Abiotic Plant Problems-Module 3 Quiz

Leaf Scorch

Combination of light interacting with high temperatures and water stress that results in insufficient water uptake leading to damage to foliage

Winter Sunscald

Damage to bark of trees caused by extreme temperature fluctuations, by direct sun exposure and by air temperature, followed by freezing temps

Sunburn

Damage to foliage, bark, or/and fruit after excessive exposure to direct sunlight, created by either excessive tissue temperatures, or high levels of ultra violet light. sunburn = summer problem.

Leaf Scorch Symptoms

necrosis on leaf margins and tips, progress to juvenile leaves, marginal necrosis that progresses inwards on leaves, mild intervenaial chlorosis, defoliation

Differential Diagnosis from lead scorch to sunburn

leaf scorch has symptoms on margin and tip of older leaves

Other causes for leaf scorch

oxygen exclusion, compacted soils, natural gas leaks, over watering, high salinity

Leaf Scorch Disorder

roots unable to supply to foliage as fast as its lost, anything that affects plants ability to take up water (insect and disease), symptoms limited to leaf margin and tip help distinguish leaf scorch

Abiotic vs Biotic Leaf Scorch Differential Diagnosis

signs in roots or vascular presence of soil borne disease, insects or nematodes, nematode root gall, degradation of pith, vector insect, progressive symptoms accompany biotic leaf scorch such as chlorosis and stunting, or root or root tip lesions dead roots

Sun scald Winter Injury physiological cause

cold winter weather after the tree bark warms from direct sunlight exposure, de-acclimates, and then cools as sun drops below horizon

Sunscald Symptoms

elongated area of dead bark, south and west sides of trunk and limbs, upper sides of poorly shaded horizontal branches, bark a reddish/brown, dried bark separates from wood shrinks and appears sunken, symptoms may not show till following season

Plants most susceptible to sunscald

young trees, recently planted trees, tress that received hard pruning and expose new limbs, trees w/ think bark, deciduous tress more prone than evergreen

Management Prevention

wrap young tree trunks with tree wrap or paint with white latex, prune carefully, retain lower 7 years after planting, choose species well-adapted to climate, good cultural care with adequate irrigation, mulch to retain moisture and moderate soil temp, avoid placing trees with west to south west, temp fencing

Management Corrections

remove dead and loose bark with sterilized knife, do not treat with tar or paint, callus and close over wound, wound dressing

When is Sunburn most likely to occur?

summer, periods of high temp, appear on plant parts directly facing sun, other disorders resembling sunburn=water stress, salt stress, nutrient toxicity, gas injury, and herbicide injury

2 Ways Light affects plants

light energy for photosynthesis, creates heat energy

3 Ways plants can lose heat

evaporation of water vapor through stomata, convection of air currents around foliage, radiation from leaves

Solar Heat

many plant injuries attributed to excess light are caused by the transferred heat energy, growers compensate by reducing light in greenhouses, ensuring transplants are properly adapted

Plant Adaptations of Sunburn

leaves cool efficiently, plant can make minor adjustments with tropism and wilting, developing new fruit have few stomates

Genotypic Susceptibility Sunburn

early maturing cultivars of summer fruiting crops, fruit with less lead canopy-high harvest index, fruit production mid to early summer longest days and highest light intensity

Genotypic Susceptibility Sunburn ex

eggplant, tomato, pepper, melon, cumcumber bean, sweet corn, and some tree fruits

Photo-Oxidative Bleaching

Development of white, “bleached” tissue from direct sun exposure

Photo-Oxidative Sunburn

symptoms makes fruit and foliage unmarketable, create entry points for fungal and bacterial pathogens, especially fruit rots, damages leaves senesce reduces fruit yeild

Photo-Oxidative Symptoms

area of leaf or fruit turns papery white or tan, sudden onset, at normal temp, leaf tissue quickly desiccates and senesces, wrinkling of fruit

Causes of Photo-Oxidative bleaching

accessory pigments unable to protect the chloroplast from excess light radiation, bleaching occurs at lower temps, damage from short wavelength, high energy UV, disrupting cell membrane, thylakoid membrane become dismantled

