不同基因型春小麦对磷胁迫适应性研究

采用盆栽试验,测定了4种基因型春小麦在不同生育期,3种磷水平下植株体内酸性磷酸酶活性、根长、根半径、根干重、根冠比、地上部干重、产量等指标,研究了小麦生长对磷素的利用效率。结果表明：甘春20号对磷素的敏感性在酸性磷酸酶活性、根干重、地上部干重、增产潜力均强于陇春16号、会宁18号和定西33号,是磷高效基因型;高磷对陇春16号的根冠比和根干重影响显著,定西33号和会宁18号的根长较长,因此陇春16号、会宁18号和定西33号仍具有一定的磷素利用潜势。     

土壤水分对两个冬小麦品种产量和竞争能力的影响

研究了黄土塬区两个旱作冬小麦品种(长武135和平凉40,前者是后者的换代品种)在不同土壤水分条件下竞争能力和产量形成的关系。研究设2种土壤水分条件(土壤含水量为田间最大持水量的75%～80%和40%～45%),采用生态替代法设计了同一播种密度的6个播种比例组合的盆栽试验。低水分单播条件下,长武135具有较高的产量(长武135为27.59g/pot,平凉40为24.91g/pot),而混播条件下平凉40在产量和相对产量上较长武135品种具有明显的竞争优势。高水分条件下,平凉40产量随播种比例的减小下降较快(长武135产量曲线斜率35.468,平凉40为36.237)。平凉40低水分单播时花后干物质积累量较少(长武135为0.67g/pot,平凉40为0.55g/pot),而混播时较多(长武135各比例均值0.58g/pot,平凉40为0.71g/pot),导致了平凉40品种单播时产量较低和混播时产量较高。平凉40地下生物量显著大于长武135(高水分条件下,长武135为10.03g/pot、平凉40为11.51g/pot;低水分条件下二者分别为8.41g/pot和10.69g/pot),且耗水量大(高水分条件下平凉40多耗水2.72kg/pot,低水分条件下多耗0.98kg/pot),而耗水量/地下生物量的比值平凉40低于长武135,从而平凉40品种单位根量消耗的水分低于长武135。总之,在两个生长属性接近的冬小麦品种中,老品种以较大的根系生物量赢得了较高的竞争能力,消耗了较多的水分,而新品种虽然根系生物量较低,耗水量较少,但籽粒产量却较高。亦即,小麦新品种籽粒产量的提高是与根系的减少和对水资源竞争能力的下降相伴随的。     

Exogenously applied paclobutrazol modulates growth in salt-stressed wheat plants

Effect of paclobutrazol (PBZ) treatment on salinity tolerance of wheat (Triticum aestivum) was investigated on a salt-tolerant (Karchia-65) and salt-sensitive (Ghods) cultivars. Salinity significantly reduced the investigated growth parameters such as plant height, length and area of sixth leaf, root length, fresh and dry weight of shoot, roots and sixth leaf, water content (WC) of plant and seeds weight in the both cultivars. The negative effect of salinity in Ghods cultivar was more than Karchia cultivar. However, PBZ treatment reduced the growth in both cultivars, the differences in plant growth among various levels of NaCl decreased in PBZ-treated plants. Salt stress resulted in high accumulation of Na⁺ in the sixth leaf and roots in both cultivars, particularly in Ghods cultivar. Against Karchia cultivar, salt stress decreased the storage of K⁺, P and N in sixth leaf and roots in Ghods cultivar. In the both cultivars, PBZ treatment enhanced the K⁺, P and N contents in sixth leaf and roots by increasing salinity. Although PBZ treatment decreased the growth of plants, it improved the weight of seeds against stress damage. PBZ treatment reduced the accumulation of harmful Na⁺ ion in plant tissues while increased the K⁺, P and N contents. These observations suggest that PBZ treatment may increase tolerance by diminishing ionic imbalance caused by salt stress.     

