Low-input Farming Systems Research Articles

Genetic diversity for nitrogen use efficiency in Arabidopsis thaliana

Main conclusionThe plasticity of plant growth response to differing nitrate availability renders the identification of biomarkers difficult, but allows access to genetic factors as tools to modulate root systems to a wide range of soil conditions.Nitrogen availability is a major determinant of crop yield. While the application of fertiliser substantially increases the yield on poor soils, it also causes nitrate pollution of water resources and high costs for farmers. Increasing nitrogen use efficiency in crop plants is a necessary step to implement low-input agricultural systems. We exploited the genetic diversity present in the worldwide Arabidopsis thaliana population to study adaptive growth patterns and changes in gene expression associated with chronic low nitrate stress, to identify biomarkers associated with good plant performance under low nitrate availability. Arabidopsis accessions were grown on agar plates with limited and sufficient supply of nitrate to measure root system architecture as well as shoot and root fresh weight. Differential gene expression was determined using Affymetrix ATH1 arrays. We show that the response to differing nitrate availability is highly variable in Arabidopsis accessions. Analyses of vegetative shoot growth and root system architecture identified accession-specific reaction modes to cope with limited nitrate availability. Transcription and epigenetic factors were identified as important players in the adaption to limited nitrogen in a global gene expression analysis. Five nitrate-responsive genes emerged as possible biomarkers for NUE in Arabidopsis. The plasticity of plant growth in response to differing nitrate availability in the substrate renders the identification of morphological and molecular features as biomarkers difficult, but at the same time allows access to a multitude of genetic factors which can be used as tools to modulate and adjust root systems to a wide range of soil conditions.

Genetic characterisation and agronomic and nutritional value of bitter vetch (Vicia ervilia), an under-utilised species suitable for low-input farming systems

Bitter vetch (Vicia ervilia (L.) Willd.), a grain legume crop well adapted in marginal soils, has mainly been used for animal feed. Nowadays, bitter vetch seeds in feed formulations are replaced by other protein sources such as soybean meal. However, in the context of sustainable economic development, it may be beneficial to enhance the cultivation of bitter vetch landraces in marginal areas. Fifty-six bitter vetch accessions of different provenance were preliminarily characterised by microsatellite DNA analysis to discriminate landraces suitable for specific and restricted environments. Twenty-two landraces of two genetically different groups were then selected for further characterisation by agro-morphological analyses. Being late-flowering with a seed yield of up to 3–4 t ha–1 in experimental field conditions, with neither chemical nor water input, these plants will be valuable material for long-term study to develop new cultivars adapted for seed production under organic agricultural systems in Southern Europe. The seeds of these 22 landraces were also evaluated, with positive results, as partial replacement of soybean in rabbit diets.

Koncepcja i znaczenie obszarów rolniczych o wysokich walorach przyrodniczych

Koncepcja rolniczych obszarów HNV (ang. HNV farmland, lub HNVf) została wprowadzona do nauki i polityki gospodarczej Unii Europejskiej na przełomie dwóch ostatnich wieków, jako podstawa do skutecznych działań na rzecz przeciwdziałania dalszej redukcji bioróżnorodności na gruntach rolnych. Dotychczas ta ważna kwestia nie jest zadawalająco dyskutowana i prezentowana w piśmiennictwie polskim. W niniejszej pracy przeglądowej, stanowiącej przegląd i analizę europejskiej literatury naukowej, monografii i raportów unijnych, przedstawiono ważne zagadnienia, dotyczące definicji i typów rolniczych obszarów HNV, ich znaczenia przyrodniczego i gospodarczego oraz uzasadnienia realizacji programowej ochrony. Obszar rolniczy HNV stanowi grunty rolne, na których istnieje bogata bioróżnorodność o dużym znaczeniu dla ochrony gatunków, siedlisk i krajobrazów oraz stosowane są ekstensywne systemy rolnicze, które sprzyjają dalszemu trwaniu lub wzbogacania istniejącej tam agro-bioróżnorodności. Obszary HNV pozwalają realizować wiele funkcji oraz dostarczać dóbr publicznych, środowiskowych i społeczno-gospodarczych. Uznaje się, że najlepszym sposobem ochrony wysokich walorów przyrodniczych obszarów rolniczych jest prowadzenie na nich ekstensywnej lub niskonakładowej gospodarki rolniczej. Dla spełnienia tego postulatu UE nakłada na kraje członkowskie obowiązek wdrażania koncepcji obszarów HNV, polegający głównie na ich delimitacji oraz wielostronnym i elastycznym wspieraniu rolników na tych terenach w ramach Wspólnej Polityki Rolnej i innych polityk krajowych.

