Cutting and environmental effects on growth and regrowth of a sorghum-sudangrass hybrid, cultivar sudax sx-11

Summer annual forages are an important part of the forage program of beef and dairy farmers in Tennessee. In 1966, approximately 140,000 acres of sudangrasses, pearlmillets, and sorghum-sudangrass hybrids in pure stand were grown in Tennessee. This was an increase of 100 per cent from 1961 when only 70,000 acres of the crops were grown. When used as a supplemental forage, the sorghum-sudangrass hybrids help maintain a high level of production during the summer months when unfavorable climatic conditions often bring about a decrease in production and quality of perennial forage. Although sorghum-sudangrass hybrids are accepted and widely used by farmers, very little is known about their growth and regrowth after harvesting. In order to maximize yields and profits the farmer must know when to harvest a crop for the most suitable combination of yield and quality. The expected amount and the rate of dry matter production after one or more harvests is of vital importance. An experiment was conducted to determine the effects of environment and cutting management on the growth rates and regrowth rates after harvest of a sorghum-sudangrass hybrid. Dry matter production curves were constructed for different combinations of planting date and number of harvest. An attempt was made to relate the dry matter production to plant morphological characteristics such as stem leaf ratio and height of apical meristem, as well as several environmental factors. Statistics and graphical techniques were used to illustrate the relationships.