Crop Rotation Research Articles

Determinants Of Adoption Of Soil Conservation Technologies Among Smallholder Farmers In Izzi Local Government Area Of Ebonyi State, Nigeria

The study examined the determinants of adoption of soil conservation technologies among smallholder farmers in Izzi Local Government Area, Ebonyi State, Nigeria. Multistage sampling technique was used to select 160 respondents for the study. Data collected with the aid of structured questionnaire were analyzed using descriptive and inferential statistics. Results showed that farmers in the area had average age of 47 years and operated on 1.5 hectares of land with an average farm income of ₦152,125. Further analysis revealed that the smallholder farmers had an adoption index of 2.21 which implied that they used at least two (2) soil conservation technologies with an average source of information of 2.72 showing that they got information on soil conservation technologies from at least three different sources. Furthermore, results revealed erosion, deforestation, reduced soil fertility and indiscriminate bush burning as the forms of soil degradation existing in the area while adopted coping strategies were crop rotation, use of organic manure, intercropping practices, appropriate use of fertilizer, use of mixed cropping system and planting of trees. The results of OLS multiple regression analysis showed that the coefficient of multiple determination (R2 ) of the regression model was 0.760. This implies that seventy-six percent (76%) of the variations in level of soil conservation technology adoption were accounted for by the independent variables socio-economic characteristics of the smallholder farmers included in the model. The result of factor analysis identified social, institutional and economic factors as constraints militating against adoption of soil conservation technologies among the smallholder farmers in the study area. The rejected hypothesis concluded that there is a significant relationship between the socioeconomic characteristics of smallholder farmers and their adoption of soil conservation technologies in the area. Based on the findings, the study recommends; that local government authorities and NGOs working in areas that are prone to soil fertility losses should introduce programmes that will train and promote soil conservation technologies to be adopted by farmers to improve productivity; provision of Infrastructural facilities such as good road network to ensure easy movement of agricultural inputs to the farmers field; and Agricultural extension services which are saddled with the responsibility of disseminating timely, complete actionable information should be re-positioned and strengthened to ensure smallholder farmers access to information, through appropriate channels.

Combining Masculinizing Resistance, Rotation, and Biocontrol to Achieve Durable Suppression of the Potato Pale Cyst Nematode: A Model.

The pale cyst nematode, Globodera pallida, is a pest that poses a significant threat to potato crops worldwide. The most effective chemical nematicides are toxic to nontarget organisms and are now banned. Alternative control methods are therefore required. Crop rotation and biological control methods have limitations for effectively managing nematodes. The use of genetically resistant cultivars is a promising alternative, but nematode populations evolve, and virulent mutants can break resistance after just a few years. Masculinizing resistances, preventing avirulent nematodes from producing females, might be more durable than blocking resistances, preventing infection. Our demo-genetic model, tracking both nematode population densities and virulence allele frequencies, shows that virulence against masculinizing resistance may not be fixed in the pest population under realistic agricultural conditions. Avirulence may persist despite the uniform use of resistance. This is because avirulent male nematodes may transmit avirulent alleles to their progeny by mating with virulent females. Additionally, because avirulent nematodes do not produce females themselves, they weaken the reproductive rate of the nematode population, leading to a reduction in its density by at least 20%. This avirulence load can even lead to the collapse of the nematode population in theory. Overall, our model showed that combining masculinizing resistance, rotation, and biocontrol may achieve durable suppression of G. pallida in a reasonable time frame. Our work is supported by an online interactive interface allowing users (i.e., growers, plant health authorities, researchers) to test their own control combinations.

Prospects and Issues in the Adoption of Conservation Agriculture in India

Conservation agriculture involves practices such as crop rotations, minimal soil disturbance, and maintaining permanent soil cover through crop residues or cover crops. Despite various challenges to its widespread adoption, India has made significant progress over the past two decades in developing, refining, and promoting conservation-based agricultural technologies. Notable advancements have been made in the Indo-Gangetic plains, especially in the adoption of no-till wheat within the rice-wheat cropping system. Advocates of conservation agriculture understand the trade-offs but recognize that the benefits outweigh the drawbacks. These methods offer potential advantages including reduced production costs, improved water and nutrient conservation, increased crop diversity and yields, and more efficient resource utilization.

