Study Sheet for exams, Study notes of Plant physiology

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Lecture 1 Weed: plant that interferes with welfare of men and growth of other plants Weed Science: biology and ecology of weeds and how to manage them for the betterment of mankind Weed Management: multiple weed tactics into a single weed management to solve a weed problem Allergies: - Ragweed, poison ivy Poisoning: - Poison hemlock, jimsonweed Fire Hazard: - Downy brome, eucalyptus Visibility: - Roadways and powerlines Livestock Poisoning: - Perilla mint, leafy spurge US Native: Palmer amaranth Europe: annual bluegrass Asia or Africa: barnyard grass Cotula mexicana Colula australis Holcus mollis Poa annua Poa trivialis Lecture 2 Weeds are classified by: - Habitat - Aquatic - Emergent: rooted in shallow water - Free Floating - Rooted Floating - Submersed: roots and plant under water - Terrestrial - Prostrate: flat over ground - Ascending: flat with tips pointing up - Erect: vertical growth; stem perpendicular to ground - Climbing - Twining - Tendrils - Life cycle - Herbaceous: non-woody above ground stems that die each year with temp. - Annual: summer and winter; 1 year plant - Biennials: 2 year plant; vegetative in year 1 (rosette), flower and make seed year 2 (bolting) - Perennials: many years - Simple - Creeping - Vegetative - Morphology - Rhizome: horizontal creeping underground stem bearing roots and scale leaves; perennial stems (quackgrass) - Stolon: horizontal creeping above-ground stem (bermudagrass) - Bulb: short, thick, vertical stem surrounded by scale leaves; perennial (onion) - Tuber: enlarged underground stem with buds producing aerial stems (artichoke) - Physiology - How they function internally: - C3: cool and moist; normal light - Soybean, cotton, peanut, rice, barely, wheat - C4: high temperatures and light - Bermudagrass, sugarcane, sorghum, corn, grasses - Taxonomy - Taxis (Arrangement) + Nemos (Law) - Division: angiospermae (flowering) - Class: - Liliopsida: monocots (grasses and sedges), 1 cotyledons - Leaves lack ligules and auricles; leaf sheath is continuous; stem is triangular with solid internodes - Magnoliopsida: dicots (broadleaves), 3 cotyledons - Order: Liliales - Family: liliaceae - Genus: Lilium Pinnate: compound leaf with leaflets along rachis (feather or fern looking) Palmate: compound leaf with leaflets originating from same place Taproot: derived from radicle of embryo and primary root; dicots; secondary roots emerge from taproot Fibrous Root: grasses and monocots Lecture 3 Seed: fertilized ovule, embryonic plant enclosed in a seed coat Intraspecific: same species - More intense than interspecific - High: decreases biomass per individual - Need optimum density for maxed yields - With density, think crop canopy with relation to light - Difficult management - Corn - corn - Planted soybean - volunteer soybean Interspecific: different species - Corn - pigweed - Soybean - volunteer corn - Pigweed - barnyardgrass Factors Affecting Weed and Crop Competition - Time of Emergence - First emerging plants get to use resources better - High competition when crop is young - Early season competition impacts yields more than late season - Growth Characteristics - Root development, plant height, leaf area, branching - Life Cycle - Annual vs. Perennial - Row Spacing - Narrow Row = crop is more competitive and canopy closer sooner - Weed / Crop Species - Plant Date - Relationship with emergence time - Planting Depth - Relationship with emergence time - Weed Density - Reduce resource availability; increase crop density = decreases weed density Critical Period: period during crop production that weeds must be controlled to prevent a yield loss - If summer crops are maintained weed-free fro first 4-6 weeks, they should be good Stage 1: little effect ; populations do not warrant cost of control Stage 2: linear effect; density at which control measures should be initiated Stage 3: intraspecific competition; density so high that weeds begin to compete with another Allelopathy: interference where one plant, through its living or decaying tissue, interferes with growth of another plant via chemical inhibition (effects germination) - True Allelopathy: plants releases chemical into environment toxic to other plants - Functional Allelopathy: plant releases chemical that is NOT toxic, but it is turned toxic by microbes in the soil - Autotoxicity: - Inhibits growth or reproduction of members of that same species - Alfalfa self thinning - Allelopathy affects nutrient uptake Allelochemicals: plant metabolites - Very from simple molecules (ammonia) to complex (flavonoids) F. Parasitism: one plant interferes with growth and development of another plant - Parasitic plants can live in or on hist and derive resources from host plant - Obligate Parasites: survive in presence of living host - Non-Obligate Parasites: survive with or without host - Root Parasite: witchweed - Stem Parasite: mistletoe, field dodder - Most are flowering plants - Attach to host via Haustorium Lecture 6 Weed Prevention: not allowing a weed to be introduced into an uninfested area Weed Control: suppression of a weed to the point of its effect is minimal Weed Eradication: elimination of all plants and parts of a weed from an area Federal Seed Act: labels of % pure/weed; 9 weeds not permittable to US; more than 2% weed is not allowed in the US Federal Noxious Act: more strict; instead of 9, now 33; inspections at ports MS Pure Seed Law: more than 2.5% weed is not allowed Primary Tillage: - Moldboard: total inversion of soil - Dics: slices through soil - Chisel: beaks up, but does not not invert Secondary Tillage: - Rotary Hoe - Field Cultivator - Harrow Biological Control - Using nature to win the war - Utilization of organisms for the regulation of host plant densities - Organisms can consume or disrupt weeds Conservative Bio Control - Natural enemies of a given weed - Introducing insect that will eat that weed Inundative Bio Control - Releasing mass populations of a known natural enemy at high doses - Most commonly used with pathogens - Often applied as a spray - Bioherbicide Selective Herbicide: leave desired crops unharmed Non-selective: kill plants indiscriminately Types of Herbicide Use: - Pre-plant Incorporated (PPI): prior to planting; herbicide applied to soil and incorporated within - Pre-Plant Surface (PRE): prior to planting and weed emergence but not incorporated - Preplant Burndown: prior to planting to control emerged weeds