Growth,abscisic acid content,and carbon isotope composition in wheat cultivars grown under different soil moisture

Changes in dry matter accumulation and allocation, abscisic acid content and carbon isotope composition of three wheat cultivars from dry, middle and wet climate regions were recorded at full maturity after exposure to different watering regimes (100, 50 and 25 % field capacity). Compared with the wet climate cultivar, the dry climate cultivar showed lower stem height, total leaf area, total dry biomass and total grain dry mass, and higher root/shoot ratio, abscisic acid content and carbon isotope composition under all watering regimes. Both water-limited treatments significantly reduced leaf growth and increased dry matter allocation into the roots leading to a significant raise of root/shoot ratio in all cultivars tested. In addition, drought affected morphological and physiological properties more in the dry climate cultivar than in the wet climate cultivar.     

Synergistic effects of drought and ascorbic acid on growth,mineral nutrients and oxidative defense system in canola (Brassica napus L.) plants

A study was conducted to find out the role of ascorbic acid (AsA) in modulating growth and different physio-biochemical attributes of canola plants under well-watered as well as water-deficit conditions. Drought stress imposed on 60 % field capacity significantly decreased the shoot and root fresh and dry weights, leaf chlorophyll contents, shoot and root P, root K⁺, and activity of CAT enzyme, while increased chlorophyll a/b contents, MDA, NPQ, leaf total phenolics, free proline and GB contents in both canola cultivars. Foliar-applied varying levels (50, 100 and 150 mg L^?1) of AsA enhanced shoot and root fresh and root dry weights, qN, NPQ, shoot and root P, AsA as well as the activity of POD enzyme particularly under drought stress conditions. Of both canola cultivars, cv. Dunkeld was higher in shoot fresh weights, ETR and F _v /F _m, MDA, proline and GB contents, and POD activity, however, cv. Cyclone in total phenolics and qN under well-watered and water-deficit conditions. Overall, the foliar-applied AsA had a positive effect, though not marked, on salt sensitive cv. Cyclone in terms of improved growth and other attributes, whereas exogenously applied AsA had a non-significant effect on relatively salt tolerant cv. Dunkeld.     

盐胁迫环境下不同抗盐性小麦品种幼苗长势和内源激素的变化

采用两种浓度NaCl溶液,对不同抗盐性小麦品种德抗961(抗盐性强)和泰山9818(抗盐性弱)萌发期幼苗进行胁迫处理,观察其幼苗长势和内源激素含量变化.结果表明,盐胁迫抑制小麦幼苗生长,抗盐性弱的泰山9818受抑制较重.苗、根ABA含量随盐胁迫浓度增加而提高,泰山9818的增幅高于德抗961.苗、根IAA含量随盐胁迫浓度增加而降低,但德抗961的IAA含量高于泰山9818,说明盐胁迫下抗盐性强的品种具有较高IAA合成量.2品种GA3含量变化因盐胁迫浓度而异.在低盐胁迫下抗盐性强的品种苗中GA3含量提高以适应盐胁迫利于苗的生长,在高盐胁迫下2品种GA3含量降低.盐胁迫使苗中ZR含量增加,且德抗961的苗中ZR含量高于泰山9818,而根中ZR含量则前者低,说明盐胁迫下抗盐性强的品种可迅速将根部合成的ZR向苗中转移,促进苗的生长.2品种IAA/ABA、GA3/ABA比值随盐胁迫浓度增加和时间延长而下降,德抗961 IAA/ABA比值大于泰山9818.在盐胁迫下,抗盐性强的品种协调自身激素平衡的能力较强可能是其生长受抑制较小的重要原因.     

Genetic variation in pea (Pisum sativum L.) demonstrates the importance of root but not shoot C/N ratios in the control of plant morphology and reveals a unique relationship between shoot length and nodulation intensity

Nodule numbers are regulated through systemic auto‐regulatory signals produced by shoots and roots. The relative effects of shoot and root genotype on nodule numbers together with relationships to organ biomass, carbon (C) and nitrogen (N) status, and related parameters were measured in pea (Pisum sativum) exploiting natural genetic variation in maturity and apparent nodulation intensity. Reciprocal grafting experiments between the early (Athos), intermediate (Phönix) and late (S00182) maturity phenotypes were performed and Pearson's correlation coefficients for the parameters were calculated. No significant correlations were found between shoot C/N ratios and plant morphology parameters, but the root C/N ratio showed a strong correlation with root fresh and dry weights as well as with shoot fresh weight with less significant interactions with leaf number. Hence, the root C/N ratio rather than shoot C/N had a predominant influence on plant morphology when pea plants are grown under conditions of symbiotic nitrogen supply. The only phenotypic characteristic that showed a statistically significant correlation with nodulation intensity was shoot length, which accounted for 68.5% of the variation. A strong linear relationship was demonstrated between shoot length and nodule numbers. Hence, pea nodule numbers are controlled by factors related to shoot extension, but not by shoot or root biomass accumulation, total C or total N. The relationship between shoot length and nodule numbers persisted under field conditions. These results suggest that stem height could be used as a breeding marker for the selection of pea cultivars with high nodule numbers and high seed N contents.     

