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In this paper, a centrifugal filling and cleaning high-speed precision seed metering device for maize is designed based on the principle of centrifugal force generated by high-speed circular motion of seeds. Through theoretical analysis and calculation, the seeding tray and front shell of the seed metering device are designed so that the seeds can use centrifugal force for filling, cleaning, releasing, and returning. The seed metering device has a simple structure and can perform high-speed and precise seeding. A response surface experiment of central composite design was conducted with feeding and seeding speeds as experimental factors, and the omission rate, repeated rate, and pass rate as performance evaluation indexes. Through response surface experiment optimization, it was deduced that the highest seeding performance was achieved when the feeding and seeding speeds were 18.72 seeds/s and 15.12 km/h, respectively. Under these conditions, the omission, repeated, and pass rates were 2.21, 5.21, and 92.58%, respectively. The results of response surface experiment showed that, when the seeding speed of the centrifugal filling and cleaning high-speed precision seed metering device for maize is in the range of 10–20 km/h, the pass rate can be greater than 90%. In addition, the speed curve of feeding and seeding fitted from the bench experiment results is effective and reliable, which allows the seed metering device to achieve a precision seeding in a speed range of 10–20 km/h. The power of the air-suction seed metering device is 470.24 W when seeding at a speed of 14 km/h. Moreover, the power of the centrifugal filling and cleaning high-speed precision seed metering device is only 10.94 W when seeding at a speed of 20 km/h, and the energy consumption during seeding is much lower than that of the air-suction seed metering device, which performs cleaner production. [Display omitted] • A mechanical seed metering device was designed based on centrifugal force. • Designed a seed cleaning advance angle to improve seed cleaning efficiency. • A gradient surface was designed in the seed returning area to guide the seed flow. • A gradient circular chamber was designed to improve the efficiency of seeding. • Speed curve was fitted to achieve seeding at different speeds. [ABSTRACT FROM AUTHOR]

Abstract: Climate change will affect agricultural production by subsistence farms in crop centers of origin, where landraces are conserved in situ. Various strategies for adaptation to climate change have been proposed. In this paper we examine the prospects of what we call the ‘transgenic adaptation strategy’, i.e. the appeal to use transgenic seeds to adapt to climate change, through the lens of smallholder maize farming in Mexico. Landraces are the bedrock of maize production in Mexico. We consider how maize farmers may respond to climate change and the effects of those responses on crop diversity. In this paper, we argue that the promotion of the transgenic adaptation strategy is problematic for biological and social reasons. Smallholder livelihoods in southern Mexico could suffer a disproportionate negative impact if transgenic technology is privileged as a response to climate change. Agroecological and evolutionary approaches to addressing the effects of climate change on smallholder agriculture provides an alternative adaptive strategy. [Copyright &y& Elsevier]

Visual detection of plants diseases over a large area is time-consuming, and the results are prone to errors due to the subjective nature of human evaluations. Several automatic disease detection techniques that improve detection time and improve accuracy compared to visual methods exist, yet they are not suitable for immediate detection. In this paper, we propose a hybrid convolution neural network (CNN) model to speed up the detection of fall armyworms (faw) infested maize leaves. Specifically, the proposed system combines unmanned aerial vehicle (UAV) technology, to autonomously capture maize leaves, and a hybrid CNN model, which is based on a parallel structure specifically designed to take advantage of the benefits of both individual models, namely VGG16 and InceptionV3. We compare the performance of the proposed model in terms of accuracy and training time to four existing CNN models, namely VGG16, InceptionV3, XceptionNet, and Resnet50. The results show that compared to existing models, the proposed hybrid model reduces the training time by 16% to 44% compared to other models while exhibiting the most superior accuracy of 96.98%. [ABSTRACT FROM AUTHOR]

Abstract: Surface ozone concentrations in southern Africa exceed air quality guidelines set to protect agricultural crops. This paper addresses a knowledge gap by performing a preliminary assessment of potential ozone impacts on vegetation in southern African. Maize (Zea mays L.) is the receptor of interest in the main maize producing countries, i.e. South Africa, Zambia and Zimbabwe. Surface ozone concentrations are estimated for the growing season (October to April) using photochemical modelling. Hourly mean modelled ozone concentrations ranged between 19.7 and 31.2ppb, while maximums range between 28.9 and 61.9ppb, and are near 30ppb over South Africa and Zambia, while in Zimbabwe, they exceed 40ppb and translate into monthly AOT40 values of over 3000ppb h in five of the seven months of the growing season. This study suggests that surface ozone may pose a threat to agricultural production in southern African, particularly in Zimbabwe. [Copyright &y& Elsevier]