Влияние стимуляторов роста на продуктивность зерновой кукурузы

One of the most effective ways to increase grain yield per hectare is the introduction of corn for grain into the grain crop rotation, since corn is a high-yielding crop and a good precursor for spring breads, as well as a soil fertility restorer and a drought-resistant plant. Therefore, the introduction of new cultivation technologies and modern hybrids of grain corn is of great relevance at the present time. The purpose of our research was to optimize the use of growth stimulants in the cultivation of various hybrids of grain corn in the northern zone of the Krasnodar Territory. Field experiments were conducted in the production conditions of Zarya LLC in the Krylovsky district of the Krasnodar Territory in 2023 and 2024. In field experiments, three corn hybrids were used as research objects: KSS 5291, P 8834 and GS 370. In the field experiment, the scheme included options for studying the effect of pre-sowing treatment of seeds and leafy top dressing with growth stimulants on the growth, development and yield of corn. The largest root mass of grain corn was formed in the GS-370 hybrid on plots with a growth stimulant Energy M and amounted to 3,874 t/ha, which turned out to be 692 kg/ha, or 22% more than the minimum value. The maximum dry biomass in the experiment was observed in the GS-370 hybrid on plots using the growth stimulator Energy M and was 10.948 t/ha, that is, by 2.291 t/ha or 26% more than the minimum value. The maximum net photosynthesis productivity (BPF) of corn was formed in hybrid P 8834 on plots without the use of growth stimulants and was equal to 4,616 g/m2 day, that is, by 413 g/m2 day or 9.8% more than the minimum value. The highest economic yield was formed in the GS-370 hybrid, ranging from 7.08 t/ha on plots without the use of growth stimulants to 7.84 t/ha on variants using pre-sowing seed treatment and two leaf fertilizing with the Energia M stimulant.

Oribatid Mites in a Humid Mediterranean Environment under Different Soil Uses and Fertilization Management

Measuring soil quality and the use of indicators for its evaluation is a worldwide challenge. In Garrotxa Volcanic Zone Natural Park (northeastern Spain), different parameters related to oribatid mites as indicators of soil quality were evaluated under different land uses: forest, pasture, and a biennial double-crop rotation of forage crops. In forage crops, previous fertilization management (one based on mineral fertilizers, three on cattle manure, and one using both types) was also evaluated. Three samplings (April, June, and September) were performed over one season. Fifty-four oribatid species belonging to 28 families were identified. Abundance was the lowest in June for all land uses (average of 1184 individuals m−2). In the study period, abundance, diversity (Shannon index, H’), and dominance (Berger–Parker index, d) varied with different land uses, with the highest values of abundance and H’ in forests (9287 individuals m−2 and 2.19, respectively) and the lowest dominance in forests (d = 0.29) without differences between the other uses. Additionally, in the studied parameters, no differences were associated with previous fertilization management in forage crops. Hypochthoniella minutissima, Xenillus (X.) tegeocranus characterized the forest system, Epilohmannia cylindrica minima the forage crops, and Tectocepheus sarekensis the pasture. In pasture, the dominance of the parthenogenetic species Tectocepheus sarekensis raises concerns about potential management constraints.

Trichoderma Isolates Against Abiotic Stresses and Management of Collar rot of Lentil (Lens culinaris L.) Caused by Sclerotium rolfsii.

