Genotypic variation of dormancy in wheat (Triticum aestivum L.) : a thesis presented in partial fulfilment of the requirements for the degree of Master of Agricultural Science, Department of Plant Science, Massey University, Palmerston North, New Zealand

Embryo dormancy and α - amylase dormancy are desirable in wheat to minimise pre-harvest sprouting damage. The current work focuses on the embryo and graincoat colour. A loose association between grain redness and dormancy in wheat is common knowledge. But the causal relationships between colour and dormancy are not clear and need to account for dormancy variability in the gene - pool. The study's working hypothesis was that colour formation triggers hypo - oxia synthesis of ABA (vs. gibberellins) which triggers dormancy if the timing with embryo development is optimal. Development profiles for eight attributes (including dormancy) of grain were investigated from five white and five red wheat cultivars representing a wide genetic base. Tagged ears were sampled from pollination to harvest ripeness (days after pollination to 12.5% moisture). All the white - grained cultivars did not have dormancy at harvest ripeness, and there was considerable variation of dormancy levels in the red - grained cultivars. The total-grain abscisic acid was not associated with redness nor dormancy, and no evidence of ABA sensitivity could be found in cv. Brevor. The failure to detect the putative dormancy of cvs. Brevor and Kenya 321 was probably due to fine detail employed in the present work, but may also have been due to the single ripening environment used. Base α amylase and flavanol levels did not contribute to the variation in embryo dormancy. Gibberellic acid insensitivity in the Rht/Gai genotypes was not expressed in terms of embryo dormancy. Examination of the profiles suggested that redness was necessary to permit dormancy, but that dormancy timing was independent of colour. This led to varying levels of dormancy at harvest ripeness. No association with ABA was evident, nor with colour precursor. However timing and duration of polymerisation (flavanol) development (hypo-oxia) did show a weak association with dormancy delay and level. The new hypothesis suggests that colour formation hypo-oxia permits dormancy, but that its timing is flexible with respect to harvest ripeness. Broader genetic control (other than the Redness gene) is indicated. Heritability estimates indicated that timings, rather than levels, are more useful selection criteria. This included embryo dormancy attributes, colour, and harvest ripeness. For plant breeders it suggested that grain sampled at harvest ripeness could be selected for dormancy as measured in this study

Assessing the agronomic value of hog manure-derived struvite as a phosphorus source for spring wheat

Non-Peer ReviewedRecovery of phosphorus (P) from liquid hog manure is one option for minimizing P loss from hog operations to surface water bodies, where it can cause eutrophication. The P, recovered as magnesium ammonium phosphate hexahydrate (MgNH4PO4∙6H2O), commonly known as struvite, has slow-release properties, which could improve P use efficiency in cropping systems. This greenhouse bioassay evaluated the effectiveness of struvite as a P source for spring wheat. Struvite, monoammonium phosphate (MAP), and polymer-coated monoammonium phosphate (CMAP) were applied at rates of 25 and 50 kg P2O5 ha-1 either in the seed-row or in a side-band in the first of three crop cycles. Results for Cycle 1 indicated no significant P source, rate, application method, and soil main effects on aboveground wheat dry matter yield (DMY). Phosphorus uptake (PU) in Cycle 1, averaged across soils, rates, and applications methods, was significantly greater with MAP (5.1 mg kg-1) and CMAP (4.9 mg kg-1) than with struvite (4.1 mg kg-1) application. Similarly, P uptake efficiency (PUE) was greater for MAP (21%) and CMAP (18%) than for struvite (12%). For the second and third crop cycles in which wheat followed canola, DMY, PU, and PUE were similar for the P sources, regardless of rate, placement, or soil. These results suggest that while struvite was as good as the commercial P fertilizers with respect to DMY and, in Cycles 2 and 3, PU and PUE, it did not exhibit the beneficial residual effects that typically characterize slow release fertilizers. Nonetheless, it is encouraging to note that the unrefined struvite, which is a by-product of manure management for environmental goals, can perform as well as commercial fertilizers that are optimized for agronomic performance

Degree of Phosphorus Saturation as a Predictor of Redox-Induced Phosphorus Release from Flooded Soils to Floodwater

Phosphorus (P) loss from soils is often enhanced under flooded, anaerobic conditions, increasing the risk of freshwater eutrophication. We aimed to develop a predictive tool to identify soils with greater P release potential under summer‐flooded conditions, which would help in developing strategies to mitigate P losses. One in situ mesocosm study was conducted in field plots with three treatments: cattle manure amended, monoammonium phosphate amended, and unamended. Two ex situ field mesocosm studies were conducted, each having 12 surface soils from agricultural fields. Prior to flooding, soils were analyzed for various soil test P (STP, intensity) and P sorption measures (capacity), and degree of P saturation (DPS) indices were calculated using different intensity and capacity combinations. Mesocosms were flooded and redox potential, pore water, and floodwater dissolved reactive P (DRP) concentrations were determined periodically up to 42 (in situ) and 56 d (ex situ) after the onset of flooding. Floodwater DRP increased significantly in most soils with flooding time, and the maximum DRP (DRPmax) was considered as the flooding‐induced P release risk. Relationships between floodwater DRPmax and STP or DPS indices were established separately for low‐P (Olsen P ≤ 30 mg kg−1) and high‐P (>30 mg kg−1) soils. Several STP indices effectively predicted the P release risk from high‐P soils, but not from low‐P soils. However, DPS calculated using Olsen P (intensity) and P sorption capacity or P saturation index (capacity) performed better in predicting summer flooding‐induced P release across all soil categories, with a higher predictive power."This work was supported by the Manitoba Conservation and Water Stewardship Fund, Environment Canada through the Lake Winnipeg Basin Stewardship Fund (EC no. 1300328), and a University of Winnipeg major grant. We also acknowledge the Manitoba Graduate Scholarship program and the University of Winnipeg Graduate Assistantship Program."https://acsess.onlinelibrary.wiley.com/doi/10.2134/jeq2019.04.015

