. Cyclopedia of farm crops. Farm produce; Agriculture. 122 THE SHADING OF PLANTS because of greater humidity plants will always be more subject to fungous diseases. The relation of plants to fungous diseases is complex, and the general vigor of the plant is usually of more importance than any single environmental factor. (2) The evaporation of water from the soil is. Fig. 177. Cheese-cloth shelter for vegetables. unquestionably less under the covers used in shad- ing, and this has been experimentally demonstrated time and again. The extent of the benefit would necessarily be determined by the
. Cyclopedia of farm crops. Farm produce; Agriculture. 122 THE SHADING OF PLANTS because of greater humidity plants will always be more subject to fungous diseases. The relation of plants to fungous diseases is complex, and the general vigor of the plant is usually of more importance than any single environmental factor. (2) The evaporation of water from the soil is. Fig. 177. Cheese-cloth shelter for vegetables. unquestionably less under the covers used in shad- ing, and this has been experimentally demonstrated time and again. The extent of the benefit would necessarily be determined by the dryness of the season or the region. (3) Extremes of temperature are somewhat miti- gated by shading. Radiation from the soil is pre- vented to a considerable extent, and the light that does enter carries with it heat, much of which is absorbed. The minimum temperature under cover devices will always lag behind the minimum of the external air. Experiments in the North in early summer in moist seasons have shown a desirable in- crease in the temperature under cloth cover. Other experiments in .July and August, when the amount of sunshine is much greater, have shown a slightly lessened temperature under cover, yet a greater uni- formity. Repeated experiments in the South, how- ever, show that by shading a very desirable equali- zation of temperatures is effected. In the famous market-garden and floricultural region of France, east of Toulon, many crops are grown throughout the winter under the protection of half-shade. The temperature thus secured is sufficient for the main- tenance of growth in the semi-hardy ilowers and vegetables. (4) Shading devices are not wholly unimportant from a consideration of the wind relation. There is, in the first place, a lessening of the mechanical injuries, and, in the second place, the prevention of desiccation or excessive loss of water at times when the water content should be conserved. (5) Under cover the soil does not bake so readily and is
Size: 1784px × 1400px
Photo credit: © Central Historic Books / Alamy / Afripics
License: Licensed
Model Released: No
Keywords: ., bookcentury1900, bookdecade1920, booksubjectagriculture, bookyear
