Reflection by the plants in visible range was measured to identify crop signatures specific to EC treatments. Plants grown with different EC treatments clearly separated for reflectance in both blue and red regions of the visible spectrum (see above graph) where chlorophyll absorption is maximum. Most useful ratios to identify lower or higher N stress are being developed using crop reflectance information for several crops.
Lower fertilizer application rates can influence crop quality while higher rates can pose health-risk issues in humans when consumed (ex: spinach and lettuce) and increase plant susceptibility to pests. Therefore, plants should be supplied with fertilizer in the amounts they need to grow optimally. We are investigating methods to fertilize plants based on the plant nutrient demand. Our approach is to non-invasively measure crop growth rate using RGB imaging and supply nutrients that match the crop growth rate. We are currently using this approach for tomato and lettuce. Using imaging we can estimate crop dry weight on a daily basis. This can be used to predict the crop growth rates and the amount of nutrients needed by the plant to sustain the current growth. Below is an example of imaging work done on tomato and relation between image based metric and crop dry weight. We are developing simple camera and Lysimetry based system that can capture crop growth rate and crop water use. [Read More…]
Supplemental lighting is required to produce quality crops inside greenhouses in the northern US. The energy costs for supplemental lighting can be quite significant. For example, to add 5 moles of supplemental light per day using 1000 W HPS lamps during mid Nov to mid Mar for an acre of greenhouse can cost $25000. This makes lighting one of the most expensive input for production. In addition, only a fraction (1-3%) of supplemental light is actually used by plants in photosynthesis. Therefore it is important to improve supplemental light use efficiency of plants for ‘sustainable’ crop production. Our research is focused on identifying environmental factors that transiently reduce supplemental light use efficiency in greenhouses and mitigating these transient stressors during production. We use a combination of remote sensing techniques to identify supplemental light use efficiency of plants and transient environmental stressors experienced by plants in greenhouses. Our goal is to develop affordable technologies that can be easily transferred to the greenhouse[Read More…]