Phosphorus,arbuscular mycorrhizal fungi and performance of the wetland plant Lythrum salicaria L. under inundated conditions

The role of arbuscular mycorrhizal (AM) fungi in aquatic and semi-aquatic environments is poorly understood, although they may play a significant role in the establishment and maintenance of wetland plant communities. We tested the hypothesis that AM fungi have little effect on plant response to phosphorus (P) supply in inundated soils as evidenced by an absence of increased plant performance in inoculated (AM+) versus non-inoculated (AM-) Lythrum salicaria plants grown under a range of P availabilities (0-40 mg/l P). We also assessed the relationship between P supply and levels of AM colonization under inundated conditions. The presence of AM fungi had no detectable benefit for any measures of plant performance (total shoot height, shoot dry weight, shoot fresh weight, root fresh weight, total root length or total root surface area). AM+ plants displayed reduced shoot height at 10 mg/l P. Overall, shoot fresh to dry weight ratios were higher in AM+ plants although the biological significance of this was not determined. AM colonization levels were significantly reduced at P concentrations of 5 mg/l and higher. The results support the hypothesis that AM fungi have little effect on plant response to P supply in inundated conditions and suggest that the AM association can become uncoupled at relatively high levels of P supply.     

Plant Species, Host Age and Host Genotype Effects on Meloidogyne incognita Biocontrol by Pseudomonas fluorescens Strain CHA0 and its Genetically-Modified Derivatives

Pseudomonas fluorescens strain CHA0 and its antibiotic overproducing derivative CHA0/pME3424 repeatedly reduced Meloidogyne incognita galling on tomato, brinjal, mungbean and soya bean roots but not in chilli. An antibiotic‐deficient derivative, CHA89, did not reduce nematode invasion in any of the plant species tested. When plant species were compared, bacterial inoculants afforded better protection to tomato, mungbean and soya bean roots against root‐knot nematodes than to brinjal and chilli. Antibiotic overproducing strain CHA0/pME3424 markedly reduced fresh shoot weights of chilli and mungbean while antibiotic‐deficient strain CHA89 enhanced fresh shoot weights of mungbean. While strains CHA0 had no significant impact on fresh root weights of any of the plant species, strain CHA0/pME3424 consistently reduced fresh root weights of brinjal and mungbean. In none of the plant species the bacterial strains had an influence on protein contents of the leaves. Regardless of the plant species, the three bacterial strains did not differ markedly in their rhizosphere colonization pattern. However, colonization was highest in brinjal rhizosphere and lowest in the mungbean rhizosphere. A slight host genotype effect on the biocontrol performance of the bacterial inoculants was also detected at cultivar level. When five soya bean cultivars were compared, biocontrol bacteria exhibited best suppression of the root‐knot nematode in cv. Ajmeri. Antibiotic overproducing strain CHA0/pME3424 substantially reduced fresh shoot weights of the soya bean cultivars Centuray 84 and NARC‐I while strain CHA89 enhanced shoot weights of the cultivars Ajmeri, William‐82 and NARC‐II. Wild type strain CHA0 had no significant impact on fresh shoot weights of any of the soya bean cultivars. Strain CHA0/pME3424 reduced fresh weights of root of Century 84, NARC‐I and NARC‐II while strain CHA89 increased root weights. Bacterial rhizosphere colonization was highest in variety NARC‐I and lowest in variety Ajmeri. Plant age had a significant impact on the biocontrol performance of bacterial inoculants against nematodes. The biocontrol effect of all bacterial strains was more prominent during early growth stage (7 days after nematode inoculation). A strong negative correlation between bacterial rhizosphere colonization and nematode invasion in soya bean roots was observed.     

