An effective planting model to decrease cadmium accumulation in rice grains and plants: Intercropping rice with wetland plants

Cadmium (Cd) pollution affects plant growth and poses a serious threat to food safety and human health.Cadmium-contaminated rice is assumed to be the main source of Cd exposure to humans,with grave health risks.Phytoremediation is an efficient,cost-effective,and eco-friendly approach to minimize Cd accumulation in rice.However,research on the effect of rice intercropping with wetland plants that exhibit great capacity for phytoremediation in decreasing Cd concentrations in paddies is limited.A p...     

Reducing residues of tetracycline and its resistance genes in soil-maize system and improving plant growth:Selecting the best remediation substance

Tetracycline(TC)and tetracycline resistance genes(TRGs)in plant edible tissues pose a potential risk to the environment and then to human health.This study used a pot experiment to investigate the effects of different remediation substances(worm castings,fungal chaff,microbial inoculum,and biochar)on the physiological characteristics of maize and the residues of TC and TRGs in the soil-maize system under TC stress.The results showed that TC significantly inhibited growth,disrupted the antioxidant defense system balance,and increased proline and malondialdehyde contents of maize plants.Tetracycline residue contents were significantly higher in root than in shoot,and followed the order root>stem-leaf>grain,which was consistent with the distribution of bioconcentration factors in the different organs of maize plants.The TC residue content in the soil under different treatments was 0.013–1.341 mg kg-1.The relative abundances of different antibiotic resistance genes in the soil-maize system varied greatly,and in maize plants followed the order intI1>tetW>tetG>tet B>tetM>tetX>tetO.In the soil,tetX had the highest relative abundance,followed by tetG and tetW.A redundancy analysis(RDA)showed that TC was positively correlated with TRGs.The addition of different remediation substances alleviated the toxicity of TC on maize physiological characteristics and reduced the TC and TRG residues in the soil-maize system,with biochar being the best remediation substance.These results provide new insights into the effect of biochar on the migration of TC and TRGs from soil to plants.     

Interactive and Single Effects of Ectomycorrhiza Formation and <Emphasis Type="Italic">Bacillus cereus</Emphasis> on Metallothionein <Emphasis Type="Italic">MT1</Emphasis> Expression and Phytoextraction of Cd and Zn by Willows

Single and joint ectomycorrhizal (+ Hebeloma mesophaeum) and bacterial (+ Bacillus cereus) inoculations of willows (Salix viminalis) were investigated for their potential and mode of action in the promotion of cadmium (Cd) and zinc (Zn) phytoextraction. Dual fungal and bacterial inoculations promoted the biomass production of willows in contaminated soil. Single inoculations either had no effect on the plant growth or inhibited it. All inoculated willows showed increased concentrations of nutritional elements (N, P, K and Zn) and decreased concentrations of Cd in the shoots. The lowest biomass production and concentration of Cd in the willows (+ B. cereus) were combined with the strongest expression of metallothioneins. It seems that biotic stress from bacterial invasion increased the synthesis of these stress proteins, which responded in decreased Cd concentrations. Contents of Cd and Zn in the stems of willows were combination-specific, but were always increased in dual inoculated plants. In conclusion, single inoculations with former mycorrhiza-associated B. cereus strains decreased the phytoextraction efficiency of willows by causing biotic stress. However, their joint inoculation with an ectomycorrhizal fungus is a very promising method for promoting the phytoextraction of Cd and Zn through combined physiological effects on the plant.     

Effect of Arbuscular Mycorrhizal (AM) Inoculation on Growth and Flowering in Crossandra infundibuliformis (L.) Nees

Commercially important ornamental flowering plant Crossandra infundibuliformis (L.) Nees. commonly known as ‘Fire cracker’ plant was evaluated for the possible effects of inoculation of different Arbuscular Mycorrhizal (AM) fungal species on growth, yield, flower quality, and phosphorus (P) nutrition. Five pure cultures of AM species, Acaulospora laevis, A. scrobiculata, Glomus coremioides, G. intraradices and Gigaspora albida and an un-inoculated control were used. Mycorrhizal inoculation showed positive effect on plant height, early flowering, increased flower number, increased flower weight, reduced fresh weight loss over 24 h, increased leaf P concentration, and increased total dry weight compared to un-inoculated control. The studies indicate mycorrhizal inoculation can enhance commercial flower production of this plant. Glomus intraradices proved to be the most efficient AM fungal bioinoculant and thus have the potential to enhance commercial flower production of this plant.     

