不同秸秆还田模式对大豆根系分布的影响

对免耕、灭茬还田和传统耕作条件下大豆根系在土壤剖面中的垂直分布的变化规律进行了研究,为改善在保护性耕作条件下大豆根系发育条件提供参考。结果表明,免耕、灭茬还田和传统耕作模式的根长、根表面积、根体积及根干重均主要分布于土壤剖面0～10 cm深度。在0～10 cm深度内,不同耕作模式之间的根体积密度、根干重密度差异显著,其中免耕模式最低。在10～20 cm深度内,免耕模式根长密度、根表面积密度、根体积密度和根干重密度最低,其根长、根表面积、根体积和根干重占土壤剖面比例最低。土壤剖面根长、根表面积、根体积和根干重累加值亦表现为免耕最低,灭茬还田与传统耕作差异不显著。灭茬还田模式的根长密度、根表面积密度、根体积密度及根干重密度与传统耕作差异不显著,同时其根长、根表面积、根体积及根干重的垂直分布与传统耕作间差异亦不显著。土壤机械阻力和根长密度、根表面积密度、根体积密度及根干重密度呈显著负相关,土壤机械阻力是限制免耕模式大豆根系发育的重要因素。     

难溶性无机磷酸盐对大豆苗期根系生长的影响

为了研究不同难溶性磷(钙磷,铝磷和铁磷)与大豆根系生长的关系,以田间筛选试验为基础,采用室内砂培与水培相结合的栽培方法,分别对磷高效基因型(东农44和东大1号)和磷低效基因型(黑河13和黑河24)大豆苗期根系生长进行比较。结果表明:4个基因型大豆利用难溶性磷酸盐的能力存在显著差异。难溶性磷源条件下,各基因型大豆的根干重、根冠比、总根长、根总表面积比对照处理均有显著增加,而根系全磷浓度、磷含量和平均半径均减小。磷高效基因型大豆在各处理下的根长和根表面积均大于磷低效基因型,但磷高效基因型部分性状的适应性未表现出优势。     

耕作方式对不同抛秧水稻品种立苗期根系生长的影响

对不同耕作方式2种基因型水稻的立苗期根系特性进行研究.结果表明:两优培九、金优253立苗期免耕抛秧单株根干重、单条根长、根毛区长略低于常耕抛秧,但差异不显著.免耕提高了水稻立苗后期总根数、白根数、根系活力和超氧化物歧化酶活性.立苗期超级稻两优培九的单株根生物量、总根数、一次分枝、二次分枝根数量、根系活力和超氧化物歧化酶活性均显著高于金优253.     

滴灌量对冬小麦根系时空分布及水分利用效率的影响

为了解滴灌冬小麦根系生长及水分利用对滴灌量的响应,以新冬18号为材料,利用双管分根法比较分析了拔节期后4.24、6.12、8.01和9.89 kg·管^-14种水分处理（每个处理灌水4次）下滴灌小麦根干重和根长的分布、0~100 cm土层含水量及产量和水分利用效率的差异。结果表明,加大滴灌量使0~100 cm土层湿润深度增加,尤其是提高了0~40 cm土层的含水量下限,并增加该土层的小麦初、次生根干重及根干重密度、根长及根长密度,延缓花后初、次生根干重密度的衰减。增加滴灌量显著提高小麦产量和水分利用效率。说明增加滴灌量可促进滴灌冬小麦拔节期至孕穗期根系生长,并延缓生育后期根系的衰亡,有利于产量和水分利用效率的提高。     

