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1.
Varietal mixture is a cultural technique in which the genetic and functional diversities of varieties are used to manage pests and diseases. This strategy is commonly used on grass crops such as rice, barley, maize, and wheat to mitigate some windborne and soilborne pathogens. The effects of varietal mixtures on the number and community structure of pests, including plant-feeding nematodes (PFNs), however, have rarely been studied. In experiments conducted in Martinique, we evaluated the effect of varietal mixtures of bananas on PFN communities. A growth chamber experiment was used to measure the susceptibility of three banana cultivars dessert banana cv. 902 (Musa AAA, Cavendish subgroup); a new synthetic hybrid cv. FB924 (Musa AAA); and a plantain cv. Creole blanche (Musa AAB, French Horn) to the two major PFNs. The multiplication rates of Radopholus similis and Pratylenchus coffeae were substantially different on the three varieties; for example, the multiplication rate was up to 10 times greater on plantain cv. Creole blanche than on hybrid cv. FB924. In a field experiment, we planted the three varieties in pairs that included all six possible combinations. Banana varietal mixtures significantly affected both PFN densities and community composition. Differences in community composition among the pairs involved a shifting equilibrium among nematode species and an interspecific competition for food resources. The relative abundance of the spiral nematode Helicotylenchus multicinctus increased while that of the burrowing nematode R. similis, which is the most damaging species on bananas, decreased. The use of a varietal mixture in which one variety supports a low PFN multiplication rate appears to have practical relevance, especially in systems based on very susceptible cultivars such as plantains. The use of varietal mixtures should not create management problems, especially for plantations that produce bananas for local markets.  相似文献   

2.
The aim of the present study was to determine whether arbuscular mycorrhizal (AM) inoculation with a biofertilizer containing clays as granular carriers, leek root pieces and Glomus intraradices spores could improve alkalinity tolerance of two cucumber genotypes, and to study the changes induced by AM at agronomical and physiological level. A greenhouse experiment was carried out to determine yield, growth, fruit quality, net photosynthesis (ACO2), electrolyte leakage, and mineral composition of two cucumber (Cucumis sativus L.) genotypes (hybrid “Ekron” or open-pollinated variety “Marketmore”) with inoculated and noninoculated arbuscular mycorrhizal biofertilizer. Plants were supplied with nutrient solutions at two pH values (6.0 or 8.1). The high pH nutrient solution had the same basic composition with an additional 10 mM NaHCO3 and 0.5 g l−1 CaCO3. The percentage root colonization was higher in “Marketmore” (21.8%) than “Ekron” (12.7%). Total and marketable yield and total biomass were significantly higher by 189%, 213%, and 77%, respectively, with Ekron in comparison to those recorded with Marketmore. The highest crop performance with Ekron in comparison to Marketmore was due to the improved nutritional status (higher N, P, K, Ca, Mg, Fe, Mn, and B), higher leaf area, and net photosynthesis. Increasing the concentration of NaHCO3 from 0 to 10 mM in the nutrient solution significantly decreased yield, plant growth, ACO2, N, P, Fe, Cu, Zn, Mn, and B concentration in leaf tissue, whereas the electrolyte leakage increased. The inoculated plants under alkaline conditions had higher total, marketable yield, and total biomass than noninoculated plant. Mycorrhizal cucumber plants grown under alkaline conditions had a higher macronutrient concentration in leaf tissue compared to noninoculated plants. The highest yield and biomass production in inoculated plants seems to be related to the capacity of maintaining higher net ACO2 and to a better nutritional status (high P, K, Mg, Fe, Zn, and Mn and low Na accumulation) in response to bicarbonate stress with respect to −AM plants.  相似文献   

