种植密度对川中丘陵夏玉米茎秆性状及产量的影响

以玉米品种‘正红505’为材料,设置4.50万株·hm~(-2)、5.25万株·hm~(-2)、6.00万株·hm~(-2)、6.75万株·hm~(-2)、7.50万株·hm~(-2) 5个密度处理,研究种植密度对川中丘陵夏玉米茎秆性状及产量的影响。结果表明:随种植密度的增加,株高、穗位高、节间长、茎节长粗比逐渐增加,茎粗、茎粗系数、节间干重、单位茎长干物质重、茎秆压碎强度和外皮穿刺强度逐渐减小,除穗位高外,其余各性状均存在显著性差异;其中,当种植密度增加到7.50万株·hm~(-2)时,第1、3、5茎节的外皮穿刺强度分别较4.50万株·hm~(-2)显著降低27.10%、22.78%和30.80%。在本试验设置的密度范围内,玉米产量随密度的增加而先增后减,在6.00万株·hm~(-2)处获得最大值,与4.50万株·hm~(-2)相比,6.00万株·hm~(-2)显著增产12.02%。随种植密度增加,玉米穗长、穗粗、成穗率、穗粒数和千粒重显著降低,有效穗数和秃尖长显著增加。相关分析表明,茎秆压碎强度与外皮穿刺强度呈极显著正相关(r=0.93**),且茎秆压碎强度和外皮穿刺强度分别与茎粗、茎粗系数、节间粗、节间干重和单位茎长干物质重呈显著或极显著正相关,而与株高、节间长和茎节长粗比呈负相关或极显著负相关。其中,茎秆农艺性状与茎秆压碎强度的相关性更好。单株产量与茎粗、茎粗系数、节间粗、节间干重、单位茎长干物质重、茎秆压碎强度和外皮穿刺强度呈显著或极显著正相关,与节间长和茎节长粗比呈显著负相关。逐步回归分析表明,茎粗系数和单位茎长干物质重对茎秆压碎强度的影响最大。综上所述,种植密度是影响玉米茎秆性状和产量的重要因素,适当增加种植密度可以显著增加玉米群体产量,茎粗系数和单位茎长干物质重可以作为评价玉米茎秆抗倒伏能力的重要农艺指标。     

不同种植方式对红壤旱地土壤水分及抗旱能力的影响

通过3年田间小区试验,研究不同种植方式对红壤旱地土壤水分及抗旱能力的影响.结果表明：1）与种植花生相比,种植苎麻可显著提高土壤有机质质量分数（28.44％）、田间持水量（10.06％）和总孔隙度（5.65％）,土壤密度则显著降低7.20％;2）监测期内,花生地各层土壤以及整个0～ 100 cm土体水分变异系数普遍高于苎麻地,苎麻地0 ～ 100 cm土体水分的时间稳定性和空间协调性优于花生地;3）苎麻地0～ 40 cm土壤较花生地延长抗旱时间7d以上,但随着土层的加深,差异越来越小;4）红壤坡耕地种植苎麻有利于提高红壤旱地土壤抗旱能力,特别是中、上层土壤.从扩充土壤水库的角度考虑,红壤旱地种植苎麻优于种植花生,该研究结果可为挖掘红壤区深层土壤水分提供参考.     

Increasing seed protein content enhances seedling emergence and vigor in wheat

Deep seeding of wheat, a common practice when soil moisture is deficient, causes poor seedling emergence and stand establishment. We investigated whether increasing seed protein content by nitrogen fertilization of parental plants might increase emergence rate and vigor of winter wheat seedlings from deep‐planted seeds. Four seeding depths, three cultivars, and three seed protein contents were compared in different soil mixtures and fertility regimes. Under all treatments, emergence rate and dry weight of seedlings markedly decreased as seeding depth was increased. Increasing protein content of seeds sometimes, but not always, increased seedling emergence rate and commonly increased seedling dry weight regardless of soil mixture or fertility regime. Differences were greatest at 4.8‐ and 12‐cm seeding depths; seedlings failed to emerge from 16‐cm depth under any treatments. We concluded that increasing seed protein content by nitrogen fertilization of parent plants is an economic and efficacious method of enhancing wheat establishment when seed must be deeply planted.     

