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1.
Scanning electron-microscopy observations made on the leaves of Italian ryegrass and maize, inoculated with Xanthomonas campestris pvs graminis, oryzae and oryzicola clearly showed a difference in the distribution pattern among the different pathovars tested. Pvs oryzae and oryzicola could be detected on the leaf trichomes of ryegrass, while pv. graminis was not. On maize leaves, the attachment of pvs oryzae and oryzicola to trichomes was much more pronounced than on ryegrass. In addition, pv. oryzae spread further into leaves of maize than did pvs graminis and oryzicola and could be detected in masses until at least the sixth day after inoculation. These observations suggest that non-host plants such as maize could function as alternate inoculum sources of pv. oryzae for nearby rice plants.  相似文献   

2.
Laboratory experiments were conducted to analyze the iron (Fe) tolerance of paddy weeds and rice varieties (Oryza sativa) for germination and root elongation. Under a waterlogged soil condition, the Fe(II) content in a soil solution increased with an increase in the ratio of rice straw to the soil. In the presence of 0.9% (w/w) straw to soil, which corresponds approximately to 8 t of straw applied to an area of 1 ha × 10 cm depth in the field, ～80 mg L?1 of Fe(II) was produced in the soil solution. Based on this result, the seeds of rice and the weeds were incubated in a solution with <100 mg L?1 of Fe(II). The presence of 100 mg L?1 of Fe(II) suppressed the germination of Echinochloa crus‐galli var. crus‐galli, Cyperus serotinus, Cyperus difformis, and Monochoria korsakowii. However, it had no effect on the germination of Echinochloa oryzicola, Schoenoplectus juncoides (= Scirpus juncoides var. ohwianus), and Monochoria vaginalis. This level of Fe tolerance was the same as that of rice. These findings suggest that E. oryzicola, S. juncoides, and M. vaginalis can grow under more severe conditions than E. crus‐galli, C. serotinus, C. difformis, and M. korsakowii. In relation to seminal root elongation, the order of tolerance of Fe toxicity was O. sativa cv. Dunghan Shali > O. sativa cv. Hoshinoyume > E. oryzicola > M. vaginalis > S. juncoides. Thus, the results show that the tolerance of rice is greater than that of E. oryzicola, which had a comparatively strong tolerance among the weeds examined, and also that there are differences in tolerance among the rice varieties. These findings suggest that the difference in Fe tolerance is involved in weed control systems when organic materials are applied. If this difference is an important factor in the weed control system, Fe‐tolerant rice varieties, like cv. D. Shali, could facilitate weed control systems due to their higher Fe tolerance ability.  相似文献   

3.
The 4-coumarate: coenzyme A ligase (4CL) is one of the key enzymes in the biosynthesis of lignin monomers. It has been demonstrated that the 4CL is a new potential target site for developing effective plant growth inhibitors. Although previous studies demonstrate that chalcone and naringenin differentially suppress the growth of several annual plant species, we show here that the compounds can inhibit the 4CL enzyme activity in the plants. The enzyme was extracted and partially purified from the leaf tissues of two tolerant plants (wheat and soybean) and three susceptible plants (tomato, barnyard grass, and common chickweed). A maximal 29-fold purification of the enzyme, with a yield of 32% (tomato), was achieved by a six-step procedure, including anion-exchange column chromatography. Naringenin strongly inhibited the 4CL specific activity in wheat, soybean and barnyard grass, whereas chalcone showed the highest inhibitory effect in common chickweed. A good correlation was observed between the level of growth suppression by the compounds and the total 4CL amount in the plants. These results suggest that the inhibitor treatment at the same concentration could not inactivate the entire 4CL enzyme produced in the tolerant plants. Taken together, these results highlight the possibility of the 4CL as a new action site of growth suppression.  相似文献   

