Page:Report of the Puerto Rico Experiment Station (IA CAT31294391015).pdf/19

 cages is due to a true self-sterility, to a mechanical failure in pollination, or perhaps to some slight change in environment caused by the screens.

H. E. Warmke and Elida Vivas Studies on field-grown plants of regular guinea grass (Panicum maximum Jacq.) and four of its varieties, gramalote, coarse-leaf, fine-leaf, and Borinquen, indicate that a large majority of the seeds which fall early from an inflorescence are empty and valueless. Filled seeds are retained on the plants and are not shed in any quantity until the thirteenth day after the beginning of anthesis in an inflorescence. For these varieties, as a group, 59.4 percent of the total empty caryopses are shed by the twelfth day, while only 8.3 percent of the total full ones have shed by this time. The data obtained also indicate that the percentages of filled seed produced by this group of grasses is relatively high: Gramalote 56.37 percent, fine-leaf 50.71, coarse-leaf 30.50, guinea 28.60, and Borinquen 6.47 percent. This information is of considerable practical value in commercial harvesting of seeds of these grasses. Samples of seed furnished by two commercial producers on the island appeared very immature and have been found to contain less than 1 percent of filled seeds. The above data would suggest that this seed had been harvested during the shedding of the empty caryopses, and before the filled ones had time to mature.

During studies on techniques of emasculation, it was found that these same grasses show striking differences in time and rate of anthesis. The anthers and stigmas of fine-leaf guinea begin to emerge in the late afternoon, continue through a maximum at 6:30 p. m., and finish about 11:15 p. m. The varieties coarse-leaf, regular guinea, and gramalote come in this order, with maxima at 9:15 p. m., 12:45 a. m., and 2:30 a. m., respectively. The duration of anthesis in addition to the hour is also variable, requiring approximately 7½ hours for completion in the fine-leaf variety, and approximately 2½ hours in gramalote. These differences in anthesis, although affected to some degree by temperature and perhaps other environmental factors, are surprisingly constant, and it is believed they represent true differences in physiological reaction patterns among these grasses.

E. A. Telford, R. M. Smith, and C. F. Cernuda

All essential details were carried out for the establishment of about 10 acres of improved kudzu-grass pasture to be used in pasture management studíos. Most of the procedures necessary for successful pasture-management studies were devised and put to a practical test. During the rainy season the pastures carried one animal unit or more per acre without any cut forage. Pastures without lime and fertilizer were inferior to the LP- and LPK-treated pastures, but no benefit was shown for K. Total dry forage produced per day from August to January ranged from 42 to 75 pounds on the treated pastures, according to repeated square-yard harvests. The percentage of protein in the concentrate was reduced from 20 percent to 15 percent with no influence on milk production trends.