油菜素内酯对龙葵幼苗Cd毒害耐受性的影响

以重金属超富集植物龙葵为试验材料,分析了油菜素内酯(BR)对幼苗镉(Cd)毒害耐受性影响的生理机制。Cd毒害导致龙葵幼苗出现氧化伤害,同时降低了幼苗超氧化物歧化酶(SOD)、过氧化氢酶(CAT)和抗坏血酸过氧化物酶(APX)活性。表油菜素内酯(eBL,人工合成的BR)处理增加了龙葵幼苗对Cd毒害的敏感性,与eBL处理的结果相反,施用油菜素唑(Brz,BR合成的特异性抑制剂)增加了Cd毒害下龙葵幼苗的抗氧化酶活性,降低了ROS的累积,减少了幼苗的氧化伤害。Brz处理后幼苗株高和根长较Cd处理的对照分别增加29%和28%,MDA水平和Evans blue染色程度较Cd处理的对照分别降低37%和20%,进一步证明BR增加了Cd毒害下龙葵幼苗的氧化伤害,从而加重了Cd胁迫对幼苗生长的抑制作用。表明BR通过降低龙葵幼苗的抗氧化能力,增加了幼苗对Cd毒害的敏感性。     

Ectomycorrhizal fungi and dark septate endophyte inoculation improve growth and tolerance of Pinus tabulaeformis under cadmium stress

Forest trees can establish symbiotic associations with dark septate endophytes (DSEs) and ectomycorrhizal fungi (ECMF) simultaneously. However, the combined effects of these two fungi on the growth and cadmium (Cd) tolerance of host plants remain largely unexplored. To address this knowledge gap, a pot experiment was conducted to examine the effects of the interaction between an ECMF strain (Suillus granulatus) and a DSE strain (Pseudopyrenochaeta sp.) on Pinus tabulaeformis under Cd stress, by assessing plant growth and physiological parameters, nutrient uptake, and soil properties. Notably, the colonization rates of both fungal strains were found to increase in response to Cd stress, with the extent of this increase being influenced by the specific fungal species and the Cd level in the soil. Compared to the non-inoculation treatment, single inoculation with fungal strain resulted in enhanced biomass, root development, and nutrient contents in P. tabulaeformis seedlings under Cd stress. Furthermore, a synergistic effect was observed when these seedlings were co-inoculated with S. granulatus and Pseudopyrenochaeta sp., as indicated by significantly greater measurements in various indicators compared to both the single and non-inoculation treatments. Fungal inoculation effectively regulated the antioxidant defense responses and photosynthesis of P. tabulaeformis seedlings subjected to Cd stress, particularly in the co-inoculation treatment. In addition, fungal inoculation facilitated the Cd accumulation in P. tabulaeformis, suggesting a promising potential for the implementation of bioremediation strategies in the areas contaminated with heavy metals. The findings from this study indicate that the utilization of root symbiotic fungi obtained from stress environments could potentially enhance the growth performance and tolerance of P. tabulaeformis towards heavy metals, and co-inoculation of both fungal groups may result in even more pronounced synergistic effects on the overall fitness of the plant.     

Occurrence of dark septate endophytes in Phragmites australis in the Baiyang Lake and their resistance to Cd stress

Heavy metal pollution poses a serious hazard to human health, and microbial remediation of heavy metals in soil has been widely studied. A group of ascomycetes classified as dark septate endophytes (DSEs) colonize plant roots and benefit host plants under abiotic stress conditions. In this study, Phragmites australis, a common remediation plant in the Baiyang Lake in North China, was investigated. Soils and roots of P. australis were collected in typical heavy metal-contaminated sites, and the species diversity and community structure of DSEs in P. australis roots were studied. In addition, DSE strains were isolated, cultured, and tested for their tolerance to Cd stress. The results showed that DSEs occurred extensively in P. australis roots, forming typical dark septate hyphae, with a total colonization rate of 19.7%-83.1%. Morphological and internal transcribed spacer sequencing analyses were used to identify 10 species within 9 genera of DSE fungi. Among these fungi, 6 strains with considerable resistance to Cd stress were identified. The biomasses of Poaceascoma helicoides, Alternaria doliconidium, and Acrocalymma vagum strains increased as the Cd levels increased. These results can not only help to understand plant-DSE interactions in wetland environments, but also provide a theoretical basis for making full use of DSE fungi to alleviate heavy metal contamination in soil.     