4.
This study aimed to identify the potential allelopathic indigenous rice (Oryza sativa L. ssp. indica) varieties from Bangladesh using a performance study in a weed‐infested field and to assess the extent of allelopathic interference relative to resource competition in a glasshouse experiment. Six varieties – namely, “Boterswar,” “Goria,” “Biron” and “Kartiksail” as the most allelopathic, “Hashikolmi” as weakly allelopathic and “Holoi” as nonallelopathic – were raised following a nonweed control method. The infestation levels of weed species were calculated using Simpson's Diversity Index (SDI), which ranged from 0.2 to 0.56. However, a significant correlation coefficient (0.87, P < 0.001) was obtained from these field data compared with the root inhibition percentage from the laboratory bioassay, and the “Boterswar” variety was the most allelopathic. The interactions between the allelopathic variety “Boterswar,” weakly allelopathic variety “Hashikolmi” and Echinochloa oryzicola via a target (rice)‐adjacent (E. oryzicola) cogrowth culture were determined in a hydroponic arrangement. The relative competitive intensity (RCI) and the relative neighbor effect (RNE) values showed that the crop–weed interaction was facilitation for “Boterswar” and competition for “Hashikolmi” and E. oryzicola in rice/E. oryzicola cogrowth cultures. The allelopathic effects of “Boterswar” were much higher than the resource competition in rice/E. oryzicola cogrowth cultures. The converse was observed for “Hashikolmi.” Moreover, the mineral content of E. oryzicola was severely affected by “Boterswar”/E. oryzicola cogrowth cultures’ exudate solution. Therefore, the allelopathic potential of “Boterswar” variety might be useful for developing the weed‐suppressing capacity of rice, which will likely have a significant influence on paddy weed control.  相似文献   

5.
Echinochloa oryzicola Vasing. (= Echinochloa phyllopogon Stapf ex Kessenko) is an obligate weed with an elaborated survival strategy in the flooded rice of Japan. In this review various adaptive characters of the weed, which comprise the survival strategy, are discussed through the life cycle. The weed is distributed only in flooded rice. Seeds (spikelets) buried in the soil exhibit annual cycles between dormant and non‐dormant state, and non‐dormant seeds recurrently appear in spring when rice growers start to prepare seedling beds and fields for rice transplanting. The non‐dormant seeds have unique characters metabolically adapted to submerged conditions to germinate and grow by the anaerobic respiration through alcohol fermentation. The weed has seemingly perfect mimicry of the rice plants throughout its development from seedling to heading, by which the weed escapes from manual weeding. In a rice paddy, the weed starts heading coincidentally with the rice plants at the period when the growers are reluctant to walk in the rice paddy to weed. Irrespective of plant height of the rice cultivar, the weed develops a few upper leaves above the rice canopy during the heading period of rice. This phenotypic plasticity of E. oryzicola in plant height is one of the characters conferring its competitive aggressiveness in flooded rice. When weeding is begun again after heading, the dormant weed seeds escape weeding by shattering and join the soil seedbank. The dormant seeds express the gene of an enzyme catalyzing ATP synthesis through the mitochondrial oxidative phosphorylation more abundantly, and have larger oxygen absorption and enzyme activity of the aerobic respiration than the non‐dormant seeds, suggesting that the dormant seeds maintain viability by the conventional aerobic respiration in the paddy soil drained from rice harvesting in fall to the next early spring. The various adaptive characters comprising the survival strategy of E. oryzicola in flooded rice consist of those inherited from the wild progenitor and those selected by the crop cultivation pressure. It is suggested that both the mimicry of the weed and the heading coincident with the rice plants have been acquired by the large selection pressure of frequent weeding, which has been done over the past hundred years. However, today, the manual weeding is substituted with herbicides, which cannot detect the mimicry and heading photoperiodic sensitivity. As a result, the dominant species of Echinochloa weeds in flooded rice is changing from E. oryzicola to Echinochloa crus‐galli var. crus‐galli that has neither mimicry nor photoperiodic sensitivity synchronizing to that of rice, but is more competitive against rice.  相似文献   

