Australian Centre for International Agricultural Research

Grain yields of eight representative semidwarf spring wheat ( Triticum aestivum L.) cultivars released in northwest Mexico between 1962 and 1988 have increased linearly across years as measured in this region during 6 yr under favorable management and irrigation. To understand the physiological basis of this progress and possibly assist future selection for grain yield, leaf traits were determined during 3 yr in the same study. Stomatal conductance ( g s ), maximum photosynthetic rate (A max , and canopy temperature depression (CTD), averaged over the 3 yr, were closely and positively correlated with progress in the 6‐yr mean yield. The correlation was greatest with g s ( r = 0.94, P < 0.01). Compared with the overall yield increase of 27%, g s increased 63%, A max increased 23%, and canopies were 0.6°C cooler. Carbon‐13 isotope discrimination was also positively associated with yield progress ( r = 0.71, P < 0.05), but other leaf traits such as flag leaf area, specific leaf weight, percentage N and greeness were not, nor was crop growth rate around anthesis. The causal basis of the leaf activity interrelationships is reasonably clear, with both increased intercellular CO 2 concentration and increased mesophyll activity contributing to the increase in A max . However, causal links to the yield progress, and the accompanying increase in kernels per square meter, are not clear. It is concluded that g s and CTD should be further investigated as potential indirect selection criteria for yield.

Farmers in mixed crop-livestock systems produce about half of the world's food. In small holdings around the world, livestock are reared mostly on grass, browse, and nonfood biomass from maize, millet, rice, and sorghum crops and in their turn supply manure and traction for future crops. Animals act as insurance against hard times and supply farmers with a source of regular income from sales of milk, eggs, and other products. Thus, faced with population growth and climate change, small-holder farmers should be the first target for policies to intensify production by carefully managed inputs of fertilizer, water, and feed to minimize waste and environmental impact, supported by improved access to markets, new varieties, and technologies.

ABSTRACT Yield potential is defined as the yield of a cultivar when grown in environments to which it is adapted, with nutrients and water non‐limiting and with pests, diseases, weeds, lodging, and other stresses effectively controlled. As such, it is distinguished from potential yield, which we define here as the maximum yield which could be reached by a crop in given environments, as determined, for example, by simulation models with plausible physiological and agronomic assumptions. Several implications of the definitions given above are considered, particularly those arising from cultivar interactions with agronomic practices and with the biotic and abiotic environments. We then discuss both direct and indirect methods of measuring progress in yield potential. Continuing progress in yield potential through conventional breeding is apparent in many crops, and is significant for yield progress at the farm level under a wide range of conditions. Among the small grain cereals, greater yield potential has derived mainly from the rise in harvest index associated with dwarfing, whereas in maize ( Zea mays L.), it has come from increased tolerance to closer planting. The duration of photosynthetic activity has been extended in several crops but there is little evidence of increases in photosynthetic capacity or maximum crop growth rate. The rise in genetic yield potential in wheat and maize cultivars has been associated with progressive widening of their genetic background, and there is little sign of this slowing down.

Abstract Accurate prediction of an individual’s phenotype from their DNA sequence is one of the great promises of genomics and precision medicine. We extend a powerful individual-level data Bayesian multiple regression model (BayesR) to one that utilises summary statistics from genome-wide association studies (GWAS), SBayesR. In simulation and cross-validation using 12 real traits and 1.1 million variants on 350,000 individuals from the UK Biobank, SBayesR improves prediction accuracy relative to commonly used state-of-the-art summary statistics methods at a fraction of the computational resources. Furthermore, using summary statistics for variants from the largest GWAS meta-analysis ( n ≈ 700, 000) on height and BMI, we show that on average across traits and two independent data sets that SBayesR improves prediction R 2 by 5.2% relative to LDpred and by 26.5% relative to clumping and p value thresholding.