Effect of several production factors on two varieties of rapeseed in the central United States

Two varieties of winter rapeseed (Brassica napus) (Cobra and Liborius) were planted at Brownstown, IL to evaluate the effect of planting date, nitrogen (N) rate, N application timing, and tillage on grain yield and oil content of the grain, grain moisture, plant lodging, winter survival, and plant N content. Results indicated that planting rapeseed approximately one to two weeks prior to winter wheat in this region is preferable to planting earlier. Grain yield showed a significant linear increase with delayed planting date from 25 August to 24 September. Grain yield also increased quadratically with increasing N rate (with an optimum of about 250 kg N/ha) and increased (0.15 Mg/ha) due to splitting the N fertilizer into two even applications. An increase in grain yield was accompanied by an increase in grain moisture with Liborius (late maturing) having significantly greater grain moisture than Cobra. Winter survival increased linearly with delayed planting date but, was accompanied by a significant quadratic increase in plant lodging. Chisel, as compared to disk tillage, increased plant lodging slightly, but decreased winter survival slightly. Neither delayed planting, N rate, nor splitting of spring N affected oil content. Liborius produced significantly more oil than did Cobra.     

合理密植对不同株型烤烟冠层结构及光合生产特性的影响

【目的】研究不同耐密性烤烟对密植的综合响应,为鉴选耐密品种及烤烟合理密植提供理论参考。【方法】采用两因素裂区试验设计,以云烟97 (塔形,低耐密)、NC71 (腰鼓形,中等耐密)、K326 (筒形,高耐密) 3类株型烤烟为主区,4个种植密度(13890、15150、16660、18510株/hm^2)为裂区,阐明不同株型烤烟农艺性状、冠层结构、物质积累、产量及构成对密植的响应规律。【结果】密植条件下(15150、16660、18510株/hm^2),烤烟株高显著增加,最大叶叶位明显下降,并逐渐表现为"高瘦"形态。品种因素对株高和最大叶叶位影响显著,不同品种间茎围无显著差异。随种植密度的增加,烤烟群体叶面积系数(LAI)呈增加趋势,尤其是耐密品种NC71和K326的LAI显著增加,不同密度间K326品种LAI空间分布变异最低。密植主要通过提高群体干物质生产力(单位面积有效叶片数)弥补单株生产力(上中等烟率、单叶重)的不足,从而获得结构性增产。云烟97品种群体产量以16660株/hm^2时最高,平均较对照(13890株/hm^2)显著增加15.51%;NC71品种群体产量以16660株/hm^2和18510株/hm^2间无明显差异,较对照分别显著增加17.61%和19.37%;K326密植效应最大,以18510株/hm^2群体产量最高,比对照提高24.51%。成熟期云烟97单株干物质在15150株/hm^2后持续下降,降幅范围为8.41%～21.08%,NC71和K326品种则在密度为16660株/hm^2时有显著降低。合理密植可发挥烤烟群体结构性增产潜力,紧凑品种(NC71、K326)的高耐密性表现为个体生理对密植响应迟钝,从而获得功能性增产。【结论】合理密植可充分发挥烤烟群体结构性增产潜力,不同品种耐密性差异主要表现为个体功能对密植响应的迟钝性强弱,本试验条件下,K326、NC71、云烟97品种密植分别为18510株/hm^2、16660株/hm^2、15150～16660株/hm^2时,可实现烤烟群体结构和个体功能平衡。     

