Agronomy — Open Access Journal

It has long been a great concern in deep learning that we lack massive data for high-precision training sets, especially in the agriculture field. Plants in images captured in greenhouses, from a distance or up close, not only have various morphological structures but also can have a busy background, leading to huge challenges in labeling and segmentation. This article proposes an unsupervised statistical algorithm SAI-LDA (self-adaptive iterative latent Dirichlet allocation) to segment greenhouse tomato images from a field surveillance camera automatically, borrowing the language model LDA. Hierarchical wavelet features with an overlapping grid word document design and a modified density-based method quick-shift are adopted, respectively, according to different kinds of images, which are classified by specific proportions between fruits, leaves, and the background. We also utilize the feature correlation between several layers of the image to make further optimization through three rounds of iteration of LDA, with updated documents to achieve finer segmentation. Experiment results show that our method can automatically label the organs of the greenhouse plant under complex circumstances, fast and precisely, overcoming the difficulty of inferior real-time image quality caused by a surveillance camera, and thus obtain large amounts of valuable training sets. Full article

BCS (Body Condition Score) is a method to estimate body fat reserves and accumulated energy balance of cows, placing estimations (or BCS values) in a scale of 1 to 5. Periodically rating BCS of dairy cows is very important since BCS values are associated with milk production, reproduction, and health of cows. However, in practice, obtaining BCS values is a time-consuming and subjective task performed visually by expert scorers. There have been several efforts to automate BCS of dairy cows by using image analysis and machine learning techniques. In a previous work, an automatic system to estimate BCS values was proposed, which is based on Convolutional Neural Networks (CNNs). In this paper we significantly extend the techniques exploited by that system via using transfer learning and ensemble modeling techniques to further improve BCS estimation accuracy. The improved system has achieved good estimations results in comparison with the base system. Overall accuracy of BCS estimations within 0.25 units of difference from true values has increased 4% (up to 82%), while overall accuracy within 0.50 units has increased 3% (up to 97%). Full article

Garlic (Allium Sativum L.) is a vegetable with known medicinal value. It is not only rich in nutrients, but also has the ability to combat different microbial infections. This is, however, the first study to investigate the effect of soil incorporation of the raw garlic stalk (RGS) on the growth and antioxidative defense system of eggplant. The experiments were conducted in pots using soil amendments of RGS in different ratios (RGS1 1:100; RGS2 3:100; RGS3 5:100 and control (CK) 0:100 of RGS: Soil w/w) and repeated in two consecutive years (2016 and 2017). A dose-dependent response of RGS amendment was observed in the growth and physiology of the eggplant. RGS1 and RGS2 significantly enhanced the plant height, root/shoot weight, stem diameter, leaf area, root length, root activity, pigment contents (chlorophyll a, chlorophyll b, and total chlorophyll), and photosynthetic parameters, but reduced intracellular CO₂ (Ci) and enhanced fruit yield as compared with the respective controls. Consistently, RGS also enhanced activities of antioxidative enzymes of eggplant reported as a defense against stress indicators. RGS in its higher ratios (RGS3), however, caused a reduction in all of the growth and physiological parameters and increased stress indicators such as hydrogen peroxide (H₂O₂) and malondialdehyde (MDA). Overall, RGS2 was found to be the most efficient for regulation of plant defense systems, reducing H₂O₂ and MDA and enhancing superoxide dismutase (SOD), peroxidase (POD), and phenylalanine ammonia–lyase (PAL) activity. It can be concluded that the appropriate ratio of RGS could efficiently promote plant growth and regulate the reactive oxygen-based plant defense system. Full article

