Interstock effects on growth,photosynthesis and mineral nutrition of ‘delicious’ apple seedlings

Tree growth, photosynthesis, and the mineral nutrient content were investigated in ‘Redchief Delicious’ scions double worked on seedling rootstock with a variety of interstocks. The interstocks used were ‘Redchief Delicious’, M9, and a range of F. generation hybrids with internodes designated short, medium and long. The long internode graft union consistently produced more growth and dry weight per tree than the other interstocks. The ‘Redchief Delicious’ interstock had an unexplained negative effect on leaf, shoot and new root dry weight. There was no effect of interstock on photosynthesis initially (56 days) however photosynthesis increased with shorter nodal interstocks after 111 days. There were significant differences in scion and interstock bark elemental composition due to interstock combination. However, leaf composition varied slightly among the different interstock combinations. Manganese levels, independent of tissue type, did not vary between interstocks.     

低磷胁迫下不同磷效率玉米某些特性的基因型差异

以2个磷高效玉米基因型6112、6060和2个磷低效玉米基因型6105、6128为材料进行试验,研究了低磷胁迫下不同磷效率玉米基因型生物学指数、根系分泌物指数、叶片活性氧清除酶活性(SOD、CAT)和叶片丙二醛LP/P的差异,其结果是:磷高效基因型的生物学指数、根系分泌物指数和叶片活性氧清除酶活性比磷低效基因型高,而叶片丙二醛LP/P比磷低效基因型低。表明磷高效基因型比磷低效基因型具有较强的低磷忍耐能力、分解吸收磷能力、活性氧清除能力和自我修复能力。     

Root exudation of sugars,amino acids,and organic acids by maize as affected by nitrogen,phosphorus, potassium,and iron deficiency

Root exudates play a major role in the mobilization of sparingly soluble nutrients in the rhizosphere. Since the amount and composition of major metabolites in root exudates from one plant species have not yet been systematically compared under different nutrient deficiencies, relations between exudation patterns and the type of nutrient being deficient remain poorly understood. Comparing root exudates from axenically grown maize plants exposed to N, K, P, or Fe deficiency showed a higher release of glutamate, glucose, ribitol, and citrate from Fe‐deficient plants, while P deficiency stimulated the release of γ‐aminobutyric acid and carbohydrates. Potassium‐starved plants released less sugars, in particular glycerol, ribitol, fructose, and maltose, while under N deficiency lower amounts of amino acids were found in root exudates. Principal‐component analysis revealed a clear separation in the variation of the root‐exudate composition between Fe or P deficiency versus N or K deficiency in the first principal component, which explained 46% of the variation in the data. In addition, a negative correlation was found between the amounts of sugars, organic and amino acids released under deficiency of a certain nutrient and the diffusion coefficient of the respective nutrient in soils. We thus hypothesize that the release of dominant root exudates such as sugars, amino acids, and organic acids by roots may reflect an ancient strategy to cope with limiting nutrient supply.     

