Application of light detection and ranging and ultrasonic sensors to high-throughput phenotyping and precision horticulture: current status and challenges

Ultrasonic and light detection and ranging(LiDAR)sensors have been some of the most deeply investigated sensing technologies within the scope of digital horticulture.They can accurately estimate geometrical and structural parameters of the tree canopies providing input information for high-throughput phenotyping and precision horticulture.A review was conducted in order to describe how these technologies evolved and identify the main investigated topics,applications,and key points for future investigations in horticulture science.Most research efforts have been focused on the development of data acquisition systems,data processing,and high-resolution 3D modeling to derive structural tree parameters such as canopy volume and leaf area.Reported applications of such sensors for precision horticulture were restricted to real-time variable-rate solutions where ultrasonic or LiDAR sensors were tested to adjust plant protection product or fertilizer dose rates according to the tree volume variability.More studies exploring other applications in site-specific management are encouraged;some that integrates canopy sensing data with other sources of information collected at the within-grove scale(e.g.,digital elevation models,soil type maps,historical yield maps,etc.).Highly accurate 3D tree models derived from LiDAR scanning demonstrate their great potential for tree phenotyping.However,the technology has not been widely adopted by researchers to evaluate the performance of new plant varieties or the outcomes from different management practices.Commercial solutions for tree scanning of whole groves,orchards,and nurseries would promote such adoption and facilitate more applied research in plant phenotyping and precision horticulture.

Breeding effects on the genotype×environment interaction for yield of durum wheat grown after the Green Revolution:The case of Spain

This study evaluates the changes caused by breeding in the genotype by environment(G×E)interaction of the durum wheat varieties most widely cultivated in Spain after the Green Revolution.A set of 12 cultivars was tested in 27 environments,which are understood as the combination of different sites,years,and treatments(water regime and planting dates),representative of the durum wheat growing conditions in Spain with average grain yields(GY)ranging between 2.8 and 9.1 Mg ha^-1.The most important environmental factors affecting the G×E interaction for yield were themaximum and the mean temperature during the entire crop cycle.An improvement in genetic yield was observed in warm environments and under optimal water conditions that resemble those where the germplasm originated(essentially as advanced lines)before its release in Spain.Therefore,the adaptation of semi-dwarf durum in Spain has shown a tendency to specific adaptation rather than large-scale adaptation.Two different patterns of selection have been reported due the G×E interaction and changes in the ranking of genotypes:in the high yielding environments(GY>5 Mg ha^-1),plants favor increased water uptake,with higher levels of transpiration and more open stomata(more negative values of carbon isotope composition,δ^13 C,and higher canopy temperature depression,CTD),whereas,in low yielding environments(GY<5 Mg ha^-1)plants close their stomata and favor greater water use efficiency(less negativeδ^13 C values and lower CTD values).

Multiscale assessment of ground,aerial and satellite spectral data for monitoring wheat grain nitrogen content

Wheat grain quality characteristics have experienced increasing attention as a central factor affecting wheat end-use products quality and human health.Nonetheless,in the last decades a reduction in grain quality has been observed.Therefore,it is central to develop efficient quality-related phenotyping tools.In this sense,one of the most relevant wheat features related to grain quality traits is grain nitrogen content,which is directly linked to grain protein content and monitorable with remote sensing approaches.Moreover,the relation between nitrogen fertilization and grain nitrogen content(protein)plays a central role in the sustainability of agriculture.Both aiming to develop efficient phenotyping tools using remote sensing instruments and to advance towards a field-level efficient and sustainable monitoring of grain nitrogen status,this paper studies the efficacy of various sensors,multispectral and visible red-greenblue(RGB),at different scales,ground and unmanned aerial vehicle(UAV),and phenological stages(anthesis and grain filling)to estimate grain nitrogen content.Linear models were calculated using vegetation indices at each sensing level,sensor type and phenological stage.Furthermore,this study explores the up-scalability of the best performing model to satellite level Sentinel-2 equivalent data.We found that models built at the phenological stage of anthesis with UAV-level multispectral cameras using red-edge bands outperformed grain nitrogen content estimation(R2=0.42,RMSE=0.18%)in comparison with those models built with RGB imagery at ground and aerial level,as well as with those built with widely used ground-level multispectral sensors.We also demonstrated the possibility to use UAV-built multispectral linear models at the satellite scale to determine grain nitrogen content effectively(R2=0.40,RMSE=0.29%)at actual wheat fields.