Effectiveness of two arbuscular mycorrhizal fungi on concentrations of essential oil and artemisinin in three accessions of Artemisia annua L.

A field experiment was conducted to study and compare the effectiveness of two arbuscular mycorrhizal fungi (AMF), Glomus macrocarpum (GM) and Glomus fasciculatum (GF) on three accessions of Artemisia annua. The AM inoculation significantly increased the production of herbage, dry weight of shoot, nutrient status (P, Zn and Fe) of shoot, concentration of essential oil and artemisinin in leaves as compared to non-inoculated plants. The extent of growth, nutrient concentration and production of secondary plant metabolites varied with the fungus–plant accession combination. The mycorrhizal dependency of the three accessions was related to the shoot: root ratio. Comparing the two fungal inoculants in regard to increase in essential oil concentration in shoot, the effectiveness of GF was more than that of GM. While in two accessions, GM was more effective in enhancing artemisinin concentration than GF. Increase in concentration of essential oil was found to be positively correlated to P-status of the plant. Conversely, no correlation was found between shoot-P and artemisinin concentration.     

Effect of mycorrhizal inoculation and soil restoration on the growth of Pinus halepensis seedlings in a semiarid soil

An experiment was carried out to evaluate the growth of mycorrhizal Pinus halepensis seedlings planted in a semiarid soil amended with urban refuse in southeast Spain. Three fungal species were used: Pisolithus tinctorius, Rhizopogon roseolus, and Suillus collinitus. After 8 months, inoculated seedlings grown under controlled conditions did not differ significantly from controls with regard to plant height and nutrient assimilation. Other features such as root development and stem dry weight showed that the plants grew better in the absence of mycorrhizal inoculation. The mycorrhizal seedlings and the controls were planted in three experimental plots treated with urban refuse (0, 6, and 12 Kg m^-2). After 1 year of growth under field conditions the results showed that the type of fungus inoculated significantly influenced P. halepensis development. This effect varied with the dose of urban refuse. Plant growth was encouraged by the application of refuse but only at the lowest dose. Under these conditions P. tinctorius was the most effective fungus and R. roseolus yielded poorer plant development. The highest application of urban refuse led to notably worse results and a significant decrease in seedling growth compared to controls. In the control plot (without refuse) S. collinitus was the most effective fungus in plant growth improvement. The smallest application of urban refuse had a positive effect on the assimilation of N, P, and K in seedlings inoculated with P. tinctorius and S. collinitus.     

Cadmium bioavailability to Nicotiana tabacum L., Nicotiana rustica L., and Zea mays L. grown in soil amended or not amended with cadmium nitrate

Summary Mature (flowering) tobacco (Nicotiana tabacum cv. PBD6, Nicotiana rustica cv. Brasilia) and maize (Zea mays cv. INRA 260) plants were grown in an acid sandy-clay soil, enriched to 5.4 mg Cd kg^–1 dry weight soil with cadmium nitrate. The plants were grown in containers in the open air. No visible symptoms of Cd toxicity developed on plant shoots over the 2-month growing period. Dry-matter yields showed that while the Nicotiana spp. were unaffected by the Cd application the yield of Z. mays decreased by 21%. Cd accumulation and distribution in leaves, stems and roots were examined. In the control treatment (0.44 mg Cd kg^–1 dry weight soil), plant Cd levels ranged from 0.4 to 6.8 mg kg^–1 dry weight depending on plant species and plant parts. Soil Cd enrichment invariably increased the Cd concentrations in plant parts, which varied from 10.1 to 164 mg kg^–1 dry weight. The maximum Cd concentrations occurred in the leaves of N. tabacum. In N. rustica 75% of the total Cd taken up by the plant was transported to the leaves, and 81% for N. tabacum irrespective of the Cd level in the soil. In contrast, the Cd concentrations in maize roots were almost five times higher than those in the leaves. More than 50% of the total Cd taken up by maize was retained in the roots at both soil Cd levels. The Cd level in N. tabacum leaves was 1.5 and 2 times higher at the low and high Cd soil level, respectively, than that in N. rustica leaves, but no significant difference was found in root Cd concentrations between the two Nicotiana spp.Cd bioavailability was calculated as the ratio of the Cd level in the control plants to that in the soil or as the ratio of the additional Cd taken up from cadmium nitrate to the amount of Cd applied. The results showed that the plant species used can be ranked in a decreasing order as follows: N. tabacum > N. rustica > Z. mays.     

