wind stress & its management

Outlines

What is wind?Impacts of wind on crop production (beneficial and harmful impacts)Management of wind stress

• Wind is a current of air, especial ly a natural one that moves along or parallel to the ground, moving from an area of high pressure to an area of low pressure.

• Wind is basical ly measured by anemometer.

What is wind?

Impacts of Wind on Crop Production

Wind affects crops in several ways. At lower velocity, it has its soothing and beneficial effect and at higher velocity, it has its harmful and destructive effects. 

In general, plant growth appears to be inhibited by wind speed more than 10 km per hour.

Wind causes maximum damage in association with rain at the time of flowering.

Wind direction and velocity have significant influence on crop growth.

Wind influences crop production in two ways:

1. Physiological impact 2. Mechanical impact

Physiological impact

Increases transpiration especially cuticular transpiration than stomatal transpiration. 

Hot wind accelerates the drying of the plants by replacing humid air by dry air in the inter cellular spaces. For example, rice crop during June-July months shows tip drying.

Wind increases turbulence in the atmosphere and availability of CO2 and thereby increased photosynthesis.

Beyond a certain wind speed the rate of photosynthesis becomes constant.

Mechanical impact on plants

Strong wind damages the shoots.Lodging (Paddy, Sugarcane, Banana etc.,)Flower and fruit shedding.Crops and trees with shallow roots are

uprooted. Cold wind causes chilling injuries.Causes soil erosion. Soil deposition causes poor aeration in root

zone.

Lodging due to strong wind

Uprooted tree due to strong wind

Beneficial impacts of wind

Generally the beneficial impacts of wind are:Wind increases the turbulence in atmosphere, thus

increasing the supply of carbon dioxide to the plants resulting in greater photosynthesis rates.

Strong winds develop xerophytic characters and increases root to shoot ratio.

Calm to moderate wind favor dew deposition needed under condition of soil moisture stress.

Moderate wind aids in effective pollination.A minimum wind speed of 15 km per hour is

needed for winnowing operations.

Harmful impacts of wind

Blowing soil can reduce seedling survival and growth, depress crop yields, and increase the susceptibility of plants to certain types of stress, including diseases.

Wind alters the balance of hormones.Exposure of growing plants to hot wind results in dwarfing due

to desiccation of plant tissue and reduced growth.Wind increases crop water requirements by increasing

evapotranspiration due to removal of accumulated humid air near the leaves.

Heavy wind during flowering reduces pollination, causes flower shed, increases sterility and reduces fruit set in all crops.

Wind speed more than 50 km per hour leads to lodging of crops leading to heavy loss.

Harmful impacts of wind

Soil and sand particles blown by wind strike the leaves and other plant parts making punctures, abrasions, lesions and tear the leaves in to pieces and strips. It will be well marked in maize, sugarcane and banana during summer.

Long exposure to strong winds causes morphological changes.

Wind increases the ethylene production in barley and rice.

Wind decreases gibberillic acid content of roots and shoots in rice.

Management of wind stress

Many practices can be used to reduce wind stress, some of them are given below:

1. Reduce wind velocity at the soil surface: This is done with help of:

Windbreaks crop residues cover crops surface roughness strip cropping 

Management of wind stress

2. Trap soil particlesThis is accomplished by maintaining: Crop residues on the soil surface By ridging or roughening the soil surface By mulching Deep rooted crops

Management of wind stress

3. Increase size of soil aggregates: This is done by:

• Using crop rotations that include grasses and legumes.• By growing high-residue crops and returning crop residues to the soil.• By applying manure.• By using emergency tillage, which can create stable clods on the soil surface.

Management of wind stress

4. Increasing soil cohesion:

Applications of organic matter in the surface horizons improve soil structure and increase the cohesion force among soil particles.

Management of wind stress

5. Ridges:• Ridging the soil surface can also be an effective

practice.• Ridges absorb and deflect wind energy and trap

moving soil particles.• Ridges with an ideal height to spacing ratio of 1:4

are most effective when constructed at right angles to the prevailing erosive wind.

• Ridges 4 inches high spaced 16 inches apart will provide optimum protection if oriented correctly.

• The effectiveness and persistence of ridging can be greatly affected by texture of the soil

Management of wind stress

6. Windbreaks Refers to growing trees and tall crops across the

direction of prevailing wind to reduce the physiological and mechanical damage to crops.

Management of wind stress

What windbreaks do?• Windbreaks reduce wind stress on crops and improve

crop microclimate and yield.• Wind can physically damage plants through abrasion

and leaf tearing, which can hinder plant growth.• By reducing wind speed, windbreaks can reduce this

damage to downwind crops.• Reduced wind speed in the lee of a windbreak can

also increase humidity as well as air and soil temperatures for crops.

• Studies have indicated that these favorable growing conditions were, on average, associated with a 6-44% increase in crop yield (Brandle et al., 2004).

Management of wind stress

Wind breakers

Management of wind stress

Other practices include:Use of varities or cultivars that are resistant to wind

stress and lodging.Do not irrigate field when fast wind is expected.Use recommended seed rate to avoid over population of

crop plants in the field.Proper plant to plant and row to row distance should be

maintained.Use of varities that have efficient and strong root system

that can stand against wind. (high root : shoot ratio).Adjusting the direction of planting. Providing support to the tall plants (eg) Banana.

Providing support to the tall crops (eg) Banana

Management of wind stress

Management of wind stress

References:1. Biddington NL. The effects of mechanically-induced stress

in plants—a review. Plant Growth Regul.1986;4:103–123.2. Cleugh HA, Miller JM, Bohm M. Direct mechanical effects of wind on crops. Agroforest Syst.1998;41:85–112.3. Bang C, Sabo JL, Faeth SH. Reduced wind speed improves plant growth in a desert city. PLoS ONE.2010;5:11061. [PMC free article] [PubMed]4. Telewski FW. A unified hypothesis of mechanoperception in plants. Am J Bot. 2006;93:1466–1476.[PubMed]5.  Grace J. Plant responses to wind. New York: Academic Press; 1977.