Effect of soybean plant growth on spore production byGlomus mosseae

Plants of two soybean cultivars infected withGlomus mosseae were physiologically stressed by top removal and were harvested at seven bi-weekly intervals. Removing tops stopped root growth, stimulated branching, delayed plant growth stages by approximately two weeks, but did not affect spore production. Spore numbers were significantly related only to time of harvest. Pot variation in spore number was not significantly correlated with infection percentage or root dry weight. Harvest, cultivar, and cutting effects were highly significant for root and shoot weights and root/shoot ratios.Approved by the Director as a contribution from the Missouri Agricultural Experiment Station (Journal Series No. 8123).     

Differences in developmental plasticity and growth rate among drought-resistant and susceptible cultivars of durum wheat (Triticum turgidum L. var. durum)

Understanding how growth and development of durum wheat cultivars respond to drought could provide a basis to develop crop improvement programmes in drought-affected tropical and subtropical countries. A greenhouse experiment was conducted to study the responses of five durum wheat cultivars to moisture stress at different developmental phases. Phenology, total dry matter (TDM), relative growth rate (RGR), leaf area ratio (LAR), net assimilation rate (NAR), leaf weight ratio (LWR), specific leaf area (SLA) and shoot:root ratio were compared. Pre-anthesis moisture stress delayed phenological development, whereas post-anthesis moisture stress accelerated it. TDM accumulation rate was different between drought-resistant and susceptible cultivars. RGR and its components changed with age and moisture availability. Drought-resistant cultivars had a high RGR in favourable periods of the growing season and a low RGR during moisture stress. In contrast, the drought-susceptible cultivar (Po) showed an opposite trend. LAR explained the differences in RGR (r=0.788) best, whereas the relationship between NAR and RGR was not significant. Even though both LWR and SLA were important factors determining the potential growth rate, LWR was of major importance to describe cultivar differences in LAR, and consequently in RGR. The drought-resistant cultivars Omrabi-5 and Boohai showed vigorous root development and/or a low shoot:root ratio. It is concluded that biomass allocation is the major factor explaining variation in RGR among the investigated durum wheat cultivars.     

Rice cultivar evaluation for phosphorus use efficiency

Phosphorus deficiency is one of the most growth-limiting factors in acid soils in various parts of the world. The objective of this study was to screen 25 rice cultivars (Oryza sativa L.) at low, medium, and high levels of soil P. Number of tillers, root length, plant height, root dry weight and shoot dry weight were related to tissue P concentrations, P uptake and P-use efficiency. Shoot weight was found to be the plant parameter most sensitive to P deficiency. Significant cultivar differences in P use efficiency were found. Phosphorus use efficiency was higher in roots than shoots and decreased with increasing levels of soil P. Positive correlations were found among growth parameters such as plant height, tillers, root and shoot weight, and P content of roots and shoots. These results indicate selection of rice cultivars for satisfactory performance under low P availability can be carried out using shoot and root dry weight as criteria.     

Interaction of Uromyces phaseoli and Meloidogyne incognita on Bean

Uromyces phaseoli, the causal agent of bean rust, suppressed shoot and root growth of three bean cultivars, reducing root weight more than shoot weight. The greatest suppression of root weight was on the cultivar that appeared most susceptible by visual ratings of shoot symptoms. Meloidogyne incognita suppressed shoot and root growth of all test cultivars; root weight reductions differed among cultivars identical in susceptibility to this pathogen in root-gall rating tests. Infection of plants with both pathogens suppressed plant weights significantly more than did infection by either pathogen alone, evidencing an additive effect. U. phaseoli and M. incognita on the same plant influenced the reproduction of one another, presumably through effects on the host. Fungal uredia were reduced in size and sporulation capacity; M. incognita produced fewer root galls, and fewer eggs per egg mass.     