English

Weeds represent one of the major biological constraints to upland rice production in low input agricultural systems. The effects of weeding regimes and rice cultivars on weed growth and rice yield were investigated over three seasons. Four weeding regimes [0 (no weeding control), 1, 2, and 3] and three popular rice varieties (NARIC 2, a local cultivar, and NERICA 4), were tested in 4x3 factorial experiment in a Randomised Complete block with three replicates. The most important weed species recorded were; Biden pilosa, Commelina benghalensis L., Euphorbia hirta L., Micrococca mercurialis Benth., Galisonga parviflora Cav, Sida rhombifolia L., Triumfeta spp, Guizotia scabra, Celocia trigyna, Cyprus rotundus, Panicum Maximum Jacq, and Imperata cylindrica L. Across cultivars, the best weeding regimes for weed control and rice yields were single weeding and weeding twice. Differences among interaction effects between variety and weeding regime were not significant for most traits, except ripening ratio and grain yield in experiment one and experiment two. Across weeding regimes, NERICA 4 out yielded the other varieties in all the three experiments. However, a single well timed hand hoe weeding, together with the use of a cultivar with good adaptation to unfavourable rice growing conditions, such as NERICA 4, would increase land and labour productivity of upland rice-based systems in Uganda. Key words: Genotype, rice, upland, weeding regimes, yield.

Symbiotic Effectivity of Dual and Tripartite Associations on Soybean (Glycine max L. Merr.) Cultivars Inoculated With Bradyrhizobium japonicum and AM Fungi.

Soybean (Glycine max L. Merr.) is regarded worldwide as indisputably one of the most important crops for human food and animal feed. The presence of symbiotic bacteria and fungi is essential for soybean breeding, especially in low-input agricultural systems. Research on the cooperation between different microbial symbionts is a key to understanding how the health and productivity of the plant is supported. The symbiotic effectivity of dual and tripartite symbiotic agents was investigated in two pot experiments on different soybean cultivars with special regard to compatibility. In the Selection experiment, two out of sixteen soybean cultivars (Aliz, Emese) were chosen on the basis of their drought tolerance and used in all the other investigations. In the Compatibility experiment, the compatible coupling of symbiotic partners was selected based on the efficiency of single and co-inoculation with two Bradyrhizobium japonicum strains and two commercial arbuscular mycorrhizal fungal (AMF) products. Significant differences were found in the infectivity and effectivity of the microsymbionts. The rhizobial and AMF inoculation generally improved plant production, photosynthetic efficiency and root activity, but this effect depended on the type of symbiotic assotiation. Despite the low infectivity of AMF, inocula containing fungi were more beneficial than those containing only rhizobia. In the Drought Stress (DS) experiment, co-inoculated and control plants were grown in chernozem soil originating from organic farms. Emese was more resistant to drought stress than Aliz and produced a bigger root system. Under DS, the growth parameters of both microbially inoculated cultivars were better than that of control, proving that even drought tolerant genotypes can strengthen their endurance due to inoculation with AMF and nitrogen fixing bacteria. Root electrical capacitance (CR) showed a highly significant linear correlation with root and shoot dry mass and leaf area. The same root biomass was associated with higher CR in inoculated hosts. As CR method detects the absorptive surface increasing due to inoculation, it may be used to check the efficiency of the microbial treatment.