Functional analysis of a barley high-pI alpha-amylase gene promoter has identified a gibberellin (GA) response complex in the region between -174 and -108. The sequence of the central element, TAACAAA, is very similar to the c-Myb and v-Myb consensus binding site. We investigated the possibility that a GA-regulated Myb transactivates alpha-amylase gene expression in barley aleurone cells. A cDNA clone, GAmyb, which encodes a novel Myb, was isolated from a barley aleurone cDNA library. RNA blot analysis revealed that GAmyb expression in isolated barley aleurone layers is up-regulated by GA. The kinetics of GAmyb expression indicates that it is an early event in GA-regulated gene expression and precedes alpha-amylase gene expression. Cycloheximide blocked alpha-amylase gene expression but failed to block GAmyb gene expression, indicating that protein synthesis is not required for GAmyb gene expression. Gel mobility shift experiments with recombinant GAMyb showed that GAMyb binds specifically to the TAACAAA box in vitro. We demonstrated in transient expression experiments that GAMyb activates transcription of a high-pI alpha-amylase promoter fused to a beta-glucuronidase reporter gene in the absence of GA. Our results indicate that the GAMyb is the sole GA-regulated transcription factor required for transcriptional activation of the high-pI alpha-amylase promoter. We therefore postulate that GAMyb is a part of the GA-response pathway leading to alpha-amylase gene expression in aleurone cells.

Germplasm from the spring wheat ( Triticum aestivum L.) breeding program at the International Center for Improvement of Maize and Wheat (CIMMYT) has had a major impact on the yield of irrigated spring wheats in most developing countries in the past 30 yr. The rate and nature of yield potential progress in this germplasm was measured comparing eight outstanding short cultivars released in northwest Mexico between 1962 and 1988. They were grown under irrigation and optimal management, including disease and lodging protection, in each of six winter growing seasons (1989–1990 to 1994–1995) at the CIANO (Centro de Investigaciones Agricolas del Noroeste) experiment station in Sonora, Mexico. There were highly significant effects of cultivar on grain yield, and, although cultivar × year interaction was significant, there were few significant crossover interactions between pairs of genotypes and years in the grain yield data set. Yield averaged across the 6 yr increased linearly from 6680 kg ha −1 for the earliest cultivar, Pitic 62, to 8475 kg ha −1 for Bacanora 88, the latest. The rate of progress against year of release was 67 kg ha −1 yr −1 ( r = 0.99, P < 0.001), or 0.88% per year. Grain yield progress was correlated with kernel number per square meter ( r = 0.84, P < 0.01) and harvest index ( r = 0.81, P < 0.02), but not with total biomass production, kernel weight, days to anthesis, spikes per square meter, or kernels per spike. Thus linear progress in yield within short germplasm has continued at least until the late 1980s, and the yield components studied did not indicate any clear direction for future progress, apart from that suggested by the strong relationships between grain yield and harvest index and grain yield and kernels per square meter, as has been seen in most studies of yield progress in cereals.

Wheat crops usually yield more when grown after another species than when grown after wheat. Quantifying the yield increase and explaining the factors that affect the increase will assist farmers to decide on crop sequences. This review quantifies the yield increase, based on >900 comparisons of wheat growing after a break crop with wheat after wheat. The mean increase in wheat yield varied with species of break crop, ranging from 0.5 t ha–1 after oats to 1.2 t ha–1 after grain legumes. Based on overlapping experiments, the observed ranking of break-crop species in terms of mean yield response of the following wheat crop was: oats < canola ≈ mustard ≈ flax < field peas ≈ faba beans ≈ chickpeas ≈ lentils ≈ lupins. The mean additional wheat yield after oats or oilseed break crops was independent of the yield level of the following wheat crop. The wheat yield response to legume break crops was not clearly independent of yield level and was relatively greater at high yields. The yield of wheat after two successive break crops was 0.1–0.3 t ha–1 greater than after a single break crop. The additional yield of a second wheat crop after a single break crop ranged from 20% of the effect on a first wheat crop after canola, to 60% after legumes. The mean yield effect on a third wheat crop was negligible, except in persistently dry conditions. The variability of the break-crop effect on the yield of a second wheat crop was larger than of a first wheat crop, particularly following canola. We discuss the responses in relation to mechanisms by which break crops affect soil and following crops. By quantifying the magnitude and persistence of break-crop effects, we aim to provide a basis for the decision to grow continuous cereal crops, strategic rotations or tactically selected break crops. In many wheat-growing areas, the large potential yield increases due to break crops are not fully exploited. Research into quantifying the net benefits of break crops, determining the situations where the benefits are greatest, and improving the benefits of break crops promises to improve the efficiency of wheat-based cropping systems.