A total of 30 native Trichoderma isolates were collected from the Agricultural Research Station, Ummedganj- Kota, Rajasthan, India. Out of which 9 native isolates were evaluated for bio-efficacy against Sclerotium rolfsii. Isolate ARS K-21 exhibited maximum inhibition (89.26%), followed by ARS K-11 (83.70%) in dual culture. Subsequent evaluations revealed the compatibility of efficient isolate ARS K-21 with various bio botanicals displaying minimum inhibition with Vermiwash (1.11-3.70%) followed by Beejamarat (0.38-15.92%) and Brahmastra (7.78-19.68%), while ARS K-11 displayed compatibility onlywith Dasparni ark with a minimum inhibition of 1.11-3.70%. Assessment of abiotic stress tolerance of the isolates revealed that most isolates thrived at 200 mM and 400 mM NaCl salt concentrations, with ARS K-21 and ARS K-24 demonstrating moderate growth levels across higher concentrations, except at 1200 mM. Optimal growth of the isolates occurred at 25and 30°C, with deviations leading to growth inhibition. Isolates ARS K-1, ARS K-11, ARS K-12 and ARS K-21 exhibited resilience to temperature extremes. ARS K-21 has shown exceptional growth proficiency across a wide pH spectrum (pH 5 to 8.5) followed by ARS K- 24, highlighting their versatility. Mass multiplication of efficient isolate ARS K-21 enriched with vermicompost led to the standardization of a dosage (30g/kg soil) for managing collar rot in lentil crops at 5g inoculum per kg soil of S. rolfsii.

Influence of the Weather Conditions on the Efficiency of Absorbents in the Vegetable Crop Rotation System and on the Stock of Productive Soil Moisture

Influence of the Weather Conditions on the Efficiency of Absorbents in the Vegetable Crop Rotation System and on the Stock of Productive Soil Moisture

Pepper root exudate alleviates cucumber root-knot nematode infection by recruiting a rhizobacterium

Root-knot nematodes (Meloidogyne spp.) have garnered significant attention from researchers owing to the substantial damage they cause to crops and their worldwide distribution. However, controlling these nematodes is challenging because a limited number of chemical pesticides and biocontrol agents are effective against them. Here, we demonstrate that pepper rotation markedly reduces Meloidogyne incognita infection in cucumber and diminishes the presence of p-hydroxybenzoic acid in the soil, a compound known to exacerbate M. incognita infection. Pepper rotation also restructures the rhizobacterial community, leading to the colonization of the cucumber rhizosphere by two Pseudarthrobacter oxydans strains (RH60 and RH97), facilitated by enrichment of palmitic acid in pepper root exudates. Both strains exhibit high nematocidal activity against M. incognita and have the ability to biosynthesize indoleacetic acid and biodegrade p-hydroxybenzoic acid. RH60 and RH97 also induce systemic resistance in cucumber plants and promote their growth. These data suggest that the pepper root exudate palmitic acid alleviates M. incognita infection by recruiting beneficial P. oxydans to the cucumber rhizosphere. Our analyses identify a novel chemical component in root exudates and reveal its pivotal role in crop rotation for disease control, providing intriguing insights into the keystone function of root exudates in plant protection against root-knot nematode infection.

Soil Mineral Nitrogen and Mobile Organic Carbon as Affected by Winter Wheat Strip Tillage and Forage Legume Intercropping

Diversifying crop rotations by incorporating legumes is recommended to enhance the resilience of agricultural systems against environmental stresses and optimize nitrogen utilization. Nonetheless, ploughing forage legumes or grass-legumes poses a significant risk of nitrate leaching. The study aimed to assess the impact of strip tillage intercropping management on soil mineral nitrogen, water-extractable organic carbon, mobile humic substances content, and winter wheat (Triticum aestivum L.) grain yield compared to forage legume and winter wheat monocropping with conventional tillage. In the intercropping systems, the following bicrops were used: black medick (Medicago lupulina L.) with winter wheat, white clover (Trifolium repens L.) with winter wheat, and Egyptian clover (Trifolium alexandrinum L.) with winter wheat. Research was conducted in two experiments. The results indicated that after implementing strip tillage and winter wheat intercropping, the soil mineral nitrogen content was similar to or lower than that observed in conventional tillage and winter wheat sowing after forage legumes. Winter wheat grain yield in intercrops decreased compared to the legumes monocultures that were ploughed before winter wheat sowing. The highest amount of water- extractable organic carbon was in intercropping growing white clover and winter wheat bicrops or in all fields (except Egyptian clover and winter wheat bicrops) after applying strip tillage. During the research period, the quantities of mobile humic substances and mobile humic acids exhibited similar changes. Their content increased substantially in fields with white clover and Egyptian clover, regardless of whether the legumes were ploughed or grown with winter wheat.