Fusarium root rot and stalk rot are becoming a threat to maize production worldwide. However, there is still limited information about the aggressiveness of Fusarium subglutinans Edwards and Fusarium temperatum and their relationship with fumonisin production. In this study, for the first time, the reaction of seven Korean maize cultivars to F. subglutinans and F. temperatum was investigated. The results showed that among the maize cultivars, Hik-chal and Miheung-chal had the highest Fusarium-induced root rot and stalk rot severity, while De Hack-chal had the lowest disease severity regardless of the Fusarium species. Furthermore, the disease resistant cv. De Hack-chal accumulated low levels of fumonisins (FUM) in the infected stalk, while cv. Hik-chal and Miheung-chal had the highest level of FUM. It is worth to note that, plants infected with F. temperatum had a higher FUM concentration compared to cultivars infected with F. subglutinans. The present study shows a significant correlation between stalk rot ratings and FUM levels and it also presents new information about the potential risk of FUM contamination of maize stalk with F. subglutinans and F. temperatum in South Korea. In addition, enzyme activities like polyphenol oxidase (PPO), peroxidase (POD), and the amount of total phenol content (TPC) were studied in selected susceptible cultivar Miheung-chal and resistant cultivar De Hack-chal. The activity of PPO, POD and concentration of TPC were generally higher in the roots of the resistant cultivar than the susceptible cultivar. Moreover, following inoculation of either F. subglutinans or F. temperatum, there was a significant increase in PPO and POD activity in the roots of both cultivars. Hence, the information provided in this study could be helpful to better understand the mechanisms of resistance response to infection of Fusarium root rot pathogens. Full article

Agriculture faces the challenge of feeding a growing population with limited or depleting fresh water resources. Advances in irrigation systems and technologies allow site-specific application of irrigation water within the field to improve water use efficiency or reduce water usage for sustainable crop production, especially in arid and semi-arid regions. This paper discusses recent development of variable-rate irrigation (VRI) technologies, data and information for VRI application, and impacts of VRI, including profitability using this technology, with a focus on agronomic factors in precision water management. The development in sprinkler systems enabled irrigation application with greater precision at the scale of individual nozzle control. Further research is required to evaluate VRI prescription maps integrating different soil and crop characteristics in different environments. On-farm trials and whole-field studies are needed to provide support information for practical VRI applications. Future research also needs to address the adjustment of the spatial distribution of prescription zones in response to temporal variability in soil water status and crop growing conditions, which can be evaluated by incorporating remote and proximal sensing data. Comprehensive decision support tools are required to help the user decide where to apply how much irrigation water at different crop growth stages to optimize water use and crop production based on the regional climate conditions and cropping systems. Full article

Land reclamation influences the soil carbon and nitrogen cycling, but its scale and time effects on the balance of soil carbon and nitrogen are still uncertain. Taking the Tarim Basin as the study area, the impact of land reclamation on the soil organic carbon (SOC), total nitrogen (TN), and carbon to nitrogen (C:N) ratio was explored by the multiple temporal changes of land use and soil samples. Remote sensing detected that cropland nearly doubled in area from 1978 to 2015. Spatial analysis techniques were used to identify land changes, including the prior land uses and cultivation ages. Using land reclamation history information, a specially designed soil sampling was conducted in 2015 and compared to soil properties in ca. 1978. Results found a decoupling characteristic between the C:N ratio and SOC or TN, indicating that changes in SOC and TN do not correspond directly to changes in the C:N ratio. The land reclamation history coupled with the baseline effect has opposite impacts on the temporal rates of change in SOC, TN and C:N ratios. SOC and TN decreased during the initial stage of conversion to cropland and subsequently recovered with increasing cultivation time. By contrast, the C:N ratio for soils derived from grassland increased at the initial stage but the increase declined when cultivated longer, and the C:N ratio decreased for soils derived from forest and fluctuated with the cultivation time. Lower C:N ratios than the global average and its decreasing trend with increasing reclamation age were found in newly reclaimed croplands from grasslands. Sustainable agricultural management practices are suggested to enhance the accumulation of soil carbon and nitrogen, as well as to increase the C:N ratio to match the nitrogen deposition to a larger carbon sequestration. Full article

