时,国欣12-1籽棉产量达4 014.72 kg·hm~(-2)且显著高于其它处理;2015年苗期一次性施入缓释肥氮素用量150 kg·hm~(-2)的处理比常规施肥处理增产30.96%;前述2个处理下,国欣12-1成铃也较为集中,8月15日至8月30日成铃数占总成铃数比率(成铃率)分别达31.8%,26.1%,均高于其它处理。相关分析表明同期成铃率与籽棉产量极显著正相关(r_(2014)=0.948**、r_(2015)=0.976**)。进一步分析株型指标与8月15日至8月30日成铃率、籽棉产量的关系,提出了长江流域大麦后直播棉群体优化指标。【结论】大麦后直播棉群体优化指标可以实现高产和集中成铃的协同表达。     

行距对机采棉干物质积累及氮磷利用效率的影响

【目的】新疆棉花生产的主要环节均已实现机械化,但采摘环节仍大量使用人工,农机农艺不协调是导致机收比例低的主要原因。优化机采棉行距配置是实现农机农艺融合的有效途径,因此本研究通过设置不同的机采棉行距,探究其对棉花产量形成及养分利用的影响,为机采棉行距配置的优化提供理论依据。【方法】采用随机区组设计,选择生产中最佳密度,在密度一致基础上,设置"一膜三行"(S1,平均行距76 cm)、"一膜四行"(S2,平均行距57 cm)、"一膜六行"(S3,平均行距38 cm) 3种行距,其中S3处理为常规机采行距(CK),研究行距对棉花干物质积累、分配以及对产量形成及氮、磷养分吸收利用的影响。【结果】不同行距下棉花干物质的积累符合Logistic生长函数模型。2年均值表明随着平均行距的降低,单株干物质积累总量降低43.3%,干物质最大积累速率降低(1.4 g·株~(-1)·d~(-1)),快速积累期起始时间从出苗后51.4 d逐渐推迟至62.5 d,但快速积累持续时长从19.7 d增加至35.1 d。增加行距显著提高单株成铃(0.9个),对铃重及衣分无显著影响,籽棉及皮棉产量显著增加16.7%和17.4%。行距对植株养分积累与分配有显著的影响,S1处理氮积累总量(907.0 kg·hm~(-2))、磷积累总量(58.3 kg·hm~(-2))、吐絮期经济器官氮分配率和磷分配率(N 55.7%和P_2O_5 69.1%)、每100 kg皮棉氮素吸收量(32.1 kg)均最高;而S3处理氮积累总量(664.5 kg·hm~(-2))、磷积累总量(38.9 kg·hm~(-2))最低,S2处理吐絮期经济器官氮分配率和磷分配率(N 48.5%和P_2O_5 60.3%)、每100 kg皮棉氮素吸收量(28.6 kg)最低。【结论】综合来看,一膜三行下植株养分指标及产量均优于其他行距,更适宜作为高效机采的行距。     

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。     

施氮量和种植密度对川西平原区直播粳稻产量和氮肥利用的影响

为研究施氮量和种植密度对川西平原区粳稻产量及氮肥利用的影响,以德粳3号为材料,采用裂区试验设计,主区因素为4种施氮量,即N180—纯氮用量为180 kg·hm~(-2),N210—纯氮用量为210 kg·hm~(-2),N240—纯氮用量为240 kg·hm~(-2)和N0—纯氮用量为0 kg·hm~(-2);副区因素为种植密度,即行距×株距为25 cm×20 cm、25 cm×16 cm和25 cm×12 cm,分别记为D20、D16和D12;测定水稻齐穗期叶面积指数、SPAD值和净光合速率,齐穗期和成熟期干物质积累量,成熟期产量及产量构成因素指标。结果表明,与N180处理相比,N210和N240处理有效穗数分别增加4. 14%和12. 84%,产量分别提高8. 42%和10. 05%。施氮量从180 kg·hm~(-2)增加至240 kg·hm~(-2),齐穗期和成熟期干物质积累量逐渐增加,而水稻氮肥偏生产力均逐渐降低。N180和N210处理中,增加种植密度可以明显提高成熟期有效穗数和干物质积累量、籽粒产量和氮肥偏生产力。可见,川西平原粳稻种植推荐施氮量为180～210 kg·hm~(-2),种植密度为25 cm×(12～16) cm。     