Mycorrhizal responses of barley cultivars differing in P efficiency

The purpose of this study was to investigate how barley cultivars which are different in dry matter yield at low phosphorus (P) supply (i.e. they differ in agronomic P efficiency) respond to mycorrhizal infection. In a preliminary experiment, six mycorrhizal fungi were tested for their ability to colonize barley (Hordeum vulgare L.) roots at a soil temperature of 15°C.Glomus etunicatum was the most effective species and was used in the main experiment. The main experiment was conducted under glasshouse conditions in which soil temperature was maintained at 15°C. Treatments consisted of a factorial arrangement of 8 barley cultivars, 2 mycorrhiza (inoculated and non-inoculated), and 3 rates of P (0, 10 and 20 mg kg^-1). P utilization efficiency (dry matter yield per unit of P taken up) and agronomic P efficiency among the barley cultivars was significantly negatively correlated with mycorrhizal responses. However, the response to mycorrhizal infection was positively correlated with response to P application. Poor correlation was observed between P concentration when neither mycorrhiza nor P were supplied and the percentage of root length infected. The extent of mycorrhizal infection among the barley cultivars in soil without P amendment varied from 8.6 to 28.6%. Significant interactions between cultivar and P addition, and between mycorrhiza and P addition were observed for shoot dry weight but not root dry weight.     

伴生杂草播娘蒿对小麦的化感效应

用室内生物测定方法,对播娘蒿浸提液处理过的不同品系小麦的萌发率、发芽指数、活力指数、根长、苗高、干重、鲜重以及综合效应进行了统计,对作用效果较明显的5个品系进行了丙二醛含量、叶绿素a和叶绿素b比值、胡萝卜素含量的测定以及有丝分裂指数的统计.结果表明,播娘蒿浸提液对所有供试小麦均具有一定的化感效应,但化感效应的强度在不同品系的小麦中存在差异.对效果较明显的5种供试小麦生理指标的测定结果表明,播娘蒿中化感物质的作用位点可能是小麦细胞膜.此外,试验结果还表明,播娘蒿浸提液对小麦的有丝分裂有抑制作用.     

Mycorrhizal dependency of banana (Musa acuminata,AAA group) cultivar

Seven banana cultivars (Musa acuminata, AAA group) were inoculated with two species of vesicular arbuscular mycorrhizal (VAM) fungi (Glomus mosseae and Glomus macrocarpum) in a greenhouse experiment. Inoculated plants had generally greater shoot dry weight and shoot phosphorus concentrations compared to the noninoculated plants. A great variation in dependency on mycorrhizal colonization was observed among the banana cultivars. Cv. Williams showed the highest relative mycorrhizal dependency (RMD) and cv. Poyo the lowest. For all the cultivars studied, inoculation with G. macrocarpum resulted in the highest RMD values. Both root dry weight and root hair length or density of the noninoculated plants were inverserly correlated with the RMD values of cultivars.     

Role of rye chromosomes in improvement of zinc efficiency in wheat and triticale

Using the disomic wheat-rye addition lines (Triticum aestivum L., cv. Holdfast-Secale cereale L., cv. King-II) and an octoploid triticale line (xTriticosecale Wittmark L. "PlutoxFakon") as well as the respective wheat and rye parents, greenhouse experiments were carried out to study the role of rye chromosomes on the severity of Zn deficiency symptoms, shoot dry matter production, Zn efficiency, shoot Zn concentration and Zn content. Plants were grown in a Zn-deficient calcareous soil with (10 mg Zn kg-1 soil) and without Zn supply. Zinc efficiency was calculated as the ratio of dry weight produced under Zn deficiency to the dry weight produced under Zn fertilization. In the experiments with addition lines, visual Zn deficiency symptoms were slight in the rye cultivar King-II, but were severe in the wheat cultivar Holdfast. The addition of rye chromosomes, particularly 1R, 2R and 7R, into Holdfast reduced the severity of deficiency symptoms. Holdfast showed higher decreases in shoot dry matter production by Zn deficiency and thus had a low Zn efficiency (53 %), while King-II was less affected by Zn deficiency and had a higher Zn efficiency (89 %). With the exception of the 3R line, all addition lines had higher Zn efficiency than their wheat parent: the 1R line had the highest Zn efficiency (80 %). In the experiment with the triticale cultivar and its parents, rye cv. Pluto and wheat cv. Fakon, Zn deficiency symptoms were absent in Pluto, slight in triticale and very severe in Fakon. Zinc efficiency was 88 % for Pluto, 73 % for triticale and 64% for Fakon. Such differences in Zn efficiency were better related to the total amount of Zn per shoot than to the amount of Zn per unit dry weight of shoot. Only in the rye cultivars, Zn efficiency was closely related with Zn concentration. Triticale was more similar to rye than wheat regarding Zn concentration and Zn accumulation per shoot under both Zn-deficient and Zn-sufficient conditions.The results presented in this study show that rye has an exceptionally high Zn efficiency, and the rye chromosomes, particularly 1R and 7R carry the genes controlling Zn efficiency. To our knowledge, the result with triticale and its rye parents is the first report showing that the genes controlling Zn efficiency in rye are transferable into wheat and can be used for development of new wheat varieties with high Zn efficiency for severely Zn-deficient conditions.     