The integration of Agroecological Service Crops (ASCs) into agroecosystems can provide several ecological services, such as nutrient cycling and disease and weed management. A two-year experiment on an organic orchard was carried out to compare barley (B) and horse bean (HB) ASCs with a control without ASC (Cont) in combination with fertilizers. Their effects on soil fertility and weed- and soil-borne fungi communities were evaluated by direct measurements, visual estimation, and indicators computation. A Principal Component Analysis (PCA) was used to identify latent patterns and redundancy among variables, whereas a correlation analysis was used to discriminate the compared systems within the PCA matrix. The empirical results of this study put in evidence the correlation among soil, weed, and fungal variables. A slight contribution of fertilizers on the system’s variability was observed, whereas a clear effect of ASCs was highlighted. The systems differed in weed communities, with the lowest density associated to B and the highest to Cont. B showed the highest fungal diversity, with changes in community compared to HB. HB showed a contribution on soil fertility, being associated to organic matter increase and N availability, and evidencing mixed impacts on soil quality and ecosystem functioning. Overall, the above-ground diversity and below-ground community results were inter-correlated. Full article

The estimation of the ripening state in orchards helps improve post-harvest processes. Picking fruits based on their stage of maturity can reduce the cost of storage and increase market outcomes. Moreover, aerial images and the estimated ripeness can be used as indicators for detecting water stress and determining the water applied during irrigation. Additionally, they can also be related to the crop coefficient (Kc) of seasonal water needs. The purpose of this research is to develop a new computer vision algorithm to detect the existing fruits in aerial images of an apple cultivar (of Red Delicious variety) and estimate their ripeness stage among four possible classes: unripe, half-ripe, ripe, and overripe. The proposed method is based on a combination of the most effective color features and a classifier based on artificial neural networks optimized with genetic algorithms. The obtained results indicate an average classification accuracy of 97.88%, over a dataset of 8390 images and 27,687 apples, and values of the area under the ROC (receiver operating characteristic) curve near or above 0.99 for all classes. We believe this is a remarkable performance that allows a proper non-intrusive estimation of ripening that will help to improve harvesting strategies. Full article

With the advancement of technology, the traditional e-learning model may expand the realm of knowledge and differentiate learning by means of deep learning (DL) and augmented reality (AR) scenarios. These scenarios make use of interactive interfaces that incorporate various operating methods, angles, perceptions, and experiences, and also draw on multimedia content and active interactive models. Modern education emphasizes that learning should occur in the process of constructing knowledge scenarios and should proceed through learning scenarios and activities. Compared to traditional “spoon-feeding” education, the model learning scenario is initiated with the learner at the center, allowing the person involved in the learning activity to solve problems and further develop their individual capabilities through exploring, thinking and a series of interactions and feedback. This study examined how students in the agriculture technological industry make use of AR digital learning to develop their industry-related knowledge and techniques to become stronger and more mature so that they unconsciously apply these techniques as employees, as well as encouraging innovative thought and methods to create new value for the enterprise. Full article

In this article, we review the literature regarding the yield gap between organic and conventional agriculture and then reflect on the corresponding debate on whether or not organic farming can feed the world. We analyze the current framework and highlight the need to reframe the yield gap debate away from “Can organic feed the world?” towards the more pragmatic question, “How can organic agriculture contribute to feeding the world?”. Furthermore, we challenge the benchmarks that are used in present yield comparison studies, as they are based on fundamentally distinct paradigms of the respective farming methods, and then come up with a novel model to better understand the nature of yield gaps and the benchmarks that they are premised on. We thus conclude that, by establishing appropriate benchmarks, re-prioritizing research needs, and focusing on transforming natural resources rather than inputs, organic systems can raise their yields and play an ever-greater role in global sustainable agriculture and food production in the future. Full article

Phosphorus (P) deficiency is a major factor limiting rice yield throughout the world. Fortunately, some rice accessions are tolerant and can thrive well, even in soils with low P content. The ability to uptake P is heritable, and thus can be incorporated into rice cultivars through standard breeding methods. The objective of this study was to screen for tolerance to phosphorus deficiency and validate the tolerant accessions withphosphorus uptake 1 (Pup1) gene-linked markers in Thai indigenous upland rice germplasm. One hundred sixty-eight rice varieties were screened in a solution culture and assigned a phosphorus deficiency tolerance index and plant symptom score. Eleven upland rice accessions (ULR026, ULR031, ULR124, ULR145, ULR180, ULR183, ULR185, ULR186, ULR213, ULR260, and ULR305), together with the lowland rice cultivar (PLD), were classified as tolerant. They were each validated by nine markers linked to the Pup1 locus and observed for the expected polymerase chain reaction (PCR) product of 0 to 9 markers. The presence or absence of the tolerant allele atthe Pup1 locus showed only a slight relationship with the tolerance. Moreover, some lines such as ULR183 and ULR213 expressed high tolerance without the Pup1-linked gene product. Both accessions are useful for the exploration of novel genes conferring tolerance to phosphorus deficiency. Full article

