L. Bastiaans

• Dr
• Professor (Associate) at Wageningen University & Research

Nitrogen (N) availability is crucial to maintaining crop productivity in agroecosystems, driven primarily by soil microbial processes such as nitrification and denitrification. Weeds are an integral part of agroecosystems and are involved in many processes related to the N cycle, but how weed management could shift plant–microbe interactions, and t...

Legumes can be integrated into cereal crop systems as a service crop to fix nitrogen, support cereal grain quality, and provide fodder for animals. However, competitive effects on cereal crop yields need to be avoided as much as possible. Here, we study the effect of seven legume species on yield, yield components and grain quality of rice, in depe...

Societal Impact Statement Parasitic weeds in African rice systems threaten household‐level food security and income generation. Most affected farmers are smallholders with limited capacities to address these pests. Obligate parasites Striga asiatica and Striga hermonthica (witchweed) are problematic in rainfed upland rice, affecting approximately 3...

Background and Aims Rhamphicarpa fistulosa (Hochst.) Benth. is an annual facultative parasitic plant adapted to hydromorphic soils. In sub-Saharan Africa it causes high crop losses as a weed in rainfed lowland rice (Oryza sativa L.). Fertilisers are often proposed as control measure against hemiparasitic weeds but understanding of nutrient effects...

Maize-grain legume intercrops form an important component of the cropping systems of smallholder farmers in many parts of sub-Saharan Africa. However, the effects of cropping system and fertilizer use on nitrogen fixation and nitrogen uptake of component crops in maize-legume intercrops are not well understood. Our study addressed the questions: (i...

Intercropping of maize with grain-legume crops predominates on smallholder farms in East Africa. However, the growth and development of crops and their interaction with fertilizer in intercropping systems are not well understood. We sought to answer the questions: (i) what are the effects of fertilizer on the growth and development of maize-pigeonp...

Intercropping has frequently been reported to provide good weed suppression. Here, we tested the hypothesis that the weed biomass in annual intercropping systems can be adequately forecasted based on the weed biomass obtained in pure stands of the component crop species. The aim of this analysis was to enlarge the understanding on the weed suppress...

Competition from weeds is the most important yield reducing factor in African rice production systems. Generally important weed management practices in rice are controlled flooding and the use of herbicides. Smallholder rice farmers in Africa however often lack the necessary water management infrastructure, access to affordable, good quality herbic...

p>Intercropping has been advocated as an environmentally benign method to suppress weeds in agriculture. However, it is not evident from the literature what size of weed suppressive effect is achieved on average by intercropping, and how species choice and crop management affect this effect. We conducted a global meta-analysis of published data to...

List> •The literature on intercropping comprises thousands of papers. •Evidence synthesis is needed to develop general conclusions. •Quantitative evidence synthesis requires meaningful comparative performance metrics. •The background, meaning, and limitations of some performance metrics is explained. •Future challenges are identified. Intercr...

The abundance of weedy rice ( Oryza sativa L.) in the soil seedbank was estimated in 2011 in Italian rice ( Oryza sativa L.) fields with different histories of IMI-resistant Clearfield® rice varieties (CL), non-Clearfield® varieties (NCL) and planting methods. A model was used to predict weedy rice seedbank dynamics over time under different contro...

Planting cover crops after harvest of the main crop has become a key practice in temperate agriculture to reduce N leaching and increase soil organic matter. However, the growth of cover crops can be affected by adverse weather. Growing mixtures is thought to increase yield and reduce variation in productivity, but quantitative information on this...

Little is known about productivity of smallholder maize–pigeonpea intercropping systems in sub-Saharan Africa. We conducted a survey of 277 farm households in Northern Tanzania to assess socio-economic factors, field management characteristics, and their association with productivity of maize–pigeonpea intercrops. On each farm, crop assessments wer...

Context Cover crops are sown in autumn after harvest of a main crop to capture residual nitrogen and to build biomass that will contribute to soil organic matter after being ploughed under. Mixtures are purportedly more productive than pure stands of single species. Research problem Dry matter accumulation in field crops can be separated in the pr...

Rhamphicarpa fistulosa is a facultative root parasitic annual forb, of the family Orobanchaceae that is native to sub-Saharan Africa. Parasitism results in yield reductions by the host plants but it is not known how exactly R. fistulosa affects its host or how the host responds physiologically. In three pot experiments, we investigated whether and...

