With increasing interest in the application of spectral reflectance/remote sensing technique to crop growth studies encourages a close examination at appropriate sensors to monitor crop growth. Electromagnetic radiation from sun is found at wavelength 300-3000nm. Green vegetation and soil absorb part of this radiation; the remainder is reflected back into the atmosphere. This reflected radiation provides information about physical and physiological status of the plant. Plant absorbs blue and red light and reflects green light thats why they look like green. Mostly reflection is in near infrared regions because of spongy mesophyll tissue of the plant. These are the air spaces between the cells that make the mesophyll cell spongy. The mesophyll cells and air spaces strongly reflect and transmit radiation. Structural differences of the mesophyll cells, varies from species to species. When comparing young to mature leaves of healthy vegetation, the young leaves have a lower reflectivity than mature leaves. This is because young leaves are still developing structurally and are more compact with less airspace in the mesophyll tissue than the mature leaves. When vegetation is stressed, reflectivity is lower than that of healthy vegetation. Stress can include nutrient stress deficiencies, lack of moisture and disease. When vegetation is stressed, reflectivity in the near infrared is influenced either by the collapsing of the intercellular spaces in the mesophyll layer or by cell wall degeneration. The destruction of the intercellular air spaces may reduce light scattering within the leaf causing reflectance to decrease. It was mentioned before that different species of plants have different mesophyll structures that cause the plants to vary in the amount of near infrared light they reflect. Estimation of cereal crop production is considered a priority in most research programmes due to relevance of food grain to world agricultural production. This technique is helpful in assessing basic nutrient response, yield potential and abiotic stresses and also provide an instantaneous, non-destructive and qualitative assessment of the crops ability to intercept radiation and photosynthesize. Spectral reflectance (SR) can be used to estimate a range of physiological traits, including leaf area index (LAI), water status, chlorophyll concentration, and photosynthetically active radiation. Normalised Difference Vegetative Index (NDVI), the most widely used spectral vegetative index, is positively correlated with crop dry matter, leaf area index (LAI) and green area index. It has been used to estimate photosynthetic capacity. In-season grain yield can also be predicted based on canopy reflectance (NDVI). This is helpful in assessing the in season biomass to predict the yield especially in wheat and barley. In conclusion Spectral reflectance indices (SRI) is a technique in which Normalised Difference Vegetative Index (NDVI) scores are used to assess the abiotic stresses of the field crops and then remedification measures for the abiotic stresses can be suggested to farming community for achieving the high economic yield. Author is a PhD student of Agro- Climatology Lab, Department of Agronomy, UAF, working under supervision of Prof. Dr. Ashfaq Ahmad Chattha