Longevity of<i>Striga</i>seeds reconsidered: results of a field study on purple witchweed (<i>Striga hermonthica</i>) in Bénin

Gbèhounou, G.; Pieterse, A.H.; Verkleij, J. A. C.

doi:10.1614/ws03-0221r1

Cited by 20 publications

(18 citation statements)

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“…High mortality rates found in previous studies (Pieterse et al . 1996; Gbéhounou, Pieterse & Verkleij 2003) correspond with the mortality rates of the higher density treatments in this study. The lower densities created in this study decreased mortality to a level similar to results from studies that used soil sampling methods (Van Delft et al .…”

Section: Discussionsupporting

confidence: 60%

“…The seed bag burial method is used for monitoring the longevity and dormancy of plant seeds in soil seed banks (Rampton & Ching 1966; Lewis 1973; Egley & Chandler 1978). This method is frequently used when very small seeds are being studied, such as those of parasitic weeds (Lopez Granados & Garcia Torres 1999; Gbéhounou, Pieterse & Verkleij 2000, 2003; Van Mourik, Stomph & Westerman 2003). Seed bags have also been used to study the effect of fungi on soil seed mortality (Crist & Friese 1993; Dalling, Swaine & Garwood 1998).…”

Section: Introductionmentioning

confidence: 99%

“…With the seed bag burial method, mortality rates of S. hermonthica seeds have been estimated to range between 80% and 100% in the course of one rainy season in field soils (Pieterse et al . 1996; Gbéhounou, Pieterse & Verkleij 2003; Van Mourik, Stomph & Westerman 2003). In these studies samples of about 1000 seeds were buried in the field in nylon gauze bags with a 90–100 µm mesh, and vegetation cover was prevented by frequent weeding.…”

Section: Introductionmentioning

confidence: 99%

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Why high seed densities within buried mesh bags may overestimate depletion rates of soil seed banks

Mourik

Stomph

Murdoch

2005

Journal of Applied Ecology

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Summary 1.Estimates of seed bank depletion rates are essential for modelling and management of plant populations. The seed bag burial method is often used to measure seed mortality in the soil. However, the density of seeds within seed bags is higher than densities in natural seed banks, which may elevate levels of pathogens and influence seed mortality. The aim of this study was to quantify the effects of fungi and seed density within buried mesh bags on the mortality of seeds. Striga hermonthica was chosen as the study species because it has been widely studied but different methods for measuring seed mortality in the soil have yielded contradictory estimates. 2. Seed bags were buried in soil and exhumed at regular time intervals to monitor mortality of the seeds in three field experiments during two rainy seasons. The effect of fungal activity on seed mortality was evaluated in a fungi exclusion experiment. Differences in seed-to-seed interaction were obtained by using two and four densities within the seed bags in consecutive years. Densities were created by mixing 1000 seeds with 0, 10, 100 or 1000 g of coarse sand. 3. The mortality rate was significantly lower when fungi were excluded, indicating the possible role of pathogenic fungi. 4. Decreasing the density of seeds in bags significantly reduced seed mortality, most probably because of decreased seed-to-seed contamination by pathogenic fungi. 5. Synthesis and applications . Models of plant populations in general and annual weeds in particular often use values from the literature for seed bank depletion rates. These depletion rates have often been estimated by the seed bag burial method, yet seed density within seed bags may be unrealistically high. Consequently, estimates of seed mortality rates may be too high because of an overestimation of the effects of soil or seedborne pathogens. Species that have been classified from such studies as having short-lived seed banks may need to be re-assessed using realistic densities either within seed bags or otherwise. Similarly, models of seed bank dynamics based on such overestimated depletion rates may lead to incorrect conclusions regarding the seed banks and, perhaps, the management of weeds and rare species.