Crop phenotyping in a context of global change:What to measure and how to do it

High-throughput crop phenotyping,particularly under field conditions,is nowadays perceived as a key factor limiting crop genetic advance.Phenotyping not only facilitates conventional breeding,but it is necessary to fully exploit the capabilities of molecular breeding,and it can be exploited to predict breeding targets for the years ahead at the regional level through more advanced simulation models and decision support systems.In terms of phenotyping,it is necessary to determined which selection traits are relevant in each situation,and which phenotyping tools/methods are available to assess such traits.Remote sensing methodologies are currently the most popular approaches,even when lab-based analyses are still relevant in many circumstances.On top of that,data processing and automation,together with machine learning/deep learning are contributing to the wide range of applications for phenotyping.This review addresses spectral and red-green-blue sensing as the most popular remote sensing approaches,alongside stable isotope composition as an example of a lab-based tool,and root phenotyping,which represents one of the frontiers for field phenotyping.Further,we consider the two most promising forms of aerial platforms(unmanned aerial vehicle and satellites)and some of the emerging data-processing techniques.The review includes three Boxes that examine specific case studies.

Host selection by the autoparasitoid Encarsia pergandiella on primary （Bemisia tabacl） and secondary （Eretmocerus mundus） hosts

In autoparasitoids, females are generally primary endoparasitoids of Hemiptera, while males are hyperparasitoids developing in or on conspecific females or other primary parasitoids. Female-host acceptance can be influenced by extrinsic and/or intrinsic factors. In this paper, we are concerned with intrinsic factors such as nutritional status, mating status, etc. We observed the behavior of Encarsia pergandiella Howard （Hymenoptera： Aphelinidae） females when parasitizing primary （3rd instar larvae ofBemisia tabaci Gen- nadius [Homoptera： Aleyrodidae]） and secondary hosts （3rd instar larvae and pupae of Eretmocerus rnundus Mercet [Hymenoptera： Aphelinidae]） for a period of 1 h. Females had different reproductive （virgin or mated younger） and physiological （fed elder or mated elder） status. Virgin females killed a large number of secondary hosts while investing a long time per host. However, they did not feed upon them. Mated females killed a lower number of secondary hosts and host feeding was observed in both consuming primary and secondary hosts. It was common to observe host examining females of all physiological statues tested repeatedly stinging the same hosts when parasitizing, killing or rejecting them. Fed elder females parasitized more B. tabaci larvae than E. mundus larvae or pupae, while investing less time on the primary host than on the secondary host. They also para- sitized more B. tabaci larvae than mated elder females, while investing less time per host. The access of females to honey allowed them to lay more eggs.

Gastric and small intestinal lipid digestion kinetics as affected by the gradual addition of lipases and bile salts

We studied the effect of evolving from static in vitro digestion conditions towards the gradual addition of essential digestive compounds for lipid digestion.Two oil-in-water emulsions were considered:a low(5%w/w)and high(20%w/w)triolein-based emulsion with identical surfactant-to-oil ratio(0.2).Emulsions were subjected to in vitro static digestion conditions or gradual gastric lipase addition,gradual pancreatic lipase addition,and/or gradual bile salt addition.For these three latter cases,similar amounts of gastric/pancreatic lipase and/or bile salts were provided as in the static case,however divided over 4 doses added during the first 30 min of each digestive phase.For the low-lipid emulsion,gradually adding lipases and bile salts did not significantly affect lipolysis kinetics.This can be related to the sufficient amounts of digestive compounds present even in the smallest initial dose.For the high-lipid emulsion,the gradual addition of bile salts significantly reduced the lipolysis rate.Bile salts are essential to remove lipid digestion products from the interface and thus allow the continuation of the lipid digestion process at the interface.Oppositely,the lipolysis extent after 2 h of small intestinal phase was not significantly influenced by the digestion approach.This is again explained by the simple nature of the emulsions studied and the excess of lipase even in the smallest initial dose.Overall,this work showed that evolving towards more(semi-)dynamic digestion conditions can impact(lipid)digestion kinetics,even for relatively simple food compositions,and is of interest to obtain more physiological relevant digestion kinetics.