香蕉对低pH和铝毒胁迫的响应

香蕉是世界重要的热带亚热带水果,在热带经济的发展中占有重要的地位.我国是世界香蕉重要生产国之一,总产量仅次于印度,位居世界第二.低pH和铝毒是香蕉生产中面临的重要限制因子,严重影响香蕉的产量和品质.明确低pH和铝毒胁迫对香蕉生长和养分吸收的影响,为调控酸性土壤提供重要的理论依据.本研究分别在盆栽和水培条件下开展试验,盆...     

Assessment of aluminum sensitivity of maize cultivars using roots of intact plants and excised root tips

Maize cultivars (Zea mays L.) were evaluated for their aluminum (Al) sensitivity using intact plants and excised root tips exposed to 25 μM Al in nutrient solution of low ionic strength and pH 4.3. Aluminum supply increased callose formation and Al concentrations in root tips of intact plants as well as in excised root tips. Using intact plants, differences in Al sensitivity among cultivars could be characterized by Al‐induced callose formation, Al‐induced inhibition of root elongation, as well as Al contents in root tips as parameters. Significant correlations between Al‐induced callose formation and Al contents in root tips (r² = 0.64**) and inhibition of root elongation (r² = 0.80***) were found. Excised root tips did not show a significant Al‐induced inhibition of root elongation. While average Al‐induced callose formation was similar for root tips of intact plants and excised root tips, mean Al contents in excised root tips were up to 1.5‐fold higher than in root tips of intact plants after 24 h of Al treatment. Aluminum‐induced callose formation as found in excised root tips did neither correspond to Al‐induced callose formation nor to inhibition of root elongation of intact plants. The addition of 10 mM glucose to the incubation medium led to a significant increase in the elongation of excised root tips and a 2‐3‐fold increase in Al‐induced callose formation. Staining with triphenyl‐tetrazolium‐chloride (TTC) revealed increased viability of these root segments. However, these effects of glucose supply did not improve the characterization of the cultivars for Al resistance. The results presented suggest that Al exclusion mechanisms expressed in root tips of intact plants might be non‐operational in excised root tips. Therefore, the characterization of maize germplasm for Al resistance using excised root tips appears not to be reliable.     

铝对马尾松菌根苗生长及营养元素吸收的影响

以接种褐环乳牛肝菌和未接种的马尾松幼苗为试验材料,采用水培法研究不同浓度铝(Al^3+)处理(0、0.2、0.4、0.8和1.2 mmol·L^-1)对菌根化和非菌根化马尾松幼苗生长、营养元素吸收的影响,揭示菌根化马尾松苗木对Al^3+的适应机制,为减轻马尾松苗木铝毒害现象提供理论和技术依据。结果表明,在相同浓度Al^3+胁迫下,接种褐环乳牛肝菌的马尾松幼苗苗高、生物量、根系形态以及对氮(N)、磷(P)、钾(K)的吸收能力均优于不接种的马尾松苗。马尾松幼苗苗高、干物质量积累以及根系生长随着Al^3+浓度的增大均呈现先升后降再升的趋势,随着Al^3+浓度的逐渐增大,马尾松幼苗根、茎、叶中的N、P、K含量呈现出低促高抑的趋势,根、茎、叶中Al^3+含量的分配为根>茎>叶。Al^3+胁迫下,接种褐环乳牛肝菌的马尾松幼苗,通过改变马尾松幼苗根系结构,促进了幼苗的生长,特别是根系的生长,以及对N、P、K等营养元素的吸收,抑制了根系吸收Al^3+,提高了马尾松幼苗的耐铝能力。     

Steedman’s wax包埋切片DAPI染色法证实铝诱导花生根尖细胞程序性死亡

【目的】检验Steedman’swax包埋切片DAPI染色法是否适用于观察花生根尖细胞核形态。【方法】分别采取100μmol/L AlCl3处理不同时间（0、4、8、12 h）后两个花生品种（铝敏感型中花2号和耐铝型99-1507）的根尖,经过Steedman’s wax包埋切片等一系列过程,利用荧光染料DAPI染色观察细胞核形态变化。【结果】100μmol/L AlCl3可引起花生根尖细胞核形态发生改变,核质浓缩、核边缘化、呈新月状等,具有明显的PCD特征。花生根尖细胞在铝胁迫下发生PCD,PCD程度与花生耐铝性呈负相关,与处理时间呈正相关。【结论】Steedman’swax包埋切片DAPI染色法是一种快速、高效的适用于观察花生根尖细胞核形态的方法。     

Desorption Characteristics of Three Mineral Oxides and a Non-crystalline Aluminosilicate for Supplying Phosphate in Soilless Root Media

The objective was to evaluate phosphate desorption characteristics of synthetic hematite, goethite, and allophane and commercial alumina after loading at maximum adsorbed phosphate levels to determine their potential to release phosphate at a constant, low level to sustain plant growth in soilless media and reduce phosphate leaching. Desorption isotherms were measured at pH 6.4 ± 0.1 using a continuously stirred-flow reactor. The time period during which dissolved phosphate was maintained within the range of 5–0.2 mg·L^?1 phosphate-P decreased in the order: allophane (12.4 d) > alumina (4.6 d) > goethite (3.6 d) > hematite (1.9 d). Allophane released the most phosphate during the desorption process (40% of maximum adsorbed phosphate; 12.7 mg?g^?1) followed by alumina and goethite (19–20%; ≈2.5 mg?g^?1) and lastly hematite (5%; 0.1 mg?g^?1). Allophane demonstrated the greatest potential as a phosphate-charged source for soilless root media, in amount and duration of phosphate release.     