Precision horticulture is fundamental to ensure high quality production with a minimal
environmental footprint. It offers the possibility to manage climatic and fertilization inputs closer
to the plant needs. In practice, there is a tendency to over‐fertilize, as nitrogen limitation can
decrease photosynthesis and consequently fruit yield, but also because nutrient recycling does not
lead to any substantial costs increase, thus ignoring the influence of nitrogen input on the balance
between growth and metabolism. Nitrogen recommendation for tomato greenhouse production on
rockwool is 16mM, even it is well established that only 50% of nitrogen amount is really absorbed
by plants. This study compares the usual practice (16 mM) to a nitrogen supply to meet plant’s
needs (5 mM). We analyzed plant growth and development, yield, leaf photosynthetic activity and
fruit quality (sugars, acids, vitamin C,) over the entire crop period (December to October).
Over‐fertilization favoured the accumulation of nitrogen in leaves and stem but yield, leaf
photosynthetic activity and plant architecture were not significantly improved. In addition, it
decreased the quality of the tomatoes as the sugar:acid ratio decreased dramatically in the pericarp,
whereas the locular gel composition remained similar. A reduction of the nitrogen supply is one
solution to improve tomato quality without any reduction of yield in greenhouse. These data have
to be incorporated in tomato fertigation management to define a new standard based on overall
quality of tomato fruit and low environmental footprint. Full article

Drought is one of the major factors limiting rice yield worldwide. A total of 46 hybrid rice varieties were chosen to investigate their root distribution and their response to drought. A field experiment was carried out in a dry shed building to evaluate the drought tolerance capacity of hybrid rice varieties on the basis of CTIRDE (complex tolerance index of rice under drought environment) values. Next, the experiment was conducted in a specially designed pot system and seed bags to analyze the root distribution and activity of antioxidant enzymes in different rice varieties. Moreover, the DEEPER ROOTING 1 (DRO1) gene was sequenced to elucidate its role in the root distribution of typical rice varieties. On the basis of CTIRDE values, the 46 hybrid rice varieties were classified as tolerant (CTIRDE ≥ 0.75), semi-tolerant (0.75 > CTIRDE > 0.65), or sensitive (CTIRDE ≤ 0.65) to drought stress. The tolerant varieties (Chuanguyou208 and Deyou4727) displayed a significantly larger length, had higher number and weight of roots in the 30–50 cm soil layer, and exhibited a significantly higher activity of Superoxide dismutase (SOD) and Peroxidase (POD) enzymes in roots during the drought stress period. The DRO1 gene sequencing results revealed that the tolerant and sensitive varieties exhibited a single-nucleotide polymorphism (SNP) in the 3-exon region, and the tolerant varieties (Chuanguyou208 and Deyou4727) exhibited a larger root growth angle with the horizontal axis, hence developing a deeper root system as compared with the other two group varieties. A significant correlation was found not only between the DRO1 gene and root distribution but also between DRO1 and the activity of SOD and POD enzymes. Conclusively, as a key feature, a deep root system enabled tolerant rice varieties (Chuanguyou208 and Deyou4727) to avoid drought stress by absorbing more water stored in deep soil layers. The root distribution, activity of POD and SOD enzymes in roots, and DRO1 gene can be used to screen tolerant rice varieties that can survive better under drought stress during the seedling stage of rice growth. Full article