6.
The effects of root-applied chalcone at 0.15 mmol L−1 on the growth and lignin biosynthesis in maize were investigated. The contents of 4-coumarate: CoA ligase (4CL, EC 6.2.1.12) substrates in maize shoots were increased more rapidly in the samples with chalcone application than in the control and the increase occurred at ≤ 3 h after the application (HAA). The lignin content was reduced by chalcone at ≤ 6 HAA. The shoot growth was suppressed by chalcone at ≤ 9 HAA. Consequently, the results suggest that chalcone suppressed maize growth by inhibiting monolignol biosynthesis.  相似文献   

7.
Evaluation of rice allelopathy in hydroponics   总被引：3，自引：0，他引：3  
The inhibitory activity of water extracts from the shoots and roots of three rice cultivars, Taichung native 1 (TN1) and IAC165 (both allelopathic rice) and AUS196 (non-allelopathic rice), grown in hydroponics was evaluated. The release of germination inhibitors by allelopathic rice plants into hydroponic solution was also determined with freshly collected solution and XAD-4 resin desorbate. The degree of the inhibition was quantified in terms of root growth in Echinochloa colona, Echinochloa crus-galli, Echinochloa crus-galli var. oryzicola, Triantema portulacastrum and Lactuca sativa. The allelopathic activity of rice was species specific, and depended on source and concentration. Root length of all test species was inhibited by the different concentrations of shoot extract of allelopathic and non-allelopathic rice. However, of the three cultivars, TN1 showed higher inhibition than IAC165 and AUS196 in all test species. Water extracts of shoots and roots significantly inhibited root growth in E. crus-galli but the shoot extract gave a greater inhibitory effect on E. crus-galli than the root extract. Root exudate of TN1 inhibited root elongation of E. crus-galli from 2 weeks after transplanting (WAT) and the inhibition continued for 4 WAT. The results confirmed the previous finding of a laboratory bioassay that the TN1 had allelopathic activity and produced allelochemicals that inhibit growth of some weed species.  相似文献   

8.
Changes in phenolic metabolism and lignin deposition have been studied in roots of tomato plants after elicitation with four elicitors which are Fusarium mycelium extract (FME), chitosan (CHT), Fusarium culture filtrate (FCF) and Trichoderma mycelium extract (TME). Most profound effect of elicitors was observed on ferulic acid among the phenolic compounds. After 24 h elicitation, the increase in ferulic acid content of root cell wall was 3.71 and 3.30 times by FME and CHT, respectively. The increase of 4-hydroxybenzoic acid was 2.71 and 2.16 times by these two elicitors. The level of 4-coumaric acid was little more than double by these two elicitors after 24 h elicitation. Most pronounced increase in lignin synthesis was also effected by FME followed by CHT. Lignin deposition in the root cell wall was increased 3.6, 5.4 and 7.1 times by FME during 12, 24 and 36 h after elicitation, respectively. Similarly, CHT increased lignin deposition by 2.8, 5.1 and 6.8 times at 12, 24 and 36 h after elicitation, respectively. FCF and TME also increased lignin deposition significantly in the cell walls of tomato roots during the above time periods of elicitation. Activity of phenylalanine ammonia lyase reached highest level at 24 h post elicitation under the influence of the elicitors. Peroxidase activity registered a sharp increase at 24 h post elicitation. Markedly increased level of polyphenol oxidase activity was found at 12 h post elicitation. Cinnamyl alcohol dehydrogenase activity was observed to reach highest level at 48 h post elicitation. Cell wall strengthening, through the deposition of lignin, preceded by the induction of the synthesizing enzymes appears to play an important role in the defense response of Lycopersicon esculentum in reaction to elicitors, including one derived from Fusarium oxysporum f. sp. lycopersici, the causal organism of Fusarium wilt of tomato.  相似文献   