The consequences of niche and physiological differentiation of archaeal and bacterial ammonia oxidisers for nitrous oxide emissions

The authors are members of the Nitrous Oxide Research Alliance (NORA), a Marie Skłodowska-Curie ITN and research project under the EU's seventh framework program (FP7). GN is funded by the AXA Research Fund and CGR by a Royal Society University Research Fellowship (UF150571) and a Natural Environment Research Council (NERC) Standard Grant (NE/K016342/1). The authors would like to thank Dr Robin Walker and the SRUC Craibstone Estate (Aberdeen) for access to the agricultural plots, Dr Alex Douglas for statistical advice and Philipp Schleusner for assisting microcosm construction and sampling.Peer reviewedPublisher PD

Climate-smart agriculture practices for mitigating greenhouse gas emissions

Agricultural lands make up approximately 37% of the global land surface, and agriculture is a significant source of greenhouse gas (GHG) emissions, including carbon dioxide (CO2), methane (CH4) and nitrous oxide (N2O). Those GHGs are responsible for the majority of the anthropogenic globalwarming effect.Agricultural GHG emissions are associated with agricultural soil management (e.g. tillage), use of both synthetic and organic fertilisers, livestock management, burning of fossil fuel for agricultural operations, and burning of agricultural residues and land use change. When natural ecosystems such as grasslands are converted to agricultural production, 20-40% of the soil organic carbon (SOC) is lost over time, following cultivation.We thus need to develop management practices that can maintain or even increase SOC storage in and reduce GHG emissions from agricultural ecosystems. We need to design systematic approaches and agricultural strategies that can ensure sustainable food production under predicted climate change scenarios, approaches that are being called climate-smart agriculture (CSA). Climate-smart agricultural management practices, including conservation tillage, use of cover crops and biochar application to agricultural fields, and strategic application of synthetic and organic fertilisers have been considered a way to reduce GHG emission from agriculture. Agricultural management practices can be improved to decreasing disturbance to the soil by decreasing the frequency and extent of cultivation as a way to minimise soil C loss and/or to increase soil C storage. Fertiliser nitrogen (N) use efficiency can be improved to reduce fertilizer N application and N loss. Management measures can also be taken to minimise agricultural biomass burning. This chapter reviews the current literature on CSA practices that are available to reduce GHG emissions and increase soil C sequestration and develops a guideline on best management practices to reduce GHG emissions, increase C sequestration, and enhance crop productivity in agricultural production systems

The impact of COVID-19 pandemic on social work education and practice

The essence of global trends in shaping the world education and related activities has not been clear-cut before the outbreak of coronavirus disease 2019 (COVID-19) pandemic. Disruptions in learning at tertiary institutions, failure of students to afford the online system of learning, lack of technological skills, disturbances in conducting internal assessments, fieldwork supervision and mentorship as well as lack of resources, to keep in pace with global developments, characterised the day in such developing countries as Zimbabwe. Social work education, research, fieldwork and practice was modified through the adoption of virtual platforms for learning, provision of counselling sessions, follow-ups and linkages. For continuity in the face of COVID-19, tertiary institutions are now using virtual platforms that include Zoom, Microsoft teams, Twitter, Facebook, Office 365, Skype for business, WhatsApp calls and group chats for educational purposes. Increased use of virtual platforms is evident among students on practicum and doing dissertations who are working from home. The author of this paper acknowledges that the COVID-19 pandemic is a turning point in social work education and practice which everyone has to adopt without compromising the Afrocentric values, principles and guidelines salient to addressing the needs of the local people. This paper entails the historical development of social work education in Zimbabwe, use of virtual platforms in tertiary learning, fieldwork practice, tele-working and policy implications to social work practice due to COVID-19 pandemic

Trends in Soil Science over the Past Three Decades (1992–2022) Based on the Scientometric Analysis of 39 Soil Science Journals

As one of the basic disciplines of agricultural, natural resource, and environmental science, soil science has played a critical role in global food security and socio-economic and ecological sustainability. The number of soil science journals and publications has increased remarkably with the development of soil science. However, there is a lack of systematic and comprehensive studies on the developmental trends of soil science based on journals and publications. In this study, 39 journals included under the soil science category in the 2022 Journal Citation Reports, and 112,911 publications in these journals from 1992 to 2022 were subjected to scientometric/bibliometric analysis to determine trends in publication, journal metrics, co-authorship, and research topics, in addition to general journal information. The results show that soil science ushered in a renaissance period with the number of publications, citations, impact factors, and CiteScore demonstrating an increasing trend. America and the Chinese Academy of Sciences had the most publications and citations. The most productive author published more than 400 articles. Soil science research focused mostly on its fundamental impact on the ecological environment based on the strongest citation bursts analysis of keywords. The analysis indicated that open access has increased in popularity. Current soil science journals still face a few common challenges, including an urgent need for a fairer evaluation mechanism on journal quality compared to the traditional use of single metrics as well as equity, diversity, and inclusion (EDI) in the whole editorial process. Artificial intelligence may bring new tools and more changes to the development of soil science. This study will help soil science researchers to better understand the development status and future trends of soil science. It will also guide authors in journal selection