In an agricultural drought risk system, crop drought loss sensitivity evaluation is a fundamental link for quantitative agricultural drought loss risk assessment. Summer maize growth processes under various drought patterns were simulated using the Cropping System Model (CSM)-CERES-maize, which was calibrated and validated based on pit experiments conducted in the Huaibei Plain during 2016 and 2017 seasons. Then S-shaped maize drought loss sensitivity curve was built for fitting the relationship between drought hazard index intensity at a given stage and the corresponding dry matter accumulation and grain yield loss rate, respectively. Drought stress reduced summer maize evapotranspiration, dry matter, and yield accumulation, and the reductions increased with the drought intensity at each stage. Moreover, the losses caused by drought at different stages were significantly different. When maize plants were exposed to a severe water deficit at the jointing stage, the dry matter and grain yield formation were greatly affected. Therefore, maize growth was more sensitive to drought stress at the jointing stage when the stress was serious. Furthermore, when plants encountered a relatively slight drought during the seedling or jointing stage, which represented as a lower soil water deficit intensity, the grain yield loss rates approached the maximum for the sensitivity curves of these two stages. Therefore, summer maize tolerance to water deficit at the seedling and jointing stages were weak, and yield formation was more sensitive to water deficit during these two stages when the deficit was relatively slight. Full article

The use of biofertilizers is important for sustainable agriculture, and the use of nodule bacteria and endophytic actinomycetes is an attractive way to enhance plant growth and yield. This study tested the effects of a biofertilizer produced from Bradyrhizobium strains and Streptomyces griseoflavus on leguminous, cereal, and vegetable crops. Nitrogen fixation was measured using the acetylene reduction assay. Under N-limited or N-supplemented conditions, the biofertilizer significantly promoted the shoot and root growth of mung bean, cowpea, and soybean compared with the control. Therefore, the biofertilizer used in this study was effective in mung bean, cowpea, and soybean regardless of N application. In this study, significant increments in plant growth, nodulation, nitrogen fixation, nitrogen, phosphorus, and potassium (NPK) uptake, and seed yield were found in mung beans and soybeans. Therefore, Bradyrhizobium japonicum SAY3-7 plus Bradyrhizobium elkanii BLY3-8 and Streptomyces griseoflavus are effective bacteria that can be used together as biofertilizer for the production of economically important leguminous crops, especially soybean and mung bean. The biofertilizer produced from Bradyrhizobium and S. griseoflavus P4 will be useful for both soybean and mung bean production. Full article

A soybean germplasm collection was studied for the identification of accessions with low trypsin inhibitor content in seeds. Twenty-nine accessions, parental plants, and two hybrid populations were selected and analyzed using genetic markers for alleles of the Ti3 locus, encoding Kunitz trypsin inhibitor (KTI). Most of the accessions had high or very high KTI (49.22–73.53 Trypsin units inhibited (TUI/mg seeds), while the two local Kazakh cultivars, Lastochka and Ivushka, were found to have a moderately high content of KTI, at 54.16–54.87 TUI/mg. In contrast, two soybean cultivars from Italy, Hilario and Ascasubi, showed the lowest levels of trypsin units inhibited, at 25.47–27.87 TUI/mg. Electrophoresis of seed proteins in a non-denaturing system showed a simple discrimination pattern and very clear presence/absence of bands corresponding to KTI. The SSR marker Satt228 was the most effective diagnostic marker among the three examined, and it confirmed the presence of the homozygous null-allele ti3/ti3 in cultivars Ascasubi and Hilario, which were used for hybridization with the local cv. Lastochka. Heterozygote F₁ hybrid plants and homozygous ti3/ti3 lines in F₂ segregating populations were successfully identified using Satt228. Finally, through marker-assisted selection with Satt228, prospective homozygous ti3/ti3 lines were produced for further application in the breeding program aimed at improving soybean seed quality in Kazakhstan. Full article

New genotypes of winter oilseed rape bred under the Czech breeding program were subjected to performance tests within the framework of inter-institutional pre-tests. At four monitored localities in the Czech Republic, field trials were carried out on 50 genotypes in the years 2015 to 2017. In these trials, evaluations were made on infestation by the fungal pathogens Leptosphaeria maculans, Leptosphaeria biglobosa, and Sclerotiniasclerotiorum, as well as the level of infestation caused by phytoplasmas. The evaluation of new oilseed rape genotypes confirmed a medium to high level of resistance to phoma stem canker and Sclerotinia stem rot compared to the resistant reference varieties. The most severe infestations caused by Leptosphaeria spp. were observed in Chlumec nad Cidlinou in 2015 (mean severity score 22.38%) and in Opava in 2016 (mean severity score 20.72%). The same trend was observed for infestations caused by S. sclerotiorum, where the most damage to trial plots were observed at the same localities, in 2015 in Chlumec nad Cidlinou (mean severity score 36.85%) and in 2016 in Opava (mean severity score 18.84%). PCR determination of Leptosphaeria spp. showed that 98% of sampled leaves in autumn season showing symptoms were infected by L. maculans, while the remaining 2% were identified as bearing L. biglobosa. Molecular detection of infected parts of oilseed rape plants with symptoms of phyllody confirmed in all cases the presence of phytoplasma isolates from the 16SrI Aster Yellows group. Full article