Intramammary infections and milk quality in low-input dairy goat farms

Low-input goat farming is one of the earliest agricultural activities and a common occupation in arid and semi-arid regions and in developing countries worldwide.1 Its importance lies in the ability...

Response of Bradyrhizobium japonicum nodule variables to cucurbitacin-containing phytonematicides in cowpea (Vigna unguiculata L.) on N-deficient soil

The Curve-fitting Allelochemical Response Data (CARD) had been adopted to develop the non-phytotoxic concentration of phytonematicides, technically referred to as the mean concentration stimulation point (MCSP). The MCSP for cucurbitacin-containing phytonematicides on Bradyrhizobium-nodulated legume crops had not been documented in low-input agricultural farming systems. The objective of this study was to determine the MCSP values of Nemarioc-AL and nemafric-BL phytonematicides on B. japonicum-nodulated cowpea (Vigna unguiculata) on nitrogen-deficient soils. Inoculated cowpea seeds were sown in 20-cm diameter plastic pots containing steam-pasteurised N-deficient loamy soil and Hygromix at 3: 1 (v/v) ratio. Two parallel experiments comprised Nemarioc-AL and Nemafric-BL phytonematicides, each had seven treatments (0, 2, 4, 8, 16, 32 and 64%) and applied once weekly. At 56 days after the treatments, the MCSP values for Nemarioc-AL and Nemafric-BL phytonematicides on cowpea were 5.4 and 6.3%, respectively, with the overall sensitivity (Σk) of one for each phytonematicide. In conclusion, the observed MCSP and Σk values suggested that the two cucurbitacin-containing phytonematicides were suitable for Bradyrhizobium-nodulated cowpea production systems on N-deficient soils.

When the going gets tough: Performance of stress tolerant maize during the 2015/16 (El Niño) and 2016/17 (La Niña) season in southern Africa

The 2015/2016El Niño was the most severe on record in southern Africa and was associated with drought and heat stress. To help farmers to cope with such extreme production constraints the International Maize and Wheat Improvement Centre (CIMMYT), has been developing maize varieties through a rapid-cycle breeding strategy to deliver a steady stream of incrementally improved varieties with tolerance to multiple stresses. Performance of stress tolerant maize germplasm in an El Niño year was evaluated using two types of trials. The first one comprised a regional on-farm trial with forty maize varieties (20 early-intermediate and 20 intermediate-late varieties), planted across 30 locations in four countries in southern Africa. The second set comprised a multi-locational evaluation trial with six hybrids that were tested under conventional ridge tillage (CP) and conservation agriculture (CA) using a randomized block design with each farm as replicate in nine extension planning areas (EPA), across two years. In the regional on-farm trial, analysis of variance on grain yield showed significant differences (P < 0.001) in both early-intermediate and intermediate-late varieties. Stress tolerant varieties such as CZH142020 (5.6 t ha −1) and CZH131008 (4.8 t ha −1), had significantly higher yield advantage over commercial control varieties (<4.5 t ha −1) in both maturity groups, respectively during the El Niño year. Furthermore, stress tolerant hybrids had larger grains and smaller ear uniformity index (EUI) (calculated as among plots ear size variance); compared non-stress tolerant varieties. In the CA/CP evaluation trial, varieties under CA yielded ≥0.7 t ha-1 more grain compared to those under CP. Stress tolerant maize in combination with CA led to higher yield gains compared to non-stress tolerant maize planted under CP. Therefore, combinations of climate-smart agriculture technologies are required to mitigate negative effects of extreme events like El Niño and increase resilience of low-input farming systems.

An overview of process intensification and thermo stabilization for upscaling of Peste des petits ruminants vaccines in view of global control and eradication.

