PHYSIOLOGICAL PROCESSES AND CROP PRODUCTIVITY

PHYSIOLOGICAL PROCESSES AND CROP PRODUCTIVITY

1. ASSIGNMENT ON PHYSIOLOGICAL PROCESSES AND CROP PRODUCTIVITY PRESENTED BY- DEEPIKA SAHU Ph.D. Previous year Department- Soil Science and Agricultural Chemistry College of Agriculture, Raipur INDIRA GANDHI KRISHI VISHWAVIDYALAYA, RAIPUR SUBMITTED TO- Dr. NARENDRA PANDEY Professor Agronomy

2. CONTENT PHYSIOLOGY PHOTOSYNTHESIS MECHANISM OF PHOTOSYNTHESIS LIGHT REACTION DARK REACTION DIVERSITY IN DARK REACTIONS RESPIRATION GLYCOLYSIS LINK REACTION KREB CYCLE TRANSPIRATION STOAMATAL OPENEING AND CLOSING TRANSLOCATION CROP PRODUCTIVITY Major determinants of agricultural productivity Suggestions for policy implications REFERENCE

3. INTRODUCTION PHYSIOLOGY - This word is derived from Ancient Greek word " physis " meaning 'nature, origin' and "logia" meaning 'study of'. It is scientific study of functions and mechanisms in a living system . PROCESS- Processes are natural event or sequence of events. Example of physiological processes that occur in living plants are- PHOTOSYNTHESIS RESPIRATION STOMATAL OPENING AND CLOSING TRANSPIRATION TRANSLOCATION

4. PHOTOSYNTHESIS It is the process by which green plants and certain organisms transform light energy into chemical energy. During photosynthesis in green plants, light energy is captured and used to convert water, carbon dioxide into oxygen and energy–rich compounds.

5. PHOTOSYNTHESIS EQUATION : 6CO 2 +12H 2 O→C 6 H 12 O 6 +6O 2 +6H 2 O (in presence of light and chlorophyll) 90% of total photosynthesis is carried out by aquatic plants and 10% by land plants. According to Van Niel (1930), oxygen comes from water in photosynthesis. 6CO 2  + 12H 2 S → C 6 H 12 O 6  + 12S+ 6H 2 O (in presence of light and chlorophyll) Ruben, Hassid and Kamen (1941) used O 1 8 to experimentally show that O 2 in photosynthesis comes from water.

6. MECHANISM OF PHOTOSYNTHESIS Photosynthesis has two phases that are light reaction and dark reaction. Light reaction  or Hill reaction is the process of photosynthesis that converts energy from the sun into chemical energy in the form of NADPH and ATP. The reactions take place on the  thylakoid membranes. The inside of the thylakoid membrane is called the lumen, and outside the thylakoid membrane is the stroma , where the light-independent reactions take place. In each cycle of cyclic-ETS 2 ATP (Adenosine triphosphate ) and in non–cyclic ETS 1 ATP + 2NADPH ( Nicotinamide adenine dinucleotide phosphate) are produced. Six turns of both ETS will provide assimilatory power to produce one molecule of glucose.

7. DARK REACTION Blackman discovered dark reaction. Calvin and Benson gave cyclic pathway for this, thus dark reaction is called as Calvin cycle or C 3 -cycle. First stable product of this cycle is three carbon compound i.e. PGA ( Phosphoglyceric acid). The light-independent reaction of photosynthesis are the chemical reactions that convert carbon dioxide and other compounds into glucose. These reactions occur in the  stroma , the fluid-filled area of a chloroplast outside the  thylakoid membranes. These reactions take the products (ATP and NADPH) of light-dependent reactions and perform further chemical processes on them. Example of C 3 plants include sunflower, soybeans, sugarbeet , rice, wheat etc . Dark reactions are dependent on enzyme but light reactions are dependent on pigments. In dark reaction there are three pathways of CO 2 fixation.

