Location: Horticultural Crops Production and Genetic Improvement Research Unit
Project Number: 2072-30500-001-022-S
Project Type: Non-Assistance Cooperative Agreement
Start Date: Jul 1, 2026
End Date: Jun 30, 2030
Objective:
Research will be conducted to evaluate the usefulness of proximal sensors for predicting grapevine leaf tissue nutrient content and water status.
Specific objectives include:
1. Correlate soil and grape leaf nutrient status measurements to sensor response values.
2. Correlate grape water status measurements with leaf petiole images and soil moisture sensor response values.
3. Develop guidelines for grape growers for using proximal sensors to evaluate grape leaf nutrient and water status and soil moisture sensors and petiole cross section images to estimate grape vine water stress.
Approach:
The Cooperator agrees to work closely with ARS in planning and conducting the research outlined below. The Cooperator has already purchased a portable device claimed to function as a leaf nutrient sensor for field testing. The ARS scientist will provide technical expertise to support activities of a post-doctoral scholar and Ag Research Technologist II.
Objective 1: Accurately determining soil and plant nutrient status in a timely manner is critical to avoid nutrient deficiencies which negatively affect grape yield and quality, and to avoid excess fertilizer application which has adverse economic and environmental impacts. Currently, growers must take soil and plant tissue samples during the growing season and send them out to analytical laboratories for nutrient analysis. This is laborious and can take days to weeks to receive actionable data. Additionally, typically only a few samples per vineyard are collected, which limits the applicability of the results to all the plants in the vineyard because no spatial information can be extracted from the data. Proximal sensors could be used to rapidly evaluate the nutrient status of individual plants, enabling faster decision making and more precise, variable-rate nutrient applications. Sensors will be tested to determine soil and plant nutrient status; this data will be ground-truthed by correlation with conventional nutrient analysis approaches.
Object 2: Determining plant water stress in grapes is critical for making timely irrigation decisions and to avoid over- or underwatering, both of which adversely impact grape yield and quality. Current practices for measuring water stress (leaf water potential) in grapes require the removal and pressurization of individual leaves in a portable but heavy device, which is a slow process. Correlations between leaf water potential values, images of petiole cross sections, and soil moisture sensor values will be developed to better predict grapevine water status.
Objective 3:
Guidelines will be developed for grape growers to use proximal sensors to estimate grape leaf nutrient status. Additional guidelines will be developed for grape growers to use imaging and soil moisture sensors to estimate grapevine water stress.