Enhancement of Natural Control Function for Aphids by Intercropping and Infochemical Releasers in Wheat Ecosystem. In: Gao Y, Hokkanen HMT, Menzler-hokkanen I, editors. Integrative Biological Control. Cham: Springer International Publishing; 2020. pp. 85-116. [DOI: 10.1007/978-3-030-44838-7_6]

Exploring the effect of Jasmonic Acid for Aphids control for improving the yield of Triticum aestivum varieties

Many biotic and abiotic factors influence the production of wheat (Triticum aestivum L.). Among biological agents, aphids are destructive pests effecting wheat yield drastically. This study was designed to evaluate the impact of foliar Jasmonic acid spray on aphid population as well as on plant growth during aphid infestation in two wheat varieties i.e., Borlaug-2015 and Zincol-2015. Plants are cultivated in pots and treated with jasmonic acid at concentrations of 0.1 and 1 mM (JA). The results revealed that length of shoot and roots decreased after aphid stress and was improved (21-24%) by JA spray. Photosynthetic pigments increased after applying the jasmonic acid spray compared to control plants. Jasmonic acid spray helped the plants to recover from aphid stress by enhanced production of antioxidant enzymes CAT (Catalase) (65-71%), SOD (Superoxide dismutase) (71-74%) and POD (Peroxidase) (61-65%). Consequent to improved defence system, plants treated with JA had fewer aphids as compared to control (60-73% reduction), 24 h after spray. The higher concentration of JA (1 mM) proved more effective as compared to 0.1 mM jasmonic acid. Moreover, Zincol-2015 appeared tolerant as compared to Borlaug-2015 against aphid infestation. The application of jasmonic acid as an exogenous foliar application showed an overall positive impact on the physiological and biochemical attributes of both varieties. It helps the plants to enhance resistance against the biotic stress and can be adopted as future alternative for aphid management. However, detailed studies regarding understanding of underlying molecular mechanisms are needed to optimize the mode for field application.

Terpene Synthase Gene OtLIS Confers Wheat Resistance to Sitobion avenae by Regulating Linalool Emission

Sitobion avenae (Fabricius) is a major insect pest of wheat worldwide that reduces crop yield and quality annually. Few germplasm resources with resistant genes to aphids have been identified and characterized. Here, octoploid Trititrigia, a species used in wheat distant hybridization breeding, was found to be repellent to S. avenae after 2 year field investigations and associated with physiological and behavioral assays. Linalool monoterpene was identified to accumulate dominantly in plants in response to S. avenae infestation. We cloned the resistance gene OtLIS by assembling the transcriptome of aphid-infested or healthy octoploid Trititrigia. Functional characterization analysis indicated that OtLIS encoded a terpene synthase and conferred resistance to S. avenae by linalool emission before and after aphid feeding. Our study suggests that the octoploid Trititrigia with the aphid-resistant gene OtLIS may have potential as a target resource for further breeding aphid-resistant wheat cultivars.

Early Detection of Aphid Infestation and Insect-Plant Interaction Assessment in Wheat Using a Low-Cost Electronic Nose (E-Nose), Near-Infrared Spectroscopy and Machine Learning Modeling

Advances in early insect detection have been reported using digital technologies through camera systems, sensor networks, and remote sensing coupled with machine learning (ML) modeling. However, up to date, there is no cost-effective system to monitor insect presence accurately and insect-plant interactions. This paper presents results on the implementation of near-infrared spectroscopy (NIR) and a low-cost electronic nose (e-nose) coupled with machine learning. Several artificial neural network (ANN) models were developed based on classification to detect the level of infestation and regression to predict insect numbers for both e-nose and NIR inputs, and plant physiological response based on e-nose to predict photosynthesis rate (A), transpiration (E) and stomatal conductance (gs). Results showed high accuracy for classification models ranging within 96.5-99.3% for NIR and between 94.2-99.2% using e-nose data as inputs. For regression models, high correlation coefficients were obtained for physiological parameters (gs, E and A) using e-nose data from all samples as inputs (R = 0.86) and R = 0.94 considering only control plants (no insect presence). Finally, R = 0.97 for NIR and R = 0.99 for e-nose data as inputs were obtained to predict number of insects. Performances for all models developed showed no signs of overfitting. In this paper, a field-based system using unmanned aerial vehicles with the e-nose as payload was proposed and described for deployment of ML models to aid growers in pest management practices.

Effect of bamboo biochar on reducing grain cadmium content in two contrasting wheat genotypes

Wheat is the second most important food crop worldwide, which is prone to accumulate cadmium (Cd). Accumulation of Cd in wheat grains depends not only on wheat genotype, but also largely on the availability of soil Cd and its internal distribution. In this study, several experiments were used to achieve low-grain Cd content: a field trial for wheat genotype screening, a soil incubation experiment to test passivation effect of bamboo biochar on soil Cd, and a soil pot experiment to examine bamboo biochar effect on wheat grain accumulation. The results showed that of the 243 wheat cultivars tested, the variation range of grain Cd content was 0.365-1.243 mg/kg, in a field with soil Cd of 3 mg/kg. The application of bamboo biochar reduced soil Cd availability, among which 5.0% bamboo biochar treatment had the greatest effect. The content of available Cd in soil treated with 5.0% bamboo biochar decreased by 0.32 mg/kg compared with the control in a 120-day incubation experiment. Effect of bamboo biochar (0, 0.1%, 1.0%, and 5.0%) on reducing grain Cd content in two wheat genotypes (Mianyou-1 and 1279-9) was investigated. The application of bamboo biochar decreased Cd uptake by plants, while distribution of Cd in different wheat plant parts was more controlled by the plant genetic characteristics. Compared with the control, Cd content in roots, straw, and grains was decreased by 34.06% (P < 0.05), 21.57%, and 23.33%, respectively, in low-grain Cd wheat cultivar 1279-9 by 5% bamboo biochar application. Overall, the combination of low-grain Cd accumulation wheat and bamboo biochar may be a feasible strategy to lessen grain Cd accumulation in Cd-contaminated soils.