播种方式和种植密度对冬小麦根系生长和产量的影响

为探究播种方式和种植密度对冬小麦根系生长和产量的影响,以新冬22号为材料,采用二因素裂区试验设计,主区设条播（DR）和匀播（UN）2种播种方式,副区设150万粒·hm^-2（D150）、225 万粒·hm^-2（D225）、300万粒·hm^-2（D300）和375万粒·hm^-2（D375）4种种植密度,比较分析了不同播种方式和种植密度下冬小麦根系形态特征、根系伤流量和产量的差异。结果表明,随种植密度的增加,小麦总根干重、总根长呈先增后减趋势,单株次生根数、根系伤流量呈减小趋势。与条播相比,匀播下小麦总根干重、总根长显著增加,差异主要在0~30 cm土层;单株次生根数、根系伤流量增加,差异主要在生育中后期;产量显著提高（增幅9.89%）,其中以D225处理最大。综上,匀播能够促进小麦根系的生长,提高根系活性,有利于高产;在本试验条件下匀播小麦以225万粒·hm^-2种植密度最佳。     

不同密度处理下玉米根系干重空间分布动态的研究

采用根钻挖掘法对不同密度处理下玉米根系干重在土壤中的空间分布特征进行了研究。结果表明:不同密度处理下,各取样点0～100cm土层内根系干重在整个生育期内均呈单峰曲线变化,峰值出现在灌浆期前后。在1/2行距处随着密度的增加,根系干重呈增加趋势变化;在1/2株距处,中密和高密处理差异较小,但显著大于低密。在1/4行距处,根系干重则随着密度的增加而逐渐减少。根系达到干重最大值后的下降过程均以高密处理的下降速度最快。不同取样点根系干重在土壤中的垂直分布情况为在大喇叭口期以前,根系干重最大值出现在10～20cm的土层内,而后随着土层深度的增加根系干重迅速下降;大喇叭口期以后根系干重在土壤中的垂直分布呈负指数曲线趋势变化。密度对不同取样点根系干重影响主要表现在0～40cm土层内1/2行距处拔节期各密度处理间无明显差异;小喇叭口期到灌浆期表现为高密>中密>低密;成熟期表现为中密>高密>低密。1/4行距处大喇叭口期以前各密度处理之间的差异不明显;从吐丝期到成熟期,中密和低密处理各土层的根重差异不明显,但均较高密处理的大。1/2株距处在大口期以前中密处理和高密处理各土层的根重无明显差异,但均较低密处理高,吐丝期以后各土层的根重则以中密处理最大,高密次之,低密最小。     

玉米根系特征的基因型差异及与氮吸收效率的关系

在4个硝酸盐浓度下进行2个玉米品种盆栽砂培试验,研究玉米根系特征的基因型差异对硝酸盐浓度的响应及与氮素吸收效率的关系。结果表明,氮高效品种郑单958在硝酸盐浓度为0.08、0.8、4.0 mmol/L时,根重、根幅、根长、根表面积、根体积、分枝数、分形维数、根系活力均显著高于氮低效玉米品种内单314。各根系形态指标随硝酸盐浓度的增加逐渐增加,当硝酸盐浓度从4.0 mmol/L增加至8.0 mmol/L时,不同基因型品种间差异不显著。在低氮胁迫条件下,玉米主要通过增加细根比例、增加根表面积吸收更多的氮素;在氮素供应充足条件下,通过增加根系平均直径,形成高密的分枝系统吸收氮素。进一步通径分析表明,根长与根体积对氮吸收效率直接影响最大,是氮吸收效率差异的主要原因。     

不同形态氮肥对大豆根系形态及磷效率的影响

采用框栽试验方法,研究生物固氮(CK),NO-3-N,NH+4-N,Glycin-N,Protein-N和Urea-N 6种不同形态氮素对大豆各生育时期根系生物量、根冠比、根系形态及磷效率的影响.结果表明:不同形态N处理对大豆根系生物量、根系形态特征(根长、根体积、根表面积及根尖数等)及磷吸收、利用效率影响不同,随着生育期的推进,NO-3-N和Protein-N均显著高于其它处理,但二者之间差异不显著;Glycin-N,Urea-N和NH+4-N均高于CK(生物固氮),但Glycin-N、Urea-N和NH+4-N处理间差异不显著.不同形态N处理的根干重、根长、根体积、根表面积均高于CK,而根冠比、平均直径以及磷利用效率则低于CK.     