Evaluation of Alternative Break Crops in Rotation with Bread Wheat (triticum aestivum l.) in South-Eastern Ethiopia

Crop rotation could be a possible intervention to resolve multifaceted problems of monoculture. In recent years, there is a concern about soil depletion caused by intensive farming. In crop rotation legume crops, which capture atmospheric nitrogen and “fix” it into forms available to plants will increase soil fertility. Faba bean (Vicia faba L.), rapeseed (Brassica napus L.), oat (Avena sativum L.) and vicia (Vicia dasycarpa Ten.) forage mixture were considered as a break/precursor crops. The result showed that most profitable cropping sequence was faba bean grown in a 3 year cycle with 2 crops of wheat (Amanuel et al., 1994). Thus, searching for promising and alternative break crops for wheat based rotation could increase productivity and maximize profit. Adaptaion trial around Bekoji showed that sweet lupine seems an option in tolerating acidity where faba bean is found susceptible. Thus, the objectives of this study was to evaluate alternative break crops on yield and yield components of the succeeding wheat and soil fertility maintenance in the rotation scheme. Thus, this study was executed for three consecutive years from 2017- 2019 main cropping seasons at Kulumsa, Bekoji and Asasa Arsi zone, South-Eastern Ethiopia to evaluate advantage of alternative break crops on yield and yield components of the succeeding wheat and its effect on soil fertility maintenance in the rotation scheme. The experiment was laid out in randomized block design with five replications. The treatment include: wheat-sweet lupine-wheat-wheatwheat in year one (2017), sweet lupine-wheat-wheat faba bean-Ethiopian mustard in year two (2018) and wheat-wheat-wheat-wheat-wheat in the third year (2019). These leguminous crops have improved physico-chemical properties of soil. Plant nutrients of soil on which legumes were grown were increased. This improvement of soil properties by leguminous crops has resulted in higher yield of wheat than plots on which wheat was grown after wheat. Although non-significant, the third year Bekoji and Asasa combined analysis of variance revealed that the highest wheat grain yield (4197kg/ha) was obtained at sweet lupine-wheat-wheat followed by wheat-faba bean-wheat (4003kg/ha). However, plant height was significantly (P<0.05) affected by rotational crops effect. The tallest plant height of wheat (105.0cm) was recoded from wheat-Ethioian mustard-wheat treatment. From this study, sweet lupine-wheat-wheat followed by wheat-faba bean-wheat with proper agronomic packages could be forwarded as a temporary recommendation in Asasa, Bokoji and Kulumsa areas and in areas with similar agro ecologies.

Diversification of crops and intensification of canola impact the diversity, community structure, and productivity in successive crop systems: A study on arbuscular mycorrhizal fungal communities in roots and rhizosphere

The widespread cultivation of canola, conventionally still considered a non-host plant for AM fungi, coupled with its increasing frequency in crop rotations, raises concerns about its impacts on soil microbial diversity and overall crop productivity. The main objective of this study is to assess the influence of different crop succession systems, incorporating canola, on AM fungal diversity and community structure in both the roots and in the rhizosphere, as well as on productivity of each crop present within the succession. Doubling the frequency of canola occurrence in a 4-year crop succession did not reduce the productivity of the other crops in the succession, nor did it result in a decrease in AM fungal biodiversity in the roots or rhizosphere of these crops. Interestingly, the diversity of AM fungi was higher in canola roots compared to wheat roots, indicating that canola might serve as a rudimentary host of AM fungi. The succession systems did, however, alter the AM fungal community structure in both roots and rhizosphere environments, exhibiting positive or negative correlations with crop productivity. This suggests that a simple modification of the cropping system could potentially be employed to manipulate root or rhizosphere microbiomes. Results of this study add to the growing body of evidences that plants that were thought to be non-AM fungi host, such as plants from the Brassicaceae family, could in fact interact with AM fungi.

