Accurate and up-to-date spatial agricultural information is essential for applications including agro-environmental assessment, crop management, and appropriate targeting of agricultural technologies. There is growing research interest in spatial analysis of agricultural ecosystems applying satellite remote sensing technologies. However, usability of information generated from many of remotely sensed data is often constrained by accuracy problems. This is of particular concern in mapping complex agro-ecosystems in countries where small farm holdings are dominated by diverse crop types. This study is a contribution to the ongoing efforts towards overcoming accuracy challenges faced in remote sensing of agricultural ecosystems. We applied time-series analysis of vegetation indices (Normalized Difference Vegetation Index (NDVI) and Enhanced Vegetation Index (EVI)) derived from the Moderate Resolution Imaging Spectrometer (MODIS) sensor to detect seasonal patterns of irrigated and rainfed cropping patterns in five townships in the Central Dry Zone of Myanmar, which is an important agricultural region of the country has been poorly mapped with respect to cropping practices. To improve mapping accuracy and map legend completeness, we implemented a combination of (i) an iterative participatory approach to field data collection and classification, (ii) the identification of appropriate size and types of predictor variables (VIs), and (iii) evaluation of the suitability of three Machine Learning algorithms: Support Vector Machine (SVM), Random Forest (RF), and C5.0 algorithms under varying training sample sizes. Through these procedures, we were able to progressively improve accuracy and achieve maximum overall accuracy of 95% When a small sized training dataset was used, accuracy achieved by RF was significantly higher compared to SVM and C5.0 (P < 0.01), but as sample size increased, accuracy differences among the three machine learning algorithms diminished. Accuracy achieved by use of NDVI was consistently better than that of EVI (P < 0.01). The maximum overall accuracy was achieved using RF and 8-days NDVI composites for three years of remote sensing data. In conclusion, our findings highlight the important role of participatory classification, especially in areas where cropping systems are highly diverse and differ over space and time. We also show that the choice of classifiers and size of predictor variables are essential and complementary to the participatory mapping approach in achieving desired accuracy of cropping pattern mapping in areas where other sources of spatial information are scarce.

In Asia, direct-seeded rice (DSR) is becoming popular as an alternative to puddled transplanted rice (PTR) due to its potential to save scarce resources (labor, water, and energy), reduce greenhouse gas emissions, improve soil physical properties, and increase yields in rotational crops. However, weed management in DSR is more difficult because the initial size differential between weeds and rice is small, reducing crop competitiveness and limiting opportunities for selective control measures including flooding. In this context, preventive approaches-those which focus primarily on limiting dispersal and persistence of weed propagules-may play a critical role in complementing the current reliance on curative tactics such as herbicides. Greater understanding and integration of preventive approaches in DSR may reduce the risks of herbicide resistance development, limit adverse effects of herbicides on human health and the environment, and lower the overall weed management costs. However, information on preventive weed management in DSR is relatively limited. Therefore, the central objectives of this review are to: (i) summarize existing knowledge regarding preventive strategies; (ii) discuss key integrated preventive weed management approaches that have the greatest potential for practical application in DSR systems; and (iii) identify knowledge gaps that limit our ability to optimize preventive approaches. Based on an extensive review of existing literature, we conclude that (i) Minimizing weed seed production in the field is critically important for managing weed seedbanks in DSR, but that given seed dispersal in both time and space, prevention of seed production from neighboring bunds, rice-fallow land and irrigation channels bordering DSR areas may be equally important; (ii) Minimizing dispersal of weed seeds into DSR fields may be a practical approach for species that are dispersed primarily by humans (e.g., as contaminants in crop seeds or through irrigation canals), but not for species that are dispersed primarily by other means (wind and birds); (iii) Promotion of seed predation may be a useful strategy in managing certain weed species in DSR-especially where zero-tillage is used-but more research is needed on the identity of seed predators and management factors that promote their activity; (iv) available evidence suggests that the potential for promotion of seed decay is limited in scope but may be valuable for the management of certain relatively nonpersistent weeds in some cropping systems; (v) strategies that stimulate fatal germination of weed seeds (e.g., stale seedbed) appear to be one of the most promising means of prevention in DSR, but increased information on the mechanisms and timing of dormancy release for key species is needed to optimize and enhance the value of this approach; (vi) Prevention of weed germination and emergence in DSR through mulching-especially in zero-till systems-has proven benefits, but its widespread applicability is limited by the economic tradeoffs associated with using mulch as a source of livestock feed; and (vii) development of anaerobic germination (AG)-tolerant rice cultivars and complementary flooding strategies which can tolerate anaerobic conditions/ flooding hold great potential for the suppression of weeds in DSR. Successful integration of preventive approaches for managing weeds in DSR will depend on the development of multidisciplinary approaches which are biologically effective, economically feasible, and socially acceptable. Preventive weed control measures alone are unlikely to be sufficient for the effective and economical management of weeds in DSR systems, but their integration with curative approaches should reduce weed management costs and increase both the likelihood of adoption of DSR and the realization of its benefits for food security.