旱地全膜覆土穴播和全沙覆盖平作对小麦田土壤水分和产量的调节机理

以春小麦品种‘陇春27’为试材,采用田间试验法,以裸地平作为对照,研究半干旱区旱地全膜覆土穴播和全沙覆盖平作对小麦田土壤水分和产量的调节作用。结果表明:与裸地平作(CK)相比,全膜覆土穴播(PM)和全沙覆盖平作(SM)小麦田0~40 cm土壤水分条件明显改善,尤其在干旱年份,能满足小麦前期生长,同时促进小麦出苗后对0~200 cm土壤水分的利用;种植第1年PM在60~80 cm土层耗水量最大,SM和CK在40~60 cm土层耗水量最大;种植第2年PM以120~180 cm土层耗水量最多,SM和CK则以60~80 cm土层耗水量最多。连续种植两年后,PM耗水深度从120 cm延伸到200 cm,SM耗水深度从120 cm延伸到140 cm,CK耗水深度无变化;小麦田休闲效率PM最大,SM次之,CK最小,但是各处理休闲效率随种植年限增加而降低。可见,PM和SM能改善小麦前期生长水分环境,促进出苗后耗水,并加快小麦对土壤深层水分的利用,因而与CK相比,PM产量增加48.77%~815.79%,SM产量增加49.41%~702.24%。但随种植年限增加,耗水深度加大,休闲效率降低,多年种植可能对土壤水分生态产生不利影响。     

土壤硬度对播种苗和栽植苗根系发育的影响(英文)

 以赤松为实验材料,研究土壤硬度对播种苗和栽植苗根系发育的差异性。土壤硬度被设计为5个等级(用山中式土壤硬度计测定分别为10,15,20,25和30 mm)。分别调查播种苗与栽植苗根长、根系形态、苗高以及地上部和地下部生物量。结果表明:与播种苗相比,栽植苗形成细、短的根系,但根系数量较多;所有处理的栽植苗的主根丧失,而播种苗的主根则相对较为完整;播种苗的根径比随着土壤硬度的增加而增加(土壤硬度为10,25和30mm时的根径比分别为2．1,3．3和5．8),而栽植苗的根径比则随着土壤硬度的增加而减小(土壤硬度为10,25和30mm时的根径比分别为4．0,2．5和2．4)。这就意味着在紧实的土壤条件下,播种苗的根系生长要优先于地上部的生长;当土壤硬度大于25mm时,栽植苗的根系很难穿透植树穴,从而使根系发生缠绕。播种苗与栽植苗根系发育的这些差异,将会影响到树木的生长量、稳定性、水土保持能力以及对气候变化如干旱等的适应能力。因此,当恢复退化土地的植被时,进行土壤改良并采用播种恢复技术,将是成功恢复植被、形成稳定的森林群落的重要和必要的积极措施。     

Preliminary observations on effects of tillage systems on soil physical properties, cotton root growth and yield in Gezira Scheme, Sudan

The decline in cotton yields in the Gezira Scheme, Sudan, has been partially attributed to deterioration in soil physical properties and the formation of a plough pan 20 cm deep as a result of the repeated use of the disc plough for land preparation. This field study was conducted during the 1990/91 season at the Gezira Research Station Farm to evaluate the effect of tillage on some soil physical properties of Vertisols, root growth and yield of cotton (Gossypium barbadense L.). Three tillage systems were used: disc harrowing (DH), three bottom disc plough (DP) and subsoiling (SS). Infiltration rates, bulk densities, soil penetration resistance, moisture depletion and root and shoot growth were measured. The results indicated that infiltration rate was not increased significantly by SS. Plant height and shoot dry matter were significantly higher with SS at later growth stages. Bulk density of the plough pan at 135 days after sowing accounted for 90% of the observed variation in subsoil root dry weight while soil penetration resistance accounted for 59% of the variation. Subsoiling increased water use efficiency 25 and 13% over DH and DP respectively. Subsoiling increased cotton yields over DH but the increase over DP was not significant.     

