PLANT PHYSIOLOGY TRANSPORT IN PLANTS PLANT PHYSIOLOGY PLANT

PLANT PHYSIOLOGY TRANSPORT IN PLANTS

PLANT PHYSIOLOGY

PLANT PHYSIOLOGY INTRODUCTION v There are two perspectives in the description of structure and variation of living organisms. v The two perspectives essentially rested on two levels of organisation of life forms and the related phenomena. v One described at organismic and above level of organisation while the second described at cellular and molecular level of organisation. v The first resulted in ecology and related disciplines. v The second resulted in physiology and biochemistry.

PLANT PHYSIOLOGY v The processes of mineral nutrition of plants, photosynthesis, transport, respiration and ultimately plant growth and development are described in molecular terms but in the context of cellular activities and even at organism level. v Wherever appropriate, the relation of the physiological processes to the environment is also discussed.

PLANT PHYSIOLOGY Sir J. C. Bose v In the 19 th century when people considered plants as non-living things, it was because of Sir Jagadish Chandra Bose that the scientific world came to know that plants too have life and feelings. 1858 -1937 v Sir J. C. Bose, born on November 30, 1858 in traditional Bengali family was the first Indian to become a Fellow of Royal Society.

PLANT PHYSIOLOGY v Interestingly, he began his career as a demonstrator in physics and contributed in generating electromagnetic waves of minute wavelength and designed an instrument called ‘Coherer’ for detecting radio waves. v His proficiency in physics won him the first US patent by any Indian. v However, his passion for nature and plant life made him apply his proficiency in physics to the understanding of plant life.

PLANT PHYSIOLOGY v Through his Pulsating Theory, he explained the various bio-electrical responses shown by plants. v Sir J. C. Bose designed a very sophisticated instrument called Crescograph which was so sensitive that it could record even a minute growth of a plant upto a millioneth part of a millimeter. v Apart from establishing the Bose Research Institute at Kolkata, he also authored several books like Research on irritability of plants and Nervous Mechanism in plants.

PLANT PHYSIOLOGY

PLANT PHYSIOLOGY INTRODUCTION v Plants need to move molecules over very long distances, much more than animals do. Besides, plants do not have a circulatory system.

PLANT PHYSIOLOGY v Water taken up by the roots has to reach all parts of the plant, up to the very tip of the growing stem.

PLANT PHYSIOLOGY v The photosynthates or food synthesised by the leaves have also to be moved to all parts including the root tips embedded deep inside the soil. v Movement across short distances, like within the cell, across the membranes and from cell to cell within the tissue has also to take place.

PLANT PHYSIOLOGY v In a flowering plant the substances that would need to be transported are water, mineral nutrients, organic nutrients and plant growth regulators.

PLANT PHYSIOLOGY v Over small distances substances move by diffusion and by cytoplasmic streaming supplemented by active transport. v Transport over long distances proceeds through the vascular system (the xylem and the phloem) and is called translocation.

PLANT PHYSIOLOGY v In rooted plants, transport through xylem (of water and minerals) is essentially unidirectional, from roots to the stems. v Organic and mineral nutrients, however, undergo multidirectional transport.

PLANT PHYSIOLOGY v Organic compounds synthesised in the photosynthetic leaves are exported to all other parts of the plant including storage organs. From the storage organs they are later re-exported.

PLANT PHYSIOLOGY The mineral nutrients are taken up by the roots and transported upwards into the stem, leaves and other growing regions. v When any plant part undergoes senescence, nutrients may be withdrawn from such regions and moved to the growing parts.

PLANT PHYSIOLOGY Hormones or plant growth In a flowering plantregulators there is a and complex traffic of compounds other (but probably verychemical orderly)stimuli moving in different directions. are also transported, though in very small amounts. Each organ receiving some substances and giving out some others.

PLANT PHYSIOLOGY 1. Water absorption takes place through …. . 1) Stem 2) Leaves 3) Roots 4) Flowers MCQS

PLANT PHYSIOLOGY 2. Transport through xylem is essentially…. . 1) Bidirectional 2) Unidirectional 3) No transport 4) Multidirectional

PLANT PHYSIOLOGY 3. Transport through phloem is essentially…. . 1) Bidirectional 2) Unidirectional 3) Multidirectional 4) 1 & 3

PLANT PHYSIOLOGY Thank you…