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1.
《Journal of Crop Improvement》2013,27(2):121-161
Summary A number of crops exhibit allelopathic interactions that play a significant role in the complex environment of agroecosystems. Several studies have shown that allelopathic crops reduce growth, development and yield of other crops growing simultaneously or subsequently in the fields. Another aspect of interest regarding crop allelopathy is that allelochemicals may exhibit inhibitory effect on the same crop which is commonly called as crop autotoxicity. It is predominantly common in fields where sole cropping under reduced or no-tillage system is practiced. Though any crop part can be allelopathic, including even the pollens, but decomposing crop residues exhibit more influence on other plants. Furthermore, the extent of allelopathy by a crop plant varies with age, part and type of cultivar being used. Nowadays allelo-pathic crops are being used as an important tool in managing weeds and harmful pests under sustainable pest management programs. In this context several cover/smother and green manure crops with allelopathic nature hold a good promise as well as challenge for the future as they have a potential to suppress noxious weeds. Likewise, the decomposing residues of such crops can also be used for managing harmful weeds and pests vis-à-vis maintaining the sustainability of the system. The traditional practice of crop rotation which declined with the discovery of synthetic herbicides can also be revived, if allelopathic potential of rotational crops is well understood. Selection of cultivars with high allelopathic potential/high competitiveness is another possible way by which crop allelopathy can be better utilized for weed control and yield enhancement. Crops with less allelopathic potential can be genetically improved by incorporating desired genes encoding the synthesis of allelochemicals. Pure allelochemicals extracted and identified from some crop plants can also be used as bioherbicides. 相似文献
2.
《Journal of Crop Improvement》2013,27(2):323-333
Summary Live plants and plant material in various forms have important roles in ecological processes. Weeds may be involved in interactions with desirable species at different trophic levels through the production and release of allelochemicals. The allelopathic potential of the weed Cyperus esculentus (yellow nutsedge) was assessed by preparing aqueous extracts from tubers and foliage from immature or mature plants, and testing their effects on an ectomycorrhiza and two higher plant species. The extracts from tubers and both foliage types significantly reduced the colony diameter of the ectomycorrhiza Boletus maxaria, which was isolated from roots of the forestry species Pinus patula, on agar medium. Extracts (2% m/v) from C. esculentus tubers and the foliage of immature plants inhibited the germination of lettuce (Lactuca sativa) seeds significantly. At 5% concentration, the extracts from foliage of immature weed plants completely inhibited the germination of lettuce seeds at the end of the 7-day trial period. The emergence of corn (Zea mays) was retarded in soil where C. esculentus tubers were planted 28 days before planting the crop, irrespective of whether the weeds continued to grow or were physically removed at the time the corn was sown. In contrast, where weed tubers and corn seeds were planted at the same time, emergence of corn was not affected. It is suggested that the growth stage of weeds be considered in the assessment of their direct and indirect allelopathic effects, and in predictions for their impacts on crop development and yield. 相似文献
3.
《Journal of Crop Improvement》2013,27(2):415-432
Summary This paper reviews the effects of allelopathic interactions in agroecosystems in Spain on plant physiological activity and their ecological advantages. The phenological stage of growth of donor plants and the effective allelochemicals in the soil solution while studying the role of phenolic compounds were highlighting. Finally possible future prospects and conclusions regarding weed control by allelochemi-cals under integrated crop management strategies are discussed. 相似文献
4.
《Journal of Crop Improvement》2013,27(2):303-312
Summary Allelopathy is well known as an interaction among plants (including microbes) through chemicals produced by plants. Recently, many investigations have evaluated the possibility of the use of allelo-pathic substances as a natural herbicide. Alfalfa (Medicago sativa L.) is reported to contain allelopathic chemicals that inhibit the growth of weeds. Experiments were conducted in Laboratory of Crop Science, Experimental Farm of Miyazaki University and Kobayashi city in Miyazaki Prefecture, Japan to determine the allelopathic impact of alfalfa pellet (commercial forage fodder) on germination and growth of lowland weeds, and its potential as a natural herbicide in paddy field. The results indicated that alfalfa pellet significantly inhibited germination and growth of 4 weed species, viz., Echinochloa orygicola, Digitaria ciliaris, Cyperus difformis and Monocholia vaginalis in rice paddies. Among the 4 tested weeds, the maximum inhibitory effect of alfalfa pellet was seen against Cyperus difformis. The degree of inhibition of weed growth by alfalfa pellet became stronger as the application of concentration increased. The results showed that alfalfa pellet might be used as a natural herbicide in rice paddies and might reduce the amount of herbicide used in paddy fields. 相似文献
5.
