Premature Drying of Plants

injury to plants caused by extreme dryness, as during drought or dry winds. In trees the sign of premature drying is the withering of leaves while they retain their green color, and in cereals the sign is usually undersized grain. Premature drying results from a disruption of the water balance, so that evaporation from a plant exceeds the amount of moisture it absorbs from the soil, causing dehydration of the cells. Sometimes the water balance is disrupted when the plant is overheated by hot air, resulting in the scorching of plants. Under natural conditions, premature drying and scorching usually occur simultaneously; thus, the terms are interchangeable. In cereals premature drying during the formation of the pollen and ovules adversely affects fertilization, resulting in lax or even empty ears. If premature drying of cereals occurs when grain begins to fill the ear (before milky ripeness), a grain is obtained that has almost a single husk and a small starch content. If drying occurs in later periods, the grain is wrinkled and undersized.

In the USSR, grain crops in the Ukraine, the Northern Caucasus, the Volga Region, the Central Chernozem Zone, and the arid regions of the Urals and of Kazakhstan periodically suffer from premature drying. To combat it various farming practices are used that ensure a good supply of water in the soil and better growth and development of the crops: deep plowing in the fall, snow retention, irrigation, the planting of cereals on clean fallows, and the planting of shelter-belts. The sowing of drought-resistant varieties is also very important.