Stress Physiology - Physiology of Stress - Stress and Your Body - Temperature Stress

Plant Physiologists have long been interested in knowing the environmental limits for the growth of plants. Plant responses to environmental extremes such as deficiency of water, mineral salts, high and low temperature and atmospheric pollutants have been extensively worked out.

Water is scarce commodity. Agricultural production of an area is seriously limited by the availability of water for irrigation. Unfortunately, plants absorb large quantities of water and nearly 98% of it is lost by transpiration. Therefore, it is a challenging task for plant physiologists to work out whether it is possible to cut down the unnecessary loss so that crops can be raised with limited availability of water.

The work on stomatal physiology to reduce water loss by spraying antitranspirants has given encouraging response. The main thrust in agriculture of this country is on dry farming. While some crops fare well, others cannot do so under limited availabity of water.

Adequate facility for canal irrigation has lead to rapid rise in water table posing severe threat to soil productivity. The problem is accentuated because the rising water is also saline in many places. Some plants like rice can grow in standing water while vegetables pulses and others are adversely affected even by a few hour of water logging.

Metabolic adaptations to resists water logging have been unrivalled and critical stages of plant growth when drought or water logging would be most harmful have been determined. Basing on this information proper irrigation schedule for various crops has been worked out.

Although minerals are essential for plants, their excess quantity in the soil is injurious. Large areas of land Indo-Gangetic plain are fast becoming saline owing to irrigation with brakish underground water. Better understanding of membrane permeability and physical structure of protoplasm has helped in understanding the mechanism of damage due to high salt in the soil. Varieties of crops which can be cultivated in the saline soil have been identified.