《Journal of Crop Improvement》2013,27(1):77-93
Abstract Economic and environmental issues are driving efforts to improve cover crops for weed management. Cover crop residues on the soil surface interfere with weeds by releasing allelochemicals and by physical suppression. Optimizing allelopathic potential, biomass production, and other desirable cover crop characteristics using classical and molecular genetic approaches holds great promise for improving the efficacy and selectivity of cover crops. Likewise, investigating allelopathy at the genetic and molecular level should aid in understanding the biochemical basis for allelopathy in plants. 相似文献
6.
《Journal of Crop Improvement》2013,27(1):169-202
Summary Allelopathy includes both positive and negative effects of one plant on the other through environment, though most of the studies seem to focus on its deleterious impacts. It plays a key role in both natural and managed ecosystems. In agroecosystems, several weeds, crops, agroforestry trees and fruit trees have been shown to exert allelopathic influence on the crops, thus, affecting their germination and growth adversely. Some of the agricultural and horticultural crops affect their own seedlings grown in succession which is commonly known as replant problem/syndrome. Available studies indicate that allelochemicals act via bringing certain changes in physiological functions like respiration, photosynthesis and ion uptake. These, in turn, result in visible changes in seed germination, further growth reduction and overall performance of the target plants. The studies on interplant interactions assume significance in agroforestry programmes for selecting the types of crops complementary to the selective tree species. In the recent past, however, scientific attention has also been drawn to exploit the positive significant roles this phenomenon can play in enhancing crop productivity. In this context, we discuss the tremendous scope of allelopathy towards weed and pest management, apart from nitrogen conservation, and synthesis of novel agrochemicals based on natural product chemistry. The use of natural products of plant or microbial origin as pesticides/herbicides have gained much attention of the scientists as they offer many advantages over synthetic chemicals. The production of such chemicals should be enhanced by devising suitable protocols based on biotechnological procedures for their widespread utilization. 相似文献
7.
《Journal of Crop Improvement》2013,27(2):185-196
Summary The concept that some crop plants have allelopathic effects is receiving greater attention as a potential mean that can be exploited in various ways for controlling agricultural pests. Wheat residues have been reported to inhibit growth of certain weeds, crops that follow wheat crop in crop rotation, soil nitrification and biological nitrogen fixation. Thus, crop production can be enhanced by avoiding the inhibitory effects or by exploiting favorable interactions. The present article presents an overview of research on the allelopathic influence of wheat residues in agroecosystems. 相似文献
8.
《Journal of Crop Improvement》2013,27(2):401-414
Summary Agricultural productivity is very dependent upon the successful establishment of crops and pastures. High populations of vigorous seedlings enable the crop or pasture to withstand competition from weeds and infection from diseases as well as providing good utilisation of nutrient inputs and water. Residues of weed and pasture species can interfere with crop establishment and pasture regeneration. Research at Charles Sturt University (CSU) and elsewhere in Australia has focused on a better understanding of these relationships and the management of each situation to advantage the pasture and to minimise the impact of the allelopathic effects. Such effects include poor germination and early seedling growth and are influenced by the variety and species of agricultural plants being grown. 相似文献
9.
By the microbiological action, lignin from vegetal wastes is transformed at soil level in organic prebiotic products with physiological activity on plants development. On the other hand, some micromolecular compounds resulted from plant wastes decomposition, along with polyphenols coming from extraction of plant residues could play a role of allelochemicals. The understanding of the allelochemical action mechanisms allow us to use these compounds to enhance crop production and develop a more sustainable agriculture, including weed and pest control through crop rotations, residue management and a variety of approaches in biocontrol. Other goals are to adopt allelochemicals as herbicides, pesticides and growth stimulants, modify crop genomes to manipulate allelochemicals production and better elucidate chemical communications between the components of ecosystem. The result obtained in the utilization of lignins and polyphenols as allelochemicals are presented in this review. 相似文献
10.
《Journal of Crop Improvement》2013,27(1):59-76
Abstract Increasing the ability of crops to compete against weeds, through either enhancing crop tolerance or crop interference to weeds, provides an attractive addition to current weed control practices and could be an integral component of weed management systems. Research has shown that considerable variability exists among crop culti-vars with respect to their ability to compete with weeds. Despite this evidence, directed research on competitive crops has been minimal. Reasons for this lack of emphasis in plant breeding programs include the effectiveness of current weed management with tillage and herbicides, and the lack of easily identifiable crop characteristics that are indicative of weed competitiveness. Expanded knowledge of specific crop-weed interactions would facilitate crop competitiveness to weeds through either crop management practices or plant breeding. Plant breeders need basic and applied information to identify favorable crop-weed competitive traits in order to enhance or incorporate those traits into crop cultivars. Accelerated research on weed competitive crops should lead to more economical, effective, and feasible integrated weed management programs for all crops. 相似文献
11.