长期秸秆还田与氮肥调控对稻田土壤质量及产量的影响

为了揭示土壤对长期秸秆还田及氮肥调控的响应,采用大田小区试验,考察了秸秆不还田+N 300kg/hm~2(TB)、秸秆全量还田+不施肥(T0)、秸秆全量还田+N 255 kg/hm~2(T17)、秸秆全量还田+N 300kg/hm~2(T20)、秸秆还田+N 345 kg/hm~2(T23)对稻田土壤理化特性、重金属含量、活性有机质、微生物炭、碳库管理指数及水稻产量的影响,探索长期秸秆还田(5年)条件下土壤质量对氮肥配施的响应,为提高氮肥利用率、减轻环境污染、提高资源利用效率,提供理论依据和技术支撑。结果表明:长期秸秆还田条件下,随着氮肥施用量的增加,T17、T20、T23 3个处理的全氮、全磷、全钾、速效氮、速效磷、速效钾、总有机质、活性有机质、微生物量碳含量上升,但总有机质、全氮、全磷、全钾的差异不明显;土壤容重下降;土壤中汞、砷、铅、镉、铬、铜、锌7种重金属(全量)未出现明显积累现象。施肥量相同的条件下,秸秆还田(T20)显著提高了土壤速效氮、速效磷的含量,较秸秆不还田(TB)速效氮、速效磷、速效钾分别提高21. 1%,8. 9%。综合考量经济、土壤质量、产量等因素,无污染的秸秆还田后,合理的配施氮肥(300 kg/hm~2)不仅可以避免秸秆腐解过程中与作物争夺氮肥,而且可以促进土壤碳、氮的更新,培肥土壤,提高产量,改善土壤质量。     

Nitrogen Fertilizer and Its Residual Effect on Cotton Yield and Biomass Accumulation

[Objective] The optimum nitrogen rate of 300 kg·hm^－2 is well documented for cotton in the Yangtze River Valley, China. It can be reduced to 225 kg·hm^－2 without reducing yield in late sowing under high planting density. The aim of this study was to determine the possibility of further reducing the nitrogen application rate at the first flower stage, its residual effects and influence on cotton yield formation rule. [Method] A pot experiment was conducted with five nitrogen levels (120, 150, 180, 210 and 240 kg·hm^－2) in 2014, but only 180 kg·hm^－2(for studying nitrogen residual effect) in 2015, to study the cotton growth process, yield and its components and biomass accumulation. [Result] Nitrogen levels significantly affected the yield and biomass accumulation, but not the growth process and nitrogen residual effect. Maximum seed cotton yield (30.5 g·plant^－1), boll weight (3.8 g) and biomass accumulation, especially in the reproductive and vegetative organs, was recorded in the 180 kg·hm^－2 nitrogen treatment. In the rapid accumulation period, the proportion of biomass accumulation in the reproductive organs was the highest. [Conclusion] In a soil with medium fertility level, the application of 180 kg·hm^－2 nitrogen was optimal, because the strength of biomass accumulation in reproductive organs increased during the rapid accumulation period.     

氮素对滨海盐土棉花产量、品质及生物量的影响

为研究不同施氮量对滨海盐土花后棉株生物量、生物量累积特征及其与产量、品质的关系,于2010年和2012年在江苏滨海盐土设置了氮肥水平试验。结果表明:在0~600 kg·hm-2范围内施氮量越大棉株总生物量累积越多,而皮棉产量2010年和2012年分别在施氮375 kg·hm-2和300 kg·hm-2时达到最大;成铃数在施氮300~375 kg·hm-2范围内达到最大;铃重和衣分随施氮量增加而增加,达到最大值后(≥300 kg·hm-2)差异不显著。在300~375 kg·hm-2施氮量范围内纤维比强度最高;高氮有利于上部、顶部果枝纤维长度、比强度、伸长率的提高和马克隆值的优化,但显著降低中下部果枝棉纤维比强度,导致中部纤维马克隆值变劣、下部果枝纤维伸长率下降,说明高氮对中下部果枝棉纤维品质的形成利弊各半,适量高氮可提高上部及顶部果枝产量、品质。在滨海盐土条件下,利于产量、品质及氮素利用效率提高的适宜施氮量为375 kg·hm-2。     