Tillage influence on agrophysical soil properties and crop productivity in the irrigated conditions of the steppe zone of Ukraine

The main goal of the study was to establish the influence of various tillage systems on the agrophysical properties of dark-chestnut soil under short-grain crop rotation in the irrigated conditions of southern Ukraine. The research was carried out during 2021-2022 in a stationary experiment on a four-field crop rotation: grain maize – winter rapeseed – winter wheat – soybeans. The experimental field was in the semi-arid steppe climate zone at the Institute of Climate-Smart Agriculture of the National Academy of Agrarian Sciences of Ukraine. Three tillage systems were studied for their influence on soil bulk density, porosity, and water permeability, namely: mouldboard-differentiated ploughing tillage; differentiated chisel tillage; and differentiated ploughless tillage with soil slitting. Soil bulk density was determined using the core method. Soil porosity was calculated as the ratio of total bulk density to solid fraction bulk density. Water infiltration rates, established through the water absorption test method, were used to measure soil water permeability. The results of the study were statistically analysed using the common ANOVA procedure with Fisher’s least significant difference test at P<0.05. In addition to the agrophysical parameters of the soil, the energy output of the crop rotation was assessed. It was established that mouldboard tillage did not provide significant benefits in terms of bulk density and soil porosity. However, ploughing showed the best results for soil water permeability across all crops in the rotation. The highest energy output of crop rotation (119.1 GJ/ha) was recorded for the ploughless-differentiated tillage system with soil slitting, whereas the mouldboard ploughing and chisel tillage systems produced somewhat lower energy yields of 112.0 and 108.6 GJ/ha, respectively. Therefore, ploughless-differentiated tillage with soil slitting is the most effective option for short-grain crop rotations in irrigated conditions of southern Ukraine, in terms of creating optimal soil agrophysical properties and achieving the highest crop productivity

Effect of Tillage, Crops Residues and Crops Management Practices on Runoff Erosion, Soil Loss and Soil Properties in Ethiopa: Review

The conducted investigations showed that tillage practices with crop residue and proper cropping systems protect loss of soil from runoff erosion which depletes soil nutrients and affects soil physical and chemical properties. The review was conducted with aim of reviewing the effect of tillage, crops residues and crops management practices on runoff, soil loss and soil properties in Ethiopia. The three years study conducted in the Upper Blue Nile basin of Northwestern Ethiopia showed that reduced tillage reduced soil loss over conventional tillage, row planting reduced soil loss over broadcast planting, without trampling reduced soil loss over with trampling planting, and the sediment concentration was ranged from 0.01 to 5.37g/L and total soil loss was 0.20 to 0.50t/ha. The study conducted in the humid highlands of Ethiopia showed that the lower average soil loss was 16 t/ha.yr under zero tillage with crop residue and maximum was 30 t/ha.yr in conventional tillage without crop residue. The investigation indicated that zero tillage with maize soya bean intercrop, maize rotation, continuous maize and continuous soya bean improved soil properties than conventional tillage system. The investigation which was carried out to evaluate the effects of tillage and cropping system on soil properties showed that enrichment ratio ≤1 under no tillage with intercropping and no tillage with mulch reduce nutrient losses and enrichment ratio. The study conducted at Derashe and Arba Minch Zuriya in Ethiopia showed that some selected properties were statistically significant (P<0.05) and conservation tillage is favored for soil management relative to conventional tillage. Therefore, tillage practices like zero tillage and minimum tillage with crop residue management like mulching and crop management such as intercropping and crop rotation reduce surface runoff erosion, soil loss and soil fertility depletion, but additional continual research is needed to reveal trends in tillage, crops residues and crops management.

Effect of long-term liquid dairy manure application on activity and structure of bacteria and archaea in no-till soils depends on plant in development.

This study aimed to evaluate the impact of long-term liquid dairy manure (LDM) application on the activity and structure of soil bacterial and archaea communities in two cropping seasons over 1year of a no-till crop rotation system. The experiment was run in a sandy clay loam texture Oxisol, in Brazil, including LDM doses of 60, 120, and 180 m3ha-1year-1, installed in 2005. Soil sampling was conducted during spring 2018 and autumn 2019 at 0-10-cm depth. Microbial biomass carbon and nitrogen, 16S rRNA gene sequencing, microbial respiration and quotient were performed. Over the 14-year period, LDM application increased soil microbial community activity. Analysis of 16S rRNA gene sequencing revealed dominance by Proteobacteria, Acidobacteria, and Actinobacteria phyla (67% in spring and 70% in autumn). Genera Pirulla and Nitrososphaera showed enrichment at LDM doses of 120 and 180 m3ha-1year-1 doses, respectively. During spring, following black oat cropping, shifts in the relative abundance of Bacteroidetes, Proteobacteria, Firmicutes, Gemmatimonadetes, Verrucomicrobia, Chloroflexi, Actinobacteria, and AD3 phyla were observed due to LDM application, correlating with soil chemical indicators such as pH, K, Ca, Mn, and Zn. Our findings indicate that plant development strongly influences microbial community composition, potentially outweighing the impact of LDM. Our findings indicate that the application of liquid dairy manure alters the soil bacterial activity and community; however, this effect depends on the developing plant.

