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The first objective in the plant pathology PA project was to evaluate the ability of infrared transducers (IRT) to differentiate between biotic and abiotic stresses. IRTs were purchased and attached to the new center pivot at Bushland in such a way that they scanned plots in multiple crops exhibiting a diversity of biotic and abiotic stresses (Fig. 3). Because foliar symptoms of root diseases often mimic the appearance of plants under water stress, we scanned plots during periods of high evaporative demand and also during the evening when water stressed plants would regain turgor while those wilted due to disease would still be flaccid. Results of this work were encouraging and demonstrated that IRTs could easily differentiate between stressed and unstressed plants. Scanning during periods of peak evaporative demand and again early in the evening may allow differentiation between water stress and disease stress (Fig. 4).
Although IRTs attached to the center pivot are able to detect stress and possibly differentiate between biotic and abiotic stress, the system in its present configuration is unsuitable for adaptation by farmers. Although the system has promise for wheat, which completely covers the ground during early stages of development, row crops exhibit too much soil for accurate readings, especially when diseases are present. However, the most serious problem with the current system is accuracy and durability of the IRTs. The IRTs we purchased are not rugged enough for field use and after only one year, many began to give highly variable readings. Based on our greenhouse work, differences of two - three degrees might differentiate between biotic and abiotic stresses and this much variation was seen in our IRTs. Although our system, in its present configuration, is unsuitable for on farm use, it is still beneficial for research because results with our IRTs should relate to other methods of remote sensing, such as aerial or satellite, using infrared radiometry. |