9.
Recently, flavonoids were shown to modulate the outcome of clubroot development in Arabidopsis thaliana after infection with the obligate biotrophic pathogen Plasmodiophora brassicae. Therefore, the development of clubroot disease was investigated in Arabidopsis after treatment with prohexadione‐calcium (ProCa), an inhibitor of ascorbic acid/2‐oxoglutaric acid‐dependent dioxygenases such as flavanone‐3‐hydroxylase. The treatment resulted in a reduction of the flavonols quercetin and kaempferol in clubroots, whereas the precursor naringenin highly accumulated. The root system of ProCa‐treated plants was better developed although galls were still visible. Thus, ProCa treatment resulted in reduced gall size. Flavonoids are thought to inhibit polar auxin transport by modulating auxin efflux carriers. It was investigated whether the auxin response might change as a consequence of the accumulation of naringenin in ProCa‐treated plants. In the areas of gall development an auxin response was indicated by the auxin‐responsive promoter DR5 coupled to the reporter β‐glucuronidase (GUS), whereas very little staining was found in healthy root parts. No differences in GUS activity were found between P. brassicae‐infected and ProCa‐treated plants, and plants only infected with P. brassicae, indicating that the effect of ProCa treatment on clubroot reduction is not via changes in auxin responses. As ProCa is also an inhibitor of late steps in gibberellin biosynthesis, a specific gibberellin biosynthesis inhibitor, chlormequatchloride (CCC), was tested on club development. However, CCC did not reduce disease symptoms, indicating that the observed reduced gall development was not because of gibberellin biosynthesis inhibition by ProCa.  相似文献   

10.
Coffea arabica cultivars Catuaí 44 and IAPAR 59, susceptible and resistant, respectively, to the root knot nematode Meloidogyne exigua, were grown in pots containing Si‐deficient soil amended with either calcium silicate (+Si) or calcium carbonate (?Si). There was an increase of 152 and 100%, respectively, in Si content of root tissue of cvs Catuaí 44 and IAPAR 59 in the +Si compared to the ?Si treatment, but no significant difference between Si treatments for calcium content. Plants, assessed 150 days after inoculation (d.a.i.) showed that the number of galls (NG) and number of eggs (NE) significantly decreased by 16·8 and 28·1% respectively, for susceptible cv. Catuaí 44 in the presence of Si, whilst both NG and NE were significantly lower for cv. IAPAR 59 compared to the susceptible cultivar regardless of Si treatments. In a separate experiment, biochemical assays were carried out 5 and 10 d.a.i. There was no significant difference between Si treatments and cultivars for concentration of total soluble phenolics. The concentration of lignin‐thioglycolic acid (LTGA) derivatives significantly increased by 11·5% in roots of nematode‐inoculated plants of susceptible cv. Catuaí supplied with Si. In roots of inoculated plants of resistant cv. IAPAR 59, the increase was 23 and 10%, respectively, for treatments with and without silicon. Peroxidase (POX), polyphenoloxidase (PPO) and phenylalanine ammonia lyase (PAL) activities significantly increased in roots of inoculated plants compared with roots of non‐inoculated plants, regardless of cultivar or Si treatment. In +Si treatments at 10 d.a.i., POX activity in roots of nematode‐inoculated plants of cvs Catuaí 44 and IAPAR 59 increased by 39·9 and 31·3%, respectively; PPO increased by 54·9 and 56·1%; and PAL activity was also higher at 26·6 and 62·9%. It was concluded that supplying Si to coffee plants increases root resistance against M. exigua by decreasing its reproductive capacity.  相似文献   

11.
The accumulation of soluble and cell wall-bound phenolics in the sugarcane stems of young plants from highly resistant cv. My 5514 and susceptible cv. B 42231, inoculated or not inoculated with smut sporidia, was studied. The ratio of inoculated to uninoculated plants of some cell wall-bound phenolics, such as ferulic, caffeic, and syringic acids increased for the resistant cv. My 5514, whereas it was maintained more or less constantly for the susceptible cv. B 42231. The highest increase of this ratio in the resistant cv. My 5514 corresponded to both caffeic and syringic acids. This could result in a better capacity to cv. My 5514 for an increase in the frequency of bridges between lignin fragments through ester-ether linkages for reinforcing the cell wall and major resistance to the disease. This reinforcement of the cell wall could provide an effective barrier to pathogen entry and spread. Soluble sub-fractions of all phenolics detected showed non-stable patterns. Caffeic acid, that regulates phenylalanine ammonia-lyase activity in sugarcane, showed a significant decrease in its titre at 24 h in the resistant cultivar, principally in the free soluble fraction, whilst the susceptible cultivar enhanced it. We hypothesise that the pathway of hydroxybenzoic acids is only activated once the level of p-coumaric acid justifies the accumulation of hydroxycinnamic acids required for reinforcing the cell wall after inoculation.  相似文献   