旱作农田不同结构垄作的生态生产效益研究

垄作是沙区旱作农田常用的集水抗旱耕作技术。通过野外试验,对油菜生长季内不同结构的垄作与平作下土壤水分和地上生物量进行了动态观测,并对油菜理论产量和实际产量进行了分析。结果表明,垄作下土壤耕作层水分含量比平作下增加了3.5%~12.2%。垄作还降低了生长季内土壤含水量的波动幅度,改变了其垂直分布,使湿润锋位于耕作层,有利于油菜对土壤水分的吸收,对缓解干旱对作物生长的胁迫有积极作用。对生长季内油菜干物质的累积速率、生长季末地上生物量、单株角果数及千粒重比较,垄作均高于平作。但结构不合理的垄作下植株密度的降低会导致油菜实际产量和理论产量低于平作。而垄高25 cm、垄沟比1/24的垄作不仅具有集水抗旱的生态效益,而且较其它结构的垄作及平作更能促进油菜生长和产量的提高,是旱作农田油菜种植较为适宜的耕作方式。     

玉米宽窄行交替休闲保护性耕作的根系和光分布特征研究

为探明宽窄行交替休闲种植玉米产量变化的原因,在2007—2008年设置大田试验,比较研究了宽窄行和均匀垄两种耕作方式下玉米光合有效辐射和根系分布等指标的变化动态。结果表明:深松后(6月25日—9月20日),宽窄行处理的土壤紧实度低于均匀垄处理,降低25.17%~52.04%,在0~45 cm不同土层间平均降低14.08%~53.16%,差异最大值出现在11~20 cm土层。在0~45 cm土层,均匀垄处理的根系干重在乳熟期和成熟期显著高于宽窄行处理,分别高13.47%和29.62%;但在根系垂直分布中,宽窄行比均匀垄处理显著增加了根系在深层土壤所占的比例,在15~30 cm土层,宽窄行和均匀垄处理在吐丝期、乳熟期和成熟期根系分布比例分别为6.59%、8.21%、9.00%和5.21%、7.48%、5.42%,在30~45 cm土层分别为2.30%、2.61%、3.24%和1.62%、2.53%、2.09%;不同品种和当年的降雨情况均会影响宽窄行模式下根系的生长。均匀垄处理中部透光率整体上低于宽窄行处理,6月18日、7月24日、8月29日宽窄行底部透光率分别比均匀垄处理高16.12%、5.15%、4.95%,差异达显著水平。因此,提高种植密度将有利于宽窄行处理截获更多的光合有效辐射,从而提高群体的光能利用率。     

广西旱地晚花生增产技术研究

不同播期、密度、土壤含水量与旱地晚花生产量的关系试验结果表明：早播能缩短生育期，减轻秋旱对花生生育的影响，提高花生从花针期起的叶面积指数和干物质积累量，增加结荚数和果重，比晚播增产率达７３．８％～１７６．７％，达到显著水平。种植密度从目前广西大面积生产上每ｍ２下种３０粒扩大到３８粒，对花生也有一定的增产作用。其主要原因是扩大了绿叶面积指数，提高了群体的净同化总量和干物质积累量，增加总结果数和总饱果数。选择低地种植，可容纳较多的雨水，保水抗旱，增产作用较明显。     

土壤调理剂对旱、盐条件下草种萌发的影响

利用田间和盆栽试验研究了不同材料土壤调理剂对草的生长影响,并探讨其使用条件和使用方法。结果表明,干旱条件下,应用调理剂可减轻干旱土壤盐碱的危害,提高出苗率在75%以上。土壤调理剂作种子包衣有较好的抗旱保苗效果,包衣处理的草籽出苗率较对照提高约19%;包衣处理的苗期土壤水分较对照高5%～11%;包衣处理的苗期耗水量较对照降低5%～12%。播期土壤水分为田间持水量的40%(土壤含水量约11%)和20%(土壤含水量约5%)的土壤上,土壤调理剂处理的出苗数分别较对照提高11%～14%和14%～24%;0～20cm土层含水量较对照增加4%～15%。当土壤水分为田间持水量的40%时,土壤调理剂处理的苗期生物量较对照增加3%～42%,单位耗水量较对照降低9%～34%;土壤水分在田间持水量的20%时,调理剂处理的苗期生物量和单位耗水量较对照亦分别表现为增加和降低趋势。     