株行配置对春玉米根冠空间分布及产量的影响

以先玉335为试验材料,设置7.50万株/hm2和9.75万株/hm2两个种植密度,60 cm+60 cm等行距和40 cm+80 cm宽窄行两个行距配置,比较株行配置对春玉米冠层、根系结构与功能及产量的影响。结果表明,随种植密度增加,果穗、茎鞘干重百分比垂直分布明显上移,叶片干重百分比在垂直分布变化较小,行距配置对果穗、茎鞘干重百分比在垂直分布上影响较小。相对于等行距种植,宽窄行种植叶片干重百分比有下移趋势,群体不同叶位叶面积指数也表现为同一密度下,宽窄行种植群体上层LAI较小,穗位叶高效叶层LAI较大;随密度增加,根重有纵向下移的趋势,根系TTC还原强度在不同土层深度都显著降低。同一密度下,宽窄行种植根重的垂直分布出现下移趋势,根系TTC还原强度略高于等行距种植。高密度条件下,宽窄行种植降低了玉米果穗秃尖长,显著增加果穗穗粒数,因而显著提高产量,增产2.73%~10.86%,说明在宁夏扬黄灌区较高种植密度下,采用宽窄行种植能优化不同叶层结构,适当增加深层土壤根系所占比例及活力,有利于获得高产。     

不同基因型冬小麦根系生长及产量的差异

通过了解不同基因型冬小麦根系生长的差异,为提高小麦产量潜力提供参考。本研究选用6个小麦品种,通过PVC管柱种植试验,研究小麦根长、根表面积、根体积、平均直径的差异以及与产量的相关性。结果表明:不同品种间根系生长量存在明显差异,洛麦23和洛麦24在根长、根表面积以及根干质量上表现出了明显的优势。与参试品种均值相比较,洛麦23和洛麦24总根长分别较平均值高4.90%、7.70%,根表面积分别较均值高9.46%、14.09%,根体积分别较均值高8.54%、17.13%,平均直径分别较均值小6.83%、3.11%,根干质量分别较均值高6.26%、13.26%。分析表明根长、根表面积、根体积与产量均达到了显著正相关。     

Rooting traits of peanut genotypes with different yield responses to pre-flowering drought stress

Water stress during the vegetative development normally is not detrimental and sometimes actually increases yield of peanut (Arachis hypogaea L.). Root growth might play an important role in response to early season drought in peanut and might result in an increase in yield. Information on the response of root characters of diverse peanut genotypes to these conditions will provide useful information for explaining mechanisms and improving peanut genotypes for exploiting positive interaction for pod yield under pre-flowering drought. The aim of this study, therefore, was to investigate the root dry weight and root length density of peanut genotypes with different yield responses to pre-flowering drought stress and their relationships with pod yield. Field experiments were conducted at the Field Crop Research Station of Khon Kaen University, Khon Kaen, Thailand during February to July 2007 and during February to July 2009. A split-plot experiment in a randomized complete block design was used. Two water management treatments were assigned as the main plots, i.e. field capacity and pre-flowering stress, and six peanut genotypes as the sub-plots. Total crop dry matter, root dry weight and root length density were recorded at 25 DAE, R5 and R7. Top dry weight and pod yield were measured at harvest and pod harvest index (PHI) was computed using the data on pod yield and biomass. Peanut genotypes were categorized into three groups based on their responses to drought for pod yield, e.g. increasing, decreasing and non-responsive groups. The genotypes of each group showed a differential response for root quantity and distribution. The increasing pod yield group had more root dry weight and root length density in the deeper soil layers during pre-flowering stress compared to the non-stress treatment. The non-responsive group showed no root response under pre-flowering drought conditions compared to the non-stress treatment. A larger root system alone without considering distribution may not contribute much to pod yield but a higher RLD at deeper layers may allow plants to mine more available water in the sub-soil. However, as yield is a complex trait, several mechanisms may be involved. The increasing pod yield group also had the ability to maintain a high PHI.     