低磷胁迫下马尾松无性系磷效率性状对氮沉降的响应

【目的】剖析不同类型低磷胁迫下马尾松应对大气氮沉降的生长表现和适应机制,为在大气氮沉降背景下选育营养高效利用的马尾松速生优质新品种提供理论依据。【方法】以来自马尾松 (Pinus massoniana) 全同胞子代的 5 个优良无性系 1 年生扦插幼苗为材料,分别在同质低磷 (介质表层与深层均缺磷) 和异质低磷 (介质表层磷丰富、深层缺磷) 两种土壤磷素环境下设置两种浓度梯度的模拟氮沉降试验,以研究低磷胁迫下马尾松无性系苗木生长、根系发育及氮、磷效率对模拟氮沉降的响应差异和规律。【结果】1) 不同类型低磷胁迫下马尾松苗高和干物质积累量均表现出显著的无性系变异,且在同质低磷下存在明显的无性系 × 氮交互效应 (P < 0.05)。2) 马尾松无性系在不同类型低磷胁迫下应对氮沉降的适应机制有所差异。同质低磷、高氮环境下,33-4 和 19-5 等生长势较强的无性系,其根系长度、根表面积以及根分泌的酸性磷酸酶活性显著高于生长势较弱的无性系,干物质积累量与酸性磷酸酶活性之间的相关性增强,表明根系可通过增加在土壤中的分布面积和提高酸性磷酸酶活性来应对高氮、低磷的外界环境;异质低磷下,生长势较强的无性系,其根系长度和表面积在高氮沉降下显著增加,但比根长反而显著下降,意味着根系在高氮下增加吸收面积的同时,降低自身内部消耗可能是马尾松高磷效率的重要生物学基础之一。3) 马尾松无性系的磷吸收效率受氮沉降影响较大,在不同氮、磷水平下,其磷吸收效率与氮吸收效率均呈极显著正相关 (P < 0.01),表明模拟氮沉降有利于马尾松无性系对土壤中磷素的活化吸收,但磷利用效率无显著差异。4) 马尾松无性系的干物质积累量、根系长度、根表面积以及根分泌的酸性磷酸酶活性等指标的变幅较大,且无性系重复力均达到 0.75 (P < 0.05) 以上,这为高氮、低磷环境下马尾松耐受型植株的选择提供了可能。 【结论】以马尾松根系形态和根分泌的酸性磷酸酶活性变异为突破口,选育氮沉降下具有高磷效率的马尾松无性系将有利于遗传效益的提高。     

Plant Growth in Response to Phosphorus Fertilizers in Acidic Soil Amended with Limestone or Organic Matter

Liming or adding organic matter may improve productivity of soils receiving phosphorus (P) fertilizers. This study assessed the effectiveness of amendment of acidic soil with limestone and organic matter on growth of tomato (Lycopersicon esculentum Mill.), corn (Zea mays L.), and cucumber (Cucumis sativus L.) with different P fertilizers. These crops were grown in a greenhouse to evaluate superphosphate, bone meal, and rock phosphate as fertilizers and calcitic limestone and peat moss as amendments. Superphosphate was the superior P source to sustain crop growth, limit deficiency symptoms, and enhance P accumulation. Bone meal was less effective than superphosphate but exceeded rock phosphate in these capacities. Rock phosphate was better than adding no P fertilizer. The amendments of limestone or organic matter singly or together had little effect on growth, appearance, or P accumulation. The availability of P in the fertilizers governed the growth responses of the plants.     

Phosphorus Use Efficiency of Wheat Genotypes Grown in Calcareous Soils

ABSTRACT

Phosphorus (P) deficiency and low P-use efficiency are induced by soil properties, especially in calcareous soils, which are dominant in semi-arid regions of the world such as the Mediterranean region. Alternative approaches to P fertilization involve exploiting plant genetics in order to achieve more efficient use of P by the growing crop. Accordingly, in a greenhouse pot experiment, we evaluated P-efficiency in wheat genotypes grown in typical calcareous soils in southern Turkey. Ten common local genotypes were grown in six soil series for eight weeks using five P application rates (0, 25, 50, 100, and 200 mg P kg^?1). Dry matter (DM) yield and P content were significantly increased by increasing P rates, with significant differences between soils. Some genotypes performed better under P stress because of better P utilization efficiency. Shoot DM was the most sensitive indicator of genetic variability under P-deficient conditions. Genotypes classified as efficient-responsive (Adana-99, 1014, Golia, Balatilla) had above average DM yield when P was not added, and responded well to P applications; efficient-non-responsive genotypes (Firat-93, Seri-82, Genc-99, Panda) had below average DM yield, but responded to P applications; inefficient-non-responsive genotypes (Fuat Bey and Ceyhan-99) had below average DM yield; and no genotypes were in the inefficient responsive category. Such P response categorization is needed for better breeding programs for nutrient-use efficiency. The study may aid in selecting P-efficient genotypes in low-P soils, especially where little P is used. The use of P-efficient genotypes should be seen as complement to, rather than a substitute for, chemical P fertilization depending on local conditions.     