Defoliation effects on Plantago lanceolata resource allocation and soil decomposers in relation to AM symbiosis and fertilization

Plants can mediate interactions between aboveground herbivores and belowground decomposers as both groups depend on plant-provided organic carbon. Most vascular plants also form symbiosis with arbuscular mycorrhizal fungi (AMF), which compete for plant carbon too. Our aim was to reveal how defoliation (trimming of plant leaves twice to 6 cm above the soil surface) and mycorrhizal infection (inoculation of the fungus Glomus claroideum BEG31), in nutrient poor and fertilized conditions, affect plant growth and resource allocation. We also tested how these effects can influence the abundance of microbial-feeding animals and nitrogen availability in the soil. We established a 12-wk microcosm study of Plantago lanceolata plants growing in autoclaved soil, into which we constructed a simplified microfood-web including saprotrophic bacteria and fungi and their nematode feeders. We found that fertilization, defoliation and inoculation of the mycorrhizal fungus all decreased P. lanceolata root growth and that fertilization increased leaf production. Plant inflorescence growth was decreased by defoliation and increased by fertilization and AMF inoculation. These results suggest a negative influence of the treatments on P. lanceolata belowground biomass allocation. Of the soil organisms, AMF root colonization decreased with fertilization and increased with defoliation. Fertilization decreased numbers of bacterial-feeding nematodes, probably because fertilized plants produced less root mass. On the other hand, bacterial feeders were more abundant when associated with defoliated than non-defoliated plants despite defoliated plants having less root mass. The AMF inoculation per se increased the abundance of fungal feeders, but the reduced and increased root AM colonization rates of fertilized and defoliated plants, respectively, were not reflected in the numbers of fungal feeders. We found no evidence of plant-mediated effects of the AM fungus on bacterial feeders, and against our prediction, soil inorganic nitrogen concentrations were not positively associated with the concomitant abundances of microbial-feeding animals. Altogether, our results suggest that (1) while defoliation, fertilization and AMF inoculation all affect plant resource allocation, (2) they do not greatly interact with each other. Moreover, it appears that (3) while changes in plant resource allocation due to fertilization and defoliation can influence numbers of bacterial feeders in the soil, (4) these effects may not significantly alter mineral N concentrations in the soil.     

Breeding of a practical rice line ‘TJTT8’ for phytoextraction of cadmium contamination in paddy fields

ABSTRACT

Previously, we showed that qCdp7, an allele identified in the high-Cd-accumulating indica rice variety ‘Jarjan,’ is associated with effective phytoextraction of Cd from paddy soils. However, ‘Jarjan’ may not be practical for phytoextraction because it is susceptible to seed shattering and culm lodging, which are unfavorable traits for mechanical rice harvesting. In this study, to develop a practical rice line for phytoextraction, we introduced the qCdp7 allele into ‘Tachisugata,’ a rice variety with a nonshattering habit and lodging resistance, to produce a new high-Cd-accumulating rice line designated ‘TJTT8.’ This line inherited high-Cd accumulation and brown pericarps from ‘Jarjan’ and a nonshattering habit and lodging resistance from ‘Tachisugata;’ all of these traits are necessary for rice intended for Cd phytoextraction in Japan. Backcross inbred lines (BILs) were produced by two backcrosses to ‘Tachisugata’ after a cross between ‘Jarjan’ and ‘Tachisugata.’ ‘TJTT8’ was selected from the BILs by means of marker-assisted selection and phenotypic evaluation. When ‘TJTT8,’ the parents, and ‘Cho-ko-koku’ which is a high-Cd-accumulating indica variety were cultivated in Cd-contaminated paddy fields in four locations in Japan, ‘TJTT8’ exhibited lodging resistance and shattering resistance that were higher than those of ‘Jarjan’ and ‘Cho-ko-koku’ and equivalent to those of ‘Tachisugata.’ ‘TJTT8’ accumulated Cd in the aerial parts of the plants at concentrations ranging from 6.5 to 22.7 mg m^?2: it showed significantly higher Cd accumulation than ‘Tachisugata’ and was equivalent to ‘Jarjan’ and slightly superior to ‘Cho-ko-koku.’ Soil Cd concentration was estimated to have been reduced by 8.7–33.6% based on the amount of Cd accumulation in the aerial parts of the plants. Thus, we succeeded in using the qCdp7 allele to produce a practical rice line for Cd phytoextraction by improving several agronomic traits for compatibility with Japanese cultivation systems.     