3.
Barren desert soil that otherwise could not support perennial plant growth was amended with six levels of common agricultural compost. Seedlings of the giant cardon cactus, one of the primary plant species responsible for soil stabilization in the southern Sonoran Desert, were inoculated with the plant-growth-promoting bacterium Azospirillum brasilense Cd, planted, and grown for 18 months under nursery conditions typical for slow-growth cacti. Control plants were grown without compost amendment, without inoculation (negative control), or in fertile, rare “resource island” soil preferred by cardon seedlings (positive control). During the prolonged growth period, the decisive factor in seedling growth in barren soil was the addition of small amounts of common compost; 6 to 25% of the growth substrate volume gave the best growth response and, to a lesser extent, so did inoculation with A. brasilense Cd. Although the bacteria significantly affects plant growth when amended with “resource island” soil and added to barren soil, its effect on plant growth was far smaller than when compost alone was added. Compost added to barren soil significantly increased the dry weight parameters of the plant to almost similar levels obtained by the “resource island” soil; however, the compost amendment supports a more voluminous and greener plant with elevated pigment levels. This study shows that barren soil supplemented with compost can replace the rare “resource island” soil for cardon nurseries destined to abate soil erosion in the desert.  相似文献   

4.
In this study, the effect of an arbuscular mycorrhizal fungus (AMF) and two migratory endoparasitic nematodes on Musa plant growth, including the root system, were examined. In addition, the AMF-nematode interaction was studied. Seven Musa genotypes with different root systems were selected. Based on their relative mycorrhizal dependency, two genotypes (Calcutta 4 and Obino l'Ewai) were selected for AMF-nematode interaction studies. The experiments were performed under greenhouse conditions. Mycorrhization with Glomus mosseae resulted in a significantly better plant growth even in the presence of nematodes. The effect of AMF on the root system was genotype-dependent and seemed to be related to the relative mycorrhizal dependency of the genotype. The nematodes also affected the root system, decreasing branching. Nematode population densities were significantly reduced in the presence of AMF, except for Pratylenchus coffeae in Obino l'Ewai. In the root system, it appeared that the decreased branching caused by the nematodes was counterbalanced by the increased branching caused by the AMF.  相似文献   

5.
Despite low yields and soil fertility problems, fertilizer use in the East African Highland banana (AAA-EA) production is absent. High fertilizer costs increase the need for site-specific fertilizer recommendations that address deficiencies. This study aimed to derive and compare norms for AAA-EA bananas, using Compositional Nutrient Diagnosis (CND), Diagnosis and Recommendation Integrated System (DRIS), and a DRIS that includes a filling value (DRIS-Rd), and study nutrient interactions. Data on foliar nitrogen, phosphorus, potassium, calcium, and magnesium concentrations, and plant performance were obtained from 300 plots in Uganda. CND indices were closely related to DRIS and DRIS-Rd indices (R2 > 0.965). Four nutrient interactions were common in both low and high bunch weight subpopulations. Although the three approaches can be used to determine nutrient imbalances in AAA-EA bananas, we recommend CND for ease of use. Diagnosis of nutrient deficiencies should be based on methods that identify plant nutritional imbalances.  相似文献   

6.
ABSTRACT

A pot experiment was carried out to investigate the tolerance of cucumber plants (Cucumis sativus L.) to root-knot nematode after inoculation with Glomus intraradices. Plants were inoculated with G. intraradices for four weeks and then transplanted in soil treated with Meloidogyne incognita for a further five weeks. The low phosphorus (P) loamy soil was amended with 50 and 100 mg P kg?1 soil. Mycorrhizal colonization increased shoot dry weight, shoot length, leaf numbers, root fresh weight and shoot P concentration, whereas nematode penetration and reproduction were significantly decreased. Similarly, P fertilization usually increased shoot growth and significantly decreased the number of galls and the number of egg masses and eggs per g root. Our results indicate that inoculation with G. intraradices and P fertilizer confer tolerance of cucumber plants to M. incognita by enhancing plant growth and by suppressing reproduction and/or galling of nematodes during the early stages of plant growth.  相似文献   