Physiology of the Potato: New Insights into Root System and Repercussions for Crop Management

Potato roots are concentrated mostly in the plow layer up to 30 cm in soil depth. Some roots extend up to 100 cm depth and the total root length throughout the soil profile reaches about 10–20 km m^?2 area. There are large differences in root mass (dry weight and length) in the plow layer between cultivars, breeding lines and wild relatives. The differences are generally stable across different environmental conditions, such as locations with different soil types, fertilizer rates and planting densities. Under favourable environmental conditions without severe shortage of water and nutrients, root mass differences between genotypes are related to maturity class: late genotypes continue root growth longer, and attain larger root mass and deeper rooting than early genotypes. Differences in root mass become clear at the start of flowering, much earlier than differences in shoot mass. Root mass is negatively correlated with early tuber bulking. However, root mass generally shows positive correlations with shoot mass and final tuber yield. Differences in root mass also exist amongst genotypes of the same maturity class. Using root mass in the plow layer and tuber yield as selection criteria, Konyu cultivars were bred in Japan. They showed significantly less reduction of leaf conductance and photosynthesis, leaf area and tuber yield than commercial cultivars under dry soil conditions. To assist breeding for root characters, new methods have been developed to assess the ability of roots to penetrate into hard soil layers using pots with paraffin-vaseline discs and the ability to absorb under low water potential in vitro. Physiological research on root characteristics contributed in the past, and will continue to do so in the future, to the development of new cultivars with high drought tolerance and to the improvement of irrigation practice.     

玉米不同部位根系生长发育规律的研究

采用PVC管栽法对不同密度处理下玉米初生根系和各层次节根的生长发育及生理活性变化规律进行了研究。结果表明:随着玉米生长发育进程,各部位根系干物重、表面积及活性表面积的变化趋势基本相同,均呈单峰曲线变化;不同部位根系干物重、表面积及活性表面积达到峰值的时间和数值并不相同,表现为一个交替消长的过程,发生时间越晚、根层位越高,其峰值也越大,且高密处理的峰值均大于低密处理。根冠生长发育关系表明:在一定范围内玉米根系发生的层位及干重达到最大值的根系层位均能用叶龄来表述,且相关性达到了极显著。     

不同灌溉方式对春玉米根系分布、养分累积及产量的影响

通过田间试验,研究不同灌溉方式下东北中部春玉米区土壤结构、根系形态、地上部养分累积及产量构成。结果表明,灌溉后土壤三相比显著变化,土壤固相下降,液相和气相比例显著增加,0～20 cm土壤容重降低6.7%～17.9%;灌溉后0～60 cm根系干重及根长总量略有增幅,且在深层土壤中的比例增加,有利于植株对养分和水分的吸收;与不灌溉（CK）相比,隔沟交替灌溉（T1）、全垄灌溉（T2）下植株氮、磷、钾含量平均提高14.5%、42.6%、16.1%,生物量和产量平均提高19.8%和14.3%。因此,在春玉米关键生育期合理补水可以改善土壤结构,降低土壤容重,促进根系合理分布,增加植株养分吸收,进一步增加产量。     

Root architecture of sorghum genotypes differing in root angles under different water regimes