Rice fields are ecosystems with many types of plants, microbes, invertebrates, birds and animals. The rice farming protects the biodiversity of the region and maintains the ecosystem for the benefit of environment. Some rice varieties release biocidal allelochemicals which might affect major weeds, microbial and pathogenic diversity around rice plants, even soil characteristics. A large number of compounds such as phenolic acids, fatty acids, indoles and terpenes have been identified in rice root exudates and decomposing rice residues, as putative allelochemicals which can interact with surrounding environment. Since these allelopathic interactions may be positive, they can be used as effective contributor for sustainable and eco-friendly agro-production system. Genetic modification of crop plants to improve their allelopathic properties and enhancement of desirable traits has been suggested. Development of crops with enhanced allelopathic traits by genetic modification should be done cautiously, keeping in view of the ecological risk assessment(non-toxic and safe for humans and ecosystem, crop productivity, ratio of benefit and cost, etc.). 相似文献
12.
A. E. Smith 《Crop Protection》1990,9(6):410-414
Laboratory and growth chamber research was conducted to determine the potential allelopathy of tissue harvested from certain weeds commonly found in pastures. Results of bioassays indicated that the weeds dogfennel and mayweed chamomile are potentially allelopathic to alfalfa and Italian ryegrass seedlings. Leaf-tissue extracts from the two weed species reduced seedling growth more than stem and root extracts. In most experiments alfalfa seedlings were influenced more than Italian ryegrass seedlings and seedling growth was influenced more than seed germination. Leaf tissue from the weed species mixed into potting soil at a concentration as low as 0.25% (w/w) significantly reduced alfalfa and Italian ryegrass plant development and foliage production. Extract and tissue concentration used in this research were estimated to be similar to concentrations expected to occur within the pasture ecosystem and below concentrations that would result in hypertonicity in the bioassays. 相似文献
13.
《Crop Protection》1986,5(1):66-72
The potential changes in weed problems in British agriculture and horticulture over the next decade are reviewed. The attributes which confer survival and success to weed species are considered, of which the most important for arable weeds is seed behaviour. These attributes are then discussed in relation to the changes which are deemed likely to occur in various cropping systems. In arable land, the main factors influencing weed population composition are method of straw disposal, level of cultivation, season of drilling, crop grown, fertilizer regime, herbicide usage and herbicide resistance. Few major changes in agriculture are foreseen, but there will be a trend towards increasing specialization in many areas. The predominance of winter cereals and oilseed rape will continue, which will favour autumn-generating weeds such as Galium aparine and Alopecurus myosuroides. It is postulated that most weed problems over the next decade will arise from existing weeds or from native plants common in field margins from which they could invade fields through changes in management. A few new aliens, especially grasses, may well appear, e.g. Phalaris paradoxa. Weeds could also arise from recently introduced crop plants, e.g. Bromus willdenowii and B.carinatus, which may present problems in the future, just as cereal volunteers are often a problem at present. 相似文献
14.
15.
系统调查海南芦笋种植区的主要杂草种类,明确芦笋园的杂草优势种群,并以此为基础进行盆栽芦笋化学除草药效试验及覆盖控草试验。结果表明,海南芦笋园常见杂草有21科106种,其中优势种群由马齿苋、红尾翎、短颖马唐、龙爪茅、牛筋草、砖子苗、假臭草、伞房花耳草及鳢肠9种构成。采用覆盖控草和化学除草可在一定程度上控制杂草的发生：覆盖9种植物60 d后,防效可达60%以上,且覆盖葛藤、毛蔓豆、飞机草、薇甘菊、肿柄菊后,芦笋抽笋数和新笋径围都显著高于其余各处理;施用4种除草剂60 d后,盖草能和乙草胺对盆栽芦笋的防效较高且安全。因此,在实际生产中,通过覆盖控草和化学除草相结合,可最大限度的控制芦笋园中杂草。 相似文献
16.