红壤丘陵区不同种草模式的水土保持效果与生态环境效应

研究探讨了红壤丘陵区将牧草纳入不同利用方式后的水土保持效果及对生态环境的影响。 3年的试验结果表明 :种植牧草能明显地减少径流量和泥沙量 ,截留雨水 ,提高土壤水分含量 ,降低高温干旱期地表温度 ,提高土壤有机质含量 ,培肥土壤。然而 ,梯田果园区种植暖季型禾本科牧草将在高温干旱期影响果树生长 ,果园牧草应以根系浅的豆科牧草罗顿豆或夏季枯死的冷季型牧草为主。在梯田作物区的梯边上种植牧草不仅没有产生明显的水土保持效果 ,而且引起牧草和作物竞争而减产 ,因而不宜提倡。     

地膜覆盖、FA旱地龙在师宗经果林建设中的应用

经果林营造是小流域水保生态建设的重要内容。为在旱季提高苗木的成活率,在溜子田小流域经果林建设中采用了地膜覆盖和喷施FA旱地龙技术。地膜覆盖能保证树苗根部有足够的水分供应,FA旱地龙能减少植株水分蒸腾,从而使苗木成活率达96％以上。这两种技术措施对植株增高也有显著作用。     

种植年限及密度对渭北旱塬苹果园深层土壤干燥化的影响

为探究种植年限及密度对苹果园土壤干燥化变化的影响,以渭北旱塬洛川县不同种植年限和密度的果园为研究对象,采用烘干法测土样,2008年及2015年分别2次测得不同果园15 m深土层含水量,以自然条件下农田为对照,分析其干燥化变化规律。结果表明:1)2008年测定5、10、15、20、25 a果园的土壤干燥化指数分别为6.46%、32.68%、37.65%、63.33%和62.81%,2015年测定当年果园经过7 a后的12、17、22、27、32 a果园的土壤干燥化指数分别为35.98%、59.65%、42.21%、75.06%和70.09%,随着树龄增大,土壤干燥化指数整体增大,干燥化程度加剧;5 a生苹果幼园土壤干燥化轻微,程度接近自然条件下农田;树龄15 a后的果园土壤干燥化波及深度达11 m左右的古土壤蓄水层,至17 a后渭北旱塬古土壤层的缓冲作用已经丧失,果园产量及果实品质受限于当年降雨。2)研究中株行距密度从3 m×4 m变为4 m×6 m的22、25和32 a果园,干燥化进程得到控制,干燥化速率大幅下降,降低果园密度可以缓解因苹果树树龄增长造成的果园干燥化加剧,间伐措施后的果园降雨有所盈余,可以改善土壤干燥化现状;但在亏水年,间伐后的果园在充分利用降雨时,还需深层土壤水分的弥补,在树龄大的果园尤为常见,单靠间伐措施只能延迟土壤干层的形成。因此,要控制和减缓土壤干燥化的发展,应在干燥化影响波及古土壤层前采取措施,也即种植12 a左右,果园处于中度干燥化程度时采取相应对策最佳。     