7.
A greenhouse experiment was conducted at the University of Çukurova, Rhisosphere Lab, Adana, Turkey, on a growth medium to assess the impact of several selected mycorrhiza including indigenous AMF-maize hybrid combinations on spore production, plant growth and nutrient uptake. In the experiment, six maize (Zea mays L.) (Luce, Vero, Darva, Pegasso, P.3394, and P.32K61) genotypes were used. Control, Glomus mossea, G. caledonium, G. etunicatum, G. clarium, G. macrocarpum, G. fasciculatum, G. intraradices, Dr. Kinkon (Japanese species), indigenous mycorrhizae (Balcal? series) and cocktail mycorrhizae species spores were used. The growth of maize genotypes was found to depend on the mycorrhizal species. For shoot and root dry weight production G. intraradices is one of the most efficient mycorrhiza species on average on all maize genotypes. Genotypes P.3394 and P.32K61 produced the highest shoot and root dry weight as well. Pagasso and Darva genotypes compared to the other genotypes have high root colonization percentages. On average G. clarium inoculated plants also have high percentages of root colonization. It has been found that the P.32K61 genotype has a high phosphorus (P)% content and Pagasso genotypes have higher zinc (Zn) content uptake than other genotypes. G. clarium inoculated maize genotype plant tissues have high P% and Zn content. G. intraradices is also efficient for P and Zn uptake. Mycorrhizal dependent maize genotypes showed variability in P efficiency from inefficient to efficient genotypes.  相似文献   

8.
Banana (Musa AAA) and plantain (Musa AAB) are important dietary staples for over 70 million people in sub-Saharan Africa. Banana weevil (Cosmopolites sordidus) and nematodes (Radopholus similis, Helicotylenchus multicinctus) are often the largest constraints to production. Leguminous crops in the genera Canavalia, Mucuna and Tephrosia have been reported as having repellent or insecticidal properties. We assessed: weevil and nematode populations and damage; banana growth and development; soil and foliar nutrient concentrations; and soil moisture status in banana intercropped with three legumes (Canavalia ensiformis, Mucuna pruriens and Tephrosia vogelii). The research took place at Kawanda, Uganda, on a field site infested with weevils and nematodes. The legume intercrops did not affect weevil populations or damage. The legumes also provided no benefit in terms of nematode control; in fact, banana root necrosis was higher in the T. vogelii intercrop than in the banana monoculture. Banana fruit yield was not adversely affected by the legume intercrops. The low yield noted across treatments was attributed to the high level of damage by the weevils and the nematodes. Significantly more NO3-N accumulated from 0- to 0.3-m depth in the M. pruriens intercrop than in the other treatments. There was no treatment difference in soil moisture. In summary, there was no significant advantage in banana production associated with the legume intercrops. However, the lack of a significant difference in banana fruit production between the monoculture and the intercrops suggests that land use efficiency may be increased by incorporating food and or/fodder legumes into the banana cropping system.  相似文献   

9.
The interactive impacts of arbuscular mycorrhizal fungi (AMF, Glomus intraradices) and earthworms (Aporrectodea trapezoides) on maize (Zea mays L.) growth and nutrient uptake were studied under near natural conditions with pots buried in the soil of a maize field. Treatments included maize plants inoculated vs. not inoculated with AMF, treated or not treated with earthworms, at low (25 mg kg−1) or high (175 mg kg−1) P fertilization rate. Wheat straw was added as feed for earthworms. Root colonization, mycorrhiza structure, plant biomass and N and P contents of shoots and roots, soil available P and NO3−–N concentrations, and soil microbial biomass C and N were measured at harvest. Results indicated that mycorrhizal colonization increased markedly in maize inoculated with AMF especially at low P rate, which was further enhanced by the addition of earthworms. AMF and earthworms interactively increased maize shoot and root biomass as well as N and P uptake but decreased soil NO3−–N and available P concentrations at harvest. Earthworm and AMF interaction also increased soil microbial biomass C, which probably improved root N and P contents and indirectly increased the shoot N and P uptake. At low P rate, soil N mobilization by earthworms might have reduced potential N competition by arbuscular mycorrhizal hyphae, resulting in greater plant shoot and root biomass. Earthworms and AMF interactively enhanced soil N and P availability, leading to greater nutrient uptake and plant growth.  相似文献   

10.
Phosphorus uptake and biomass production may vary between arbuscular mycorrhizas (AM) species of contrasting life cycles and their modes of interaction with host plants. This research investigated differences among three AM fungi from different genera isolated from the jarrah forest with respect to their colonisation, biomass production and P uptake over time. The understorey plant Phyllanthus calycinus, has been shown to be extensively mycorrhizal. We examined differences in the capacity of fungi associated with this plant to access a P point source from increasing distances from the root. The methodology simulated “pockets” of P in forest soil. Phosphorus sources in root-exclusion mesh bags were inserted 2, 4 and 6 cm from plant roots restrained in separate mesh bags. Acaulospora laevis colonised plants to the greatest extent, producing higher plant biomass and P uptake compared to the other two fungi. Plant biomass and P uptake were enhanced where P sources were closest to the root, as expected, but there were differences among fungi in response to level of inoculum used for each fungus. The capacity of individual AM fungi to access a point source of P at different distances varied in a highly mycorrhizal native forest understorey plant in parallel with plant growth and P uptake.  相似文献   