巨尾桉挥发物化感作用初步研究 总被引：3，自引：0，他引：3
在实验室条件下进行巨尾桉(Eucalyptus grandis×E.urophylla)新鲜桉叶和桉油的挥发物对4种受试植物种子萌发和幼苗生长的影响试验.结果表明:巨尾桉挥发物对受试植物的种子萌发和幼苗生长均有抑制作用,且抑制作用强度,桉油挥发物均显著或极显著大于桉叶自然挥发物.桉油挥发物的作用强度有明显的浓度效应,浓度增大,抑制作用增强.不同受体植物对巨尾桉挥发物化感作用的敏感性差异明显,其中甜菜心和白萝卜敏感性较强,水稻和热研2号柱花草敏感性则较弱. 相似文献
17.
Sustainable crop production is necessary to ensure global food security and environmental safety. Conservation agriculture (CA) is gaining popularity around the globe due to its sustainable approaches such as permanent soil cover, minimal soil disturbance, planned crop rotations and integrated weed management. Weed control is the biggest challenge to CA adoption. Weed ecology and management is different in CA than in conventional agriculture. In CA, weeds expression, seed bank status, distribution, dispersal mechanisms, diversification, growing patterns and competition trends are complex and differ from conventional systems. It is due to reduced tillage of the soil and the flora that thrives in CA. Reduced tillage systems affect the efficacy of herbicides and mechanical weed control measures. So, it is an important task to find out the differences and to fabricate new management options. In this review, changing weed dynamics have been framed. A novel aspect of this review is the comprehensive account of sustainable weed management strategies in relation to CA. Modified tillage operations, improved cultural practices, bioherbicides, chemical herbicides, allelopathy, and crop nutrition have been identified as suitable weed management tools. None of these offers complete control but the integration of these tools in suitable combinations works efficiently. Weeds dominating CA and their responses to CA components are highlighted. For example, small seeded and perennial weeds are more abundant in CA. The role of herbicide resistance in weeds and herbicide tolerant (HT) crops in CA is also highlighted. Allelopathy and crop nutrition are discussed as modern weed management tools for CA. A detailed account of weed responses to fertilizer management options is also given. Integrated weed management compatible to cropping patterns and climatic conditions offers the best results in CA. Future efforts must be directed towards the optimization and integration of these weed management practices. 相似文献
18.
《Journal of Crop Improvement》2013,27(2):313-321
Summary The allelopathic effects of chemical substances released from the tomato plant (Lycopersicon esculentum Mill.) were investigated on various receptor plants. Bioassays under controlled conditions in a growth chamber showed that germination and seedling growth of Lactuca sativa and growth of Vitis were reduced when grown near tomato plants. It was also observed that when plants were grown in a U-tube pot with tomato plant, the tomato roots excreted allelochemicals that inhibit growth of tested species. To identify the phytotoxic compounds from tomato plant, a GC/MS method was employed. Forty compounds, such as trans-2-hexenal, a-terpineol, linalool, phenylace-taldehyde, methylsalicylic acid and tetradecanoic acid were identified from the essential oil of tomato plants. The volatile substances from leaves inhibited seed germination and seedling growth of receptor plants in laboratory tests. Inhibitory response varied with the concentration of compounds. These findings suggest that the tomato plant may have an interesting allelopathic potential. 相似文献
19.
Weeds are a major constraint to crop production, and are responsible for considerable yield losses in maize production systems throughout the world. Herbicides are widely used for weed control in maize production systems, but can have negative environmental consequences. Researchers have evaluated the use of crop competition and suppression to manage weeds in various crop combinations, including maize-based systems. Crop competition in maize may involve techniques such as reduced row spacing, increased planting density, and the use of competitive cultivars that exhibit weed suppressive potential. In this review, examination of the literature has revealed the considerable value of using crop competition in integrated weed management programs. Research has demonstrated that narrowing row spacing to half the standard distance reduced weed biomass by 39–68%, depending on weed species. Researchers have also demonstrated that increasing maize planting density by up to twice the standard rate achieved a reduction in weed biomass of 26–99%. While little research has been conducted into the use of competitive maize cultivars for weed management, several studies have documented cultivars with potential to suppress weeds. Attributes of weed competitive cultivars include high leaf area index, and other elements of leaf architecture that improve light interception by the crop, so increasing the shading of weeds. Combining crop competition methods with other agronomic practices can increase their effectiveness in controlling weeds. For example, biomass of Setaria italica (L.) Beauv was reduced by 60% when maize planting density was increased by 1.5 times the recommended spacing, and this effect was more pronounced when fertilizer was banded rather than broadcast. In summary, the strategic use of crop competition to control weeds has been a success in many regions, and is an important tool in integrated weed management. The importance of crop competition methods has particular relevance where farmers are unable to afford herbicides, as making use of crop competition is more economical. 相似文献