ABSTRACT Eco‐efficiency in the simplest of terms is about achieving more with less—more agricultural outputs, in terms of quantity and quality, for less input of land, water, nutrients, energy, labor, or capital. The concept of eco‐efficiency encompasses both the ecological and economic dimensions of sustainable agriculture. Social and institutional dimensions of sustainability, while not explicitly captured in eco‐efficiency measures, remain critical barriers and opportunities on the pathway toward more eco‐efficient agriculture. This paper explores the multidimensionality of the eco‐efficiency concept as it applies to agriculture across diverse spatial and temporal scales, from cellular metabolisms through to crops, farms, regions, and ecosystems. These dimensions of eco‐efficiency are integrated through the presentation and exploration of a framework that explores an efficiency frontier between agricultural outputs and inputs, investment, or risk. The challenge for agriculture in the coming decades will be to increase productivity of agricultural lands in line with the increasing demands for food and fiber. Achieving such eco‐efficiency, while addressing risk and variability, will be a major challenge for future agriculture. Often, risk will be a critical issue influencing adoption; it needs explicit attention in the diagnosis and intervention steps toward enhancing eco‐efficiency. To ensure food security, systems analysis and modeling approaches, combined with farmer‐focused experimentation and resource assessment, will provide the necessary robust approaches to raise the eco‐efficiency of agricultural systems.

Abstract Many different techniques have been used to estimate biomass for ecological, agricultural and forestry research. The most suitable technique depends on available budget, accuracy required, structure and composition of the vegetation, and whether species and component biomass are required. A survey of the methods that have been used to estimate biomass is given, and the advantages and disadvantages of direct sampling, calibrated visual estimation and double sampling techniques are discussed. The relative cost and accuracy of each technique are summarized and recommendations are made for the use of the techniques in different vegetation complexes, such as discrete shrubs or trees, patchy vegetation, homogeneous vegetation, and species‐rich inhomogeneous heathland.

Worldwide, one in three cancers is skin-related, with increasing incidence in many populations. Here, we demonstrate the capacity of a DNAzyme-targeting c-jun mRNA, Dz13, to inhibit growth of two common skin cancer types-basal cell and squamous cell carcinomas-in a therapeutic setting with established tumors. Dz13 inhibited tumor growth in both immunodeficient and immunocompetent syngeneic mice and reduced lung nodule formation in a model of metastasis. In addition, Dz13 suppressed neovascularization in tumor-bearing mice and zebrafish and increased apoptosis of tumor cells. Dz13 inhibition of tumor growth, which required an intact catalytic domain, was due in part to the induction of tumor immunity. In a series of good laboratory practice-compliant toxicology studies in cynomolgus monkeys, minipigs, and rodents, the DNAzyme was found to be safe and well tolerated. It also did not interfere in more than 70 physiologically relevant in vitro bioassays, suggesting a reduced propensity for off-target effects. If these findings hold true in clinical trials, Dz13 may provide a safe, effective therapy for human skin cancer.