旱期水肥耦合对贵州山区辣椒生长及产量的影响

在贵州东南部山区,田间试验研究了沟垄覆膜集雨以及旱期水肥耦合对辣椒生长及产量的影响。结果表明,在传统施有机肥的基础上,采用沟垄覆膜集雨可以明显改善辣椒株高、单株果实数及百果重,鲜椒的平均产量提高了49.9%,其增产效果优于增施复合肥。旱期节水灌溉也能明显增加辣椒株高、单株果实数、百果重及鲜椒产量,旱期分次浇灌和滴灌后的鲜椒平均产量分别提高了7.8%和17.8%;而旱期浇灌及滴灌后表土层(10 cm处)的平均含水率则分别增加了10.00%和16.92%。因此,在合理施用肥料的基础上,采用沟垄覆膜集雨和雨季水窖蓄水及旱季提水灌溉是贵州山区优质辣椒栽培的主要措施。     

水氮梯度对饲用甜高粱生长和水分利用效率的影响

  【目的】  探究不同灌溉量和施氮水平对饲用甜高粱生长特性、单株耗水规律以及水分利用效率的影响,为确定饲用甜高粱适宜种植密度、优化水氮管理措施以及提高栽培生产潜力提供理论支撑。  【方法】  在温室条件下进行二因素三水平随机区组试验,供试饲用甜高粱品种为‘大力士’。设置了3个灌溉量,分别为达到田间持水量的30%～50% (I1)、50%～70% (I2)、70%～90% (I3);设置了3个施氮水平,分别为0 kg/hm2 (N0)、200 kg/hm2 (N1)、400 kg/hm2 (N2)。在饲用甜高粱拔节期取样,测定甜高粱株高、茎粗、鲜重与干重。同时,采用自动称重式蒸渗仪测定单株耗水动态,计算了干物质水分利用效率。  【结果】  1)增加灌溉量显著增加了饲用甜高粱株高和茎粗,与I1相比,I2、I3灌溉量下甜高粱株高分别提高了20.0%和34.5%,茎粗分别增加了18.0%和36.6%。施氮对株高和茎粗无显著影响。2)增加灌溉量显著提高甜高粱植株茎、叶及地上部鲜重和干重,施氮水平仅显著影响叶的鲜重和茎的干重。与I1相比,I2、I3灌溉量下地上部整株鲜重分别提高158.1%、290.1%,干重分别提高84.8%、139.3%。与N0相比,N1、N2施氮量下叶的鲜重分别提高7.6%、4.6%,茎的干重分别降低8.5%、10.4%。I1灌溉量下茎叶比<1,I2和I3灌溉量下茎叶比>1,随着灌溉量增加,饲用甜高粱茎叶比显著增加。在I1、I3灌溉量下,茎叶比随着施氮量的增加而降低。3)随着灌溉量的增加,甜高粱单株耗水量显著增加,而水分利用效率则显著下降。与I1相比,I2、I3灌溉量下累积耗水量分别提高了101.3%、178.9%,水分利用效率分别降低了8.0%、13.9%。施氮对甜高粱单株累积耗水量及水分利用效率均无显著影响。  【结论】  灌溉量显著影响着甜高粱的生长、干物质量的积累以及干物质向茎秆的分配,过高的灌水量会增加饲用甜高粱的耗水量,降低水分利用效率。氮素对甜高粱的生长未显现出促进作用,高施氮量还会增加干物质在叶片中的分配。因此,适度灌溉并施用少量氮肥可能更适合甜高粱的饲用品质和高水分利用效率。     

Organic and Inorganic Blended Materials for Use as Pop-Up Fertilizer for Cotton Seedlings