Short Retraction Notice This article has been retracted according to COPE's Retraction Guidelines. Since authors have their personal reasons, they have to withdraw this paper from journal Advances in Remote Sensing. The full retraction notice in PDF is preceding the original paper which is marked "RETRACTED".

Ongoing increases in the human population necessitate that rice will continue to be a critical aspect of food security for the twenty-first century. While production must increase in the coming decades to meet demand, such increases will be accompanied by diminished natural resources and rising production costs that will alter how rice is grown and managed. Such resource constraints are the impetus for the ongoing transition from traditional flooding and transplanting to direct-seeded rice (DSR). However, such a transition can result in an increase in pest pressures, especially weeds. Rice production can be particularly vulnerable to weed competition, with significant yield losses (i.e., >50%) occurring. Among pernicious weeds, weedy (red) rice (Oryza sativa L.) is increasingly recognized as a major constraint in achieving maximum yield in DSR. Weedy rice is congeneric to crop rice with phenotypic similarity; hence, its ability to negatively influence qualitative and quantitative aspects of production is substantial. As rice will continue to serve as a cornerstone for future food security and sustainability, a comprehensive assessment of weedy rice impacts associated with increasing adoption of DSR is both timely and critical. In this chapter, we examine the biological basis for the competitive ability of weedy rice, including its evolution, ecophysiology, and genetics; quantify spatial–temporal shifts in its distribution and spread; and emphasize and outline a number of regional and global management strategies for its detection and control. Lastly, a number of critical research areas are suggested that deserve additional scrutiny with respect to weedy rice management.

Ongoing increases in the human population necessitate that rice will continue to be a critical aspect of food security for the twenty-first century. While production must increase in the coming decades to meet demand, such increases will be accompanied by diminished natural resources and rising production costs that will alter how rice is grown and managed. Such resource constraints are the impetus for the ongoing transition from traditional flooding and transplanting to direct-seeded rice (DSR). However, such a transition can result in an increase in pest pressures, especially weeds. Rice production can be particularly vulnerable to weed competition, with significant yield losses (i.e., >50%) occurring. Among pernicious weeds, weedy (red) rice (Oryza sativa L.) is increasingly recognized as a major constraint in achieving maximum yield in DSR. Weedy rice is congeneric to crop rice with phenotypic similarity; hence, its ability to negatively influence qualitative and quantitative aspects of production is substantial. As rice will continue to serve as a cornerstone for future food security and sustainability, a comprehensive assessment of weedy rice impacts associated with increasing adoption of DSR is both timely and critical. In this chapter, we examine the biological basis for the competitive ability of weedy rice, including its evolution, ecophysiology, and genetics; quantify spatial-temporal shifts in its distribution and spread; and emphasize and outline a number of regional and global management strategies for its detection and control. Lastly, a number of critical research areas are suggested that deserve additional scrutiny with respect to weedy rice management.

The participatory varietal selection approach is the first attempt in Myanmar through collaborative efforts from IRRI-LIFT. Sixteen and 12 varieties/lines were evaluated in the monsoon and dry season, respectively, through PVS in different villages in three townships of the Ayeyarwady Delta. Four varieties/lines (Saltol Sin Thwe Latt, Shwe Pyi Htay, Sin Thu Kha, and Shwe Ta Soke) in the wet season of 2012 and four varieties/lines (IR10T107, IR10T108, IR10T111, and CSR36) in the dry season of 2012-13 were selected by farmers through preference analysis, grain yield and sensory evaluation. After field evaluation, Saltol Sin Thwe Latt was released as a variety in Myanmar. Farmer-managed trials (baby trials) were carried out using the selected lines from the wet season. Based on baby trials in the 2013 wet season, Saltol Sin Thwe Latt (Saltol STL) and Sin Thu Kha (STK) were the first and second most adapted and stable high-yielding varieties for three townships in the Ayeyarwady Delta. PVS has the potential to become one of the best approaches in research for developing a variety based on farmers choice and enhancing their productivity and dissemination, especially in the Ayeyarwady Delta, Myanmar, to help resource-poor farmers in obtaining easy access to rice-based technology for improving their livelihood.