The present paper focuses on the physiology of yield potential in wheat (Triticum aestivum L.), because breeding progress in yield potential has overtaken farm yield progress. The paper examines developments largely in the last 10 years seeking routes to higher yield potential. Lately this subject has come under pressure from two new imperatives: perceived slowing of genetic progress and ambitious functional genomics. Analysis of trials between 1996 and 2005 at the CIANO research centre in northwest Mexico suggests that yield potential progress in CIMMYT spring wheats has slowed to around 0·50% per year, but has not ceased there nor in winter wheats elsewhere. Meanwhile, in the last 10 years or so, physiological understanding has advanced somewhat. Increased kernel number/m2 remains strongly associated with genetic progress in grain yield, and new research reinforces the importance of spike dry weight (g/m2) at anthesis in its determination. Lengthening the spike growth period through manipulation of sensitivity to photoperiod looks promising, but more attention to kernels per unit of spike weight is also urged. With respect to plant height, an optimum somewhere between 0·7 and 1·0 m is accepted and we are moving away from infatuation with the Norin 10 dwarfing genes as a way of reaching that. What has not been achieved is good lodging resistance in all short spring wheats, nor a complete understanding of its physiological basis. New information is coming to light on the possible role of stored stem reserves at anthesis, for these reserves appear to have increased as yield potential has increased. Part of the benefit may be related to assimilate supply per kernel around anthesis, which new understanding suggests is important for maximum potential kernel weight. Nevertheless, results continue to suggest that despite more kernels/m2, the most recent wheats are still largely sink-limited during grain filling. Growing evidence from spring and winter wheat (and from rice and maize) now points to the importance of increased photosynthetic activity before and around flowering for recent genetic increases in yield potential. This opens up new possibilities for selection in field plots. Finally, attention is given to effects of weather on yield potential and recent advances in techniques for elucidating the physiological basis of genotype by year interactions. From physiological understanding such as described, traits can be suggested as possible selection criteria for yield potential. However, apart from the ACIAR/CIMMYT project looking at stomatal aperture-related traits as well as source and sink traits (Condon et al., in press; Reynolds et al., in press; van Ginkel et al., in press), there appear to have been few attempts to validate physiological (or morphological) selection criteria for wheat yield potential in the last decade, but recent promising results with spectral reflection indices could foreshadow more validation work. This contrasts with efforts to improve the performance of wheat (and maize) under water-limited conditions, and with the new plant type and super rice approaches of IRRI and China, respectively. Such research could be mapped out for wheat yield potential improvement, and could lead to more efficient breeding for yield potential and/or faster progress, but it requires a multidisciplinary team, including, nowadays, molecular biologists. It also needs suitable controlled and field environments and substantial long-term support. All this may no longer be available in the public sector, at least at a single location.

GAMYB is an MYB transcription factor which is expressed in cereal aleurone cells in response to gibberellin (GA). HvGAMYB binds to the TAACAAA box of a high-pl alpha-amylase gene promoter and transcriptionally activates its expression. In this study, we examined the role of HvGAMYB in activating expression of other GA-regulated genes encoding hydrolytic enzymes. In transient expression experiments, HvGAMYB transactivated expression of reporter genes fused to a low-pl alpha-amylase gene promoter, an EII (1-3, 1-4)-beta-glucanase gene promoter and a cathepsin B-like protease promoter. HvGAMYB DNA binding specificity was determined using a PCR-based random site selection using HvGAMYB fusion protein isolated from E. coli. The deduced consensus closely resembled gibberellin response elements in alpha-amylase promoters. Functional analysis of HvGAMYB by transient expression of C terminal HvGAMYB deletions in barley aleurone cells identified two transcriptional activation domains (TADs) which function in transcriptional regulation of both high- and low-pl alpha-amylase promoters. The same TADs were identified using a heterologous yeast expression system. Together, these results indicate that HvGAMYB has two TADs. These domains are C-terminal to its DNA-binding domain.

