EFFECT ON PLANTS

ZOHAIB UL HASSAN

email: zuhaib1144@gmail.com

PLANT PATHOLOGY

University College of Agriculture ,

University of Sargodha,

Pakistan.

Water is an important requirement for growthand survival of plants.

The plant's physiology and biochemistry areaffected .

Both water deficiency and excess can causeinjury to plants.

. Sometimes the injury is short-lived (acute;several hours) or long-lived (chronic; days orweeks).

Diagnosis of water status problems can bedifficult.

Symptoms confused with injury from salts orherbicide etc.

Certain infectious diseases such as root-rot(e.g., Phytophthora spp.) and vascular wilt (e.g.,Ophiostoma ulmi) also cause similar symptomssuch as wilting.

A soil test might be necessary .

If soil appears to be excessively wet, isdiscolored, or smells strongly of rotten eggs,water drainage in the area should beaddressed.

Plant samples should be collected and sent toa reputable diagnostic lab for analysis.

occur either as a short-term or chronicdeficiency.

SHORT- TERM:

A short-term deficit of water might result inonly minor effects on the plant such as wiltedleaves or shoots .

These symptoms may be temporary andoccur during the warmest part of the daywhen transpiration rates are highest.

Once the environmental stresses are relievedthe symptoms of low water status maydisappear.

CHRONIC PERIOD:

During chronic periods of water deficit, theinjury sustained by plants may be moresevere.

Plants may grow more slowly or not at all.

young leaves may not fully expand.

foliage may not appear as colorful relative tofoliage.

In severe cases "scorching" or marginal leafnecrosis can occur on deciduous trees.

needle necrosis can occur on conifers.

During winter months when rain or snowfallmight be scarce, plant roots may not be ableto absorb water.

The result is winter desiccation, in which thefoliage might appear off-color, "scorched", ornecrotic .

Excessive soil moisture can result in reducedoxygen availability to roots.

primary symptom of flooding is plant wilt.

excess soil moisture can manifest as acute orchronic.

roots are subjected to low oxygen status andcell weakening and/or death occurs.

Symptoms include discolored and/or water-soaked and mushy roots.

Way of entry for different pathogens likePhytophthora spp. , anaerobic and low-oxygen conditions can be detrimental tonematode populations.

plants appear stunted and haveunderdeveloped shoots.

In severe cases bleeding cankers on stemscan occur.

Adventitious roots may form at the rootcrown.

Edema or corky, blister-like swelling canoccur on the underside of leaves on plantsgrowing in waterlogged soils.

. Edema can be worse during cloudy, overcastperiods.

In areas where waterlogged soils prevail forlong periods of time, an odor of rotten eggsmay be noticeable, due to sulfur gasproduction in the anaerobic soil.

How can plant water stress be managed?

Crop selection

plant groups and how they behave undermoisture stress can be used to guidedecisions about crop selection for droughtand saline conditions.

Determinate crops

Indeterminate crops

Forages

Table. Crop selection for water stress management.

Crop type Water stress limitations Management tips

Determintate cropsResistant to water stress

during vegetative stages.

Avoid water stress during reproductive

stages.

Indeterminate cropsNo specific critical

periods.

Sugarbeets are more stress tolerant than

potatoes, carrots, and onions.

Forages

Perennial forages are least affected by

moisture stress in the long run.

Concentrate irrigation efforts early in the

season to maximize production.

How can the consequences of plant waterstress be minimized?

Wtaer stress timing

Crop selection

Water stress timing

1st choice - Early in the crop growth cycle

2nd choice - Close to harvest

Crop selection choices

1st choice - Perennial forages

2nd choice - Annual forages

3rd choice - Short season indeterminate crops

4th choice - Short season determinate crops

5th choice - Long season determinate crops