Deficiency and Toxicity Symptoms in Rice Plant.docx
- 1. SUBMITTED BY: Ronnie Naag SUBMITTED TO: Ms. Vigilia Armendi
- 2. Deficiency and Toxicity Symptoms in Rice Plant Carbon (C), Hydrogen (H), Oxygen (O) Carbon, hydrogen, and oxygen, which are common to all organic matter, are obtained by the plant from the carbon dioxide (CO2) and water (H2O) which enter via the photosynthetic process. The other (following) elements are supplied from the soil and are either naturally occurring or added in the form of fertilizers. Nitrogen (N) Rice plants require a large amount of nitrogen at early and mid-tillering stages to maximize the number of panicles. Nitrogen absorbed at panicle initiation stage increases spikelet number per panicle. Nitrogen absorbed during ripening stage, in the presence of adequate solar radiation, enhances the grain filling process. Specific functions of nitrogen in rice growth and development include: Acting as an essential component of amino acids, nucleotides, and chlorophyll Giving plants their dark green color Promoting rapid growth - increase in height, tiller number, size of leaves and grains Improving grain yield and quality - increase in number of spikelets per panicle, percent filled spikelets, and protein content in grains Nitrogen deficiency symptoms include: Stunted yellowish plants with limited number of tillers Except for the young leaves that are greener, narrow, short, erect, leaves that become yellowish-green as they age Old leaves and sometimes all leaves become light green and chlorotic at the tip - leaves die under severe nitrogen stress Early maturity or shortened growth duration
- 3. Phosphorus (P) Phosphorus is involved in the supply, transfer, and storage of energy for all biochemical processes in the plant. Specific functions of include: Playing an important role in the formation of plant hormones and maintenance of membrane integrity Inducing root development Promoting rapid growth of the plant - active tillering, early flowering, and hastened ripening and grain development Acting as an essential constituent of adenosine triphosphate (ATP), nucleotides, nucleic acids, and phospholipids Deficiency symptoms include: Narrow, dark green, stiff and erect leaves - young leaves remain healthier than older leaves which turn brown and die Except for the young leaves that are greener, narrow, short, erect, leaves that become yellowish-green as they age Reddish or purplish color which may develop on leaves that tend to produce anthocyanin pigment Leaves that appear pale green when phosphorus and nitrogen deficiency occur simultaneously
- 4. Potassium (K) Potassium is not a constituent of any organic compound of plant, but it is a co-factor for 40 or more enzymes. Specific functions of include: Playing an essential function in osmoregulation, enzyme activation, regulation of cellular pH, cellular cation-anion balance, regulation of transpiration by stomata, and transport of photosynthetic products Aiding tillering and increasing the size and weight of the grains Increasing vigor and resistance to some rice diseases Strengthening straw and stems of the rice plant Deficiency symptoms include: Dark green plants with yellowish brown leaf margins or dark brown necrotic spots first appearing on the tips of the older leaves Stunted plants, tillering slightly reduced, weak straw, droopy leaves Wilting when there is an excessive imbalance with nitrogen (low K-N ratio) in plant Dark brown spots on leaves
- 5. Zinc (Zn) Specific functions of include: Playing an essential role in the following biochemical processes: auxin metabolism, nitrogen metabolism, cytochrome and nucleotide synthesis, chlorophyll production, and enzyme activation Acting as an essential component in the cellular membrane as well as being present in some essential enzymes Deficiency symptoms include: Dusty brown spots on upper leaves of stunted plants appearing 2-4 weeks after transplanting Midribs near the leaf base of younger leaves become chlorotic; leaves lose turgor and turn brown as blotches appear on the lower leaves 2-4 weeks after transplanting, uneven plant growth and patches of poorly established hills in the field Under severe zinc deficiency, decreased tillering which may stop completely; lengthened time to maturity or growth duration of the plant Increased spikelet sterility
- 6. Sulfur (S) Specific functions of include: Acting as an essential constituent of amino acids (cystine, cyteine, and methionine) involved in chlorophyll production and protein synthesis; and acting as an essential component of plant structures Acting as an important component of thiamine and biotine which are both involved in carbohydrate metabolism Factoring importantly into the functioning of many plant enzymes, enzyme activators, and oxidation-reduction reactions Deficiency symptoms include: Yellowing of the whole plant - chlorosis is more pronounced in young leaves, the tips of which may become necrotic. This is in contrast with nitrogen deficiency wherein older leaves are affected first. In comparison with nitrogen deficient plants, no necrosis in lower leaves, and leaves are generally paler yellow. Reduced plant height and tiller number, fewer and shorter panicles, and reduced numbers of spikelets per panicle at maturity Delayed plant development and maturity by 1-2 weeks Reduced plant height and tillering (IRRI)
