Anna Mårtensson Pengarang

5. Alleviation of salt stress by increasing potassium sulphate doses in four medicinal and aromatic plants Gülsüm Yaldı za, Ferit Özenb, Mahmut Çamlıcaa and Ferit Sönmezc aDepartment of Field Crops, Faculty of Agriculture and Natural Sciences, Abant Izzet Baysal University, Bolu, Turkey; bMedicinal and Aromatic Plants Department, Mudurnu Süreyya Astarcı Vocational School, Bolu, Turkey; cDepartment of Seed Science and Technology, Faculty of Agriculture and Natural Sciences, Abant Izzet Baysal University, Bolu, Turkey ABSTRACT In this study, the effects of potassium doses (control, 150, 300 and 450 mg K2SO4 kg −1 ) and salt stress (control, 100 mM NaCl) on the yield and some element content of four medicinal and aromatic (Coriandrum sativum, Anethum graveolens, Ocimum basilicum and Foeniculum vulgare) plants were investigated in climate chamber. Both salinity and K fertiliser levels affected the fresh and dry weight of all evaluated plants. Anethum graveolens, Ocimum basilicum species are more sensitive to salinity, particularly at the vegetative productive stages. The highest fresh and dry weights of leaves, stems, roots and herb in Coriandrum sativum and Foeniculum vulgare species was observed in 300 mg kg −1 fertiliser applications. In general, there was a relatively consistent and positive correlation between root element content and aerial parts element content. The result of the present study showed that NaCl treatment caused an increase in Na+ concentration, and a decrease in K+ and Ca+2 concentration in Coriandrum sativum, Anethum graveolens, Ocimum basilicum and Foeniculum vulgare. There was an interaction between K2SO4 application and salinity effects on Na+ concentration in the all evaluated plants. Given the experimental results, especially Foeniculum vulgare and Coriandrum sativum species were the most resistant to salt stress. KEYWORD S Salinity; potassium; medicinal and aromatic plants; nutrients Bacillus pumilus WP8 exhibits biocontrol efficacy against tomato bacterial wilt via attenuation of the virulence of the pathogenic bacterium Min Shena,b, Dan Xiab, Zhifeng Yinb, Qingxin Zhaob and Yijun Kanga,b aJiangsu Key Laboratory for Bioresources of Saline Soils, Yancheng, People’s Republic of China; bCollege of Marine and Bio-engineering, Yancheng Teachers University, Yancheng, People’s Republic of China ABSTRACT Bacillus pumilus WP8 is a plant growth-promoting rhizobacterium (PGPR) with good biocontrol efficacy against tomato bacterial wilt caused by Ralstonia solanacearum Rs1115. Biocontrol, however, is not due to antagonism of the pathogenic bacterium. Thus, we hypothesised that the biocontrol efficacy of WP8 was achieved by attenuation of Rs1115 virulence. Here, pot experiments for comparison of Rs1115 in different plant parts were conducted to investigate the ability of WP8 to prevent entry of Rs1115 into the regions of the plant above ground. Primary and secondary metabolite contents of WP8 and their inhibitory effects on twitching and swarming motilities of Rs1115 were determined by microscopic examination and crystal violet staining. The effects of WP8 metabolites on the expression of typical virulence genes in Rs1115 were established by quantitative PCR. Rs1115 abundance in the rhizosphere increased with time after inoculation. However, the shoots treated with WP8 were pathogen-free on days 3 and 6 after inoculation. In the WP8 + Rs1115 treatment group, the abundance of Rs1115 in shoots was 1.5 lg units higher on day 9 post-inoculation than that in the Rs1115 treatment group, while less Rs1115 was observed in the leaves. This indicated that WP8 prevented Rs1115 from spreading to the regions of the plant above ground. Furthermore, some heat-resistant secondary metabolites of WP8 (e.g. lipopeptides) inhibited the twitching and swarming motility of Rs1115. Moreover, the metabolites decreased the expression of typical virulence genes in Rs1115. Therefore, WP8 was shown to attenuate Rs1115 virulence, possibly through pumilacidin secretion. KEYWORD S Attenuation of virulence; Bacillus pumilus; biocontrol; plant growth-promoting rhizobacteria (PGPR); Ralstonia solanacearum Changes in sorghum production, soil P forms and P use efficiency following long-term application of manure, compost and straw in a Ferric Lixisol Dohan Mariam Somaa, Delwendé Innocent Kibaa, Nana Ewusi-Mensahb, Zacharia Gnankambarya, François Lompoa, Michel Papoaba Sedogoa and Robert Clement Abaidoob,c aDépartement Gestion des Ressources Naturelles/Systèmes de Production, Institut de l’Environnement et de Recherche agricole, Ouagadougou, Burkina Faso; bDepartment of Crop and Soil Sciences, Faculty of Agriculture, Kwame Nkrumah University of Science and Technology (KNUST), Kumasi, Ghana; cSoil Microbiology Unit, International Institute of Tropical Agriculture, Ibadan, Nigeria ABSTRACT Low