Peste des petits ruminants (PPR) has been recognized as a globally distributed disease affecting the small ruminant population. The disease results in severe economic losses mainly to small land holders and low input farming systems. The control of PPR is mainly achieved through vaccination with available live attenuated vaccines. The thermo labile nature of PPR virus poses a major constraint in production of quality vaccines which often results in vaccine failures. The lack of quality vaccine production jeopardize the wide vaccination coverage especially in countries with poor infrastructure due to which PPR persists endemically. The vaccine production system may require augmentation to attain consistent and quality vaccines through efforts of process intensification integrated with suitable stabilizer formulations with appropriate freeze drying cycles for improved thermo tolerance. Manufacturing of live attenuated PPR vaccines during batch cultures might introduce defective interfering particles (DIPs) as a result of high multiplicity of infection (MOI) of inoculums, which has a huge impact on virus dynamics and yield. Accumulation of DIPs adversely affects the quality of the manufactured vaccines which can be avoided through use of appropriate MOI of virus inoculums and quality control of working seed viruses. Therefore, adherence to critical manufacturing standard operating procedures in vaccine production and ongoing efforts on development of thermo tolerant vaccine will help a long way in PPR control and eradication programme globally. The present review focuses on the way forward to achieve the objectives of quality vaccine production and easy upscaling to help the global PPR control and eradication by mass vaccination as an important tool.

The relationship between rainfall characteristics and Proso millet (&lt;i&gt;Panicum miliaceum&lt;/i&gt; L.) cultivation in low country dry zone, Sri Lanka

Proso millet (Panicum miliaceum L.) is a drought tolerant minor millet found in rainfed low input agricultural systems in Sri Lanka. This paper presents an analysis of characteristics of rainfall, of the onset, retreat and length of the ‘Yala’ growing season (March-September) and the relationship between rainfall and crop husbandry strat-egies in a Proso millet growing area. Daily rainfall data (1983-2015) obtained from Udawalawa, Sewanagala, Pelwatta, Thanamalwila and Kuda Oya meteorological stations were analysed along with information gathered from a survey of farmers. Among these 5 stations significant (p < 0.05) differences were found in retreat date, the length of the season and rainfall amount during the season. It was observed that onset date can be used to predict the season length with high accuracy (r = -0.7335, significant at p < 0.05). The selection of crops and the timing of crop management practices in the Proso millet growing area coincided with the distribution of rainfall. However, the yields reported by farmers (mean 1.18 t ha-1) are far below the expected potential (4 t ha-1). Soil moisture con-servation and water management strategies could be critical to reduce the risk of water-related damage in the susceptible flowering stage.

Assessing the importance of High Nature Value farmlands for the conservation of Lesser Kestrels Falco naumanni

AbstractAgricultural areas, such as cereal cultivations, that support species of European and/or national conservation concern are considered as ‘High Nature Value’ farmlands (HNVf) and are very important for the preservation of biodiversity in Europe. The lesser kestrel Falco naumanni is a migratory falcon breeding largely in the HNVf of the Mediterranean basin. The main cause of its decline in Europe has been habitat loss and degradation as a result of agricultural intensification driven largely by the EU Common Agricultural Policies (CAP). In Greece, its population dropped by about 50% since the 1970s and its preferred habitats have shrunk. The aim of this study was to assess habitat preferences of breeding Lesser Kestrels in agro-ecosystems of Greece and relate these habitats to HNVf for conservation purposes. The study area is located in the plain of Thessaly, Central Greece, holding the main lesser kestrel breeding populations in the country, where dry cereal crops have been significantly depleted over the past decades. Species distribution models were developed with generalised additive models for the analyses. Predicted probability of lesser kestrel occurrence was found to be positively associated with farmed landscapes of dry cereal cultivations. Other important predictors were cultivated irrigated farmland and landscape heterogeneity. Main results of the statistical models agree with the findings of other habitatbased studies that highlight the importance of low-input farming systems, that is, HNVf, for safeguarding vital Lesser Kestrels habitats in their breeding grounds in the Mediterranean. A key conservation priority for conserving species dependant on HNVf is the maintenance of those low-input farming systems and the implementation of a greener CAP that would promote environmental-friendly farming practices to preserve and enhance biodiversity in the agro-ecosystems of Europe.