Pea (Pisum sativum L.) was the original model organism used in Mendel’s discovery (1866) of the laws of inheritance, making it the foundation of modern plant genetics. However, subsequent progress in pea genomics has lagged behind many other plant species. Although the size and repetitive nature of the pea genome has so far restricted its sequencing, comprehensive genomic and post genomic resources already exist. These include BAC libraries, several types of molecular marker sets, both transcriptome and proteome datasets and mutant populations for reverse genetics. The availability of the full genome sequences of three legume species has offered significant opportunities for genome wide comparison revealing synteny and co-linearity to pea. A combination of a candidate gene and colinearity approach has successfully led to the identification of genes underlying agronomically important traits including virus resistances and plant architecture. Some of this knowledge has already been applied to marker assisted selection (MAS) programs, increasing precision and shortening the breeding cycle. Yet, complete translation of marker discovery to pea breeding is still to be achieved. Molecular analysis of pea collections has shown that although substantial variation is present within the cultivated genepool, wild material offers the possibility to incorporate novel traits that may have been inadvertently eliminated. Association mapping analysis of diverse pea germplasm promises to identify genetic variation related to desirable agronomic traits, which are historically difficult to breed for in a traditional manner. The availability of high throughput ‘omics’ methodologies offers great promise for the development of novel, highly accurate selective breeding tools for improved pea genotypes that are sustainable under current and future climates and farming systems.

BACKGROUND: The US National Institutes of Mental Health Research Domain Criteria (RDoC) seek to stimulate research into biologically validated neuropsychological dimensions across mental illness symptoms and diagnoses. The RDoC framework comprises 39 functional constructs designed to be revised and refined, with the overall goal of improving diagnostic validity and treatments. This study aimed to reach a consensus among experts in the addiction field on the 'primary' RDoC constructs most relevant to substance and behavioural addictions. METHODS: Forty-four addiction experts were recruited from Australia, Asia, Europe and the Americas. The Delphi technique was used to determine a consensus as to the degree of importance of each construct in understanding the essential dimensions underpinning addictive behaviours. Expert opinions were canvassed online over three rounds (97% completion rate), with each consecutive round offering feedback for experts to review their opinions. RESULTS: Seven constructs were endorsed by ≥ 80% of experts as 'primary' to the understanding of addictive behaviour: five from the Positive Valence System (reward valuation, expectancy, action selection, reward learning, habit); one from the Cognitive Control System (response selection/inhibition); and one expert-initiated construct (compulsivity). These constructs were rated to be related differentially to stages of the addiction cycle, with some linked more closely to addiction onset and others more to chronicity. Experts agreed that these neuropsychological dimensions apply across a range of addictions. CONCLUSIONS: The study offers a novel and neuropsychologically informed theoretical framework, as well as a cogent step forward to test transdiagnostic concepts in addiction research, with direct implications for assessment, diagnosis, staging of disorder, and treatment.

Abstract Expertise in research integration and implementation is an essential but often overlooked component of tackling complex societal and environmental problems. We focus on expertise relevant to any complex problem, especially contributory expertise, divided into ‘knowing-that’ and ‘knowing-how.’ We also deal with interactional expertise and the fact that much expertise is tacit. We explore three questions. First, in examining ‘when is expertise in research integration and implementation required?,’ we review tasks essential (a) to developing more comprehensive understandings of complex problems, plus possible ways to address them, and (b) for supporting implementation of those understandings into government policy, community practice, business and social innovation, or other initiatives. Second, in considering ‘where can expertise in research integration and implementation currently be found?,’ we describe three realms: (a) specific approaches, including interdisciplinarity, transdisciplinarity, systems thinking and sustainability science; (b) case-based experience that is independent of these specific approaches; and (c) research examining elements of integration and implementation, specifically considering unknowns and fostering innovation. We highlight examples of expertise in each realm and demonstrate how fragmentation currently precludes clear identification of research integration and implementation expertise. Third, in exploring ‘what is required to strengthen expertise in research integration and implementation?,’ we propose building a knowledge bank. We delve into three key challenges: compiling existing expertise, indexing and organising the expertise to make it widely accessible, and understanding and overcoming the core reasons for the existing fragmentation. A growing knowledge bank of expertise in research integration and implementation on the one hand, and accumulating success in addressing complex societal and environmental problems on the other, will form a virtuous cycle so that each strengthens the other. Building a coalition of researchers and institutions will ensure this expertise and its application are valued and sustained.

