334 Plant Physiology 



ing involves production under abnormal, or what may be 

 termed intensified, conditions, that is, under conditions 

 stimulating rapid growth, then factors may enter in 

 which require special attention from the standpoint of 

 growth-stimulation. High temperature, increased mois- 

 ture, and an abundant food-supply are the factors com- 

 monly involved in forcing. Under such conditions there is, 

 of course, up to a certain maximum, a stimulation of vege- 

 tation. High succulence and brittleness are characteris- 

 tics of forced crops. 



For the production of salad crops, radishes, etc., forcing 

 may be continuous, while in other cases, forcing condi- 

 tions are employed to start resting plants or roots into 

 rapid and vigorous growth for early market, as in the case 

 of roots of rhubarb and asparagus brought in from the 

 open. Large roots of rhubarb grown in the open for three 

 of four years may be lifted in the late winter or early 

 spring, reset in loose soil in a special cellar, hot bed, or 

 greenhouse, and then forced into rapid leaf -stalk produc- 

 tion. Forcing may also be employed for bulbs, tubers, 

 and seed in the seed bed. The practice in general requires 

 special care with ventilation ; it often demands subirriga- 

 tion, and it repays a constant watchfulness with respect 

 to sanitary surroundings. Otherwise, the conditions may 

 greatly encourage the growth and spread of fungous 

 diseases and the development of other pathological dis- 

 turbances. 



A special phase of forcing has become important in 

 recent times. This consists in awakening activity in 

 dormant plants or organs by means of warm water or 

 anaesthetics. 