The Plant Architecture of Direct-Sowing Cotton Planted after Barley Harvested with High Yield and Centralized Boll-Setting

[Object] The study was conducted to investigate the plant architecture characteristic of direct sowing cotton planted after barely harvested with high yield and centralized boll-setting in the Yangtze River basin. [Method] In 2014, the cultivars Guoxin 12-1, Yijimian and Lumianyan 36 were used and the two conventional fertilizer (CF) application rates (namely pure nitrogen 45 kg·hm^－2, 150 kg·hm^－2) and Guoxin 12-1 was used in 2015. Two slow release fertilizer (SR) utilization rates (namely pure nitrogen 150 kg·hm^－2 and 225 kg·hm^－2) and two SR topdressing at different growth stages (namely 100% topdressing at seedling stage, 70% topdressing at seedling stage + 30% at flowing stage) were set with CF (pure nitrogen 150 kg·hm^－2) and no fertilizer treatment as the controls. [Result] While the pure nitrogen (CF) amount was 150 kg·hm^－2, the seed cotton yield of Guoxin 12-1 were 4 014.72 kg·hm^－2. In 2015, the seed cotton yield for the treatment, application SR (pure nitrogen 150 kg·hm^－2)and application ratios of seedling stage and flowering stage of 100% and 0, respectively, increased by 30.96%. The ratios of bolls setting from 08-15 to 08-30 to total bolls (RBT) for the two treatments were 31.8% and 26.1%, respectively. Then a significantly positive correlation between the seed cotton yield and RBT was found（r2014＝0.948^**, r2015＝0.976^**）. Based on the analysis of relationship between the plant architecture indexes and RBT, plant architecture characteristics of cotton population with high yield and centralized boll-setting was proposed. [Conclusion] These indexes would be used to supervise the cotton culture management to achieve high yield and centralized boll-setting for the direct sowing cotton planted after barely harvested.     

氯甲基吡啶对滴灌棉花生物量、氮素吸收及氮肥利用率的影响

在田间滴灌条件下,采用单因素随机区组设计,设置CK(不施氮肥)、Urea(尿素)和Urea+Nitrapyrin(尿素+氯甲基吡啶)3个处理,重复4次,分别于2012和2013年研究了尿素添加硝化抑制剂氯甲基吡啶(Nitrapyrin)对棉花生物量、氮素吸收及氮肥利用率的影响。2年试验结果表明,尿素添加氯甲基吡啶随水滴施能增加棉株的生物量、吸氮量及产量,使植株地上部分的生物量和吸氮量较单施尿素分别提高4.1%~5.1%、4.3%~4.4%,皮棉产量提高4.1%~4.4%;其中,茎、叶、蕾花铃的生物量较单施尿素分别增加2.7%~4.5%、14.9%~16.2%和2.5%~3.9%,吸氮量则分别提高0.4%~1.1%、12.2%~16.3%以及2.9%~3.4%;氯甲基吡啶的添加能提高棉田氮肥利用率11.5%~12.5%。研究结果可为应用硝化抑制剂氯甲基吡啶促进滴灌农田氮肥高效利用提供理论依据。     