11.
Population parameters (mortality of females, reproductive success, longevity of juveniles) of the common woodlouse, Porcellio scaber (Isopoda, Oniscidea), were examined with respect to the influence of varying leaf litter attributes: pH level, microbial cellulase activity, microbial dehydrogenase activity, protein content, nitrogen content, water content, tannin content, total phenol content and toughness of the leaves. These attributes were combined by using Principal Component Analysis. We obtained three Principal Components (PC) that were defined as “acidification,”“microorganisms” and “tree species.” The PCs explained 85% of the variance of leaf litter attributes. The PC “acidification” mainly influenced the mortality of females (P<0.001), while the longevity of juveniles showed significant correlation to the PC “microorganisms” (P<0.05). The PC “tree species” showed no influence on the observed population parameters, indicating that the leaf litter species itself had no direct influence on the population parameters of P. scaber. The reproductive success of females could not be explained by either of the PCs, but was influenced by cellulolytically active microorganisms (P<0.01). From these results, we conclude that acidification and reduced microbial activity in the field will cause a decrease in population density of P. scaber. Received: 30 July 1996  相似文献   

12.
Recent reports have shown a surprising diversity of agricultural crops in Omani oases which was attributed to the country’s traditional role at the crossroads of cultures and trade between the Middle East and Asia. Recent surveys have indicated a relatively small diversity of banana (Musa spp.) germplasm which was thought to reflect the prevailing hyperarid conditions of Oman where this drought-sensitive species can only be cultivated in well-watered oases in the North or in Dhofar, the monsoon-dominated south eastern tip of the Sultanate. Surveys near Umq Bi’r, a half-abandoned oasis in the hardly accessible spring area of Wadi Tiwi, famous with Arabic sailors for its abundant fresh water resources, led to the discovery of a so far undescribed triploid Musa acuminata cultivar surviving in a limestone rock niche. Its morphological traits are different from any of the currently grown banana cultivars. Since acuminata bananas are quite sensitive to drought spells, characteristic for the Arabian Peninsula, the occurrence of this specimen provides further evidence for Oman’s role as a refuge of relict crops imported from a more humid region such as coastal East Africa and nearby islands, or Indonesia.  相似文献   

13.
Aim of this work was to investigate if the variation among tomato genotypes in selenium (Se) uptake and accumulation observed in short term experiments are maintained over longer growth periods and if there is a positive correlation in shoot between sulphur (S) accumulation and Se accumulation across different genotypes or if higher tissue S results in greater feedback inhibition of Se uptake. Two experiments were carried out under greenhouse conditions and different genotypes of Lycopersicon lycopersicum (UC82B and LA2711), Lycopersicon pennellii (LA716) and Lycopersicon peruvianum (LA2157) were grown until fruit ripening. The results obtained in the two experiments confirmed that sulphate in the growth solution reduced selenate uptake by plants and increased the S content of the leaves. Under low sulphate treatment there was a clear correlation (R2=0.82) between leaf S content and shoot Se content across genotypes in both experiments, indicating that the overall activity of the S transport systems also determines Se transport. Selenium was translocated from shoot to fruit, but the edible portion of the plant contained much less total Se than the inedible plant parts. The difference in Se content between the low and the high sulphate treatments was significantly higher in shoot than in root, confirming that the Se translocation from root to shoot is probably more affected by high sulphate supply than Se uptake by root. In the first experiment the genotype LA716 showed ah higher Se, accumulation together with higher S content in leaves, indicating a marked ability of this genotype to absorb ions from substrate. In the second experiment UC82B appeared to be more capable to accumulate Se and S rather than LA2711 and LA2157. In both experiments Lycopersicon peruvianum appeared to be less affected by the high concentration of ions in the growth solution and to be able to reduce ion uptake than Lycopersicon lycopersicum and Lycopersicon pennellii.  相似文献   