12.
为明确富亮氨酸重复类受体蛋白激酶（leucine-rich repeat receptor-like kinase,LRR-RLK）编码基因OsLRR-RLK18在调控水稻对褐飞虱Nilaparvata lugens防御中的作用及机理,以野生型水稻品系、OsLRR-RLK18基因敲除纯合水稻品系为研究对象,测定不同水稻品系的株高和根长、不同水稻品系对褐飞虱生物学参数的影响及褐飞虱为害后不同水稻品系中防御信号分子含量和防御化合物含量。结果显示,敲除OsLRR-RLK18基因后水稻株高和根长降低,褐飞虱为害后期诱导的茉莉酸、茉莉酸-异亮氨酸和脱落酸含量显著增加,但水稻组成型（未受褐飞虱为害）和为害早期的水杨酸和过氧化氢含量降低,引起水稻多种挥发物组分释放量增加,木质素、对香豆酰腐胺及樱桃苷、刺苞菊苷和大波斯菊苷3种类黄酮含量下降,最终导致褐飞虱卵孵化率和产卵量显著降低。表明OsLRR-RLK18基因参与了水稻对褐飞虱为害的防御反应,在调控水稻对褐飞虱的抗性中发挥着一定作用。  相似文献   

13.
The effect of soluble silicon (Si) on photosynthetic parameters and soluble sugar concentrations was determined in leaves of rice cv. Oochikara and mutant plants of Oochikara defective in active Si uptake [low silicon 1 (lsi1)]. Plants were grown in hydroponic culture amended with 0 (?Si) or 2 mm Si (+Si), under either low or high photon flux density (PFD) and with or without inoculation with Bipolaris oryzae, the causal agent of brown spot of rice. Leaf Si concentration increased by 141 and 435% in +Si cv. Oochikara and by 119 and 251% in +Si lsi1 mutant plants under high and low PFD, respectively, compared with ?Si plants. Plant biomass accumulation was improved by Si regardless of PFD, especially plants for cv. Oochikara. Brown spot severity was highest in ?Si plants for cv. Oochikara and lsi1 mutant plants under low PFD. In the presence of Si, disease severity in plants grown under both low and high PFD was reduced, except for lsi1 mutant plants under high PFD. Plant inoculation reduced the photosynthetic parameters measured regardless of plant material or Si supply. A decrease of net carbon assimilation rate (A) of inoculated plants under low PFD compared with non‐inoculated plants was associated with damage in the photosynthetic apparatus, except for +Si cv. Oochikara in which stomatal restriction [low water vapour conductance (gs)] contributed to A reduction. Under high PFD, damage to the photosynthetic apparatus of inoculated plants was the main reason for the reduction in A for +Si and ?Si lsi1 mutant plants. In addition, for ?Si cv. Oochikara, a reduction in gs contributed to reduced A. However, for +Si cv. Oochikara, gs was the limiting factor for A. Inoculated plants of +Si cv. Oochikara had higher A values than +Si lsi1 mutant plants, regardless of environmental conditions. Soluble sugars were not detected in leaf tissues of plants under low PFD. For high PFD, Si improved the hexose concentration in non‐inoculated plants at 144 h after inoculation (hai) for lsi1 mutant plants and from 96 hai onwards for cv. Oochikara compared with ?Si plants. However, plant inoculation reduced hexose concentration compared with non‐inoculated plants, mainly in +Si plants, regardless of plant material. Sucrose concentration increased in leaves of cv. Oochikara in the presence of Si whether inoculated or not. For +Si lsi1 mutant plants, sucrose concentration increased only at 48 hai compared with ?Si plants, whether inoculated or not. The results of this study show that a minimum Si concentration is needed in leaf tissues of rice plants to avoid the negative impact of B. oryzae infection on photosynthesis and sugar concentration. High leaf Si concentration resulted in an increased soluble sugar concentration and together, but in independent ways, soluble sugar and Si reduced brown spot severity of rice.  相似文献   