Characterization of leaf cuticular wax classes and constituents in a spring Camelina sativa diversity panel

Among oilseed species, Camelina has received considerable attention as an oilseed crop that can be manipulated easily to meet important non-food bioenergy requirements, where it is relatively high in oil content and polyunsaturated fatty acids, and has a very short growing season with fairly good adaption to marginal lands and low input agricultural systems. To expand Camelina cultivation zones into more arid regions, it is important to develop new drought resistant cultivars that can grow under water-limited conditions. Increasing accumulated leaf cuticular wax in Camelina could be one of the strategies to reduce nonstomatal water loss and thus increase crop tolerance to drought. To extend the understanding of phenotypic variations in cuticular wax content and composition in Camelina sativa, leaf wax constituents from a spring Camelina diversity panel containing 163 accessions were extracted and analyzed. The diversity panel exhibited a wide range in total leaf wax contents, wax classes and constituents. Among primary alcohols, the dominant constituents were the C24, C26 and C28 homologues, while the C31 homologue was the most abundant alkane among all Camelina accessions. High heritability values of the primary alcohol class and its dominant constituent C24, C26 and C28 homologues, as well as the alkane class and abundant C29, C31, and C33 constituents, suggested the feasibility for selection of these traits during early generations of Camelina breeding programs. Positive correlations among leaf wax content, wax classes and their constituents suggest that modifying specific wax constituents could increase the wax loads, which in turn could enhance cuticle composition and properties. Quantification of leaf wax traits in the Camelina diversity panel will underpin future analysis of the Camelina wax biosynthetic pathways, help dissect its genetic regulatory elements, identify candidate genes controlling these traits, and enable the development of molecular markers for molecular breeding programs aimed at increasing drought tolerance of Camelina.

Chemical Composition of Seed Propagated Chestnut Genotypes from Northeastern Turkey

Turkey ranked third place in the world for chestnut production after China and Bolivia and the country has unique chestnut populations including valuable and diverse seed propagated chestnut genotypes. In this study, chestnuts (Castanea sativa) were collected during the 2016 harvest season from Northeastern part of Turkey from promising 12 different seedling origin genotypes. Tree growth habit, nut weight, kernel ratio, kernel color, moisture, crude protein, crude fat, dietary fiber, total polyphenols, antioxidant activity and fatty acid content of fruits belongs to 12 genotypes were determined. The results showed that, the majority of genotypes had semi upright tree growth habit. The nut weight and kernel ratio were between 5.05 g (K-10) and 10.10 g (K-5) and 71.10% (K-1) and 82.44% (K-3) among genotypes. The total crude fat content ranged from 0.87% (K-7) to 2.61% (K-1) while the crude protein ranged from 4.80% (K-7) to 7.65% (K-1). The dietary fiber content made up no more than 3.61% of the remaining portion of the kernel. It was found that total polyphenols was between 1.66 and 2.70 g GAE/kg and antioxidant activity was between 5.80 and 9.07 μmol Trolox equivalent/g dry weight basis. Oleic and linoleic acid were the major fatty acids in all chestnut fruits and followed by palmitic and linolenic acid. The results showed that there was enough variations among seed propagated chestnut genotypes for most of the searched parameters and this highlights the importance of conserving the genotypes, as their high levels of heterogeneity allow them to respond to abiotic and biotic stresses and adapt to low-input farming systems.

