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A Report On Plant Water Stress

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9. Introduction:
Plant water stress is a major factor affecting crop yield. With the ever-increasing human population, there is a constant stress exerted on water resources (McGwire et al., 2000). So irrigation to avoid or relieve this stress must be done judiciously, not only to avoid environmental problems such as groundwater pollution and runoff, but also to keep the cost down on a limited and expensive resource. Soil moisture sensors are often used for precision irrigation control purposes. However, soil moisture sensors can only assess the degree of water deficit stress that is imposed to the plants, but not necessarily the level of water deficit stress that is actually experienced by the plants (Sinclair and Ludlow, 1985). An …show more content…

Conventional methods of estimating leaf water content in the field are time consuming and location specific. Remote sensing is an effective alternative to field sampling for the retrieval of leaf water content, being non-destructive and providing continuous spatial coverage of a large area (Sepulcre-Cantó et al., 2006; Ullah et al., 2012c). Plant water status can be assessed remotely by measuring canopy reflectance, since they change in response to crop water content (Pen˜uelas et al., 1997; Ustin et al., 1998; Stimson et al., 2005). As a technique, canopy spectral reflectance offers a number of advantages, such as easy and quick measurements, integration at the canopy level and the fact that additional parameters can be estimated simultaneously via a series of diverse spectral indices (i.e. photosynthetic capacity, leaf area index, intercepted radiation, and chlorophyll content) (Araus et al., 2001). Given its versatility, canopy reflectance is a valuable tool for high throughput phenotyping (Montes et al., 2007; Chapman, 2008). Leaf water status has been successfully estimated using the near infrared and shortwave infrared (Zygielbaum et al., 2009). In contrast, the mid and thermal infrared (2.5–14 μm) domain is mostly ignored because of a number of challenges, including unavailability of spectroradiometers (i.e. sensitive to the mid to thermal infrared), and the subtle variations in

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