Effect of Morpholine Systemic Fungicides on the Chloroplast Pigments of Wheat and Maize

Abstract

The growth, chlorophyll and carotenoid contents of wheat and maize seedlings as influenced by a soil drench of 250 μM of tridemorph or fenpropimorph, were studied. It was found that the length of the shoot, primary leaf, and root, as well as the leaf area were significantly reduced in the fungicide treated seedlings. Although the dry matter percentage was higher in the treated seedlings as compared to the control, the fresh or dry weight per shoot remained lower in the fungicide treated seedlings. The chloroplast pigments in the treated seedlings of both crops were unaffected, suggesting that the fungicides had no significant effect on the chlorophyll or carotenoid biosynthesis.     

Uniconazole-induced thermotolerance in wheat seedlings is mediated by transpirational cooling

Seed treatment of thermotolerant and sensitive cultivars of wheat ( Triticum aestivum L. cv. Frederick and Glenlea, respectively) with uniconazole reduced shoot and increased root fresh and dry weights. When subjected to 48°C for 6 h, treated seedlings had lower leaf-temperatures and overall higher rates of evapotranspiration. Percent survival 11 days after high temperature incubation in untreated seedlings was 53% in Frederick and 30% in Glenlea, whereas in uniconazole-treated seedlings it was 94% and 80%, respectively. Transpiration resistance markedly increased in the control cultivars after 4 h of high-temperature incubation, but remained relatively unchanged in the treated cultivars. The increased root to shoot ratio exhibited in treated plants may have alleviated guard cell stress, even under high evaporative demand. Chlorophyll fluorescence measurements on leaves of heat-stressed seedlings indicated that increased photosynthetic metabolism in treated seedlings was correlated with lower leaf temperatures. High-temperature stress resulted in a dramatic decline in pigments and proteins in thylakoid extracts of control seedlings but not in extracts from treated seedlings. Integrity of thylakoid pigment protein complexes, as illustrated by reduced relative amounts of free pigment, was maintained after exposure to high temperatures in treated seedlings. Furthermore, the treated Glenlea seedlings displayed a reduction in the monomeric form of Sight-harvesting chlorophyll protein II (LHCP II) compared to control and Frederick seedlings. The heat-tolerant Frederick cultivar showed a greater protective effect from uniconazole treatment than the sensitive Glenlea cultivar. Uniconazole treatment did not affect heat-shock protein (HSP) synthesis in mesocotyl tissue.     

松嫩平原不同株型玉米品种根系分布特征比较研究

采用土柱模拟栽培法与大田试验相结合的方法,对松嫩平原不同株型玉米的根系分布特征进行了比较。结果表明,平展型玉米和紧凑型玉米根干重最大值出现的时期不同,二者根干重分别在抽丝后15d和抽丝后30d时达到最大值,成熟时紧凑型玉米根干重比平展型高12．2％,二者根系垂直分布有明显的差异,在20cm以下的根干重比率,平展型玉米在19％以下,而紧凑型玉米高于23％,紧凑型玉米的深层根量较多,在深40～100cm土层内根干重比率比平展型高42．3％,二者的根系水平分布也不同,紧凑型玉米根系水平分布较集中,在距植株0～10cm水平范围内,根系分布比率比平展型玉米高9．6％,紧凑型玉米深层根量较多,水平分布集中,耐密植,是易获得高产的重要原因之一。