ADAPTATION TO LIGHT REGIME
• Plants can be classified ecologically based on their light requirements
• Those that require full sunlight for good growth are called heliophytes, while those that thrive in the shade are called sciophytes.
The Heliophytes plants
• These are more adaptable than others, which can survive in partial shade,
• these are the pioneer species of tropical forests,
• Under natural conditions, heliophytes can never reach photosynthetic saturation, no matter how bright the light is.
• Heliophytes' growth and reproduction, as well as yields, are severely hampered when they are shaded.
• Sugar cane, sunflower, and maize are examples of heliophytes.
The Sciophytes plants
• These are unaffected by brief bursts of bright light.
• Secondary species that colonised the area after the establishment of heliophytic trees.
• Less efficient at using high light intensities than heliophytes.
• Can often achieve saturation at light intensities as low as 20% full sunlight.
• Also known as photophobous plants, reach saturation in only 20% of the light they receive.
ADAPTATION TO WATER-SCARCITY AND HEAT
• Plants with short life cycles are known as ephemerals. The term ephemeral refers to something that is fleeting or quickly disappearing. When it comes to plants, it refers to a variety of different growth strategies.
• Spring ephemeral plants emerge quickly in the spring and die back to their underground parts after a brief growth and reproduction phase.
• Desert ephemerals are plants that have evolved to take advantage of arid climates' brief wet periods.
• Weedy ephemerals are very short-lived plants that live for less than a growing season in areas subjected to recurring human disturbance, such as ploughing.
• A xerophyte is a plant species that has evolved to survive in a dry environment, such as a desert or an ice- or snow-covered region in the Alps or the Arctic.
• Cacti, pineapple, and some Gymnosperm plants are examples of xerophytes.
• Xerophytes' structural characteristics (morphology) and fundamental chemical processes (physiology) have been adapted in various ways to conserve water, which is also used to store large amounts of water during dry periods.
• They have deep-spreading roots and the ability to store water, xerophytes like cacti can withstand prolonged periods of drought.
• The leaves are waxy and thorny, which prevents water and moisture from escaping.
• Even their fleshy stems have the ability to store water.
• Xerophytic adaptations include small leaves, sunken stomata, leathery leaf surfaces, thorns in place of leaves, leaves reduced to spines, no leaves, and so on.
• Many xerophytes may accumulate proline (an amino acid) in response to stress or chaperonins (heat shock proteins), which help other proteins maintain their structure and avoid denaturation in high temperature conditions.
• It also known as succulents, are plants with thickened and fleshy parts that are thickened and fleshy in places where water is scarce, such as arid climates or soil conditions.
• The term "succulent" is derived from the Latin word sucus, which means "juice" or "sap."
• Water can be stored by succulent plants in a variety of structures, including leaves and stems.
• The term "succulent" is sometimes used in horticultural contexts to exclude plants that botanists would consider succulents, such as cacti. Because of their striking and unusual appearance, succulents are frequently grown as ornamental plants.
• It also known as carbon assimilation, is the process by which living organisms convert inorganic carbon (carbon dioxide) into organic compounds.
• Photosynthesis is the most well-known example, but chemosynthesis is another form of carbon fixation that can occur in the absence of sunlight.
• Autotrophs are organisms that grow by fixing carbon.
• Photo-autotrophs use the energy of sunlight to synthesise organic compounds, whereas litho-autotrophs use the energy of inorganic oxidation to synthesise organic compounds.
• Heterotrophs are organisms that grow by consuming carbon from autotrophic organisms. Heterotrophs use organic compounds to produce energy and construct body structures.
Various organic compounds are referred to as "fixed carbon," "reduced carbon," or "organic carbon." In some plants, C4 carbon fixation, also known as the Hatch–Slack pathway, is a photosynthetic process. It is the first step in removing carbon from carbon dioxide so that it can be used in sugar and other biomolecules. The four-carbon molecule that is the first product of this type of carbon fixation is referred to as "C4". Because the key feature of C4 photosynthesis is the operation of a CO2-concentrating mechanism in the leaves, which serves to saturate photosynthesis and suppress photorespiration in normal air, plants with this pathway perform better in low-soil water environments.
ADAPTATION TO AQUATIC ENVIRONMENTS
• Plants that are naturally adapted to growing in water or waterlogged soil are known as aquatic plants, hydrophytes, or hydrophytic or water-loving plants.
• They can grow completely submerged, partially submerged, floating on the water's surface, or with roots anchored to the ground in swamps or near bodies of water.
• Because of morphological and anatomical changes, they can thrive in watery environments as their natural habitat.
• Aerenchyma (large air spaces in the leaves and petioles) may be present, which aids in the transportation of oxygen produced during photosynthesis.
• Free floating plants and hydrophytes have poorly developed or absent roots. As a result, they usually have emergent leaves (i.e. leaves that protrude above the water surface), which aid in gas exchange and provide buoyancy
ADAPTATION IN SALINE ENVIRONMENT
• Under hot and dry conditions, halophytes can become succulents and dilute salt concentrations by storing water in their stems and leaves.
• The presence of salt glands aids in the excretion of excess salt into the soil.
• Osmoregulation also aids in the prevention of salt accumulation. Glycerol, proline, and sobritol are organic compounds that aid in osmoregulation.
• Because halophytes are exposed to saline and anaerobic conditions in wetlands, tidal marshes, and other similar environments, they have evolved special adaptations such as vivipary (Seeds germinate while attached to trees) and pneumatophores (Seeds germinate while attached to trees) (respiratory roots).
• Such roots aid in the transport of oxygen from the atmosphere to the main roots. Prop and stilt roots are common in plants that provide support in wet substratum.
ADAPTATION TO OLIGOTROPHIC CONDITIONS
• A nutrient deficiency exists in an oligotrophic environment.
• An oligotroph is an organism that can survive in a low-nutrient environment.
• Deep oceanic sediments, caves, glacial and polar ice, deep subsurface soil, aquifers, ocean waters, and leached soils are all examples of oligotrophic environments.
• Nutrient accumulation in vegetation is high in nutrient-deficient soils.
• Mychorrhizae, which have a mutualistic relationship with roots, are found on many plants that grow in Oligotrophic conditions. They aid in the efficient absorption of nutrients from the soil (for example, phosphorus).
• Ectomychorrhizae form a mat outside the roots of plants, whereas Endomychorrhizae live inside the roots.