Susceptibility of Oilseed Radish (Raphanus sativus subsp. oleiferus) Cultivars and Various Brassica Crops to Plasmodiophora brassicae.

Oilseed radish (OR; Raphanus sativus var. oleiferus) is grown as a cover crop and develops a unique taproot, absorbing nitrogen left by the previous crop. The aim of this project was to investigate the resistance of OR cultivars (cvs.) to Plasmodiophora brassicae, the causal agent of clubroot disease. Twelve market cvs. were compared with cvs. of clubroot-resistant (CR) winter oilseed rape (OSR; Brassica napus) and other selected species of the Brassicaceae family. The study was performed as a replicated bioassay in a growth chamber using a specially composed mixture of field soils holding the natural inoculum of P. brassicae. The results show that the OR cultivars were infected, which implies that OR multiplies the pathogen. The susceptibility of the OR cultivars was not significantly different from that of the CR OSR cultivars Alister and Archimedes, but it was significantly different from that of the OSR cv. Mendel. The disease severity index (DSI) for OR cultivars ranged from 2.3 to 9.3, and disease incidence was 3-17%. The best performance was shown by black radish (Raphanus sativus var. niger) with a DSI of 0.3. For sustainable brassica crop production, we suggest avoiding OR as a cover crop in crop rotations, including OSR or other brassica crops, since there is a risk of increasing inoculum in the soil.

Crop Rotation and Diversification in China: Enhancing Sustainable Agriculture and Resilience

Crop rotation and diversification (CRD) are crucial strategies in sustainable agriculture, offering multiple benefits to both farmers and the environment. By alternating crops or introducing diverse plant species, CRD practices improve soil fertility, reduce pest populations, and enhance nutrient availability. For example, legume-based rotations increase soil nitrogen levels through biological nitrogen fixation, reducing the need for synthetic fertilizers. Moreover, these practices promote more efficient water and nutrient use, reducing the reliance on synthetic fertilizers and minimizing the risk of pests and diseases. This review synthesizes findings from recent research on the role of CRD in enhancing sustainable agriculture and resilience, highlighting the potential contributions of these practices towards climate change mitigation and adaptation. Specific crop rotation systems, such as the cereal–legume rotation in temperate regions and the intercropping of maize with beans in tropical environments, are reviewed to provide a comprehensive understanding of their applicability in different agroecological contexts. The review also addresses the challenges related to implementing CRD practices, such as market demand and knowledge transfer, and suggests potential solutions to encourage broader adoption. Lastly, the potential environmental benefits, including carbon sequestration and reduced greenhouse gas emissions, are discussed, highlighting the role of CRD in building resilient agricultural systems. Collectively, this review paper emphasizes the importance of CRD methods as sustainable agricultural practices and provides key insights for researchers and farmers to effectively integrate these practices into farming systems.

Extent of Adoption of Selected Climate-smart Agricultural Practices among Smallholder Farmers in Laikipia County, Kenya