8. DIVERSITY IN DARK REACTIONS Also known as Hatch and Slack pathway. Hatch and Slack Astralia (1967) studied in detail and proposed pathway of dark reaction in sugarcane and maize leaves. First stable product is 4C compound ( oxaloacetic acid). Kranz (Wreath or ring) Anatomy present in leaves of C4 plants. Green bundle sheath cells present around the vescular bundles. Such chloroplast are dimorphic and large. Example of C4 plants- sugancane , maize, sorghum, bajra , Amaranthus , Chenopodium etc.

9. Oleary and Rouhani discovered CAM-process. CAM stands for Crassulacean acid metabolism. 30 ATP and 12 NADPH used for producing of 1 glucose. It occur in Crassulaceae family. CAM plants exhibit ecophysiological adaptaion with xeric habits ( environment with little water, such as a desert or an ice- or snow-covered region). Example of CAM plants are-Agave, Aloe, Opuntia , Bryophyllum , Pineapple etc.

10. RESPIRATION The process of respiration in plants involve using the sugars produced during photosynthesis plus oxygen to produce energy for plant growth. It is the breaking down of organic substances viz. carbohydrate, fat and protein into carbon dioxide, water into energy. Stages in respiration- GLYCOLYSIS LINK REACTION KREB’S CYCLE

11. GLYCOLYSIS Site of Occurance Glycolysis - Occurs in cytosol /cytoplasm Formation of Acetyl COA - (Link Reaction) Perimitochondrial space (outer chamber)/Matrix. TCA cycle or Kreb's cycle - Matrix of mitochondria & cytosol in bacteria. ETS - Occurs in cristae or inner memberane of mitochondria and Oxidative phosphorylation - Occrus in Oxysome head (F1 particle) Glycolysis - EMP ( Embden , Meyerhof, Parnas ) pathway. 1932. The glycolysis is common phase for aerobic & anerobic respirations. Glycolysis involves a series of ten biochemical reactions in cytoplasm. In glycolysis , neither consumption of oxygen nor liberation of carbon dioxide take place. In glycolysis , 1 glucose produces 2 molecules of pyruvic acids (3C) and 2NADH, & 2ATP are generated in glycolysis , which are equal to 8 ATP.

12. GLYCOLYSIS PATHWAY

13. LINK or GATEWAY REACTION Here, Acetyl Co-A is a connecting link between glycolysis and Krebs-cycle KREB CYCLE It was discovered by H.A. Kreb . Kreb cycle begins by formation of citric acid (TCA Tricaboxylic acid). In Kreb cycle 2C02 3NADH,, 1FADH, & 1GTP (ATP) produced by each turn of TCA cycle.

14. Types of transpiration FOLIAR LENTICULAR (.1-1%) STOMATAL (80-90%) CUTICULAR (9%) TRANSPIRATION - The loss of water in the form of vapor from the living aerial parts of the plant is known as transpiration. The principal part of transpiration is leaf.

15. STOAMATA Stomata- Stomata are specialized epidermal cells which are distributed all over leaf surface but in case of terrestrial plants, mainly on lower surface of leaves. Therefore approximately 97% of transpiration takes place from the lower surface in such plants. Each stoma (open) has two kidney (or bean) shaped guard cells. Inner wall of guard cell is thick and outer wall is thin. These cells are surrounded by epidermal or subsidiary or accessory cells. Classification of Stomata :According to the distribution of stomata, plants are of five categories: Apple and Mulbery type : In such plants, stomata are present on under surface only. Potato type : More stomata on the lower (or under) surface than on upper surface. Oat type : Stomata are equally distributed on both surfaces. Water Lily type : Stomata present only on upper surface. Potamogeton type : In such plants stomata are either absent or functionless. Such plants are most of the submerged aquatic plants.