More than 216 million t (238 million tons) of corn stover (dry basis) is produced annually in the USA of which a portion could possibly be collected for conversion to ethanol and other industrial products. This paper examines published data on collecting corn stover using field machinery, including moisture content, mass fractions, and the amount of stover removed from the field. It is shown that a typical sequence of shredding, windrowing and round baling operations may result in a collection efficiency of <40%. Other factors such as weather, season, and leaving stover for environmental reasons may also reduce the amount of stover collected per unit area. Collection cost would depend on the amount of stover collected per unit area, the number of operations, machine efficiency in each operation, and bulk density. A typical cost calculated for round baling and delivering the bales to a storage 8 km (5 miles) away from a harvested field amounted to $21.60/dry t ($19.70/dry ton). [Copyright &y& Elsevier]

The goal to improve food security in sub-Saharan Africa (SSA) through domestic, resource efficient and low carbon agriculture is importance. Interventions to produce more food could impact the resource-base and lead to increase in greenhouse gas (GHG) emissions from agroecosystems. Unfortunately, existing methods are limited in analyzing small-scale agricultural systems, and this situation is an obstacle to decision making which aims at sustainable agriculture. In this paper, we showcase the recently developed Emergy-Data Envelopment Analysis (EM-DEA) approach to assess the resource use efficiency (RUE) and sustainability in maize production systems in Ghana, SSA. Using the Agricultural Production Systems sIMulator (APSIM), five land use and resource management scenarios were modeled to represent practices as decision making units (DMUs) in small-scale maize systems. The carbon footprint of the systems was assessed using an approach, which we adapted from the FAO Ex-Ante Carbon balance Tool (EX-ACT). The overall trend of the results showed that the yield, total emergy, GHG emissions and carbon footprint all increased with increase in urea application intensity. However, the relationship between the yield and urea intensity was not always linear. A system that used more renewable or fewer resources to produce a yield equal to that of its peer was considered more efficient and sustainable in relative terms. In particular, the business-as-usual scenario (12 kg/ha/yr NPK input to rainfed maize system, i.e. Extensive12) was inefficient when compared to the four contrasting scenarios. The ecological intensive scenario (20 kg/ha/yr urea input to rainfed maize-legume intercropping system, i.e. Intercrop20) achieved the greatest marginal yield, better RUE and sustainability. The high input scenario (100 kg/ha/yr urea input plus supplemental irrigation to maize monoculture, i.e. Intensive100) produced the greatest yield, but the demand for purchased inputs as well as GHG emissions and carbon footprint were greatest. The no external input scenario (0 kg/ha/yr urea input to rainfed maize system, i.e. Extensive0), and the moderate input scenario (50 kg/ha/yr urea input plus supplemental irrigation to maize monoculture, i.e. Intensive50) showed the greatest and least yield gaps relative to Intensive100 , respectively. Based on these results and trade-off analysis, it was evident that Intercrop20 and Intensive50 were the two best case scenarios. As such, land use policy that aims at sustainable agriculture could recommend Intercrop20 and Intensive50 for implementation in low and high input maize production systems, respectively. Comparison between our results and other existing empirical studies revealed similarities that confirm our results. We conclude that the information derived using the EM-DEA and EX-ACT approaches could be useful when making informed decisions that aim at sustainable agriculture. Despite the limitation caused by scarcity of data, the use of the EM-DEA approach led to inclusive information on RUE and sustainability of the DMUs. Hence, the EM-DEA approach represents a way forward to better assess energy footprint in agricultural land use as a whole. [ABSTRACT FROM AUTHOR]

Abstract: It has been paid more and more attention on maize tissue culture as it is a basic work in maize genetic transformation, especially huge breakthrough has been made in maize tissue culture utilizing mature embryos as explants in the recent years. This paper reviewed the study progress on maize tissue culture and plant regeneration utilizing mature embryos as explants from callus induction, subculture, plant regeneration and browning reduction and so on. [Copyright &y& Elsevier]