Advanced Botany

  Photoreceptors allow living organisms to optimize perception of light in the natural environment and thus to gain information about their external world. Analyses performed in different organisms have revealed wonderful examples of structural modifications of the light‐sensing proteins themselves, as well as diversification of the signal pathways they use in relation with their evolutionary history and function. In different organisms, the same photoreceptor may have a very conserved role or may modulate different responses. Two different photoreceptors may be involved in the control of the same physiological response. Light signals are amongst the most important environmental cues regulating plant growth and development which is achieved through a suite of photoreceptor proteins. These photoreceptors can detect the presence, intensity, direction and color of light, and in turn utilize this information to direct their growth. In plants, many types of photore...

  Plants are fixed, so they must encounter abiotic stresses such as drought, salinity, extreme temperatures and more. These stressors alter their growth and development, and reduce crop productivity. Heat stress can be defined as rise in temperature beyond a threshold level for a period of time sufficient to cause irreversible damage to plant growth and development. In general, a transient elevation in temperature, usually 10–15 °C above ambient, is considered heat stress. High temperatures affect plant growth at all developmental stages however, anthesis and grain filling stage is more susceptible. High temperature may adversely affect photosynthesis, respiration, water relations and membrane stability and also modulate levels of hormones and primary and secondary metabolites. The major physiological injuries observed under elevated temperatures include scorching of leaves and stems, leaf abscission and senescence, shoot and root growth inhibition or fruit damage, which ...

  During the last half century, the protection of crops is depended on synthetic pesticides which are highly toxic and have adverse residual effects on crops, groundwater and soil. Moreover, their excessive application, leading to increased resistance of pests.   Few years back, when farmers used pesticides such as DDT and malathion, there was little understanding of how dangerous and long-lasting these chemicals are. It was only later that the degree to which these pesticides remain in the environment was discovered. Organophosphates designed to affect the brain and nervous system of insects, sometimes damage those of humans and animals. These pesticides killed bald eagles, birds, fishes and even people. The World Health Organization (WHO) reported that around two hundred thousand people were killed every year due to chemical pesticide poisoning. World Resource Institute reported that more than 500 insects were resistant to insecticides. Many researchers have suggested usin...

  Spectrophotometer A spectrophotometer is an instrument that measures the number of photons emitted to estimate the intensity of light spectra absorbed and transmitted by a sample. This provides information on the concentration of a compound in the sample. Scientist Arnold J. Beckman and his colleagues at the National Technologies Laboratory (NTL) invented the Beckman DU spectrophotometer in 1940. In 1981 Cecil Instruments produced a spectrophotometer that was microprocessor controlled. This automated the device and improved the speed. From 1984 to 1985, development was made in double beam versions of the instrument which developed into the Series 4000 model. With the 1990s came the addition of external software that provided PC control and onscreen displays of the spectra. Today, the development of the spectrophotometer continues and its applications range from science and medicine to crime scene investigation and law enforcement. Working Principle Spectrophotometer is b...