Q.Briefly describe factors affecting rate of Transpiration.

Anti-transpirants reduce a plant's water loss by lowering the rate of transpiration, and this is put to practical use to conserve water and to keep newly transplanted or cut plant material from wilting.

Anti-transpirants are chemical substances applied to plant foliage (or roots) that reduce the rate of water loss through transpiration, typically by causing stomata to close partially, by forming a thin film over the leaf surface that reduces evaporation, or by reflecting light and reducing leaf temperature.

Their main practical uses include:

1. Conserving water — reducing overall water loss from the plant helps it cope with water scarcity, drought, or hot/dry conditions, improving the plant's chances of survival with limited water supply. …

Transpiration (loss of water vapour, mainly through stomata) is influenced by both environmental conditions and plant-related factors.

Factors affecting the rate of transpiration:

Environmental (external) factors:

• Light: Increases stomatal opening (stomata open in light for photosynthesis), so transpiration is higher in light than in darkness.
• Temperature: Higher temperature increases the rate of evaporation of water from the leaf surface and cell walls, increasing transpiration.
• Humidity: Higher atmospheric humidity reduces the water-vapour concentration gradient between the leaf's intercellular spaces and the outside air, decreasing transpiration; low humidity increases it.
• Wind speed: Moderate wind removes the humid air layer around the leaf surface, increasing transpiration; very high wind speed may cause stomatal closure and reduce it.
• Availability of soil water: Adequate soil moisture keeps cells turgid and stomata open, favouring transpiration; water stress causes stomatal closure and reduces it. …