14.
Echinochloa crus‐galli (L.) Beauv. var. formosensis Ohwi (2n = 6x = 54, AABBCC genomes) and Echinochloa oryzicola (Vasinger) Vasinger (2n = 4x = 36, AABB) are major paddy weeds in East and Southeast Asia. E. oryzicola has been generally considered to be a paternal genome donor of E. crus‐galli s. l., which includes E. crus‐galli var. formosensis based on cpDNA sequences. Thus, molecular characterization using polymerase chain reaction‐restriction fragment length polymorphism analysis of cpDNA has been proposed as a reliable method for discriminating between the two species. In this study, we report that four accessions of E. crus‐galli var. formosensis from Okinawa, Nagasaki, Shizuoka and Tokyo had similar cpDNA sequences to E. oryzicola and had been misidentified as E. oryzicola using molecular methods. In addition, our results demonstrated that these accessions likely inherited their chloroplast genomes from E. oryzicola and not from an anonymous diploid species during polyploidization. Our findings provide new insights into the evolution of E. crus‐galli s. l. and suggest that identification using the cpDNA molecular method alone is not an appropriate approach to differentiate E. crus‐galli var. formosensis and E. oryzicola.  相似文献   

15.
Echinochloa species are amongst the most problematic weeds in rice fields of Korea. The steady reliance on the Acetyl‐CoA carboxylase (ACCase) and acetolactate synthase inhibiting herbicides for control of these weeds has led to resistance to these herbicides. The objective of this study was to assess the genetic diversity among populations of ACCase inhibitor‐resistant and ‐susceptible Echinochloa crus‐galli and E. oryzicola in Korea, to better understand their population structure and possible origins of resistance. Seven simple sequence repeat markers were applied to assess the genetic diversity between resistant and susceptible E. crus‐galli and E. oryzicola from 12 populations in Korea. Genetic diversity was slightly higher in the resistant group. The Unweighted Pair Group Method using Arithmetic algorithm (UPGMA) dendrogram generated two distinct clades. One clade consisted of Echinochloa spp. from three populations, i.e. Anmyeondo, Gimje 4 and Gongju, which are resistant and differentiated from the susceptible populations, and the other clade contained the rest of the populations. Structure modelling supported two clades of UPGMA clustering. Based on these data, we can infer that some resistant populations are greatly differentiated, whereas other resistant biotypes are still building up resistance in rice fields in Korea. Resistance traits will be fixed and continue to spread over time without proper control measures.  相似文献   

16.
Abstract

In a survey of plant parasitic nematodes associated with or affecting rice throughout Nigeria, some important nematode pests, especially the white tip disease nematode, Aphelenchoides besseyi and the rice root nematodes Hirschmanniella spinicaudata and H. oryzae were identified from seed, soil and root samples from swamp rice fields respectively. The sugarcane cyst nematode, Heterodera sacchari occurred in swamp rice fields only around the major sugarcane estates in Nigeria. The root‐knot Meloidogyne incognita and the root lesion nematode, Pratylenchus brachyurus were also encountered in upland (rainfed) rice fields. The white tip disease nematode, A. besseyi occurred at low levels in soils and rice seeds throughout the country. High population levels of H. spinicaudata and H. oryzae were encountered especially in areas where monoculture of rice is practised. General chlorosis, poor tillering and significantly reduced yield have been observed due to H. spinicaudata. Rice plants attacked by H. sacchari also showed intense chlorosis, delayed and reduced tillering and reduced grain yield. The roots of attacked plants were twiggy, very necrotic and blackened. The root‐knot M. incognita and the root lesion nematodes P. brachyurus have both been observed to reduce rice yields. Rice cultivars screened for reactions to the nematodes showed varying degrees of susceptibilities. Some varieties were however resistant to the root‐knot nematode, M. incognita.  相似文献   