Host plant defence mechanisms (resistance and tolerance) and plant nutrition are two of the most widely proposed components for the control of hemiparasitic weeds of the genus Striga in tropical cereal production systems. Neither of the two components alone is effective enough to prevent parasitism and concomitant crop losses. This review explores...

Winter cover crops are used by farmers to cover the soil between two cash crops. Their aim is to reduce nutrient leaching by recovering nutrients from the soil and to produce biomass that will be incorporated into the soil to increase soil organic matter. Weather conditions in autumn and winter are usually challenging for cover crop growth and resi...

Mixtures of plant species are often higher yielding due to species complementarities. Such effects may be beneficial to agriculture but are under-used in practice. It is therefore important to demonstrate beneficial effects of mixtures that are easy to implement for farmers. Here, we study yield in mixtures of agricultural cover crops. We hypothesi...

Plant species mixtures improve productivity over monocultures by exploiting species complementarities for resource capture in time and space. Complementarity results in part from competition avoidance responses that maximize resource capture and growth of individual plants. Individual organs accommodate to local resource levels, e.g. with regard to...

Autumn cover crops are grown in between two cash crops to cover the soil, prevent leaching of nutrients and produce biomass that may be incorporated into the soil to enhance organic matter content. Weather conditions in autumn are variable and difficult to predict. They may be unfavorable for some but not necessarily all species. Hence, growing mix...

Cropping systems in the lowlands of temperate South America have been based on irrigated rice and beef-cattle production. Plough-and-harrow is still the most used method to prepare the soil after a season of irrigated rice, but it causes high soil disturbance and is time- and energy-demanding. To improve the sustainability of a rice–soybean rotatio...

Developing cropping systems that meet multiple demands of high production, resource-use efficiency and low ecological footprint is a major global challenge. In Southern Brazilian lowlands, irrigated rice (Oryza sativa L.) in combination with fallow for beef production is the dominant cropping system. This system is key to Brazilian food security bu...

The rain-fed lowland rice weed Rhamphicarpa fistulosa (Rice Vampireweed) is a facultative root parasitic plant. Growth and reproduction of R. fistulosa benefit considerably from parasitism, but how this affects the host plant is not well established. We determined accumulation and partitioning of rice–parasite biomass in two pot experiments. First,...

Parasitic weeds are a severe problem in rain-fed rice production ecosystems in sub-Saharan Africa. In this study, effects of sowing time of rice on parasitic weed infection and crop yields were investigated. Field experiments were conducted in Striga asiatica-infested upland and Rhamphicarpa fistulosa-infested lowland systems from 2012 to 2014 in K...

Crop-weed competitive relations are an important element of agroecosystems. Quantifying and understanding them helps to design appropriate weed management at operational, tactical and strategic level. This chapter presents and discusses simple descriptive and more mechanistic models for crop-weed interaction. Along with an elaboration of underlying...

Rain-fed rice production in sub-Saharan Africa is often hampered by parasitic weeds. This study assessed farmers' awareness, use, preference and adoption criteria of parasitic weed management practices in rain-fed rice production environments in Tanzania. Surveys and workshops were organized in three affected rice growing areas in Morogoro-rural, S...

Sowing time influence parasitic weeds infection in rain-fed rice production systems, but this effect is ecosystems dependent

Parasitic weeds invade around 1.34 million hectares of rainfed rice areas in Africa causing damages estimated at USD 200 million.

Parasitic weeds pose increasing threats to rain-fed rice production in Africa. Most important species are Striga asiatica, S. aspera and S. hermonthica in rain-fed uplands, and Rhamphicarpa fistulosa in rain-fed lowlands. Information on the regional spread and economic importance of parasitic weeds in cereal production systems is scant. This articl...

The objective of this work was to investigate the impact of the application of wood biochar, combined with N fertilizations, on N2O-N fluxes, nitrogen availability, and water-filled pore space (WFPS) of a clayey Oxisol under rice (wet season) and common bean (dry season) succession. Manual static chambers were used to quantify N2O-N fluxes from soi...

Weeds compete with crop plants in several different ways. First there can be interference competition where there is physical exclusion from some aspect of the shared habitat. Second there is exploitation competition, which is indirect, and takes the form of competition for a wide variety of resources such as light, water and nutrients. There may a...