Differential Diagnosis

Check orientation of bleaching injury relative to sun and distribution on plant, Consider pigment inhibiting herbicide drift or oil carryover, Consider failure to harden young plants prior to transplanting in field

Potential Issues of Photo-Oxidative

Cultural practices and weather conditions influence incidence of photo-oxidative sunburn, Poorly acclimated (hardened) plants or, transplants planted in field before acclimation, Sunny days that follow periods of cloudy wet weather, After storms where leaf canopy cover is lost, Late pruning or trellising

Sunburn Browning & Necrosis

caused by the heat energy of solar radiation (long waves)

Sunburn Browning

Damage/loss of pigmentation on exposed side of the leaf or the fruit, plant temperature of 110°to 115°F, Degradation of pigments, but cells remain alive, and organelle membranes retain integrity

Symptoms of Sunburn Browning

Bronze, chlorotic yellow, or brown discoloration spots on foliage or fruit angled in the direction of sun exposure

Sunburn Necrosis

death of epidermal tissue and underlying tissue on stems, leaves, or fruit, on the side exposed to direct sun

Causes of Sunburn Necrosis

Long wavelength sun radiation causes overheating thermal death of plant cells and tissues, Loss of cell membrane integrity –leaking of cellular content, Temperature thresholds vary depending on spp.

Plants use light energy between

390-730 nm

Chloroplast Mobilization

Under low light the leaf plastids either fail to develop into functional chloroplasts, or revert to etioplasts, Remobilization can occur in hours to days, Dependent of age of plant tissue, Green plant parts are pale, mimicking N deficiency

Plants growing under low light twill show no response to what?

Nitrogen Fertilization and become more susceptible to disease

Light Level Requirements Of Plants

Propagation of plugs & cuttings: 8-12 mol/m2/day (after callus) ,Bedding plants: 10-12 mol/m2/day or > , Hydroponic lettuce: 15-17 mol/m2/day, Tomato: 20-30+ mol/m2/day for maximum yield

Low Light Effect

plant cannot gain biomass, DLI levels, low instantaneous light levels need to meet and exceed compensation point, sugars made by photosynthesis are less than the sugars required for respiration, interacts with temp, water and cultivar characteristics, decreased root:shoot biomass

Eitolation

Leaves pale green, Leaves smaller and thinner than normal but more of them, Herbaceous stems stretch taller and are weak, few flower buds, higher leaf area index

Variegation Reversion

Combination of genotype and light environment interaction Low light reduces the amount of variegation in new growth

Oedema

Occurs when plant's roots absorb water faster than the leaves can release it through transpiration, when soil is warm and moist, water pressure builds in the lead cells causing swelling and protrusions, stomatal openings plug, cells burst of become tan

Odema Differential

Spider mite and thrips damage may also cause necrotic spots Necrotic spots also looks like early sunburn damage

Odema Prevention and Managment

Choose less susceptible species or cultivars, Increase light intensity, Increase airflow, Increase greenhouse temperatures to reduce relative humidity, Adjust (reduce or earlier in day) irrigation schedule

Causes of Pepper strip

Insufficient light levels and shading of fruit, Reduced transpiration and limited calcium movement under low light and high temperatures, Sporadic occurrence, Blamed on a combo of environmental (temperature & light) and genetic causes, as well as nutrient imbalances

Almond Management Frost Damage

blossoms are most sensitive at post bloom petal fall; 30 min of subfreezing temps

A slow decrease in temperature causes what

Ice crystals to form gradually on the cell walls of plant tissue, can lead to dehydration, rapid freeze causes crystals in cells

Acclimation & Other protective measures from freeze

withhold nitrogen and cut back on irrigations in fall, acclimated cells also accumulate more solutes

Other Protective Measures for Crop Managments’s

Keep soil bare and avoid use of winter cover crops, keep soil flat clean and moist to allow absorption of heat, keep roots hydrated to help prevent dehydration of cells

Protective Measures to Reduce Frost Risk

Running sprinklers-insulates, wind machines, helicopters during inversions

Insufficient Chill hours

chilling requirement is minimum period of cool temp for normal bloom to occur the following growing season