phosphorus availability in cultivated soils limits sustainable crop production in sub-Saharan Africa. This study aimed at evaluating the effect of long-term application of different types of organic amendments on soil P forms, P use efficiency and sorghum yields. A long term experiment established in 1980 at Saria in Burkina Faso, comparing the effects of manure, compost and sorghum straw was used. Manure and compost significantly increased organic P and resin-P by about 35% and 64%, respectively after 10 and 32 years of sorghum cultivation, and HCl-P after 32 years of cultivation compared to the control. Manure significantly increased NaHCO3-Pi and NaOH-Pi by 63% and 26%, respectively compared to the control. Sorghum straw had little effect on measured soil P forms. Manure and compost were the best in increasing sorghum grain yield, which effect were strongly correlated to soil pH, carbon and nitrogen. The partial factors productivities of P resulting from the application of studied organic amendments were similar and low, but significantly higher than that of the control treatment. Organic amendments with high P content, maintaining soil carbon and pH could be used to improve soil P availability, sorghum yield and reduce the demand for mineral phosphorus fertilizers. KEYWORD S Organic amendments; phosphorus fractions; phosphorus use efficiency; sorghum production; Lixisol Modelling nitrogen transport and transformation in a transplanted rice field experiment with reduced irrigation Yong Lia,b, Chun Xub, Shuang Wangb and Yingying Wangb aMinistry of Education Key Laboratory of Integrated Regulation and Resource Development on Shallow Lakes, Hohai University, Nanjing, People’s Republic of China; bCollege of Environment, Hohai University, Nanjing, People’s Republic of China ABSTRACT Application of water-saving irrigation technologies in transplanted rice (TPR) cultivation resulted in different soil water regimes compared to traditional flood irrigation and consequent diverse nitrogen transport and losses in paddy fields. In this study, nitrogen transport and transformations in a TPR field under multiple shallow irrigation (MSI) conditions in the Taihu Lake Basin of Eastern China were observed and simulated (Hydrus-1D model) during the 2008-2009 seasons based on a previous study. MSI controlled well the depth of floodwater and reduced nitrogen losses substantially through percolation and surface runoff, in particular during the 2008 season with relative less rainfall. Nitrogen balance analysis showed that both denitrification and NH3 volatilisation were the two major paths of nitrogen loss during the two seasons. Most nitrogen transformations occurred in top soil (0–40 cm) during early-middle seasons. The overall nitrification and denitrification differed slightly between the two seasons but largely between soil depths, averagely 92.7% and 73.0% of respective total in a 120 cm soil profile occurred in 0–40 cm soil, respectively. MSI method coupled with deep applied fertiliser is recommended to substantially reduce nitrogen losses through surface runoff, percolation, and NH3 volatilisation in TPR fields. KEYWORD S Hydrus-1D; multiple shallow irrigation; nitrogen; Taihu Lake Basin; transplanted rice Nitrogen application influences quality, pharmacological activities and metabolite profiles of Athrixia phylicoides DC. (Bush tea) cultivated under greenhouse and field conditions Itani Tshivhandekanoa, Wonder Ngezimanab, Thilivhali E. Tshikalangec, Nokwanda P. Makungad and Fhatuwani N. Mudaua aDepartment of Agriculture and Animal Health, University of South Africa, Florida, South Africa; bMarondera College of Agricultural Science and Technology, University of Zimbabwe, Marondera, Zimbabwe; cDepartment of Plant science, University of Pretoria, Hatfield, South Africa; d Department of Botany and Zoology, Stellenbosch University, Stellenbosch, South Africa ABSTRACT Bush tea ( Athrixia phylicoides DC.) is a popular aromatic plant, indigenous to South Africa. For many decades, indigenous people have widely consumed the tea as a healthy beverage and a medicine. The objective of the study was to investigate the influence of nitrogen fertiliser application on the quality, pharmacological activities and metabolite profiles of the leaves and twigs of bush tea cultivated under greenhouse and field conditions. Treatments consisted of 0, 75, 150, 225, 300 and 375 kg/ha N, arranged in a randomised complete block design with five replicates. Parameters measured were leaf tissue nitrogen, total polyphenols, total flavonoids, total tannins, total antioxidants, antimicrobial activity and cytotoxicity. In addition, metabolites were identified and measured using gas chromatography linked to mass spectrometry (GC-MS) and liquid chromatography linked to mass spectrometry (LC-MS). The results of this study showed a significant quadratic