Arbuscular mycorrhizal fungi inoculation and exogenous indole-3-acetic acid application induce antioxidant defense response to alleviate cadmium toxicity in Broussonetia papyrifera

Cadmium (Cd) contamination in soil poses a huge threat to plants even at low concentrations; Broussonetia papyrifera has great potential in remediation of soil heavy metal contamination. However, whether exogenous indole-3-acetic acid (IAA) application and arbuscular mycorrhizal fungi (AMF) have synergistic effects on Cd tolerance of B. papyrifera remains unclear. To investigate the effects of AMF inoculation and IAA application on the tolerance of B. papyrifera to Cd stress, two experiments were conducted: the first to investigate the effect of AMF (Rhizophagus irregularis) inoculation on the tolerance of B. papyrifera to Cd stress and the second to investigate the combined effects of AMF inoculation and IAA application on the tolerance of B. papyrifera to Cd stress. Parameters including endogenous hormone concentration, antioxidant defense response, malondialdehyde (MDA) content, and gene expression related to antioxidant enzyme system and hormone were measured. The results indicated that AMF alleviated Cd toxicity of B. papyrifera by reducing MDA content and improving antioxidant enzyme activities and Cd absorption capacity. Furthermore, the combination of AMF inoculation and IAA application had a synergetic effect on the tolerance of B. papyrifera to Cd stress through upregulating BpAUX1 and BpAUX2, which might contribute to root growth and root xylem synthesis, and by upregulating BpSOD2 and BpPOD34 to enhance the antioxidant enzyme system. This work provides a new insight into the application of IAA in the remediation of soil Cd pollution by mycorrhizal plants.     

羟基磷灰石–植物联合修复对Cu/Cd污染植物根际 土壤微生物群落的影响

针对江西贵溪Cu、Cd重金属污染土壤,通过田间试验,比较无机生物材料羟基磷灰石及3种植物(海州香薷、巨菌草、伴矿景天)与羟基磷灰石联合修复对土壤总Cu、Cd的吸收及对活性Cu、Cd的钝化吸收能力差异。采用磷脂脂肪酸(PLFA)分析法,比较不同修复模式对土壤微生物群落结构的影响,以评估土壤微生态环境对不同修复措施的响应。研究结果表明:羟基磷灰石的施加可显著提高土壤pH,并有效钝化土壤活性Cu、Cd含量,但对土壤总Cu、Cd的含量影响较小。植物与羟基磷灰石的联合修复在显著降低土壤活性Cu、Cd(P0.05)的同时,减少了植物根际土壤总Cu、Cd的含量(P0.05)。不同修复措施对土壤微生物群落组成影响差异明显。单独施加羟基磷灰石与土壤真菌群落呈显著正相关,使土壤真菌生物量提高,从而引起真菌/细菌(F/B)的升高。植物与羟基磷灰石的联合修复可有效缓解土壤真菌化的趋势,其中巨菌草与羟基磷灰石的联合修复可有效提高土壤革兰氏阳性、革兰氏阴性细菌生物量及多样性,降低F/B值,从而降低土壤真菌病害的风险。不同植物根系活性代谢引起有机质的积累促进植物与羟基磷灰石处理中根际有机碳含量显著提高。聚类增强树(Aggregated boosted tree,ABT)分析结果表明:不同修复模式是影响土壤微生物群落的重要因素,其次土壤pH和Cu的含量及活性也是改变重金属污染区域微生物群落的因子。该研究从微生物群落结构角度解释了植物与羟基磷灰石联合修复对土壤微生态体系的作用,为开展Cu、Cd等重金属污染地植物与无机生物材料的联合修复方式的筛选及实施提供可靠的理论依据。     

Mycorrhizal fungi and earthworms reduce antioxidant enzyme activities in maize and sunflower plants grown in Cd-polluted soils