SUMMARYSeedling vigor is important to help ensure good crop establishment. In direct-seeded rice, this is particularly relevant when soil conditions are marginal. In Asia, about one third of the area of rainfed rice is situated on unfavorable soils, many of which are low in plant available P. In such environments, as farmers tend to have few resources, options to overcome poor crop establishment should be low cost and preferably seed-based. The P content of seed depends on genotype and can be augmented by soaking seeds in a P-containing solution prior to seeding (P-priming). In addition, the presence of the Pup1 quantitative trait locus can reportedly confer tolerance to low soil P availability. We tested combinations of seed priming (unprimed control, water priming, P-priming), and inherent seed P concentrations in contrasting rice genotypes (DJ123, Sadri Tor Misri), and two near isogenic sister lines of IR74 with (+Pup1) and without (−Pup1) the Pup1 QTL. Treatment effects on germination were studied in Petri dishes, while seedling growth and P accumulation were assessed using pots with P deficient soil. Germination was less than 75% in seeds with low seed P content. Seed priming with both water and P enhanced germination and seedling growth. In plants growing from high P seeds, water priming outperformed P-priming. In Sadri Tor Misri with low seed P, we observed a tendency for better performance in some parameters when P-primed. While the presence of the Pup1 QTL in IR74 increased shoot biomass and total root length, these effects could be further enhanced by water priming. Combining genetic and seed management approaches may contribute to improved rice establishment in P deficient soils but its effectiveness depends on genotype and seed attributes.

methodologies for specific plant types (lower plants, rice, other monocots and dicots, respectively). The transformation protocols cover a range of organisms, including Chlamydomonas reinhardtii, the major monocot crops rice, wheat, barley and oil palm and dicots, including plum, grapevine, cotton, Impatiens and Torenia. A further four sections encompass a range of associated technologies, approaches and example applications. These include protocols for selection of transformants, targeted gene silencing and mutation, molecular pharming (production of biopharmaceuticals) and a curious single chapter section on Arabidopsis field trials. It is a pity that a more extensive treatise on field trialling genetically modified crops was not included, as this is an on-going and topical area worthy of an update. The layout of the chapters follows a well-tested formula for this Methods and Protocols series: a brief introduction, detailed materials and step by step methods sections, and perhaps uniquely, a notes section with hands-on tips, and a list of references which are adequate without being comprehensive. The protocols are easy to follow, usually contain all the critical detail and are therefore an effective laboratory guide. This volume is a second edition and also follows on from a previous volume in the same series (Methods in Molecular Biology 478) targeted specifically at wheat, barley and oats, edited by H. D. Jones and P. R. Shewry and published in 2009. This current volume represents a useful companion volume with updates in some areas and many unique topics. It is a worthy purchase for any plant biotechnology laboratory.

Aerobic rice describes a management adaptation to reduced irrigation water supplies but, due to reduced intervals of flooding in this system, this requires revised weed management approaches to reduce costs and provide effective weed control. One approach is to make the crop more competitive and reduce the effects of weeds on the crop by using higher rice seeding rates. A study was conducted in the Philippines and India in 2008 and 2009 to assess the relations of seeding rates (15-125 kg ha(-1)) of hybrid and inbred varieties to crop and weed growth in aerobic rice. Plant densities, tillers, and biomass of rice increased linearly with increased in seeding rates under both weedy and weed free environments. Weed biomass decreased linearly with increasing seeding rates from 15 to 125 kg ha(-1). Panicles and grain yields of rice in competition with weeds increased in a quadratic relation with increased seeding rates at both locations; however, the response was flat in the weed free plots. A quadratic model predicted that seeding rates of 48-80 kg ha(-1) for the inbred varieties and 47-67 kg ha(-1) for the hybrid varieties were needed to achieve maximum grain yield when grown in the absence of weeds, while rates of 95-125 kg seed ha(-1) for the inbred varieties and 83-92 kg seed ha(-1) for the hybrid varieties were needed to achieve maximum yields in competition with weeds. On the basis of these results, seeding rates greater than 80 kg ha(-1) are advisable where there are risks of severe weed competition. Such high seeding rates may be prohibitive when using expensive seed, and maximum yields are not the only consideration for developing recommendations for optimizing economic returns for farmers. Results of the present study do suggest however that increasing seeding rates of aerobic rice does suppress weed growth and reduce grain yield losses from weed competition. This information could be incorporated in integrated crop management packages to manage weeds more effectively. (C) 2010 Elsevier B.V. All rights reserved.

