Plant Nutrition PDF

Plant Nutrition Madara Jayanetti Question Explain the Cyclic and Non-cyclic electron transport in photosynthesis in plants. Lecture outline Introduction to Plant form and Function Plant nutrition Nutrient requirement of plants – minerals Plant reproduction Sexual reproducti...

Plant Nutrition Madara Jayanetti Question Explain the Cyclic and Non-cyclic electron transport in photosynthesis in plants. Lecture outline Introduction to Plant form and Function Plant nutrition Nutrient requirement of plants – minerals Plant reproduction Sexual reproduction and asexual reproduction methods of plants Reproductive organ of angiosperms – flower- structure and function (pollination and fertilization) Plant growth regulators Differences between monocots and dicots ILO Describe the form of plants and animals and functions, pollination, fertilization Growth Requirements 1. Nutrients 2. Water 3. Temperature 4. Light 5. Growth Regulators Concepts of Limiting factors Almost always, one of the growth requirement is limiting production The limiting factor could be any of the growth requirements Once you correct the limiting factor, another growth factor will likely limit production If all the growth requirements are optimized, genetics will limit production Nutrients About 20 Essential elements C, H, O, & N –95% of plants solids Nutrientso Ncont. Primary macronutrients Importance Nitrogen N Proteins, amino acids Phosphorus P Nucleic acids, ATP Potassium K Catalyst, ion transport Secondary macronutrients Calcium Ca Cell wall component Magnesium Mg Part of chlorophyll Sulfur S Amino acids Iron Fe Chlorophyll synthesis Micronutrients Copper Cu Component of enzymes Manganese Mn Activates enzymes Zinc Zn Activates enzymes Boron B Cell wall component Molybdenum Mo Involved in N fixation Chlorine Cl Photosynthesis reactions Nutrient & Water Absorption Most absorption occurs near the apexes of young roots Older roots tend to get “ corky “(layers resistant to water/ Nutrient absorption) Young plants have a relatively small root area: have a relatively high water and nutrient requirements Water The amount of water required by plants for their development depends on varying conditions. According to its type, stage of development and the soil properties. Most crops have a high water content (lettuce-95%) Water is often the limiting factor in vegetable production Water Quality and Quantity are equally important –Salinity is often the major quality problem Water Loss Most water is lost from plants through the stomata on leaves Environmental factors that affect water loss Humidity, wind and temperature Plants may become deficient in water even when soil supplies are adequate Stomata will close, reduce moisture loss and also reduce CO2 uptake Temperature Optimum temperature Range Maximum photosynthesis and normal respiration Diurnual Temperature Fluctuation between day and night temperatures For all crops optimum day temperature is higher than optimum night temperature Optimum temp for photosynthesis is higher than optimum temp for respiration The diurnal temperature range (DTR) reflects the temperature variation within a day Temperature Effects on Crops Warm season crops produce maximum yields under relatively high temperatures Cool season crops produce maximum under relatively low temperatures Excessive temperature will adversely affect crop yields Light Intensity and quality affect crop growth Warm season crops tend to require higher light intensity compared to cool season crops Growth Regulators Plant growth regulators or phytohormones are organic substances produced naturally in higher plants. Controls growth or other physiological functions at a site remote from its place of production and active in minute amounts Growth Regulators Hormones Auxins, Gibberellins, Cytokines, Inhibitors Auxins: -Cell elongation, proliferation & differentiation Gibberellins -Stem elongation, dormancy, flowering, light & temperature responses Cytokines -Cell growth & differentiation -Inhibitors -Restricted growth, dormancy, senescence Type of Growth & Development Vegetative phase Reproductive phase Vegetative Phase From seed germination through growth of the primary supportive structure Three important processes 1. Cell division 2. Cell enlargement 3. Cell differentiation Require large quantities of Carbohydrates Growth rates determined by growth potential and availability of Carbohydrates Quality influenced by growth rates Reproductive phase Maturation of tissues manufactured during vegetative phase Production of growth regulators Development of flower buds, flowers, fruit and seed, or the development of storage organs Relatively little cell division occurs Most of the carbohydrates are accumulated in the fruit, seed or storage organs Differences between monocots and dicots Monocot Vs and Dicot Plant Reproduction Asexual reproduction Asexual reproduction occurs through: Vegetative Propagation Budding Fragmentation Spore formation Sexual Reproduction Self Pollination vs. Cross Pollination Fertilization Fruits and seed formation Seed dispersal Plant Growth Plants are able to grow throughout their lifetime due to the presence of undifferentiated tissues called meristems. Apical meristems add primary growth and cause the stem to increase in length. Apical meristems are located at the tips of stems and roots. Lateral meristems add secondary growth and cause the plant to increase in girth. Reproduction in Angiosperms Flowers –reproductive structures of angiosperm sporophytes, both male and female organs are present in some Flower Vocabulary Complete vs. incomplete flowers Complete flowers = have all 4 floral parts (sepals, petals, stamens, carpels) Incomplete flowers = missing at least one floral part Perfect vs. imperfect flowers Perfect flowers have both stamens and carpels Imperfect flowers are missing either stamens or carpels Pollination and Fertilization Pollination has two forms: self-pollination and cross-pollination. Self-pollination occurs when the pollen from the anther is deposited on the stigma of the same flower, or another flower on the same plant. Cross-pollination is the transfer of pollen from the anther of one flower to the stigma of another flower on a different individual of the same species. Self-pollination occurs in flowers where the stamen and carpel mature at the same time. 31 32