Mechanical weed control in organic winter wheat

Three field experiments were carried out in organic winter wheat in three consecutive years (exp. 1, 2005-06; exp. 2, 2006-07; exp. 3, 2007-08) in central Italy (42°57' N - 12°22' E, 165 m a.s.l.) in order to evaluate the efficacy against weeds and the effects on winter wheat of two main mechanical weed control strategies: 1) spring tine harrowing used at three different application times (1 passage at T1; 2 passages at the time T1; 1 passage at T1 followed by 1 passage at T1 + 14 days) in the crop sowed at narrow (traditional) row spacing (0.15 m) and 2) split-hoeing and finger-weeder, alone and combined at T1, in the crop sowed at wider row spacing (0.30 m). At the time T1 winter wheat was at tillering and weeds were at the cotyledons-2 true leaves growth stage. The experimental design was a split-plot with four replicates. Six weeks after mechanical treatments, weed ground cover (%) was rated visually using the Braun–Blanquet cover-abundance scale; weeds on three squares (0.6 x 0.5 m each one) per plot were collected, counted, weighed, dried in oven at 105 °C to determine weed density and weed above-ground dry biomass. At harvest, wheat ears density, grain yield, weight of 1000 seeds and hectolitre weight were recorded. Total weed flora was quite different in the three experiments. The main weed species were: &lt;em&gt;Polygonum aviculare&lt;/em&gt; L. (exp. 1 and 2), &lt;em&gt;Fallopia convolvulus&lt;/em&gt; (L.) Á. Löve (exp. 1 and 3), &lt;em&gt;Stachys annua&lt;/em&gt; (L.) L. (exp. 1), &lt;em&gt;Anagallis arvensis&lt;/em&gt; L. (exp. 2), &lt;em&gt;Papaver rhoeas&lt;/em&gt; L. (exp.3), &lt;em&gt;Veronica hederifolia&lt;/em&gt; L. (exp. 3). In the winter wheat sowed at narrow rows, 2 passages with spring-tine harrowing at the same time seems to be the best option in order to reconcile a good efficacy with the feasibility of treatment. In wider rows spacing the best weed control was obtained by splithoeing alone or combined with finger-weeder. The grain yield, on average 10% higher in narrow rows, the lower costs and the good selectivity of spring-tine harrowing treatments seems to suggest the adoption of narrow rows spacing in wheat in organic and low-input farming systems.

Lesser Kestrel Foraging Habitats in Special Protection Areas in Agro-ecosystems

The European Union (EU) Wild Birds Directive recognises that the most serious threats to wild birds’ conservation in Europe are habitat loss and degradation, and hence, habitats of threatened and migratory species must be protected with the establishment of the network of the special protection areas (SPAs) for migratory and endangered bird species in the EU member states. The major European population of the lesser kestrel Falco naumanni, a migratory falcon listed in Annex I of the Birds Directive, occurs in low-input farming systems in the Mediterranean basin, including Greece. The aim of this study was to identify foraging habitats of lesser kestrels and relate them to the delimited SPAs in the agro-ecosystems of Greece, where the stronghold of the species population for Greece occurs. Foraging habitat preferences were assessed using Poisson regression models (PRMs). SPAs were examined on whether they can effectively protect foraging habitats for breeding lesser kestrels in the study area. Foraging lesser kestrel abundance was positively associated with grasslands and non-irrigated land (dry cereals), and negatively associated with irrigated land (wet cotton), scrubland and woodland. Electricity facilities were used as foraging perches by lesser kestrels. The current SPAs cover a small percentage of the species’ foraging sites and cannot be considered coherent enough to support and protect the foraging habitats of lesser kestrels and other priority species in the agro-ecosystems of the study area. Proposals for effective conservation of low-input farming systems, supporting priority species, are also presented.

