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P. C. Biemond Oluwole Oguntade Tjeerd-Jan Stomph P. Lava Kumar Aad J. Termorshuizen Paul C. Struik 《European journal of plant pathology / European Foundation for Plant Pathology》2013,137(3):563-572
Many Nigerian farmers depend for their seed on seed-producing farmers, the so-called informal Seed System (SS), but seed quality of the SS is unknown. Farmers planting low quality seed risk poor field emergence and low plant vigour as a result of low physiological quality or infection with seed-borne pathogens. The objective of this research was to test seed quality of maize seed from the informal SS in north-east Nigeria. A total of 46,500 seeds (93 samples of 500 seeds each) were tested for germination, off-types and seed health. Seed pathology was quantified by plating disinfected seeds onto agar, and identifying the fungi present after 3 days incubation. Twelve seed-borne pathogens were identified including Bipolaris maydis (found in 45 % of the farmer-produced samples), Botryodiplodia theobromae (97 %) and Curvularia lunata (38 %). All samples were infected with Fusarium verticillioides, with a median infection incidence of 59 % (2009) and 51 % (2010). None of the 93 samples tested passed the demands for certified seed of the National Agricultural Seeds Council (NASC) in Nigeria, in particular the maximum limit of five off-types per kg seed sample. Based on these results, seed-producing farmers must improve the health of seed. The NASC should revise the standards for off-type seeds to minimize the time spent by farmers sorting planting material. 相似文献
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Qi WANG Zhanxiang SUN Wei BAI Dongsheng ZHANG Yue ZHANG Ruonan WANG Wopke VAN DER WERF Jochem B. EVERS Tjeerd-Jan STOMPH Jianping GUO Lizhen ZHANG 《农业科学与工程前沿(英文版)》2021,8(3):432-446
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Bereket Haileselassie Tjeerd-Jan Stomph Ellis Hoffland 《Soil Science and Plant Nutrition》2013,59(4):587-596
Thirty samples of grassland surface soil, which had a diverse management history and consequently displayed a wide range of soil properties, were studied to analyze the relationships between soil microbial activity and soil properties. The microbial measurements included the number of bacteria, number of Gram negative bacteria, number of fungi obtained by the plate method, TTC reducing activity and nitrifying activity. In the uppermost layers (at the 0 to 2 cm depth), Simple correlation analyses showed that bacterial numbers were positively correlated with soil pH and negatively correlated with Bray No. 2 P, total C, and grassland age. TTC reducing activity and nitrifying activity were also positively correlated with soil pH, while the fungal number was not significantly related to any soil properties. In the lower layer (at the 5 to 15 cm depth), all of the microbial measurements were negatively correlated with grassland age and were positively correlated with microbial substrate level. soil pH and exchangeable K were positively correlated with the microbial measurements except for the Gram negative bacteria, and significant correlations among almost all the microbial measurements were observed. These results suggest that soli pH accounted primarily for microbial activities in the uppermost layers. Also microbial substrate level, soil pH and probably amounts of exchangeable K, which inevitably decreased with grassland age, appeared to control the microbial activities in the lower soil layers. 相似文献
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THOMAS A. VAN MOURIK TJEERD J. STOMPH ALISTAIR J. MURDOCH 《Weed Biology and Management》2011,11(2):100-110
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. 相似文献
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Wopke VAN DER WERF Lizhen ZHANG Chunjie LI Ping CHEN Chen FENG Zhan XU Chaochun ZHANG Chunfeng GU Lammert BASTIAANS David MAKOWSKI TjeerdJan STOMPH 《农业科学与工程前沿(英文版)》2021,8(3):481-489
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The parasitic weed Striga hermonthica poses a serious threat to cereal production in sub-Saharan Africa. Striga hermonthica seedbanks are long-lived; therefore, long-term effects of control strategies on the seedbank only emerge after several years. We developed a spatially explicit, stochastic model to study the effectiveness of control strategies in preventing invasion of S. hermonthica into previously uninfested fields and in reducing established infestations. Spatial expansion of S. hermonthica and decrease in millet yield in a field was slower, on average, when stochasticity of attachment of seedlings to the host was included and compared to the deterministic model. The spatial patterns of emerged S. hermonthica plants 4–7 years after point inoculation (e.g. seeds in a dung patch) in the spatial-stochastic model resembled the distribution typically observed in farmers' fields. Sensitivity analysis showed that only three out of eight life cycle parameters were of minor importance for seedbank dynamics and millet yield. Weeding and intercropping millet with sesame or cowpea reduced the seedbank in the long term, but rotations of millet with trap crops did not. High seedbank replenishment during years of millet monoculture was not sufficiently offset by seedbank depletion in years of trap crop cultivation. Insight from simulations can be employed in a participatory learning context with farmers to have an impact on S. hermonthica control in practice. 相似文献
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