Rice Vampireweed, Rhamphicarpa fistulosa, was a minor parasitic weed until recently when rice cultivation in sub‐Saharan Africa was expanded into marginal wetlands, that are the parasite's natural habitat. Unlike most of the parasitic weeds, R. fistulosa is facultative, meaning that the parasite is able to complete its life cycle without a host. Ho...

Suppression of weed growth in a crop canopy can be enhanced by improving crop competitiveness. One way to achieve this is by modifying the crop planting pattern. In this study, we addressed the question to what extent a uniform planting pattern increases the ability of a crop to compete with weed plants for light compared to a random and a row plan...

Biomass dry matter partitioning and growth characteristics are important selection criteria for energy crops. The objective of the study was to examine the response of switchgrass (cv. Alamo) to irrigation (2 levels: rainfed and irrigated with 250 mm) and N-fertilization (4 levels: 0, 80, 160 and 240 kg N ha−1) under two different soil-climatic con...

Competition for light among plants is an important factor determining plant trait evolution and community dynamics. It may also strongly modulate crop production. Canopy models provide a useful means of analyzing light competition. This use however entails that these models take account of the interactions between individual plants in vegetation st...

Major issues challenging the sustainability of conventional flooded rice systems in Pakistan are: low input conversion efficiencies, productivity stagnation, rising costs of production, and shortage of water, labour, and energy. An emerging opportunity is an alternative, eco-efficient production system called ‘aerobic rice’, which entails the growi...

The continuous increasing of herbicide resistance urges the implementation of Integrated Weed Management (IWM) to establish more sustainable cropping systems. An important question is whether application of IWM strategies can provide a sufficient level of weed control, and perhaps favour a reversion of the resistance evolution process. Theoretical...

Germination is a key process in the dynamics of weed populations. In no-tillage systems, crop seeding is often found to induce seed germination in the seeding strip. In this research, experiments to investigate options for reducing weed seedling establishment were conducted in no-till soyabean fields located in two sites in south Brazil. A first ex...

This paper provides a retrospective look at a systems-oriented research program, on the increasing occurrence of parasitic weeds in rainfed rice in sub-Saharan Africa, to qualitatively assess merits and identify challenges of such approach. We gained a broad contextual overview of the problem and different stakeholders' roles, which enabled identif...

Rhamphicarpa fistulosa (Hochst.) Benth is a parasitic weed species in large areas of rain-fed, low land rice fields of sub-Saharan Africa (SSA). The species has been a minor weed until recently, when rice cultivation expanded into marginal wetlands, the natural habitat of the weed. In contrast to other parasitic weeds of rice, such as Striga asiati...

Keywords: Agricultural research for development (AR4D) Rapid Appraisal of Agricultural Innovation Systems (RAAIS) Rain-fed agriculture Orobanchaceae Oryza sativa L. a b s t r a c t Parasitic weeds in smallholder rice production systems, of which Striga asiatica, Striga hermonthica and Rhamphicarpa fistulosa are the main representatives, form an inc...

Striga asiatica and Rhamphicarpa fistulosa are important parasitic weeds of rain-fed rice, partly distributed in similar regions in sub-Saharan Africa (SSA). It is not evident whether their ecologies are mutually exclusive or partially overlapping. In Kyela, a rice-growing area in south Tanzania where both parasites are present, three transects of...

In parts of Pakistan, the sustainability of conventional flooded rice systems is threatened by diminishing resources, particularly – land, water, and labour. The adoption of aerobic rice system (ARS), an alternative to the conventional systems, could considerably increase resource-use efficiencies. Information on farmer perceptions is vital to iden...

This paper introduces Rapid Appraisal of Agricultural Innovation Systems (RAAIS). RAAIS is a diagnostic tool that can guide the analysis of complex agricultural problems and innovation capacity of the agricultural system in which the complex agricultural problem is embedded. RAAIS focusses on the integrated analysis of different dimensions of probl...

Rhamphicarpa fistulosa is a facultative hemi-parasitic plant of the Orobanchaceae family, adapted to wet soils. Apart from tropical Australia, it is only found in sub-Saharan Africa, where it is considered a minor weed in cereal crops such as rice. Due to this status, the species has received only sporadic attention. Recent field observations and e...

The main objective of this study was to assess the impact of biochar rate (0, 8, 16 and 32Mgha−1) on the water retention capacity (WRC) of a sandy loam Dys- tric Plinthosol. The applied biochar was a by-product of slow pyrolysis (∼ 450 ◦C) of eucalyptus wood, milled to pass through a 2000µm sieve that resulted in a material with an intrinsic porosi...