The implications of adopting alternative seeding methods for rice and wheat establishment were examined at three geographically separate sites in the rice-wheat system of the Indo-Gangetic plains, across northern India. Rice yields in cultivated plots, established by either wet or dry seeding methods, were evaluated in comparison to yields from zero-tillage plots and under conventional transplanting methods. In the same trials, the effects of crop establishment methods in wheat were assessed both on wheat yields and rice yields. Rice crop establishment methods markedly influenced the emerging weed flora and attainable yields were measured in relation to intensity of weed management. Over four years, average rice grain yields in the absence of weed competition were greatest (6.56 t ha(-1)) under wet seeding (sowing pre-germinated rice seed on puddled soil), and similar to those from transplanted rice (6.17 t ha(-1)) into puddled soil, and dry seeded rice after dry soil tillage (6.15 t ha(-1)). Lowest yields were observed from dry seeded rice sown without tillage (5.44 t ha(-1)). Rice yield losses due to uncontrolled weed growth were least in transplanted rice (12%) but otherwise large (c. 85%) where rice had been sown to dry cultivated fields or to puddled soil, rising to 98% in dry seeded rice sown without soil tillage. Weed competition reduced multiple rice yield components, and weed biomass in wet seeded rice was six-fold greater that in rice transplanted into puddled soil and twice as much again in dry seeded rice sown either after dry tillage or without tillage. Wheat grain yields were significantly higher from crops sown into tilled soil (3.89 t ha(-1)) than those sown without tillage (3.51 t ha(-1)), and also were elevated (5% on average) where the soil had been dry cultivated in preparation for the previous rice crops rather than puddled. The method of wheat cultivation did not influence rice yield. Soil infiltration rates in the wheat season were least where the land had been puddled for rice (1.52 mm h(-1)), and greater where the soil had been dry-tilled (2.63 mm h(-1)) and greatest after zero-tillage (3.54 mm h(-1)).These studies demonstrated at research managed sites across a wide geographic area, and on farmers' fields, that yields of dry seeded rice sown after dry cultivation of soil were broadly comparable with those of transplanted rice, providing weed competition was absent. These results support the proposition that direct seeding of rice could provide an alternative to the conventional practice of transplanting, and help address rising costs and threats to sustainability in the rice-wheat rotation. Further, analysis of patterns of long-term rainfall data indicated that farmers reliant on monsoon rainfall could prepare fields for dry direct seeded rice some 30 days before they could prepare fields for either transplanting or seeding with pre-germinated seed. Dry, direct seeding of rice contributes a valuable component of an adaptive strategy to address monsoonal variability that also may advance the time of wheat establishment and yield. Whilst the results illustrate the robustness, feasibility and significant potential of direct seeded rice, they also highlight the critical nature of effective weed control in successful implementation of direct seeding systems for rice. (C) 2010 Elsevier B.V. All rights reserved.

Ludwigia is an important broadleaf weed of direct-seeded rice in Asia. Crop interference that relies on shading may have potential as a component of integrated weed management strategies but it requires understanding the extent to which rice can interfere with weed growth and how these weeds may respond. The growth of ludwigia was studied when grown alone and in competition with 4 and 12 rice (cv. IR72) plants. Rice interference reduced ludwigia height, number of branches, and shoot and root biomass. However, ludwigia showed the ability to reduce the effects of rice interference by increasing leaf weight ratio, increasing stem and leaf biomass in the upper half of the plant, and increasing specific stem length. At 11 wk after seeding, for example, ludwigia grown with 12 rice plants had 38% greater leaf weight ratio compared to plants grown alone. When grown with 12 rice plants, the weed had 82% of its leaf biomass in upper half of the plant compared to only 25% in weeds grown alone. The results showed that ludwigia responded to rice interference with a combination of adaptations typical of many weed species. Despite such plasticity, the control of ludwigia may be achieved by dense rice stands and increasing interference.