Probiotic Pseudomonas communities enhance plant growth and nutrient assimilation via diversity-mediated ecosystem functioning

Plant-associated microbes play an important role in plant growth and development. While the introduction of beneficial microbes into the soil could improve plant production in low-input agricultural systems, real-world applications are still held back by poor survival and activity of the probiotic microbes. In this study, we used a biodiversity-ecosystem functioning (BEF) framework to specifically test how Pseudomonas community richness shapes the bacterial inoculant survival and functioning in terms of plant growth. To this end, we manipulated the richness of a probiotic Pseudomonas spp. bacterial community inoculant (1, 2, 4 or 8 strains per community) and compared diversity and strain identity effects on plant biomass production and nutrient assimilation in vivo with tomato. We found that increasing the richness of the bacterial inoculant enhanced the survival and abundance of Pseudomonas communities leading to higher accumulation of plant biomass and more efficient assimilation of nutrients into the plant tissue. Diversity effects were clearly stronger than the Pseudomonas strain identity effects and diversity-mediated plant growth promotion could be linked with increased production of plant hormones, siderophores and solubilization of phosphorus in vitro. Together these results suggest that multi-strain microbial inoculants can promote plant growth more reliably and effectively compared to single-strain inoculants.

Barley undersown with red clover in organic and conventional systems: nitrogen aftereffect on legume growth

Nitrogen (N) deficiency is a major problem in organic and low-input farming systems. Growing spring cereals with undersown legumes has a positive effect on soil fertility, enriching it with nitrogen, through symbiosis of legumes with nodule bacteria. Two hypotheses were tested: 1) undersowing of red clover increases the protein content of barley grains and 2) mineral N has negative aftereffect on growth of legume plants. The aim of this study was to investigate the effect of organic (cattle manure, off-season cover crop) and mineral N in organic and conventional farming systems on (i) barley (Hordeum vulgare L.) grain yield and quality, (ii) biomass yield formation of undersown red clover (Trifolium pratense L.) and (iii) the aftereffect of mineral and organic N fertilisers on the red clover crop biomass yield in the following year. The experiment was established in 2008 at the Estonian University of Life Sciences (58°22ʹ N, 26°40ʹ E) on the soil described as Stagnic Albic Luvisol (LV ab-st) (WRB, 2014) with sandy loam surface texture, 1.38% C, 0.13% N, 133 mg kg-1 P, 210 mg kg-1 K and pHKCl 6.0. The crops were treated using different farming systems: three organic (Org0, OrgI and OrgII) and four conventional (N0, N40, N80 and N120); nitrogen sources during crop cycle period: N0 and Org0 = symbiotically fixed atmospheric N2, N40 = N2 + mineral N 40 kg ha-1 N, N80 = N2 + mineral N 80 kg ha-1 N, N120 = N2 + mineral N 120 kg ha-1 N, OrgI = N2 + N taken up by cover crops (NCC) and OrgII = N2 + NCC + N applied with manure (Nm). Our study revealed that grain yield of barley was strongly affected by undersown red clover; because of competition for nutrients in cereallegume mixture the grain yield of barley in organic system was 11‒61% lower than that in conventional system. The seed rate of undersown red clover (2.84 million viable seed per ha) was too high. The content of proteiin depended on the availability of mineralised nitrogen. The mean protein content of barley grains over the trial years and treatments was 99 ± 1.6 g kg-1 in the conventional system, which was 17% higher than that in the organic system. Undersowing of red clover had no significantly positive effect on the grain yield and protein content of barley. Mineral N fertiliser had no negative aftereffect on growth of the red clover crop the following year. Mean above ground biomass yield over the trial years for the red clover crop 2nd cut was 17% higher in the conventional system than in the organic system.