Aim: Climate Smart Agriculture (CSA) is an integrative approach to address the challenges of food security and climate change. This study sought to assess the extent of adoption of climate smart agricultural practices in Laikipia County, Kenya. Study Design: This study used correlation research design. Place and Duration of Study: The study was carried out in Laikipia county. Specifically in the sub-counties Laikipia West, Laikipia East and Laikipia North. The study was carried out in July – August 2022. Methodology: A multi-stage sampling technique was used to obtain a representative sample of 384 smallholder farmers households across the three sub-counties. Systematic random sampling was used to select every tenth household from the sample size. A questionnaire was used to collect data from the sampled households (all of whom were smallholder farmers). Descriptive statistical analysis was used to determine the extent of adoption of selected Climate Smart Agricultural Practices among smallholder farmers in Laikipia County, Kenya. The study used a chi-square (X²) test of independence to establish a relationship in the adoption of CSA practices across the three study sites Results: This study found that crop diversification (87%), mixed farming (crop farming and livestock keeping) (83%), use of pesticides and fungicides (80%) and crop rotation (74%) were the most adopted climate smart agricultural practices (CSAPs). On extent of adoption, full adoption was highest on pest and disease control (54%) and diversification of farming practices (52%); partial adoption was highest in conservation agriculture (54%); and non-adoption was highest on agroforestry (42%). Conclusion: It is recommended that stakeholders should improve the adoption of water harvesting/use, conservation agriculture and agroforestry – critical climate smart agricultural practices in semi-arid environments.

Developing genomic tools to assist turnip rape [Brassica rapa (L.) subsp.oleifera (DC.) Metzg.] breeding

IntroductionTurnip rape is recognized as an oilseed crop contributing to environmentally sustainable agriculture via integration into crop rotation systems. Despite its various advantages, the crop’s cultivation has declined globally due to a relatively low productivity, giving way to other crops. The use of genomic tools could enhance the breeding process and accelerate genetic gains. Therefore, the present research investigated 170 turnip rape accessions representing its global gene pool to identify SNP markers associated nine phenological and agro-morphological traits and estimate the genomic breeding values (GEBVs) of the germplasm through GWAS and genomic prediction analyses, respectively.MethodsField trials were conducted at two sites in northern and southern Sweden to obtain the phenotypic data while genotyping was conducted via the genotyping-by-sequencing (GBS) method. The traits studied include days to flowering (DTF) and maturity (DTM), plant height (PH), seed yield (YLD), thousand seed weight (TSW), silique length (SL), number of siliques (NS), number of seeds per silique (SS), and pod shattering resistance (PSHR).Results and conclusionAnalysis of variance revealed substantial variation among accessions, with significant genotype-by-environment interaction for most traits. A total of 25, 17, 16, 14, 7, 5, 3, and 3 MTAs were identified for TSW, DTF, PH, PSHR, SL, YLD, SS and DTM, respectively. An 80%–20% training-test set genomic prediction analysis was conducted using the ridge regression – BLUP (RR-BLUP) model. The accuracy of genomic prediction for most traits was high, indicating that these tools may assist turnip rape breeders in accelerating genetic gains. The study highlights the potential of genomic tools to significantly advance breeding programs for turnip rape by identifying pivotal SNP markers and effectively estimating genomic breeding values. Future breeding perspectives should focus on leveraging these genomic insights to enhance agronomic traits and productivity, thereby reinstating turnip rape as a competitive and sustainable crop in Sweden and broader global agriculture.

Grasslands support more diverse and resilient earthworm communities to climate change than croplands in Central Europe

Diversity and community composition of earthworms, key drivers of ecosystem functions, are increasingly threatened by global change, including climate and land-use change. However, empirical evidence for interactions of these concurrent drivers in affecting earthworm communities is scarce. Here, we investigated the effects of an experimentally imposed climate change scenario, including warming and altered precipitation patterns, and land use with two croplands (both conventional farming and organic farming characterize a three-year crop rotation) and two grasslands (intensively-used meadow and extensively-used meadow) on earthworm communities across different seasons and years in a field experiment. Compared with grasslands, earthworms in croplands have lower species richness (-26 %), abundance (-80 %), and biomass (-73 %), particularly the abundance of juveniles (-83 %) and Aporrectodea rosea (-76 %) as well as the biomass of juveniles (-84 %), A. rosea (-72 %), Octolasion cyaneum (-47 %), and Lumbricus terrestris (-83 %). Due to extreme droughts in Central Europe from 2018 to 2020, earthworm abundance and biomass were low across land-use types, but in grassland they increased (abundance: +80 %; biomass: +85 %) in 2021 presumably due to increased moisture conditions. Main effects of experimental climate change and intensified management practices as well as interaction of experimental climate change and land use on abundance and biomass of earthworms were non-significant. Notably, experimental climate change and land use interactively altered earthworm community composition, with the most pronounced difference between ambient and future climate in croplands than in grasslands. This indicates that earthworm community composition more sensitively reflects changes in environmental conditions than earthworm abundance and biomass, but the latter two negatively responded to prolonged drought conditions. Our results indicate that grasslands have a higher resilience of earthworm populations to buffer adverse environmental conditions than croplands. Overall, this study provides a comprehensive overview of the response of earthworms to inter-annual climatic variability and experimental climate change under different land-use types.

