1a. Objectives (from AD-416):
Research has demonstrated that the white, reflective particle film used to repel a wide range of insects also reduces plant temperature and heat stress, while reflecting UV radiation and altering the phytochrome-sensitive wavelengths of visible light. Field studies have documented that the reduction of plant temperature results in increased photosynthesis and often water use efficiency, and the reduction of UV radiation has reduced oxidative stress. Research will identify critical plant growth stages and mechanisms by which the particle film increases photosynthesis, water use efficiency, and improve food quality. This fundamental knowledge will be incorporated with particle film application for insect control in order to effectively apply the particle film materials in a commercial setting. The results will enhance the multi-functionality of particle film technology for use in a broad range of crops.
1b. Approach (from AD-416):
1) Develop leaf and canopy reflectance/transmission models and incorporate them into sophisticated crop gas exchange models. These models will incorporate: a) the reflectance/transmission characteristics of specific minerals and formulations, b) the leaf reflectance/transmission characteristics of different plant species, and c) the reflectance/transmission characteristics of specific formulations on the plant leaf. 2) Develop leaf level gas exchange data for key horticultural and field crops. These data serve as the starting point of the crop modeling process. Data already exist for cotton, soybeans, corn, wheat, and rose. 3) Validate modeling with whole plant gas exchange studies in growth chambers. This work will provide a rational basis for selecting which crops can be expected to respond to a reflection-based treatment in specific environments. In addition, it will provide insight into the necessary characteristics of formulations.
3. Progress Report:
The end user version of software for simulating particle film (PF) effects on fruit trees and other crops has been completed and released in October 2012. This software, PFS, is capable of simulating the effects of PFs on crop photosynthesis, biomass accumulation, water use, and water use efficiency (WUE) of 13 crops including apple, peach, walnut, orange, and olive at 23 locations in California and Washington from observed weather data. PFS is also capable of predicting the effects of PF residue amount, application passes, formulation percentage, soil moisture availability, and leaf area index on crop performance. Our results indicate that canopy closure with high leaf area index (LAI) is critical to maximize the benefits of PF but also other canopy architecture traits, such as leaf angle, interact with the effectiveness of PF applications on enhancing crop WUE and biomass accumulation. Our analyses also revealed that PF benefits are more pronounced as growing season temperatures increase. These simulation results correspond well with the experimental findings obtained over many years.