Effect of organic and conventional farming systems on nitrogen use efficiency of potato, maize and vegetables in the Central highlands of Kenya

Abstract Increased per capita food production in the tropics is closely tied to soil organic matter and water management, timely nitrogen (N) supply and crop N use efficiency (NUE) which are influenced by farming systems. However, there is lack of data on the effect of organic farming systems on NUE and how this compares to conventional farming systems under tropical conditions. Therefore, the objectives of this study were to determine the effect of conventional and organic farming systems at low and high management intensities on N uptake and N use efficiency of potato (Solanum tuberosum L.), maize (Zea mays L.), cabbage (Brassica oleracea var. Capitata), kale (Brassica oleracea var. Acephala) and Swiss chard (Beta vulgaris sub sp. Cicla). The organic high input (Org-High) and conventional high input (Conv-High) farming systems are managed as recommended by research institutions while organic low input (Org-Low) and conventional low input (Conv-Low) farming systems are managed as practiced by small scale farmers in the Central highlands of Kenya. The study was conducted during three cropping seasons between October 2012 and March 2014 in an ongoing long-term trial established since 2007 at Chuka and at Thika, Kenya. Synthetic N-based fertilizer and cattle manure were applied at ∼225 kg N ha−1 yr−1 for Conv-High and at ∼50 kg N ha−1 yr−1 for the Conv-Low. Composts and other organic inputs were applied at similar N rates for Org-High and Org-Low. Nitrogen uptake efficiency (NUpE) of potato was highest in Conv-Low and Org-Low at Thika and lowest in Org-High and Org-Low at Chuka site where late blight disease affected potato performance. In contrast, the NUpE of maize was similar in all systems at Chuka site, but was significantly higher in Conv-High and Org-High compared to the low input systems at Thika site. The NUpE of cabbage was similar in Conv-High and Org-High while the NUpE of kale and Swiss chard were similar in the low input systems. Potato N utilization efficiencies (NUtE) and agronomic efficiencies of N use (AEN) in Conv-Low and Conv-High were 11–21 % and 1.4–3.4 times higher than those from Org-Low and Org-High, respectively. The AEN of maize was similar in all the systems at Chuka but was 3.2 times higher in the high input systems compared to the low input systems at the Thika site. The AEN of vegetables under conventional systems were similar to those from organic systems. Nitrogen harvest index (NHI) of potato was similar between Conv-High and Org-High and between Conv-Low and Org-Low. N partitioned into maize grain was similar in all the system at Chuka, but significantly lower (P

Lectotypification of Stylosanthes hispida (Leguminosae)

Stylosanthes is a mainly New World genus comprising about 25 species but some of them are currently poorly defined. The genus is economically important, especially for low input agricultural production systems in the tropics and subtropics. During recent research on Stylosanthes taxonomy it became apparent that the species Stylosanthes hispida had never been formally typified. In order to foster taxonomic stability within the genus Stylosanthes, we here propose a lectotype for S. hispida. Additionally, some nomenclatural comments are provided.

Characterization of leaf cuticular waxes and cutin monomers of Camelina sativa and closely-related Camelina species

Camelina sativa is an old world crop newly introduced to the semi-arid regions of the Southwestern US. Recently, Camelina gained attention as a biofuel feedstock crop due to its relatively high oil content, polyunsaturated fatty acids, very short growing season with fairly good adaption to marginal lands, and low input agricultural systems. To expand Camelina growing zones into more arid regions, it is important to develop new drought resistant cultivars that can grow under water-limited conditions. Plants having cuticles with low permeability to water can possess elevated dehydration avoidance and improved drought tolerance. To extend our understating of cuticle chemical composition among Camelina species, leaf wax and cutin monomers in seventeen accessions representing four Camelina species were analyzed. Camelina exhibited a wide range of wax and cutin contents. The primary alcohols and alkanes were the predominant classes of leaf wax, followed in abundance by wax esters, fatty acids, aldehydes, alkylguaiacols, methylalkylresorcinols, α-amyrin and ß-sitosterol. Among primary alcohols, the dominant constituents were the C24, C26 and C28 homologues, while the C31 homologue was the most abundant alkane among all Camelina accessions. Cutin monomers included monohydroxy monobasic acids, phenolics, monobasic acids, monohydroxy epoxymonobasic acids, and dibasic acids. Among the cutin monomers examined, the C16:0 diOH acid showed extensive variation among Camelina species.