玉米苗期根系生长与耐低磷的关系

在田间筛选试验的基础上,利用两个磷高效(181和186)、两个磷低效(153和197)玉米自交系,进一步研究了这些自交系苗期耐低磷能力差异及其与根系生长的关系。结果表明,在低磷胁迫(P.5.78.mg/kg)下,所有自交系玉米地上部重量、初生根重、次生根重及磷累积量降低,但磷高效自交系181和186受影响程度显著小于153和197。在试验所处的玉米生育时期(6叶龄),磷对所用自交系的初生根及次生根数量没有影响。比较181和197的根系形态,在低磷胁迫下,磷低效自交系197的初生根侧根长、轴根长均显著下降,磷高效自交系181则下降幅度很小。而且,低磷使181初生根的侧根/轴根比值、根长度/根重比值较高。说明低磷胁迫下,181自交系可以将根中的有限的养分及干物质作更合理的分配,促进细根的生长,从而获得较长的根系。     

植物根系活性对菲浓度的响应——以栾树、樟树为例

[目的]分析栾树、樟树根系分泌物在菲胁迫下的变化特征,为筛选抗多环芳烃污染树种,进一步开展植物修复多环芳烃污染提供科学依据。[方法]设置3种菲处理浓度[L_0(CK, 0 mg/kg);L_1(100 mg/kg);L_2(1 000 mg/kg)],通过盆栽试验的方法,对栾树、樟树的根系分泌物中总有机碳(TOC)、全碳(TC)、全氮(TN)含量及根系活性进行测定。[结果]①随着菲浓度的升高,栾树与樟树根系分泌物中TOC与TC含量均呈下降趋势,TN含量则呈先升后降的趋势;②随着菲浓度的升高,栾树和樟树根系的总吸收面积和活跃吸收面积总体呈下降趋势;③3个处理水平下,栾树根系分泌物中TC,TOC,TN含量均高于樟树,且栾树根系总吸收面积和活跃吸收面积也高于樟树。[结论]通过菲胁迫下栾树与樟树根系分泌量和根系活性的比较,表明栾树相较于樟树对菲具有更好的耐受性。     

外生根真菌对盐渍土中油松营养成分吸收和平衡的影响

Pinus tabulaeformis seedlings were grown under a factorial design to measure biomass accumulation and P, Na and K concentrations of plants, with 3 different ectomycorrhizal fungus (EMF) strains (Boletus edulis, Xerocomus chrysenteron and Gomphidius viscidus) and two P treatments (with or without extra P). Growth and mineral nutrition of pine seedlings were stimulated by three EMF under salinity stress. Na concentrations were changed and plant K and P concentrations were increased significantly by EMF. Adding extra P made no difference in accumulation of seedlings biomass, and did not assist element absorption of plants. Although three strains of EMF can all enhance the tolerance of pine seedlings to salinity stress, they may utilize different mechanisms because of different performance in absorption of elements. The increased P and K accumulation and the balance of ion concentrations might be due to the enhanced tolerance of EMF-inoculated plants to saline conditions.     

不同磷效率小麦对低铁胁迫的基因型差异

用营养液培养方法研究了不同磷效率小麦幼苗对低铁胁迫的基因型差异。结果表明,低铁胁迫(-Fe)对磷高效基因型小麦生长的抑制作用显著大于对磷低效基因型。低铁处理下,磷高效基因型81(85)-5-3-3-3、Xiaoyan54和Taihe-5025的植株地上部干重平均比正常供铁(+Fe)处理下降55.2%;磷低效基因型Jinghe90-Jian-17、NC37和Jing41平均33.0%。低铁胁迫显著降低了磷高效基因型小麦的叶片叶绿素含量,3个磷高效基因型的叶绿素a、叶绿素b和叶绿素a+b含量分别降低了35.6%、35.3%和35.3%,磷低效基因型分别降低了16.8%、7.7%和11.9%。低铁胁迫对小麦的根系生长、根系吸磷量和磷利用效率均未产生明显的影响,但显著降低了磷高效基因型小麦的植株地上部吸磷量和根效率比。与正常供铁的处理相比,磷高效和磷低效基因型小麦的地上部吸磷量和根效率比在低铁处理中平均降低了55.0%、54.9%和32.5%、36.4%。磷高效基因型小麦植株体内积累的磷量明显高于磷低效基因型,这是磷高效基因型不耐低铁的主要原因。磷效率越高,对低铁的反应越敏感。