Abstract This paper highlights the relevant issues influencing the amount and arrangement of ground cover in savanna rangelands in Australia, and presents field measurements from hillslope scale flumes, which demonstrate how runoff and sediment loss vary with spatial patterns in ground cover. Hillslopes with relatively high mean cover, but with small patches bare of vegetation, are shown to have between 6 and 9 times more runoff, and up to 60 times more sediment loss than similar hillslopes that do not contain bare patches. The majority of sediment lost from the hillslopes is composed of fine (suspended) rather than coarse (bedload) material, although the absolute sediment loads are comparatively low. These low loads are considered to be the result of lower than average rainfall during the measurement period (2002–2005) and the high and prolonged rates of historical hillslope erosion that have exhausted the erodible material from the A‐horizon. The collected data also demonstrate that a large proportion of soil is lost during the initial ‘flushing’ period of runoff events. The results presented have important implications for the management of savanna grazing systems by highlighting (i) the significance of bare patches in contributing to runoff and soil loss from hillslopes; (ii) the importance of having medium to high cover patches at the bottom of hillslopes for trapping and storing sediment and therefore reducing its entry into the stream network; and (iii) how maintenance of ground cover during the dry season reduces sediment concentrations in runoff occurring early in the wet season. Copyright © 2006 John Wiley & Sons, Ltd.

Summary The development of proximal soil sensors to collect fine‐scale soil information for environmental monitoring, modelling and precision agriculture is vital. Conventional soil sampling and laboratory analyses are time‐consuming and expensive. In this paper we look at the possibility of calibrating hyperspectral γ‐ray energy spectra to predict various surface and subsurface soil properties. The spectra were collected with a proximal, on‐the‐go γ‐ray spectrometer. We surveyed two geographically and physiographically different fields in New South Wales, Australia, and collected hyperspectral γ‐ray data consisting of 256 energy bands at more than 20 000 sites in each field. Bootstrap aggregation with partial least squares regression (or bagging‐PLSR) was used to calibrate the γ‐ray spectra of each field for predictions of selected soil properties. However, significant amounts of pre‐processing were necessary to expose the correlations between the γ‐ray spectra and the soil data. We first filtered the spectra spatially using local kriging, then further de‐noised, normalized and detrended them. The resulting bagging‐PLSR models of each field were tested using leave‐one‐out cross‐validation. Bagging‐PLSR provided robust predictions of clay, coarse sand and Fe contents in the 0–15 cm soil layer and pH and coarse sand contents in the 15–50 cm soil layer. Furthermore, bagging‐PLSR provided us with a measure of the uncertainty of predictions. This study is apparently the first to use a multivariate calibration technique with on‐the‐go proximal γ‐ray spectrometry. Proximally sensed γ‐ray spectrometry proved to be a useful tool for predicting soil properties in different soil landscapes.

This paper describes the development of a diffuse reflectance spectral library from a legacy soil sample. When developing a soil spectral library, it is important to consider the number of samples that are needed to adequately describe the soil variability in the region in which the library is to be used; the manner in which the soil is sampled, handled, prepared, stored, and scanned; and the reference analytical procedures used. As with any type of modelling, the dictum is ‘garbage in = garbage out’ and hopefully the converse ‘quality in = quality out’. The aims of this paper are to: (i) develop a soil mid infrared (mid-IR) diffuse reflectance spectral library for cotton-growing regions of eastern Australia from a legacy soil sample, (ii) derive soil spectral calibrations for the prediction of soil properties with uncertainty, and (iii) assess the accuracy of the predictions and populate the legacy soil database with good quality information. A scheme for the construction and use of this spectral library is presented. A total of 1878 soil samples from different layers were scanned. They originated from the Upper Namoi, Namoi, and Gwydir Valley catchments of north-western New South Wales (NSW) and the McIntyre region of southern Queensland (Qld). A conditioned Latin hypercube sampling (cLHS) scheme was used to sample the spectral data space and select 213 representative samples for laboratory soil analyses. Using these data, partial least-squares regression (PLSR) was used to construct the calibration models, which were validated internally using cross validation and externally using an independent test dataset. Models for organic C (OC), cation exchange capacity (CEC), clay content, exchangeable Ca, total N (TN), total C (TC), gravimetric moisture content θg, total sand and exchangeable Mg were robust and produced accurate results (R2adj. > 0.75 for both cross and test set validations). The root mean squared error (RMSE) of mid-IR-PLSR predictions was compared to those from (blind) duplicate laboratory measurements. Mid-IR-PLSR produced lower RMSE values for soil OC, clay content, and θg. Finally, bootstrap aggregation-PLSR (bagging-PLSR) was used to predict soil properties with uncertainty for the entire library, thus repopulating the legacy soil database with good quality soil information.