14.
The effects of calcium and humic acid on seed germination, growth and macro- and micro-nutrient contents of tomato (Lycopersicon esculentum L.) seedlings in saline soil conditions were evaluated. Different levels of humic acid (0, 500, 1000 and 2000 mg kg?1) and calcium (0, 100, 200 and 400 mg kg?1) were applied to growth media treated with 50 mg NaCl kg?1 before sowing seeds. Seed germination, hypocotyl length, cotyledon width and length, root size, shoot length, leaf number, shoot and root fresh weights, and shoot and root dry weights of the plant seedlings were determined. Macro- and micro-nutrient (N, P, K, Ca, Mg, S, Cu, Fe, Mn and Zn) contents of shoot and root of seedlings were also measured. Humic acid applied to the plant growth medium at 1000 mg kg?1 concentration increased seedling growth and nutrient contents of plants. Humic acid not only increased macro-nutrient contents, but also enhanced micro-nutrient contents of plant organs. However, high levels of humic acid arrested plant growth or decreased nutrient contents. Levels of 100 and 200 mg kg?1 Ca2+ application significantly increased N, Ca and S contents of shoot, and N and K contents of root.  相似文献   

15.
The aim of the present study was to assess the role of soil type on growth, P uptake and rhizosphere properties of wheat and canola genotypes in an alkaline soil with low P availability. Two wheat (Goldmark and Janz) and two canola genotypes (Drum and Outback) were grown in a calcareous soil (pH 8.5) at two P levels [no P addition (0P) or addition of 200 mg kg−1 P as Ca3(PO4)2 (200P)] and harvested at flowering or maturity. Shoot and root dry weight, root length and shoot P content were greater in the two canola genotypes than in wheat. There were no consistent differences in available P, microbial P and phosphatase activity in the rhizosphere of the different genotypes. Shoot P content was significantly positively correlated with root length, pH and phosphatase activity in the rhizosphere. The microbial community composition, assessed by fatty acid methylester analysis, of the canola genotypes differed strongly from that of the wheat genotypes. The weight percentage bacterial fatty acids, the bacteria/fungi (b/f) ratio and the diversity of fatty acids were greater in the rhizosphere of the canolas than in the rhizosphere of the wheat genotypes. In contrast to the earlier studies in an acidic soil, only small differences in growth and P uptake between the genotypes of one crop were detected in the alkaline soil used here. The results confirmed the importance of root length for P uptake in soils with low P availability and suggest that the rhizosphere microbial community composition may play a role in the better growth of the canola compared to the wheat genotypes.  相似文献   

16.
Phosphorus (P) deficiency is one of the most important yield‐limiting factors in acid soils in various parts of the world. The objective of this study was to evaluate the growth and P‐use efficiency of 20 upland rice (Oryza sativa L.) genotypes at low (0 mg P kg‐1), medium (75 mg P kg‐1), and high (150 mg P kg‐1) levels of applied P on an Oxisol. Plant height, tillers, shoot and root dry weight, shoot‐root ratio, P concentration in root and shoot, P uptake in root and shoot, and P‐use efficiency were significantly (P<0.01) affected by level of soil P as well as genotype. Shoot weight and P uptake in shoot were found to be the plant parameters most sensitive to P deficiency, suggesting that these two parameters may be most suitable for screening rice genotypes for P‐use efficiency under greenhouse conditions.  相似文献   