17.
Pepino mosaic virus (PepMV) was shown to be efficiently transmitted between tomato plants grown in a closed recirculating hydroponic system. PepMV was detected in all plant parts after transmission via contaminated nutrient solution using ELISA, immunocapture RT‐PCR, RT‐PCR, electron microscopy, and by inoculation to indicator plants. Detection of PepMV in nutrient solution was only possible after concentration by ultracentrifugation followed by RT‐PCR. Roots tested positive for PepMV 1–3 weeks after inoculation, and subsequently a rapid spread from the roots into the young leaves and developing fruits was found within 1 week. PepMV was only occasionally detected in the older leaves. None of the infected plants showed any symptoms on fruits, leaves or other organs. Pre‐infection of roots of tomato cv. Hildares with Pythium aphanidermatum significantly delayed PepMV root infections. When mechanically inoculated with PepMV at the 2–4 leaf stage, yield loss was observed in all plants. However, only plants of cv. Castle Rock recorded significant yield losses when infected via contaminated nutrient solution. Yield losses induced by infection with PepMV and/or P. aphanidermatum ranged from 0·4 up to 40% depending on experimental conditions.  相似文献   

18.
Barnyardgrass, hexaploid Echinochloa crus‐galli, is considered to arise from the hybridization between tetraploid Echinochloa oryzicola and an unknown diploid species. The genetic relationship between E. crus‐galli and E. oryzicola was examined to investigate the position of E. oryzicola in the evolutionary process of E. crus‐galli, based on the nuclear DNA internal transcribed spacer (ITS) and the chloroplast cpDNA trnT‐L, trnL intron, and trnL‐F regions. New World E. crus‐galli was clearly separated from Eurasian E. crus‐galli and showed a close relationship to the American taxa, Echinochloa crus‐pavonis and Echinochloa walteri, in both the ITS and chloroplast DNA. The nrDNA ITS sequences indicated no differentiation between the Eurasian E. crus‐galli and E. oryzicola, in contrast to their clear divergence in the cpDNA sequence. The present results suggest that E. oryzicola is the male donor of E. crus‐galli.  相似文献   

19.
冠菌素对玉米苗期植株形态建成的调控效应   总被引：2，自引：0，他引：2  
以玉米品种金海5号为材料,采用不同浓度植物生长调节剂冠菌素(COR)拌种和三叶期(V3)叶面喷施的方法,研究了COR对玉米苗期植株地上部和根系形态建成的影响,分析了其对叶面积、叶绿素含量和可溶性蛋白的调控效应。结果表明:不同浓度冠菌素对玉米幼苗形态建成的调控呈单峰曲线,即低浓度下促进幼苗生长,高浓度下抑制生长。用0.1 mg/L的COR拌种或叶面喷施处理,可促进玉米苗期植株株高和茎粗生长,增加单株叶面积,提高叶片叶绿素和可溶性蛋白含量,促进植株干物质积累。同时,COR可促进玉米苗期根系生长,增加根长和根表面积,进而可有效增加根系吸收能力。研究结果表明,适宜浓度的COR处理可以提高玉米幼苗光合性能,增强根系吸收能力,促进植株地上部和地下部的生长,有利于培育壮苗。  相似文献   

20.
The effect of chlorsulfuron on uptake of 45Ca was studied in maize (Zea mays L. cv. Earliking) plants grown from seeds dusted with 1, 8 naphthalic anhydride (NA). 45Ca absorption in sand-grown maize was significantly decreased when chlorsulfuron was applied to the foliage but this was not so when seeds had been dusted with NA. Uptake of 45Ca was also reduced when either root or shoot soil zones were separately exposed to chlorsulfuron. When seeds had been dusted with NA, uptake of 45Ca from main roots was similar to that of untreated plants, but only when chlorsulfuron was localized in the shoot zone. NA did not counteract the severe reduction in 45Ca absorption when chlorsulfuron was localized in the root zone.  相似文献   

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