ABSTRACT The taxonomic distribution and evolution of viviparity in Diptera is critically reviewed. The phenomenon ranges from ovoviviparity (eggs deposited at an advanced stage of embryonic development; larva emerges immediately after deposition), through viviparity (larva hatches inside female before deposition) to pupiparity (offspring deposited as pupa). Some Diptera are known to be facultatively viviparous, which is hypothesized to be a step towards the evolution of obligate viviparity. Obligate viviparity is found to comprise unilarviparity (single large larva in maternal uterus) which evolved many times independently, the rare oligolarviparity (more than one but not more than 12 larvae) and multilarviparity (large numbers of developing eggs or larvae in uterus) which is typical for the two largest clades of viviparous Diptera. Unilarviparity is either lecithotrophic (developing larva nourished by yolk of egg) or pseudo‐placental (larva nourished by glandular secretions of mother). Viviparity has clearly evolved on many separate occasions in Diptera. It is recorded in 22 families, and this review identifies at least 61 independent origins of viviparity. Six families appear to have viviparity in their ground‐plan. Some families have a single evolution of viviparity, others multiple evolutions. Guimaraes' model for the evolution of viviparity in Diptera is tested against phylogenetic information and the adaptive significance of viviparity is reviewed in detail. Possible correlations with life‐history parameters (coprophily, parasitism, breeding in ephemeral plant parts, malacophagy and adult feeding habits – especially haematophagy) are analysed critically, as are potential advantages (shorter larval life, less investment in yolk by mother, protection of vulnerable stages, better access to breeding substrates, predation on competitors). Morphological constraints, adaptations and exaptations are reviewed, including the provision of an incubation space for the egg(s), the positioning of the egg(s) in the uterus, and maternal glands. The main morphological adaptations include greater egg size, reduction of egg respiratory filaments, thinning of chorion, modified larval respiratory system and mouthparts, and instar skipping. Female morphology and behaviour is particularly strongly modified for viviparity. The terminalia are shortened, the vagina is more muscular and tracheated, and the ovaries of unilarviparous species have a reduced number of ovarioles with alternate ovulation. Many of the final conclusions are tentative, and a plea is made for more detailed morphological and experimental study of many of the viviparous species. Viviparity in Diptera provides a fascinating example of multiple parallel evolution, and a fertile field for future research.

Agricultural extension is booming. This interest is critical in the context of numerous pressing issues linked to agrarian change and rural development. Because of its importance, extension has attracted significant critique for its persistent exclusion of social and political factors. In this light, the history of extension can be thought of as a paradigm composed of approaches aimed at increasing agricultural production through the transfer of technologies from experts to farmers, and a series of criticisms of technology transfer as hampered by neglect of socio-political factors, a process labelled ‘rendering technical’. By reviewing criticisms of extension for its rendering of socio-political factors, we account for the rendering of power, place, and people. Equally important, we offer examples that consolidate critiques in order to open the possibility that humanized extension may more successfully support farmers. Our review is an effort to engage extensionists in order to speak about power to those who attempt to speak truth to power.