接种双色蜡蘑对马尾松根际土壤无机磷和活性铝含量的影响

将双色蜡蘑(Laccaria bicolor)的3个株系(Lb 270、Lb S238A和Lb S238N)分别与马尾松种子拌匀,培养在酸性土壤中,以检测根际土壤无机磷和活性铝含量,并分析外生菌根对磷有效性和铝活性的作用。结果发现,与非菌根苗相比,接种双色蜡蘑显著促进马尾松幼苗生长和对磷、铝的吸收,而对根际土壤无机磷和活性铝含量的影响因菌株而异:Lb 270和Lb S238N显著降低pH、有效磷、全铝、交换态铝含量,提高羟基态铝含量,且Lb 270还显著降低铁磷和钙磷含量;Lb S238A显著提高pH、有效磷含量,减少铝磷、全铝、活性铝、交换态铝和腐殖酸铝含量。即接种双色蜡蘑提高了磷的生物有效性,且Lb 270和Lb S238N增加、Lb S238A减少铝的活性。因此,接种供试双色蜡蘑都能提高马尾松的抗铝性,主要在于其增加磷的生物有效性,而是否降低铝的活性取决于菌株特性。     

不同基因型油菜耐铝性及其根系形态对铝胁迫的响应

本研究旨在为酸性土壤地区筛选耐铝毒的甘蓝型油菜,探讨不同基因型油菜苗期生长发育指标和生理指标的耐铝特性,分析铝胁迫对根系形态的影响。以81个油菜品种为材料,通过水培试验,设置铝浓度（AlCl3）0、100 μmol·L-1两个处理,对根系形态、株型、生物量、生理特性等13指标的耐铝系数进行相关分析、主成分分析和聚类分析,采用隶属函数法综合评价不同基因型油菜的耐铝相关指标,并分析不同耐铝类型的品种根系形态差异。结果表明,铝胁迫对不同基因型油菜苗期各单项指标有不同程度的影响,综合应用主成分分析、聚类分析和隶属函数法筛选出耐铝性较强的品种6个,耐铝性中等的品种65个,耐铝性弱的品种10个。不同直径范围根系对铝胁迫的响应不同,铝胁迫下,D1类根系（直径0.0～0.5 mm）的长度、表面积、体积、根尖数降幅最大,D3类根系（直径>2.0mm）各指标降幅最小,且铝敏感型品种不同类别的根系指标受铝胁迫的抑制程度大于耐铝型品种,其D1、D2（直径0.5～2.0 mm）、D3类根系的长度、表面积、体积、根尖数均少于耐铝型品种。因此,以综合指标对油菜耐铝性进行筛选与评价更为客观;耐铝型品种不同直径范围的根系受铝毒害的影响较轻,通过改变根系形态适应铝胁迫的能力更强,其根系拥有更多细根可能是耐性品种抗铝毒的一种作用机制。     

接种双色蜡蘑对马尾松幼苗生长、养分和抗铝性的影响

在我国南方,森林土壤的养分含量普遍较低,缺磷缺钙现象非常严重,加之土壤酸化导致活性铝含量增加,严重抑制马尾松的生长,在部分地区甚至已发生了大面积的森林衰亡现象(侯爱敏等,2002;周志春等,2003)。为提高土壤养分含量及防治铝毒害,农业上采用了施石灰、磷肥或有机肥等措施,然而林业生产的特殊性,决定了难以实施这些措施。有研究表明,优良的外生菌根真菌与树木根系形成外生菌根之后,能活化土壤中的难溶性养分,减轻铝的危害作用,并向寄主提供生长促进物质,促进森林生长,防治退化衰亡(郭秀珍等1989)。如彩色豆马勃(Pisolithustinctorius)形…     

酸铝对杉木磷吸收和代谢的影响

用＾３２Ｐ示踪原子法通过水培试验研究了酸性条件下铝对１年生杉木的根和叶磷吸收和代谢的影响。结果表明,在ｐＨ＝３时,用酸铝处理根和叶后,根中＾３２Ｐ－无机磷增加到对照的１９５％,叶片＾３２Ｐ－无机磷转运指数由４３．０降低到２０．０。根的Ｐ总含量中的各＾３２Ｐ－化俣物比例发生较大变化,无机磷增加到对照的１７５％,有机化合物,脂类化合物,ＤＮＡ,ＲＮＡ分别减少到对照的５５％,４２％,３６％,４０％;叶中     

石墨炉原子吸收光谱法测定土壤铝的条件优化

酸性土壤中的活性Al是影响作物生长发育的主要因子之一,土壤Al的测定一直是人们关注的问题。石墨炉原子吸收光谱法测土壤Al所需的样品量少、灵敏度高、离子干扰小,目前在国内外应用较为广泛。由于其测试条件多是应用单因素轮换法来确定,存在实验量大且未考虑交互作用的影响等缺点。采用双因素重复实验及正交实验可显著降低确定最佳测试条件的工作量,且实验条件代表性强,对于准确快捷测定土壤Al具有重要意义。通过双因素（波长和灯电流）重复试验对石墨炉原子吸收光谱仪测定土壤Al的波长和灯电流进行了优化选择,确定最佳波长为309.3nm,最佳灯电流为14mA;应用L2（556）正交试验法对控温程序及基体改进剂、基体酸度条件进行了优化,得出最佳的灰化温度为1400℃、灰化时间为10s,原子化温度为2300℃、原子化时间为5s,最佳基体改进剂为0.1%NH4H2PO4、最佳基体酸度为0.2%硝酸。优化后的方法检出限为1.14μg.L-1,加标回收率达到93.6%~104.1%,相对偏差均小于8%。