Changes in plant antioxidant enzymes (AOEs) in response to cadmium (Cd) pollution are an important mechanism for plant growth and tolerance to Cd-induced stress. The main objective of this greenhouse study was to determine the combined influence of earthworm and arbuscular mycorrhiza (AM) fungal inoculation and their interactions with Cd on AOEs and proline accumulation in leaves of two major crops under Cd stress. Maize (Zea mays L.) and sunflower (Helianthus annuus L.) plants were exposed to Cd stress (10 and 20 mg kg⁻¹ soil), inoculated with either earthworm (Lumbricus rubellus L.) or AM fungi (Glomus intraradices and Glomus mosseae species) in a pot experiment for three months. Exposure to Cd decreased shoot dry weights, increased shoot Cd and P concentrations, leaf proline accumulation and the activity of superoxide dismutase (SOD), catalase (CAT), peroxidase (POD) and polyphenol oxidase (PPO) in both mycorrhizal and non-mycorrhizal plants and both in the presence and absence of earthworms. Inoculation of both model plants with earthworms and AM fungi decreased shoot Cd concentrations and the activity of all AOEs, except PPO. Although earthworm activity enhanced the proline content of sunflower in Cd-polluted soils, the proline level of both plants remained unaffected by AM fungi. AM fungi and earthworms may decrease the activity of AOEs through a decline in shoot Cd toxicity and concentration, confirming that plant inoculation with these soil organisms improves maize and sunflower tolerance and protection against Cd toxicity. Generally, the effect of AM fungal inoculation on plant responses to Cd addition was greater than that of earthworm activity. Nonetheless, the interactive effect of AM fungus and earthworm is of minor importance for most of the plant AOEs in Cd-polluted soils.     

The significant contribution of mycorrhizal fungi and earthworms to maize protection and phytoremediation in Cd-polluted soils

Mycorrhizal fungi and earthworms can individually or interactively influence plant growth and heavy metal uptake. The influence of earthworms and arbuscular mycorrhizal (AM) fungi either alone or in combination on maize (Zea mays L.) growth and cadmium (Cd) uptake was investigated in a calcareous soil artificially spiked with Cd. Soils were contaminated with Cd (10 and 20 mg Cd kg⁻¹), inoculated or un-inoculated with the epigeic earthworm Lumbricus rubellus and two AM fungal species (Rhizophagus irregularis and Funneliformis mosseae) for two months of growth under greenhouse conditions. Generally, earthworms alone increased both shoot P uptake and biomass but decreased shoot Cd concentration and root Cd uptake. AM fungi individually often increased total maize P uptake, declined shoot Cd concentration, and consequently produced higher total biomass. However, R. irregularis enhanced shoot Cd uptake at low Cd level and root Cd uptake at high Cd level. In plants inoculated with F. mosseae species, earthworms increased shoot biomass and Cd uptake, decreased root biomass and Cd uptake at all Cd levels, and increased shoot Cd concentration at low Cd level. In plants colonized by R. irregularis species, however, earthworm addition decreased maize biomass only at high Cd level and root Cd concentration and total maize Cd uptake at both Cd levels. Earthworm activity decreased Cd transfer from the soil to maize roots at low Cd level, but this was counterbalanced in the presence of F. mosseae. Mycorrhizal symbiosis significantly reduced the transfer of Cd from roots to shoots, independence of earthworm effect. Overall, it is concluded that L. rubellus and AM fungi, in particular F. mosseae isolate, improved maize tolerance to Cd toxicity both individually and interactively by increasing plant growth and P nutrition, and restricting Cd transfer to the aboveground biomass. Consequently, the single and interactive effects of the two soil organisms might potentially be important not only in protecting maize plants against Cd toxicity, but also in Cd phytostabilization in soils polluted by this highly toxic metal.     

Co-inoculation of the endophytic fungus Piriformospora indica with the phosphate-solubilising bacterium Pseudomonas striata affects population dynamics and plant growth in chickpea

In this study, inoculation of the chickpea (Cicer arietinum) with the novel symbiotic fungus (Piriformospora indica) was analysed in combination with the Tn5-lacZ-tagged phosphate-solubilising bacterium Pseudomonas striata. This study aims to evaluate whether the co-inoculation of these two species would enhance the population buildup of P. striata in the rhizosphere, P uptake, growth and yield of chickpea. Single inoculation of P. indica and P. striata has a negative effect on plant growth and yield of chickpea. Data showed that the combination of the two microorganisms had a synergistic effect on population buildup of P. striata and plant dry biomass with respect to their single inoculation. However, the P uptake was not significantly influenced by single or combined inoculation of two species. At 20 days after sowing, the influence of combined inoculation on the population of P. striata was positive; at 60 days after sowing, it was neutral as the populations in treatments with single and combined inoculation were at par; and at harvest, it was negative The population of P. striata was higher at flowering stage as compared to 20 days after sowing and at harvest.     