First Report of Rhizoctonia solani AG1-IB Causing Tobacco Target Spot in China.

Tobacco target spot, caused by Rhizoctonia solani Kühn, induces shot-hole lesions on leaves that that significantly reduce yield and quality of tobacco. In July 2022, samples (n=5) with target spot were collected from three tobacco fields, one each in Puer (22.63°N, 100.72°E, cv. Yunyan87) and Mengzi (23.26°N, 103.36°E, cv. Yunyan87) of Yunnan province and one in Dandong (40.63°N, 124.18°E, cv. Liaoyan17) of Liaoning province, China; disease incidence in these fields was approximately 30%~40%. Initial symptoms (2- to 3-mm-diameter lesions) appeared on the middle to lower leaves, then expanded to 2 to 3 cm in diameter and developed the shot-hole appearance. Pieces of tissue (5×5 mm) were cut from the edge of lesions, surface sterilized, rinsed in sterile water, then placed on the surface of water agar (WA) and incubated at 25℃ for 2 days in the dark. Single hyphal tips were taken from fungal isolates identified as R. solani based on the morphological traits (Tsror 2010), then transferred onto potato dextrose agar (PDA) and cultured for 3 d as described above. A total of 15 pure cultures were obtained. With the exception of YN-3 (isolated from Puer), YN-62 (isolated from Mengzi) and LN-95(isolated from Dandong) strains, which exhibited hyphal fusion reaction with AG1-IB standard strain, all the other strains demonstrated hyphal fusion with AG-3 standard strain (Ogoshi 1987). Genomic DNA of these three strains were extracted by the CTAB method and ITS regions of rDNA were sequenced (White et al. 1990). The sequences were deposited in GenBank with accession No. OR770079, OR770080 and OR770082. All the three rDNA-ITS sequences exhibited 99.85% similar to AG1-IB found in GenBank, and a phylogenetic tree using a neighbor-joining method grouped the three strains within the R. solani AG-1 IB clade. Therefore, based on the hyphal fusion reaction and molecular methods, these isolates were identified as R. solani AG1-IB. To determine pathogenicity of the isolates, the healthy leaves of tobacco plants (cv. Yunyan 87) were used. Five-mm-diameter mycelial plugs of the strain on PDA were inoculated on leaves that had been previously wounded with a sterile needle, and cotton balls moistened with sterile water were used for moisturizing the inoculation sites. Ten leaves were inoculated for each strain and leaves inoculated with PDA plugs were as control. The experiment was conducted twice. All plants were incubated for 2 d at 15℃ to 25℃ and 90% relative humidity with a 12 h photoperiod/day. Irregularly shaped lesions appeared on the leaves around each of the inoculated sites, but not on control leaves. The pathogens were reisolated and confirmed be R. solani AG1-IB by hyphal fusion and molecular identification tests as previously described, thereby fulfilling Koch's postulates. It has been reported that AG-3, AG-2 (Mercado Cardenas et al. 2012), AG-5 (Wang et al. 2023) and AG-6 (Sun et al. 2022) of R. solani could cause tobacco target spot, but AG-3 is considered the main causal agent (Marleny Gonzalez et al. 2011). To our knowledge, this is the first report of AG1-IB causing tobacco target spot in China and worldwide. The AG1-IB strain has a wide host range including cabbage, mint, lettuce, beans, and rice (Gonzalez et al. 2006). The discovery poses a new challenge for the prevention and control of tobacco target spot, especially when contemplating disease management strategies such as crop rotation and fungicide treatments.