17.
Zinc ammonia acetate (ZAA) is marketed as an agricultural additive (ACA) and has been shown to increase the yield of corn (Zea mays L.). However, the response is sometime variable and the effective components and the mode of action are not known. To address these issues, the effect of four concentrations (0, 0.85, 8.5, and 85 ppm) of ZAA on laboratory germination and early seedling growth of three maize genotypes were evaluated. The ZAA at 0.85 and 8.5 ppm tended to increase the total seminal root length, and shoot and root dry weight of seedling in all genotypes. Hydroponic studies revealed that plant height and whole plant dry weight of 2‐week‐old seedlings tended to be increased with 0.85 and 8.5 ppm of ZAA in all genotypes compared to the control. The number of seminal and lateral root for all genotypes, and seminal root total length for two genotypes were significantly increased by ZAA at both 0.85 or 8.5 ppm. However, the high root:shoot ratio observed for ZAA‐treated seedlings was not due to increased root growth over shoot growth but resulted from a greater reduction in shoot growth at higher ZAA concentrations. The boron (B) content of the shoots of all genotypes had a positive linear response to increasing ZAA concentrations. Both 0.85 and 8.5 ppm of ZAA increased copper (Cu) and iron (Fe) contents of all genotypes. The calcium (Ca), potassium (K), magnesium (Mg), and phosphorus (P) concentrations were not significantly affected by ZAA treatments, although there was a trend toward an increase for some of these elements at both 0.85 and 8.5 ppm of ZAA. In a greenhouse test, plant height, leaf area, and shoot dry weight of 3‐week‐old seedlings of all genotypes were increased by ZAA at 0.85 and 8.5 ppm. Root volume was increased at both 0.85 and 8.5 ppm for one genotype. Considering the extremely low concentration of ZAA required to induce a plant response (0.85 or 8.5 ppm), some possible modes of action of ZAA are discussed.  相似文献   

18.
Forty six wheat genotypes from different origins were tested at stress (25 μM P) and adequate (250 μM P) levels of phosphorus (P) developed in a modified Johnson's nutrient solution. Response of wheat genotypes for tolerance to P deficiency stress was measured at two growth stages in terms of growth, P uptake, and P utilization efficiency. Substantial differences in shoot and root growth were observed among genotypes at both stress and adequate P levels in the growth medium. Reduction in shoot biomass due to P deficiency varied from >50% to 27%. Similarly P concentration in shoot and root, P uptake, specific absorption rate of P, and P utilization efficiency varied significantly at both levels of applied P. A significant negative correlation between P stress factor and root dry weight (r = ?0.396**), shoot P uptake (r = ?0.451**), and specific absorption rate of P (r = ?0.281**, P < 0.01) suggested that the genotypes with greater root biomass, higher P uptake potentials in shoots, and absorption rate of P were generally more tolerant to P deficiency in the growth medium. Wheat genotypes were grouped according to the ranking order of investigated plant characteristics and shoot dry matter yield per unit of P absorbed. Genotypes Inqlab-91, SARC-II, SARC-IV, Chakwal-86, 90627, 89626, and Parvaz-94 were P efficient, while genotypes Pak-81, Pato, 88042, 88163, 89295, 4072, 89313, and 91109 were P inefficient. All other genotypes were intermediate in P use efficiency.  相似文献   

19.
Abstract

Rapid clonal propagation potential of banana was investigated by using excised shoot tips of Musa spp. Shoot tips isolated from young suckers of ‘Anamur 2’, ‘Dwarf Cavendish’, and ‘Gazipasa 6'genotypes were used. Excised shoot tips were transferred immediately to Murashige and Skoog (MS) medium with different concentrations of 6-benzylaminopurine (BAP) and thidiazuron (TDZ) either alone or with indoleacetic acid (IAA). Rooting was achieved with indole-3-butyric acid (IBA) and α-naphthaleneacetic acid (NAA) in the presence or absence of activated charcoal (AC). The results showed that shoot proliferation rate was statistically affected by cytokinin types and their concentration. The responses to TDZ were better than to BAP. BAP or TDZ with IAA increased shoot elongation compared with BAP or TDZ alone. An increase in plant height, root numbers and average number of roots per explant was obtained using AC. Hence, for multiplication of ‘Dwarf Cavendish’, the use of MS medium with 2.5 µM TDZ with 1 µM IAA followed by rooting with AC only is recommended. For multiplication of banana genotypes ‘Anamur 2’ and ‘Gazipasa 6’, the use of MS medium with 1 µM TDZ and 1 µM IAA followed by rooting with AC only is recommended.  相似文献   

20.
A factorial nutrient solution experiment with 3 N levels and 4 plant growth regulator (PGR) rates with sunflower (Helianthus annuus, L., cv. Sorex) was conducted to investigate the effect of both variables on shoot and root development. Nitrogen shortage resulted in reduced shoot and root growth throughout the experiment, but root growth was less affected than the shoot PGR treatments drastically reduced shoot biomass production. Root growth was promoted. Both reduced nitrogen supply and application of a triazole plant growth regulator (BAS 111. W) increased the proportion of roots relative to the shoot.  相似文献   

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