Evaluation of Wild Lens Taxa for Agro-Morphological Traits, Fungal Diseases and Moisture Stress in North Western Indian Hills

Exploitation of wild gene pool for breeding is a common practice in an increasing number of cultivated plants. The cultivated lentil could not attain the substantial improvement in the yield potential due to loss of genes for higher productivity and lack of resistance against biotic and abiotic stresses. The absence of evaluation data of wild lentils for characters of economic importance, besides biotic and abiotic stresses, is one of the constraints in their use in lentil breeding programme. In the present study, 70 wild accessions from four wild Lens subsp./sp. (L. culinaris subsp. orientalis, L. odomensis, L. ervoides and L. nigricans) along with 3 checks (Precoz, PL-406 and PL-639) were evaluated for phenological and agro-morphological characters, for their reaction to three fungal diseases (wilt, powdery mildew and rust) and screened for tolerance to moisture stress. The wild accessions showed higher performance for branches/plant as compared to cultivated genotypes. Similarly, a few accessions of L. culinaris subsp. orientalis were earlier to flower and had higher seeds and seed yield/plant as compared to cultivated lentil. However, some were comparable with cultivated genotypes for flowers/peduncle, peduncle length and plant height. The mean performance for flowers per peduncle, leaflets per leaf, plant height, seeds and seed yield per plant increased, while decreased for days to flowering and maturity, and branches per plant during the evolution of cultivated lentil from the wild Lens taxa. Of Lens taxa, L. nigricans had the maximum resistant accessions for biotic and tolerance to abiotic stresses. The valuable variation existing among wild accessions can be exploited following introgression with cultivated lentils. It will help in the flow of useful genes from wild to cultivated lentil for generating wide spectrum of variability and its subsequent use in genetic restructuring of lentil.     

Genetic Variation of Blast Resistance in Foxtail Millet (<Emphasis Type="Italic">Setaria italica</Emphasis> (L.) P. Beauv.) and its Geographic Distribution

To clarify the geographic variation and isolate specificity in blast resistance, 20 cultivars of foxtail millet (Setaria italica (L.) P. Beauv.) originating from Eurasia were examined for their resistance using 11 Japanese Setaria isolates of blast fungus. Cultivars from the countries east of Pakistan generally showed resistance to most of the 11 fungus isolates, whereas those from the countries west of Afghanistan indicated higher susceptibility. The origin of this geographical regularity was discussed in relation to the deficiency or specificity of relevant resistance gene(s). No identical reaction pattern was observed among cultivars, indicating their highly distinctive isolate specificity. The virulence of isolates was also diverse, since only 2 out of 10 virulent isolates were identical for their reaction patterns. Preliminary genetic analysis of blast resistance to four fungus isolates suggests that they are governed by more than two dominant genes.     

Growth Response and Nutrient Uptake of Eriobotrya japonica Plants Inoculated with Three Isolates of Arbuscular Mycorrhizal Fungi Under Water Stress Condition

Mycorrhizal technique is a promising biotechnology in horticultural industry, benefiting plants exposed to diverse abiotic stresses. In this study, the effects of three arbuscular mycorrhizal fungi (AMF), Acaulospora laevis, Glomus mosseae, and Glomus caledonium on plant growth and nutrient uptake of loquat (Eriobotrya japonica Lindl.) seedlings under three water regimes (well watered, water stressed-slight, water stressed-heavy) were investigated. Results showed that inoculated seedlings had higher dry biomass, plant height, and total leaf areas than those un-inoculated ones. AMF effect was the greatest for water stressed-heavy seedlings, followed by water stressed-slight seedlings and well watered seedlings. All AMF species increased the uptake of nitrogen (N) potassium (K), phosphorus (P), calcium (Ca), magnesium (Mg), zinc (Zn), copper (Cu), and the mycorrhizal contributions to the nutrient uptake were positively related to that to the biomass. Data suggest that AMF inoculation increases the tolerance of loquat seedlings to drought stress, and the improved nutrient uptake by AMF contributes greatly to the tolerance.