Chill hours defined are

under 45F but not below 32F, hours above 60F are subtracted from accumulated total

Insufficient chill hours causes

reduced fruit production, delayed bud break, plant dosn’t know when to break dormancy

Insufficient chill hours for flower development

require minimum chill hours as a dormant bulb to allow proper flower development and stem elongation, flowers are deformed and have short stem if they don’t have these hours

In fruit trees what are problems with meeting chill hours too soon

short temp spikes can induce flowering if chill hours met leaving flowers susceptible flower buds to freeze, choose cultivars to match chill hours

Lightning Strikes Severity is dependent on

water status of plant, species, tree size, and strike intensity

What happens for lightning strikes?

lightning travels through trees water rich tissues and area below the bark, water heats up and turns to steam

Lightning Strikes into Crop Fields

significant damage to localized area, instant death through heat and shock waves, blacked scorched tissue on stems, leaves, and fruits, circular pattern

Water Stress-Drought what happens to plant

plants metabolic and cellular process response to salinity have much in common with drought stress, symptoms similar, requires additional testing

Drought Stress in Plants

once visual symptoms appear damage is done, know crop and most sensitive growth stages susceptible to drought/salinity stress

General Symptoms of Drought

leaf wilting or drooping tendrils or petioles not turgid, leaf dull bluish-green, grayish -green, or dark green color cast, leaf curling or rolling from midday

Progression of Drought Symptoms

marginal leaf necrosis, leaf drop, reduced new leaves, blossom drop after flowering and pollination, hot spot areas, soil crusting and poor irrigation, necrotic spots on recent growth, decreased growth, decrease sink strength, high fruit % of small deformed misshapen culls

Monocot and Dicot Drought Syptoms

Dicot: symptoms how between veins, Monocot: leaf scorch is parallel with lead vein and on leaf tip

Water Stress Drought

bean leaf scorch, veins to desiccate, leaves curl and droop drought stress, lower canopy thinning with chlorosis, necrosis and eventual leaf drop, collages of squash, pollination failure

Physiological Response to Water Stress

Abscisic is synthesized in root quickly sending signal to shoot and lead, leading stomatal closure, lead stomata close, both stomatal and non-stomatal limitations imposed

Physiological Responses to Drought

stomatal limitation, decreases leaf CO2 and photosynthesis, non-stomatal limitations, decrease leaf water potential and RuBisCO enzyme and CO2 fixation, decrease of transpiration, excess absorbed heat energy

Water Stress Salinity 2 Kinds

Osmotic or water deficit salinity stress (salt in soil reduced uptake of water) and salt specific or iron specific salinity stress (excess amounts of a specific salt enters transpiration stream)

Water Stress Salinity

salts do not build up in growing tissues at concentrations that inhibit growth, Rapidly elongating cells store incoming salt in expanding central vacuoles, salt taken doesn’t harm new leaves

Water Stress Salinity Symptoms

marginal leaf necrosis symptoms in older leaves, leaves may necrose and die, perennial plants can enter dormancy to survive stress

Solve Salinity Problem

Grow a more tolerant crop, Lots of research using soil amendments, Amending with Gypsum, Genetic engineering through plant breeding to make plants more adaptive

Plant Mechanisms of Salinity Tolerance

trait goals for plant biotechnology and plant breeding trait selection, Iorn exclusion from roots, compartmentalization withhin vacuoles, biochemical adaptations, activiating antioxidant systems to combat osidative stress, regulating hormone signiling pathways

Drought Adaptations-Negative Halotropism

plant grows away from soil/substrate areas with higher sodium, or hydrotropism- Plant cell elongation and root growth for water to find area with higher moisture

Water Stress Waterlogging

oxygen deprived conditions of the plant when water in the soil or substrate is present in excess amounts

Water Stress Water logging Symptoms

leaf wilting under wet soil or media, premature leaf abscission, decreased stomatal conductance, chlorosis due to chlorophyll loss, reduced growth, adventitious roots, increased susceptibility to disease and insect pests

Water Stress Water logging Symptoms depends on what?

depends on species, response depends on time and duration, size and length of roots, age and canopy, root cell loss more susceptibility to soil borne pathogen