SUMMARY Global changes including increases in temperature, atmospheric greenhouse gases, soil degradation and competition for land and water resources, will have multiple impacts on rice production systems in Africa. These changes will affect weed communities, and management approaches must be adapted to take this into account. Higher temperatures and limited water availability will generally advantage C4 over C3 plants (e.g. rice). Conversely, elevated carbon dioxide (CO2) levels will improve the competitiveness of rice relative to C4 weeds, which comprise many of the problem weeds of rice. Increased atmospheric CO2 levels may also improve tolerance of rice against parasitic weeds, while prevalence of parasitic species may be amplified by soil degradation and more frequent droughts or floods. Elevated CO2 levels tend to promote growth below-ground relative to above-ground, particularly in perennial (C3) species. This may render mechanical control of weeds within a cropping season less effective or even counterproductive. Increased CO2 levels, rainfall and temperature may also reduce the effectiveness of chemical control, while the implementation of adaptation technologies, such as water-saving irrigation regimes, will have negative consequences for rice–weed competition. Rain-fed production systems are prevalent throughout Africa and these are likely to be most vulnerable to direct effects of climate change (e.g. higher temperatures and changes in rainfall patterns). Effective weed management strategies in these environments could encompass off-season tillage, the use of well-adapted cultivars (i.e. those with drought and heat tolerance, high weed competitiveness and parasitic weed resistance or tolerance) and rotations, intercropping or short, off-season fallows with weed-suppressive legumes including those that suppress parasitic weeds. In irrigated, non-flooded rice systems, weeds are expected to become more serious. Specifically, perennial rhizomatous C3 weeds and species adapted to hydromorphic conditions are expected to increase in prevalence. By implementing an integrated weed management strategy primarily targeted at weed prevention, dependency on flood water, herbicides and mechanical control can be lessened. Off-season deep tillage, stale seed bed techniques, use of clean seeds and irrigation water, competitive cultivars, timely transplanting at optimum spacing and judicious fertilizer timings are suitable candidate components for such a strategy. Integrated, novel approaches must be developed to assist farmers in coping with the challenges of weed control in the future.

Horse purslane, a C(4) species, is a branched, prostrate, and annual weed of upland field crops throughout the tropics. Experiments were conducted to determine the influence of various environmental factors on seed germination and seedling emergence of two populations of horse purslane. Seeds were collected from rice fields of the International Rice Research Institute (the IR population) and from sorghum fields of the University of the Philippines (the UP population); the two sites were 5 km apart in Los Banos, Philippines. Germination response of both populations was greater at 30/20 C and 35/25 C day/night temperatures than they were at 25/15 C alternating day/night temperatures. Germination of both populations was greater in the light/dark regime than in darkness. In dark, depending on the temperature, seed germination of the UP population ranged from 37 to 62%, whereas seed germination of the IR population was < 20%. Exposure to 5 min at 117 and 119 C for the IR and UP populations, respectively, reduced germination to 50% of maximum germination. Osmotic potential of -0.26 MPa inhibited germination to 50% of the maximum for the UP population, whereas the corresponding value for the IR population was -0.37 MPa. Seeds placed on or near the soil surface had maximum emergence, and emergence declined with increase in seed burial depth. Seedling emergence of the UP and IR populations was 74% and 13%, respectively, for seeds placed on the soil surface. For both populations, no seedlings emerged from a soil burial depth of 6 cm or more. Germination and emergence responses to light and seed burial depth differed between the two populations of horse purslane. Residues on the soil surface of up to 6 Mg ha(-1) did not influence seedling emergence of either populations. Knowledge gained in this study could contribute to developing components of integrated weed management strategies for horse purslane.

Echinochloa crus-galli, a C(4) grass, is one of the world's most serious weeds. Weed management decisions for this species can be derived from knowledge of its seed biology. Studies were conducted to determine the effects of light on germination; seed burial depth and rice residue on emergence and growth; and flooding time and depth on emergence, survival and growth of this species. Light stimulated seed germination but it was not an absolute requirement for germination. The proportion of seeds germinating was greatest for seeds placed on the soil surface (92%), and emergence declined with increasing burial depth in soil; no seedlings emerged from the depth of 8 cm. A burial depth of only 0.4 cm reduced seedling emergence by 50%. Seedling emergence and seedling biomass were reduced by the addition of high level (6 ton ha(-1)) of rice residue to the soil surface. Early and deep flooding significantly suppressed growth of E. crus-galli seedlings. In flooded conditions, with increased water depth the weed allocated more biomass to shoots at the expense of roots. The information gained from this study could contribute to improve weed control approaches. Soil inversion by tillage to bury weed seeds below their maximum depth of emergence, use of crop residue as mulch and early flooding of the crop could serve as important tools for managing E. crus-galli and other weed species with similar germination requirements. These management options, however, would need to be compatible with other crop management requirements. (C) 2011 Elsevier Ltd. All rights reserved.