Various factors such as soil moisture at planting, application rate, and composition of the fertilizer materials have contributed to the erratic results from use of starter and “pop-up” fertilizers. Earlier research with ammonium polyphosphate (11–37–0) has shown some beneficial effects on growth and lint yield of cotton (Gossypium hirsutum L.) when the starter was placed in the seed furrow or surface banded at time of planting. The purpose of this research was to determine the effect of starter fertilizer composition and application rates on cotton seedling emergence and early shoot/root growth at low and medium soil moisture regimes at planting. Treatments consisted of a control (0–0–0), 7–21–0, 5–15–0, and 3–9–0 liquid blends applied directly in the seed row at 3, 6, and 9 acre^?1 to an Orelia sandy clay loam. The three blends contained 2.4%, 1.4%, and 1.0% by weight organic extract, respectively, and used ammonium orthophosphate as sole source of P. Standard-grade ammonium polyphosphate (11–37–0) was used for comparison at rates of 3 and 6 gal acre^?1. The randomized complete block (RCB) experiment was conducted in the greenhouse for 35 days after planting (DAP). All pop-up fertilizers had a definite effect on cotton seedling emergence and early growth. Ammonium polyphosphate caused a marked delay in emergence even at 3 gal acre^?1 during the first five days. Pop-up mix 3–9–0, at 6 and 9 gal acre^?1, showed significantly less damage than other blends as well as the 11–37–0. At 11 DAP and adequate soil moisture, no difference among blends was observed but blended pop-up fertilizers had significantly greater (P < 0.05) emergence than 11–37–0, which produced only 30% emergence at 6 gal acre^?1. Chlorophyll readings were only slightly greater for pop-up blends containing organic acids. Seedlings grown under less soil moisture showed a gradual decrease in plant height as pop-up rates increased whereas no effect was measured at adequate soil moisture. Fertilizer blends failed to increase final dry-matter yields of seedlings at 35 DAP when compared to the control whereas 11–37–0 decreased growth at certain rates. Where adverse effects from pop-up fertilizer treatments occurred, they were magnified by less soil moisture. Further research under field conditions is needed.     

Root development and growth of oilseed, wheat and pea crops on tilled and non-tilled soil

Field experiments were done on red brown earth soils at two sites in South Australia between 1979 and 1981. The effects of different amounts and types of tillage on root growth and plant development were compared for linseed, pea, rape, safflower, soybean, sunflower and wheat. Crops were grown in 2 × 1.5 m² plots with the following treatments: (a) tine-tilled to 120 mm; (b) non-tilled with seeds sown in 30 mm slots, (c) non-tilled with seeds sown in narrow, 30 mm deep holes, and (d) and (e) as for (b) but with vertical cracks extending from the base of the slots to depths of 120 and 300 mm, respectivley.

In the naturally-compacted non-tilled soil, penetrometer resistance was highly dependent on water content. Treatments (b) and (c) restricted seminal root growth relative to treatment (a), and the degree of restriction was dependent on penetrometer resistance in the post-planting period. Growth of lateral roots was also less in (b) and (c) than in (a). The reductions in early root growth for (b) and (c) were associated with reduced dry matter production and yield of the crops. However, the presence of cracks in (d) and (e) provided a zone for unrestricted root growth and the dry matter production and yields were comparable to those in (a).

The magnitude of the reductions in root and dry matter productions for (b) and (c) relative to (a) ranged from 0% to > 50%, depending on the crop and the planting time. On the basis of reductions in dry matter production from (a) to (b), it appears that the suitability of these crops for growth in non-tilled soil decreases in the order: wheat > pea > rape > linseed > safflower and sunflower. In separate experiments, soybean and sunflower suffered similar yield reductions in non-tilled soil.     

玉米宽窄行深旋免耕精量播种机田间试验及效果

为了解决目前玉米播种机械播种质量不高,良好农艺措施与农机不配套等问题,研发了一种基于宽窄行条带深旋免耕技术的玉米精量播种机。该文对该机作业后的土壤质量、土壤含水率、玉米出苗、群体光照、根系生长和产量等性状进行了分析。结果表明:采用该机播种后,土壤耕层容重显著降低(P0.05),土壤蓄水保水能力提高,玉米的播种质量明显提高,群体整齐度增加,群体透光性明显改善,具有显著的增产作用。与普通播种机械相比,该机播种后的玉米出苗率平均提高6.2个百分点,玉米株高变异系数降低8.33%,玉米根系生长量增加15.79%,玉米生育后期的群体光能截获量明显增加,产量增加11.15%。实现了优良农艺措施与农机的有效结合。