The main objective of this study was to assess the impact of biochar rate (0, 8, 16 and 32 t ha-1) on the water retention capacity (WRC) of a sandy Dystric Plinthosol. The applied biochar was a by-product of slow pyrolysis (∼450 °C) of eucalyptus wood, milled to pass through a 2000 μm sieve that resulted in a material with an intrinsic porosity ≤10...

The objective of this paper is to explore the extent to which systems approaches to innovation are reflected in the crop protection literature and how such approaches are used. A systematic literature review is conducted to study the relation between crop protection and systems approaches to innovation in 107 publications. The analysis of the crop...

Aerobic rice (Oryza sativa L.) is gaining in popularity across South Asia, mainly because it saves water and labor. Under warm (sub) tropical conditions of this region, this unconventional system aimed at improved resource use e ciency is still in the development phase. We tested crop performance and N uptake of three local genotypes in relation to...

Agricultural Innovation Systems (AIS) approaches have been advocated as a framework for integrated and holistic analyses of complex agricultural problems. The potential of AIS approaches to address complex agricultural problems remains largely unexplored. One of the reasons is the lack of a coherent set of conceptual and methodological building blo...

The objective of this study was to report single season effects of wood biochar (char) application coupled with N fertilization on soil chemical properties, aerobic rice growth and grain yield in a clayey Rhodic Ferralsol in the Brazilian Savannah. Char application effected an increase in soil pH, K, Ca, Mg, CEC, Mn and nitrate while decreasing Al...

Even though crop rotation is often regarded as an important component of weed management, tools for optimising the weed-suppressive character of crop rotations are lacking. The long-term character of this strategy and the variety of weed-promoting and weed-suppressing conditions and events that are involved, complicate this matter. For this reason,...

R odenburg J & B astiaans L (2011). Host‐plant defence against Striga spp.: reconsidering the role of tolerance. Weed Research 51 , 438–441. Summary Parasitic weeds of the genus Striga cause high yield losses in cereal crops across Africa. Host‐plant defence against Striga spp. can be an effective control strategy. It ideally consists of resistanc...

Kruidhof HM, Gallandt ER, Haramoto ER & Bastiaans L (2011). Selective weed suppression by cover crop residues: effects of seed mass and timing of species’ sensitivity. Weed Research 51 , 177–186. Summary Laboratory bioassays have shown that large‐seeded species better tolerate cover crop residue–mediated stress than small‐seeded species. This prov...

Cynara (Cynara cardunculus) is a perennial C3 herb that has its potential as bioenergy crop. This paper aims (a) to derive empirical relationships to predict cynara seed yield per head and per unit area, avoiding laborious extraction of seeds from the complex structure of its inflorescences; (b) to determine the head-weight distribution per unit ar...

Ryan MR, Mortensen DA, Bastiaans L, Teasdale JR, Mirsky SB, Curran WS, Seidel R, Wilson DO & Hepperly PR (2010). Elucidating the apparent maize tolerance to weed competition in long-term organically managed systems. Weed Research50, 25–36. In a long-term cropping systems trial comparing organically and conventionally managed systems, organic maize...

This paper aims (a) to derive empirical relationships to predict cynara seed yield per head and per unit area, avoiding laborious extraction of seeds from its complex inflorescence structure; (b) to determine the head­weight distribution per unit area; and (c) to estimate the range of Cynara cardunculus seed yield. We analyzed 16 field experiments,...

Rice is the world's most important staple food. Although mainly produced in Asia (91%), it is consumed on all continents and its global importance and consumption is increasing. The limited scope to expand production areas coupled with increasing resource constraints (mainly the lack of or competing demands for land and water) make it difficult to...

Rice is the world's most important staple food. Although mainly produced in Asia (91%), it is consumed on all continents and its global importance and consumption is increasing. The limited scope to expand production areas coupled with increasing resource constraints (mainly the lack of or competing demands for land and water) make it difficult to...

Although residue management seems a key factor in residue-mediated weed suppression, very few studies have systematically compared the influence of different residue management strategies on the establishment of crop and weed species. We evaluated the effect of several methods of pre-treatment and placement of winter rye (Secale cereale L.) and win...