16. On the basis of daily movement of stomata, Loftfield classified it into three main groups. Alfalfa type : Such stomata are open throughout the day and night and are found mostly in thin leaved mesophytes (plant needing only a moderate amount of water) e.g . pea, bean, radish, mustard etc . Potato type : Such stomata are open throughout day and night except for a few hours in the evening. e.g. onion plantain, cabbage, pumpkin etc. Barley type: Such stomata are open only for a few hours during the day e.g. cereals. Continued…

17. 1) The exudation of sap (water) through hydathodes (structure present at the tips of veins of leaves) is called guttation . 2) The cause of guttation is root pressure (positive hydrostatic pressure developed in the xylem ducts of the root system.) 3) Necessary condition for guttation : i )Increased absorption of water and decreased transpiration. ii)Warm soil & humid or cool atmosphere. iii)Warm day and cool night (such condition is available in winter season.) 4) Guttation normally occurs at night. 5) Accumulation of salts at leaf tip or leaf margin of some plants during winter is due to guttation . GUTTATION

18. Hydathode : It is a specialised epidermal cell found at leaf tip or leaf margin i.e . end of veins and veinlets . Bleeding The loss of sap (water) from the injured parts of the plant is called bleeding. The cause of bleeding is root pressure. Continued…

19. The movement of sucrose and other substances like amino acids around a plant is called translocation. In, general this happens between where these substances are made (the sources) and where they are used or stored (the sink) i.e. from sources in root to sinks in the leaves. TRANSLOCATION

20. CROP PRODUCTIVITY It is the quantitative measure of crop yield in given measured area of field. Productivity level of agriculture defines as the amount of crops production (Kg) in per hectare land. Agriculture productivity = Total agriculture crop production Total land area ( hectares) The output value may be compared to many different types of inputs such as labour and land (crop yield). These are called partial measures of productivity. Agricultural productivity may also be measured by total factor productivity (TFP). This method of calculating agricultural productivity compares an index of agricultural inputs to an index of outputs

21. Rice area production and yield during 2017-18 State Area (million ha) Yield (Kg ./ ha) West Bengal 5.52 2906 Uttar Pradesh 5.75 2704 Punjab 3.10 4132 Andhra Pradesh 2.21 3733 Odisha 3.71 1972 C hhattisgarh 3.61 1810 Rice area production and yield during 2018-19 State Area (million ha) Yield (Kg ./ ha) West Bengal 5.12 2926 Uttar Pradesh 5.81 2283 Punjab 3.07 4366 Andhra Pradesh 2.16 3788 Odisha 3.77 1739 chhattisgarh 3.76 1311

22. Major determinants of agricultural productivity Finances/ credit to agricultural sector Input like fertilizers, pesticides High yielding variety of seeds Farm mechanization Rainfall Irrigation facilities Incentives to farmers Minimum support price Consolidation of farm holdings Awareness campaign/ programme Proper transfer of technology

23. Physiology of grain yield in cereals Leaf growth is important in influencing light interception, crop growth and yield in cereals. WATSON reported that leaf area and leaf area duration were the main causes of yield differences rather than photosynthesis or net assimilation rate. There are some physiological aspects which affect the grain yield of cereals: Leaf Area Ratio (LAR) The term, Leaf Area Ratio was suggested by Radford (1967 ). LAR expresses the ratio between the area of leaf lamina to the total plant biomass or the LAR reflects the leafiness of a plant or amount of leaf area formed per unit of biomass . Expressed in cm 2 g -1 of plant dry weight. Leaf area per plant Plant dry weight LAR =

24. Leaf Area Duration (LAD) To correlate dry matter yield with LAI, Power et al. (1967) integrated the LAI with time and called as leaf area duration. LAD takes into account, both the duration and extent of photosynthetic tissue of the crop canopy. The LAD is expressed in days . Where: L 1 = LAI at the first stage L 2 = LAI at the second stage, (t 2 -t 1 ) = Time interval in days LAD = L 1 +L 2 2 x (t 2 -t 1 )

25. REFERENCE Khajuria Sonia and Sakshi . 2015. Agricultural Productivity in India: Trends, Challenges and Suggestions. International Journal of Soil Science and Research . 516-520. Bugbee Bruce and Monje Oscar. 1992. The Limits of Crop Productivity. Validating theoretical estimated and determining the factors that limit crop yields in optimal environment. BioScience , Vol. 42 (7), Crop Productivity for Earth and Space. pp. 494-502.