Plant root architecture offers the potential for increasing soil water accessibility, particularly under water-limited conditions. The objectives of this study were to evaluate the root architecture in two genotypes of sorghum (Sorghum bicolor (L.) Moench) differing in root angles and to assess the influence of different deficit irrigation regimes on root architecture. The response of two sorghum genotypes, ‘Early Hegari-Sart’ (EH; steep root angle) and ‘Bk7’ (shallow root angle) to four irrigation treatments was investigated in two replicated outdoor studies using large pots. The results indicated that EH possessed steeper brace and crown root angles, fewer brace roots, greater root biomass, and root length density than Bk7 at deeper soil depths (i.e., 15–30 and 30–45 cm) compared with a shallower depth (i.e., 0–15 cm). Across the soil profile, EH had greater root length density and length of roots of small diameter (<1 mm) than Bk7. Accordingly, EH showed more rapid soil-water capture than Bk7. Different levels of irrigation input greatly affected root architecture. Severe deficit irrigation (25% of full crop transpiration throughout the season) increased the angle and number of crown roots, root biomass, and root length density compared with 75 and 100% of full crop transpiration treatments. Consequently, root system architecture can be effectively manipulated through both genotypic selection and irrigation management to ensure optimal performance under different levels of soil available water.     

垄作栽培对寒地水稻根系生长的影响

 以黑龙江省早熟高产优质粳稻品种空育131为材料,通过垄作栽培与平作栽培方式对比试验,研究垄作栽培对寒地水稻根系生长的影响。结果表明，水稻根系的生长和分布在不同栽培方式间有较大差异，供试品种在不同的栽培方式下其根系体积、干质量、根长及活力均存在明显不同。与对照（平作）相比，水稻（空育131）在垄作栽培条件下根系发达，表现为根长增加、根系干质量增大，根量尤其下层根量增多，根系吸收面积增大，根冠比增大，产量提高。     

土壤剖面硝态氮非均匀分布条件下小麦根系生长和氮素吸收特征

为探讨土壤硝态氮非均匀分布条件下小麦根系生长及氮素吸收特征,选用石麦15、衡观35、H10和L14等4个小麦品种为材料,进行土壤分层培养试验,模拟土壤剖面中上下层硝态氮空间分布差异,测定和分析了小麦根系长度、直径、分布等形态学特征及植株氮素含量和累积量。结果表明,当土壤中硝态氮施用量上层较低、下层较高时,小麦植株根系总长和表面积在上下土层中分布比值降低,根系趋向下层土壤生长。上下层土壤中硝态氮施用量均较高时,上下层土壤中的根系总长和表面积比值较大,根系趋向上层土壤生长。土壤剖面不同层次中硝态氮供应非均匀条件下,小麦根系发育呈现明显的可塑性反应。小麦根系总长和表面积以及直径≤0.15mm的细根长(占整个根系的比重很大)与植株地上部氮含量和氮素积累量极显著正相关,与土壤中硝态氮含量极显著负相关。     

Root distribution under seepage-irrigated potatoes in Northeast Florida

Much of commercial potato production in Florida is irrigated using sub-surface seepage irrigation. A perched water table is maintained during the season within 50 cm below the top of the potato ridge. Fertilizer placement is critical in this system to maximize plant uptake and to minimize leaching potential. Optimal placement of fertilizers is dependent on root distribution. The objectives of this study were to develop and test a new methodology to spatially describe potato root distribution as affected by nitrogen rate and irrigation system. Soil slices containing representative samples of the potato root system at full flowering were taken from plots fertilized with ammonium nitrate at 168, 224, and 280 kg N ha^?1. The proposed sampling methodology performed satisfactorily. Root length density (cm root cm^?3 soil) and specific root length (cm root mg^?1 root dry weight) were not affected by nitrogen rate, but were affected by spatial position in the soil profile. The highest root length density value (0.72 average) was observed within 12 to 15 cm of the seedpiece. Low root length density values averaging 0.036 were observed between 24 and 36 cm from the top of the ridge. Specific root length values indicated a relatively homogeneous root system in terms of the quantity of invested biomass by unit of root length except in the two central units below 24 cm from the top of the ridge where thickened roots caused significant lower values averaging 6.47 as compared with the average of 15.87 from the surrounding Units in the slice. Root thickening in deep apical roots suggested aerenchyma formation promoted by a combination of saturated soil conditions in the root zone caused by inappropriate irrigation management and soil compaction. Fertilizer placement under the seedpiece should be a good alternative to increase potato nitrogen uptake under seepage irrigation.