Witchweed (Striga spp.) infestations are the greatest obstacle to sorghum [Sorghum bicolor (L.) Moench] grain production in many areas in Africa. The objective of this study was to evaluate the efficacy of herbicide seed treatments for controlling Striga infestation of sorghum. Seeds of an acetolactate synthase (ALS) herbicide–tolerant sorghum hybr...

We conducted an experiment in Gejiu, Yunnan Province of China during the wet season of 2002 to examine the importance of resource complementarity and prevention of lodging in the fast-spreading practice of growing rice varietal mixtures in China to suppress rice blast disease and its associated damage. The hybrid rice variety Shanyou 63 and the glu...

Relay intercropping systems with rice cultivars (WAB450-24-3-2-P18-HB (V4) and WAB56-50), the competitive Cajanus cajan and the weakly competitive Stylosanthes hamata were evaluated in the tropical savanna zone in Côte d\'Ivoire. The INTERCOM model for competition served for data analysis and understanding of the system based on phenological, physi...

Despite increased concerns regarding the heavy reliance of many cropping systems on chemical weed control, adoption of ecological weed management practices is only steadily progressing. For this reason, this paper reflects on both the possibilities and limitations of cultural weed control practices. Cultural weed control utilises a number of princi...

Cover crops grown in the period between two main crops have potential as an important component of a system-oriented ecological weed management strategy. In late summer and autumn, the cover crop can suppress growth and seed production of weeds, whereas the incorporation of cover crop residues in spring may reduce or retard weed emergence. Based on...

To assess the suitability of Leguminous species in rice intercropping systems, physiological and morphological characteristics of Crotalaria juncea, Cajanus cajan, Mucuna pruriens var. cochinchinensis, Calopogonium mucunoides, Aeschynomene histrix and Stylosanthes hamata were determined in monoculture. C. cajan and S. hamata were selected and inter...

In China, a large acreage of cultivated land is devoted to relay intercropping of winter wheat and cotton. Wheat is sown in strips with interspersed bare soil in October and harvested in June of the next year, while cotton is sown in the interspersed paths in the wheat crop in April and harvested before the next wheat sowing in October. This paper...

We gathered survey data from a random sample of 200 farmer adopters and 59 nonadopters of rice interplanting in Yunnan Province, China in 2000. The data were used to analyze the effect of interplanting on technical efficiency of rice production and to identify the sources of inefficiency, using a stochastic frontier production function. Results sho...

The aim of the present paper was to assess the potential growth and seed yield of sunflower for biodiesel production as affected by sowing time, irrigation and N-fertilization. The results served as a basis for assessing cost-benefit ratios of cropping systems in central Greece, including sunflower either in rotation or in a multiple cropping syste...

With the changing position of agriculture in the world the challenges for weed management and weed science are changing as well. In this paper recent developments in weed science with respect to several aspects of weed management are discussed in relation to those changes. Developments in cultural weed control or prevention, chemical weed control w...

To evaluate the effect of pre-spraying growing conditions on herbicide efficacy, two years of experimentation were conducted in which Persicaria maculosa plants were exposed to different light intensities for 1¿4 days before metribuzin treatment. Specific leaf area, rather than plant growth rate or plant size, was the only parameter that correlated...

Striga hermonthica (Del.) Benth. is a parasitic weed on tropical cereals causing serious yield losses in Africa. The use of host crop varieties with improved resistance and tolerance against this parasite is a key component of an integrated control strategy. Breeding for tolerance is however seriously hampered by the absence of reliable and yet pra...

Water shortage in drought-prone rice-growing areas of the world is threatening conventional irrigated rice production systems, in which rice is transplanted into fields where standing water is maintained until harvest. Aerobic rice production systems, in which rice is grown as a direct-seeded upland crop without flooding, require less water than co...

Weeds often form a major problem in weakly competitive vegetable crops, particularly in low input systems. Undersown cover crops can be used to suppress weeds, but often put too high a competitive pressure on the main crop. Cover crop selection is one of the potential means that can be used to design or optimize these intercropping systems. The obj...

Undersown cover crop species introduced for weed management purposes should ideally combine adequate weed suppression with only marginal negative competitive effects on the main crop. The aim of this research was to identify the growth characteristics of clover species that determine weed suppressive ability and competitive ability against the main...

Mathematical modelling is a commonly used tool for studying the long-term dynamics of weed populations in agriculture. This was reflected in our review by the large number of scientific papers (134 original publications) and the continuing need to gain an overview over this fast developing field (20 previous review papers were found). In this artic...