Plant-derived protein biostimulants exhibit hormone-like activities promoting plant growth and yield, yet detailed investigations on hormonal function have remained limited. This study was conducted to investigate the effects of vegetal-derived-biostimulant on morphological and metabolic changes in cuttings of three herbaceous species demonstrating different rooting ability, basil (Ocimumbasilicum L.), tomato (Solanum lycopersicum L.), and chrysanthemum (Chrysanthemum indicum L.), in comparison to auxin. Unrooted cuttings were applied with or without biostimulant (100, 1000, 5000, and 10000 mg L⁻¹) or auxin [1% indole-3-butyric acid (IBA) plus 0.5% 1-naphthaleneacetic acid (NAA); 100, 200, 300, and 500 mg L⁻¹] as a basal quick-dip, stuck into inert media, and evaluated at 20 days after placement under intermittent mist. Both compounds increased adventitious rooting in all cuttings. Biostimulant required a significantly higher threshold for a series of adventitious rooting responses than auxin, and the maximum effectiveness was achieved at 5000 mg L⁻¹ for biostimulant and 100, 200, and 300 mg L⁻¹ for auxin in basil, tomato, and chrysanthemum, respectively. Adventitious rooting responses (dry mass and length) to biostimulant showed a gradual logarithmic rise as a function of increasing dosages, which was not in agreement with biphasic dose-response of auxin. Biostimulant significantly increased or tended to increase fine roots in all tested cuttings, which was not consistent with auxin. Relatively high levels of endogenous brassinosteroids (BRs) were present in non-treated cuttings of basil, tomato, and chrysanthemum in decreasing order. Both compounds had no effects or concomitantly increased or decreased BR levels in plant tissues, with fewer effects on basil and tomato, containing high BR levels, but more prominent effects on chrysanthemum, containing relatively low BR levels. Contrasting effects of biostimulant and auxin were found in antioxidant activities, which were promoted by biostimulant but inhibited by auxin either in roots or shoots. These results indicate that the hormonal effects of vegetal-derived biostimulant are primarily exerted by BR-mediated processes while involving interaction with auxin. Both the biostimulant-derived BRs and auxin were suggested to modulate endogenous BR pool via overlapping and interdependent regulatory functions, inducing morphological and metabolic changes during adventitious rooting of cuttings in a plant species-specific manner. Full article

Eragrostis tef (teff) is a (sub-)tropical cereal crop and a staple food in Eastern Africa. As soil erosion has become increasingly worse in the Ethiopian highlands, we test the hypotheses that 1) eroded soils possess low arbuscular mycorrhizal fungi (AMF) spore densities, 2) teff growth is limited by low endophytic fungal root colonization rates and 3) colonization rates and spore densities are additionally reduced by fertilization. A pot experiment was set up to study the effect of cropland soil inoculation using pristine fungal communities (from adjacent forests) or fertilization. AMF spore densities in soil with and without teff and root colonization by AMF and dark septate endophytes (DSE) were related to straw and grain yields. AMF and DSE colonization rates were higher after inoculation, which provides evidence that a low spore density limits teff root colonization in eroded soils. However, teff yields were significantly increased after fertilisation but not inoculation. N-P fertilization further lowered root colonization rates and spore density. We conclude that forest soils serve as a refugium for soil biota in the degraded landscape of the Ethiopian highlands. As both increased AMF and DSE increase the stress resistance of plants, their inoculation potential should be considered when developing sustainable management methods for teff. Full article