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Section: Discussionsupporting

confidence: 60%

Section: Introductionmentioning

confidence: 99%

Section: Introductionmentioning

confidence: 99%

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Why high seed densities within buried mesh bags may overestimate depletion rates of soil seed banks

Mourik

Stomph

Murdoch

2005

Journal of Applied Ecology

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“…Despite these methodological obstacles, the annual mortality rates measured for seeds of P. ramosa over 2 years (4–7%) were similar to those measured for P. mutelii on a 9‐year experiment with tetrazolium tests (<10% on average, Prider et al ., ). They were, however, much lower than for two parasitic species from other genera of the Orobanchaceae family, that is O. crenata (approximately 25% per year for 2 years after burial, López‐Granados & García‐Torres, ) and Striga hermonthica (all seeds die in less than 2 years, Gbèhounou et al ., ). Seed mortality may have been overestimated in O. crenata since it was estimated from germinated seeds, ungerminated seeds being considered as dead (López‐Granados & García‐Torres, ).…”

Section: Discussionmentioning

confidence: 97%

Intraspecific seasonal variation of dormancy and mortality of Phelipanche ramosa seeds

et al. 2019

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Summary Phelipanche ramosa (Branched broomrape) is an obligate root parasitic plant that is a major pest of oilseed rape in France. Knowledge on seed viability and dormancy under field conditions is crucial to understand how to control P. ramosa, but is as yet unknown. Our study aimed to quantify these processes with a 2‐year seed burial experiment. Two genetically distinct populations of P. ramosa were studied, collected on winter oilseed rape (population O) and hemp (population H). Seed mortality was very low in both populations (4–7% per year). Although obligate parasitic seeds are assumed to germinate only after exposure to germination stimulants from host root exudates, a high proportion of population H seeds germinated spontaneously (up to 90%). Seeds of both populations displayed seasonal dormancy, with timing and magnitude depending on the population. Dormancy was low at the time each native host crop is usually sown. Populations differed in germination dynamics, with seeds of population H germinating faster. The difference in behaviour that we observed between populations is consistent with reported adaptations of pathovars to their preferred hosts. The results indicate that the parasitic plant management requires targeting at the populations concerned. For example, delayed sowing is more promising against population O than against population H.

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“…1984). However, the high depletion rates of >50% over one or two rainy seasons that have been reported in several studies on Striga in Africa cannot be attributed only to seed aging (Oswald & Ransom 2001; Gbéhounou et al . 2003; Murdoch & Kunjo 2003).…”

mentioning

confidence: 99%

Purple witchweed (Striga hermonthica) germination and seedbank depletion under different crops, fallow, and bare soil

Mourik¹,

Stomph²,

Murdoch³

2011

Weed Biology and Management

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Seedbank density is an important aspect that determines the amount of damage that the parasitic weed, purple witchweed (Striga hermonthica; hereafter, called "Striga"), causes on its crop hosts.The seedbank depletion of Striga was measured in Mali and Niger during the 2004 rainy season under the host crops, pearl millet and sorghum, the non-host crops, cowpea and sesame, the intercrops of pearl millet or sorghum with cowpea or sesame, and fallow with or without weeding. Two methods were used and compared; namely, a seed bag method and a soil-sampling method.The fate of the seeds was assessed by a seed press test. Seed germination, as determined by the presence of empty seed coats, contributed most to the seedbank depletion of Striga under a variety of crop covers and fallow.The highest seedbank depletion was found under the monocultures of the host crops.The intercrops of the host and non-host crops caused less seedbank depletion, followed by the monocultures of the non-host crops, fallow, and bare soil. The seed bag method and the soil-sampling method yielded similar percentages of seedbank depletion, while the former allowed for distinguishing between the germinated and diseased seeds.The results suggest that, although all the tested crop species can cause the seed germination and seedbank depletion of Striga, management by using host cereal crops causes the highest amount of germination and has the highest potential to deplete the soil seed bank, provided that seed production is prevented.

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Longevity ofStrigaseeds reconsidered: results of a field study on purple witchweed (Striga hermonthica) in Bénin

Cited by 20 publications

References 10 publications

Why high seed densities within buried mesh bags may overestimate depletion rates of soil seed banks

Why high seed densities within buried mesh bags may overestimate depletion rates of soil seed banks

Intraspecific seasonal variation of dormancy and mortality of Phelipanche ramosa seeds

Purple witchweed (Striga hermonthica) germination and seedbank depletion under different crops, fallow, and bare soil

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