种植密度和缩节胺调控对麦后直播棉产量和冠层特征的影响

2013―2014年以早熟棉(中棉所50)为材料,采用裂区设计,在江苏省南京市研究了种植密度(7.50万、9.75万和12.00万株·hm~(-2))和缩节胺(DPC)调控(0,52.5和105.0 g·hm~(-2))对麦后直播棉产量和冠层特征的影响。结果表明:皮棉产量在不同种植密度下以12.00万株·hm~(-2)处理最低,在不同DPC用量水平下以0 g·hm~(-2)处理最低;种植密度与DPC调控存在互作效应,以种植密度9.75万株·hm~(-2)、DPC用量52.5~105 g·hm~(-2)处理产量较高,且产量构成中以铃数对产量的直接效应最大。对冠层特征影响表明,下部果枝夹角和长度随种植密度增加而降低,而中、上部果枝的夹角和长度、叶面积指数均以种植密度9.75万株·hm~(-2)处理较高;不同部位果枝夹角和长度、叶面积指数均随DPC用量增加而降低,而透光率则相反。相关分析表明,下部果枝夹角大、中部果枝较长及上部果枝夹角小且叶面积指数和透光率较高,有利于提高产量和霜前花率。综上,该棉区麦后直播棉种植密度9.75万株·hm~(-2)、DPC用量52.5~105 g·hm~(-2)(蕾期、开花期和打顶后用量比例为1∶2∶4),有利于改善棉花冠层特征,实现早熟高产。     

Interaction of Plant Density with Mepiquat Chloride Affects Plant Architecture and Yield in Cotton

[Objective] The effect of planting density and mepiquat chloride (DPC) on cotton plant architecture, growth, yield, and quality at Anyang City, Henan Province, China, was studied. [Method] Field experiments with cotton variety Lumianyan 28 were conducted with five planting densities (15 000, 45 000, 75 000, 105 000, and 135 000 plants·hm^－2) and application of DPC at three concentrations (0, 195, and 390 g·hm^－2). [Result] Increasing cotton plant density resulted in increased internode length and plant height but also caused the decrease of inclination of fruiting branches and leaves as well as elevated dry matter allocation to leaves and fruiting branches, which led to a decrease in dry matter accumulation. Application of DPC reduced the azimuth angle of fruiting branches and plant height, but increased the insertion angle of fruiting branches with the main stem, leaf length, and petiole length. Planting density and DPC treatment showed a significant interaction on fruiting branch insertion angle, plant height, stem diameter, and dry matter allocation to fruits and leaves. The interaction of DPC and planting density had a complementary effect on the spatial distribution of cotton-yielding bolls. The final dry matter was highest (14 362 kg·hm^－2) at the planting density of 105 000 plant·hm^－2 and DPC application of 390 g·hm^－2, which resulted in the highest seed yield (3 257 kg·hm^－2). [Conclusion] For maximization of cotton yield and quality, a plant density of 75 000 to 105 000 plants·hm^－2 and DPC application of 195 to 390 g·hm^－2 in the Yellow River cotton-producing region is recommended. The results may help to optimize labor-saving cotton management and to generate a plant architecture suitable for mechanical harvesting in the Yellow River cotton-producing region.     

中国北方主要棉区土壤供钾能力及其与产量和品质的关系

2012―2013年在山东平原县、河北威县、新疆昌吉市代表性棉田上采集土壤(0~20 cm)和棉花样品,分析北方棉区土壤钾素状况、供钾能力及其与棉花产量和纤维品质的关系。结果表明,平原、威县、昌吉棉田速效钾含量平均分别为217、128、232 mg·kg-1,供钾能力平均分别为128.2、105.1、213.6 kg·hm-2,每生产100 kg皮棉棉花地上部分别吸收K 9.77、7.82、12.25 kg。不同棉区土壤速效钾含量与皮棉产量和地上部吸钾量相关性不同,在平原和昌吉,当土壤速效钾含量分别小于123 mg·kg-1和220 mg·kg-1时,与皮棉产量和地上部吸钾量具有显著正相关。3个植棉区棉花的吸钾量与子棉产量、皮棉产量都呈显著的正相关。棉花地上部吸钾量、纤维吸钾量和纤维含钾量与纤维品质指标的相关性不同地点差异大。     

Effects of Nitrogen Application Rates on Soil Nitrogen Content,Nutrient Uptake and Utilization of Cotton in Low Fertility Fields