response of total polyphenols, total flavonoids, total tannins and total antioxidants of bush tea leaves and twigs, irrespective of the growth environment ranging from 150 to 225 kg/ha N. The results further suggested that, despite the growing environment, nitrogen treatments did not improve the minimum inhibition concentration and minimum microbicide concentration of bush tea with extract concentrations ranging from 25.0 to 3.1 mg/g. Bush tea was found to be non-toxic (IC50 above 100) under both growing conditions, irrespective of nitrogen treatments. Despite trials being conducted under greenhouse and field conditions and with different nitrogen treatments, there were no distinct differences regarding the gas chromatography linked to mass spectrometry and liquid chromatography linked to mass spectrometry compounds. The future aims of the study are to investigate the effects of nitrogen fertilisation, the timing of nitrogen fertilisation and the planting density on the yield, quality, plant metabolites and pharmacological activity of field-grown bush tea. KEYWORD S Nitrogen; biomass; antioxidant activity; cytotoxicity; antimicrobial activity On-farm comparisons of soil organic carbon under no-tillage and chisel-plow systems Amitava Chatterjee Department of Soil Science, North Dakota State University, Fargo, ND, USA ABSTRACT Purpose: Role of no-tillage (NT) in soil conservation has been already established but its influence on soil organic carbon (SOC) is still under debate. Materials and methods: Three paired sites, with NT and chisel-plow (CT) fields adjacent to each other were selected for this study. Fields were under the same tillage practices for more than 20 years. Fields were sampled up to 90 cm depth to determine SOC and different C pools based on soil CO2 flux during 86 d of incubation. Results and conclusion: Significant differences in SOC and its pools were limited within the surface 0–15 cm depth only. Profile SOC did not vary between NT and CT. Tillage had a significant influence on soil C pools but the effect was not consistent across sites. KEYWORD S Northern great plains; conservation tillage; mineralization; carbon pools; C:N ratio; bulk density Optimal control of foliar disease dynamics for multiple maize varieties Obiora Cornelius Collins and Kevin Jan Duffy Institute of Systems Science, Durban University of Technology, Durban, South Africa ABSTRACT Maize is a very important food crop world-wide and is vulnerable to diseases. Maize varieties that have high disease resistance are highly recommended for economic and health reasons. We consider a maize field with multiply varieties and develop a mathematical model to investigate the impact of foliar disease on the population dynamics. The possible benefit of considering control measures in reducing the spread of foliar diseases are evaluated. Results show that farmers must be aware of the disease dynamics of each variety as the dynamics vary. Also, in controlling diseases some methods are more effective than others. For the example given here controlling susceptibility of seeds to disease was the most effective method. As controlling diseases can be costly, optimal methods are important. Our results show that the most effective controls are those introduced at the outset of an outbreak and this can reduce the spread of diseases with the least cost. KEYWORD S Population dynamics; modelling; maize varieties; maize foliar diseases; stability analyses; optimal control Short-term effects of nitrapyrin, rice straw and its biochar application on N transformation in soils of humid subtropical China Ying Zhaoa, Jing Wangb, Zucong Caia,c,d,e, Christoph Müllerf,g and Jinbo Zhanga,c,d,e aSchool of Geography Sciences, Nanjing Normal University, Nanjing, People’s Republic of China; bCollege of Forestry, Nanjing Forestry University, Nanjing, People’s Republic of China; cJiangsu Center for Collaborative Innovation in Geographical Information Resource Development and Application, Nanjing, People’s Republic of China; dState Key Laboratory Cultivation Base of Geographical Environment Evolution (Jiangsu Province), Nanjing, People’s Republic of China; eMinistry of Education, Key Laboratory of Virtual Geographic Environment (Nanjing Normal University), Nanjing, People’s Republic of China; fDepartment of Plant Ecology (IFZ), Justus-Liebig University Giessen, Giessen, Germany; gSchool of Biology and Environmental Science, University College Dublin, Dublin, Ireland ABSTRACT The features of N transformations in humid subtropical soils vary greatly due to the wide variations of soil properties, particularly soil pH. Purpose: To understand whether the effects of countermeasures regulating N transformation varied with the prevailing soil N transformation characteristics. Materials and methods: The effects of nitrapyrin, rice straw and its biochar applications