- 7. Calcium (Ca) Specific functions of include: Acting as an important constituent of calcium pectate - a cell wall constituent that is important in the maintenance of biomembrane and cell wall integrity Acting as an enzyme activator, and required for osmoregulation and maintenance of cation-anion balance in cells Promoting normal root growth and development Calcium deficiency causes little change in general appearance of the plant, except in cases of acute deficiency wherein: The tip of the upper growing leaves becomes white, rolled, and curled Necrotic tissue develops along the lateral margins of leaves which eventually turn brown and die In extreme cases, the plant is stunted and the growing point dies Symptoms resembles those of boron deficiency, requiring tissue analysis to distinguish the causes of the symptoms Leaf discoloration (IRRI)
- 8. Magnesium (Mg) Specific functions of include: Acting as a constituent of chlorophyll - involved in CO2 assimilation and protein synthesis Activating several essential enzymes Acting similarly to calcium in the regulation of cellular pH and maintenance of cation and anion balance in cells Magnesium deficiency symptoms include: Pale-colored plants, with interveinal chlorosis first appearing on older leaves and later on the younger leaves as deficiency becomes more severe In contrast with potassium deficiency (where green and yellow stripes run parallel to the leaf), green coloring appearing as strings of beads - in severe cases, chlorosis progresses to yellowing and finally necrosis in older leaves Reduced number of spikelets, grain weight, and grain quality (% of milled rice, protein and starch content). However, height and tiller number are not much affected at low to moderate deficiency ranges Interveinal chlorosis caused by Mg deficiency
- 9. Iron (Fe) Specific functions of include: Acting as an essential component of: electron transport in photosynthesis; and porphyrins and ferredoxins - essential components in photosynthesis Playing an important role as an electron acceptor in redox reactions, and acting as an activator for some enzymes such as, catalase, succinic dehydrogenase, and aconitase Inhibiting absorption of potassium in rice plants Iron deficiency symptoms include: Interveinal yellowing, and chlorotic leaves that turn whitish in color Chlorotic, and ultimately, dead plants (in cases of severe deficiency) Iron toxicity symptoms include: Tiny brown spots on lower leaves, starting from the tips and spreading toward the bases - spots generally combine on interveins Green leaves which, in severe cases, become purplish brown
- 10. Manganese (Ma) Specific functions of include: Playing an important role of O2 evolution in photosynthesis, and in oxidation- reduction processes which involve electron transport systems Activating several enzymes such as oxidase, peroxidase, dehydrogenase, decarboxylase, and kinase Enabling the following processes: formation and stability of chloroplast, protein synthesis, nitrate reduction, and tricarboxylic cycle Lessening iron toxicity Manganese deficiency symptoms include: Interveinal chlorosis which begins at the tip of the younger leaves Chlorotic streaks which spread downward from tip to the base of the leaves and become dark brown and necrotic Newly emerging leaves which are, short, narrow, and light green Stunted plants (though tillering is not affected) Manganese toxicity symptoms include: Stunted plants with limited tillers Brown spots on the veins of the leaf blade and leaf sheath, particularly the lower leave Interveinal chlorosis
- 11. Boron (B) Specific functions of include: Playing a primary role in cell wall biosynthesis and structure and plasma membrane integrity Regulating or catalyzing physiological functions such as: carbohydrate metabolism, nitrogen metabolism, nutrient uptake, sugar transport, lignification, nucleotide synthesis, and respiration Boron deficiency symptoms include: Reduced plant height White, rolled tips of emerging leaves - as in cases of calcium deficiency Dead growing points (in severe cases), though new tillers continue to be produced Reduced or arrested panicle formation Boron toxicity symptoms include: Chlorosis at the tips of the older leaves, especially along the margins. This is followed by the appearance of large, dark brown elliptical spots in the affected parts that ultimately turn brown and dry up Symptom development processes such as: i) yellowish white discoloration of tips of older leaves appearing at 6 weeks after transplanting; ii) as the toxicity progresses, yellowing of the tips and lip margins; iii) depending on the severity and variety, elliptical dark brown blotches appearing in the discolored areas; and iv) entire leaf blades turning light brown and withering Field damage caused by Boron toxicity
- 12. Molybdenum (Mo) Molybdenum's function in rice plants is limited to the reduction of nitrate to nitrite. No deficiency symptoms have been identified. Copper (Cu) Specific functions of include: Acting as a component of metalloenzymes, regulating some enzymatic actions, and catalyzing oxidation reactions Playing a role in: i) nitrogen, protein and hormone metabolism; ii) photosynthesis and respiration; and iii) pollen formation and fertilization Copper deficiency symptoms include: Bluish green leaves, which become chlorotic near the tips Development of chlorosis downward along both sides of the midrib, followed by dark brown necrosis of the tips New leaves failing to unroll and maintaining a needlelike appearance of the entire leaf or occasionally of half the leaf, with the basal portion developing normally Needle-like leaves Chlorine (Cl) Chlorine is essential in photosynthesis. Its deficiency symptoms have not been described in rice.