Summary: Post-dispersal weed seed predation can cause a substantial reduction in the number of weed seeds entering the seed bank and, as a consequence, reduce the number of weeds growing in subsequent seasons. Investigations on seed predation on four tropical rice fields in the Philippines were conducted to determine (i) the magnitude of post-dispersal seed predation after rice harvest, (ii) whether vertebrates or invertebrates are the main seed predators, (iii) whether seed predation is affected by crop residue, (iv) whether seed predation is affected by proximity to the field edge, and (v) whether predation differs among seeds of the grasses Digitaria ciliaris, Echinochloa colona and Eleusine indica. Seed removal rate over a 14-day period ranged from 78% to 91% among fields, was slightly higher in the interior of the fields (89%) than in the field margins (85%) and slightly higher without residue cover (89%) than with (86%). Selective exclosures indicated that invertebrates, presumed to be mainly fire ants (Solenopsis geminata), were the main seed predators (96%) and vertebrates, presumed to be mainly rodents, secondary predators (38%). Seed removal of D. ciliaris was higher (93%) than of E. indica (88%) and E. colona (75%). Results suggest substantial seed predation could contribute to ecologically-based weed management in rice. Further studies are required to determine season-long seed predation rates and to confirm the identity of the predators involved. Ways to integrate these seed predators into prevailing cropping practices need to be developed. © 2010 International Rice Research Institute. Weed Research

Rapid seedling growth of rice is reported to be associated with improved ability to tolerate weed competition, which is a major constraint in direct-seeded rice crops. To explore differences in growth and the effects of weed competition on yield, 20 diverse Asian rice cultivars were grown in the field and in greenhouse experiments.Differences in grain yield occurred between cultivars in the field and, after a single hand weeding, weed competition decreased grain yields by more than 60% compared with weed-free plots. Three of four cultivars producing the largest grain yields in weed-free plots also had the largest yields ill competition with weeds in the same season. Some cultivars, however, had relatively poor yields in competition with weeds compared with weed-free conditions. Rice biomass at 28 days was correlated with grain yield in competition with weeds, and with reduced weed biomass. Substantial differences in seedling growth were found among cultivars. Sabita and NSG 19 accumulated twice the total dry matter and leaf area per seedling by 12 days after sowing (DAS) as some of the least vigourous cultivars. Grain yields in competition with weeds in field experiments in two seasons significantly correlated with rice seedling biomass at 12 DAS in greenhouse experiments.Leaf area at 6 DAS had the greatest direct effect on seedling dry matter accumulation at 12 DAS. Leaf area at: 6 DAS, in turn, was associated with higher specific leaf area, greater dry matter partitioning to leaves at 4 DAS, larger embryos, heavier seeds, and earlier onset of photo-autotrophic growth. More than 90% of the variation in total rice seedling biomass at 12 DAS was associated with the parameters studied. Leaf area at 6 DAS and dry matter of rice seedlings are easily measurable traits that have potential to be used as an indirect tool for mass screening of rice for competitiveness against weeds. (C) 2009 Elsevier B.V. All rights reserved.

Cyperus difformis, Cyperus iria and Fimbristylis miliacea are troublesome annual sedges of rice grown in many countries. Laboratory and screenhouse experiments were conducted to determine the effects of temperature, light, salt and water stress, seed burial depth, and flooding time, duration and depth on germination, emergence and growth of these three species. Germination of all the three species was stimulated by light and warm fluctuating temperatures. Germination of C. difformis was influenced to a greater degree by increasing salt and water stress than C. iria and F. miliacea. In all three species, seeds sown on the soil surface gave the greatest percentage of seedling emergence, and no seedlings emerged from seeds buried in soil at depths of >= 1 cm. Flooding, although not continuous or deep, had a suppressive effect on emergence and growth of C. iria and F. miliacea. Intermittent flooding to shallow depths, however, was less effective in controlling C. difformis; deep flooding was needed to suppress growth of C. difformis seedlings. When the flooding was delayed to 21 days after sowing, there was little growth reduction in all three species.