[Objective] The effects of nitrogen (N) application rates on cotton yield, nutrient uptake and utilization rate, soil available N and urease activity were investigated in low-fertility cotton fields of the Yellow River Basin. [Methods] Six N application rate treatments, 0, 90, 180, 270, 360 and 450 kg·hm^－2 (N0, N90, N180, N270, N360 and N450, respectively), were established using cotton CCRI 79 in the field during 2016 and 2017. The cotton yield, dry matter quality, N, phosphorus and potassium accumulation levels, N use efficiency, 0–100-cm soil layer ammonium and nitrate N contents, 0–100-cm soil layer urease activity and other indicators were investigated. [Results] (1) Compared with N0, the N treatments significantly increased seed cotton yield, except the N90 treatment in 2016. Two years of N360 treatments significantly increased the number of bolls per cotton plant, while no significant differences were found among the seed cotton yields with other N treatments. The N application rates had no significant effect on lint percentage. (2) Compared with N0, N applications significantly increased the cotton dry matter accumulation. The accumulation of N, phosphorus and potassium in cotton increased along with the N application rates in the 90–360 kg·hm^－2 range. The levels of N, phosphorus and potassium in N450-treated cotton decreased compared with N360-treated cotton. As the N application rates increased, the N agronomic efficiency and N fertilizer partial productivity of cotton decreased. When the N application rates exceeded 360 kg·hm^－2, the N physiological efficiency began to decrease, but there were no significant differences among treatments. (3) The nitrate N contents in the 41–80-cm soil layers of the treatments, except for N90, significantly increased compared with N0. The nitrate N contents in the 41–80-cm soil layers of N270-, N360- and N450-treated cotton were significantly increased compared with those of N0, N90 and N180. However, N applications had no significant effects on the ammonium N contents in the soil. (4) The soil urease activities increased when N application rates were less than 360 kg·hm^－2, and then decreased when the N application rates were greater than 360 kg·hm^－2. [Conclusion] The optimum N application rate was 277.0 kg·hm^－2. When the N application rates were greater than 360 kg·hm^－2, the nitrate N contents in the soil increased. However, the nutrient accumulation levels and the N fertilization efficiencies decreased, and the soil urease activities were inhibited. No obvious increase in cotton yield was observed.     

氮素对棉株上部果枝铃￣叶系统生长及生理特性的影响

以鲁棉研28号为试验材料,不施氮肥为对照,在大田条件下研究低氮(120 kg·hm-2)、中氮(240 kg·hm-2)、高氮(480 kg·hm-2)处理对棉株上部果枝"铃￣叶系统"的形态和生理生化效应。结果表明:1)中氮和高氮显著增加棉花上部果枝的长度、叶面积,高氮显著降低上部果枝近远端直径比;2)与对照相比,中氮上部果枝铃对位叶的叶绿素含量、可溶性蛋白含量显著增加,上部果枝棉子的可溶性蛋白含量也显著提高;3)中氮棉花果枝内外围铃重最大,结铃后期显著大于对照。氮肥提高棉花上部果枝的纤维品质,以中氮内外围棉铃的纤维品质最优。表明施适量氮肥能增强棉花上部果枝的"源￣库"协调性。     

Response of Enzyme Activity of Soil to Urea Application Rate in a Cotton Field Trial

We studied the response of urease activity of soil in cotton field to different long-term urea (amide nitrogen) application (N application rates were 0, 90, 180, 270, 360, 450 kg·hm^－2), as well as responses of dehydrogenase and proteinase activity of soil at the harvest stage of cotton. The results showed that urease activity of soil increased with increased urea application rate, and urease activity at 0-20 cm soil depth were close to those at 20-40cm soil depth. In contrast, urease activity of soil greater than 40 cm soil depth decreased with increased soil depth. There was a significant positive correlation between urease activity and total N content, organic matter content, and available N content of soil. Dehydrogenase and proteinase activities increased with increased urea application rate (0-360 kg·hm^－2); however, at the urea application rate of 450 kg·hm^－2, dehydrogenase and proteinase activities declined. When the urea application rate was 270-360 kg ·hm^－2, urease, dehydrogenase and proteinase activities were much higher than those of the urea application rate less than 270 kg ·hm^－2, and there was no significant effect on urease, dehydrogenase and proteinase activities when urea application rate was 270-360 kg·hm^－2 in the cotton field.