on N dynamics at the beginning stage (first 24 h) of a zonal acid soil (JX soil, pH 5.26) and a non-zonal alkaline soil (SC soil, pH 7.62) from the humid subtropics in China were investigated via a 15N tracing laboratory incubation. Results and conclusions: Rice straw incorporation affected almost all processes involved in NH +4 and NO −3 production and consumption, and decreased the net mineralisation and nitrification rates in both soils significantly. Nitrapyrin decreased the net nitrification rates in both studied soils by affecting different N transformation processes. In the SC soil, nitrapyrin reduced the net nitrification rate by inhibiting the gross autotrophic nitrification rate while the gross autotrophic nitrification in the JX soil was negligible and nitrapyrin decreased its net nitrification via a stimulation of the gross rate of dissimilatory nitrate reduction to ammonium (DNRA). Biochar stimulated the gross rates of mineralisation, NH +4 immobilisation, autotrophic nitrification and DNRA significantly, but did not affect the net mineralisation and nitrification rates in both soils. Countermeasures to regulate N transformations are tightly linked to the prevailing soil N transformation characteristics and should be taken into account for the recommendation of suitable management options. KEYWORD S N regulation; N dynamics; gross rate; net rate; 15N tracing The impact of drought on sorghum production, and farmer’ s varietal and trait preferences, in the north eastern Ethiopia: implications for breeding Solomon Assefa Deresea,b, Hussein Shimelisa, Mark Lainga and Fentahum Mengistuc aSchool of Agricultural, Earth and Environmental Sciences, African Centre for Crop Improvement, University of KwaZulu-Natal, Pietermaritzburg, South Africa; bCereal Breeding and Genetics, Sirinka Agricultural Research Center, Woldia, Ethiopia; cEthiopian Institute of Agricultural Research, Addis Ababa, Ethiopia ABSTRACT Purpose: Sorghum [ Sorghum bicolor (L.) Moench] has been cultivated for centuries as a staple food crop for millions of people in sub-Saharan Africa and Asia. In Ethiopia a total of 4.34 million tons of sorghum is being produced per annum, predominantly in the arid and semi-arid areas. However, the yield and quality of sorghum is affected by a wide array of production constraints, notably severe and recurrent drought stress. The aim of this study were to determine the impact of drought on sorghum production and productivity over time and space, and to identify farmers’ trait preferences, production constraints and coping strategies when dealing with drought in north eastern Ethiopia. Materials and methods: Participatory rural appraisal (PRA) was employed in three administrative zones of north eastern Ethiopia. One Woreda from each Zone and two Kebeles from each Woreda were selected on the basis of sorghum area coverage, production, consumption and prior information on the intensity, duration and spatial coverage of drought. In each kebele, 30 respondents were selected for interview and 12 key informants were selected for group discussions and transect walk personal observations. Data collected from 180 respondents was subjected to statistical analysis and the information gathered from 72 key informants through focus group discussions and transect walk observations were used in discussing the results. Results and discussion: The present study found that productivity of sorghum was challenged by recurrent droughts, Striga infestation, insects, birds, diseases, a lack of varieties with farmerspreferred traits and high yield potential, limited policy support, a lack of improved seed system, poor sorghum production practices and application of crop input and poor soil fertility, in a decreasing order of importance. Among the listed sorghum production constraints, severe drought in the post-flowering stage was identified by most interviewed farmers as the leading constraint across the three study zones. Focus group discussions and transect walk observations held in each Kebele revealed that farmers’ had lost numerous valuable local landrace varieties due to extreme drought conditions over the years. A significant number of interviewed farmers preferred to grow high grain and biomass yielder medium-maturing sorghum varieties which can be sown at the normal planting time but which would escape post-flowering drought. Conclusion: Overall, sorghum breeding programme should be directed at developing farmers’ ideal sorghum varieties with high grain and biomass yield, adequate level of drought and Striga tolerance. In addition, development of farmer preferred medium-maturing sorghum varieties suitable for April planting should be strengthen to boost its productivity and to increase varietal adoption rate in the area. KEYWORD S Drought; sorghum; participatory rural appraisal; medium-maturity; grain yield