Study of Capacity for Multiple Cuts, Productive Abilities and Changes in Forage Chemical Composition in Sudan Grass (Sorghum sudanensis P.)

摘要

During the last years, the work on sorghum and Sudan grass takes an important share in the research activity in our country, as well as in the world.The main objective of this study was to determine the capacity for multiple cuts, productivity and changes in forage chemical composition of Sudan grass Sorghum sudanensis P., Targovishte variety. The trials were carried out during the period 2002-2004. A sowing rate of 50 germinable seeds / m2 at 15 cm. interrow spacing and a fertilizing rate of P6N12were used. The harvesting for green mass was made in three cuts at the phenological stage of heading. The meteorological facts during the period of study provided a possibility for Sudan grass growth and development under different environment-limitingconditions, which made the study exceptionally valuable. It was found that when harvesting Sudan grass at the phenological stage of heading three cuts could be harvested in a calendar year, under which the dry mass yield reached to 3539 kg/da. The secondcut was the most high-productive and formed 40.4 % of the total yield followed by the third cut with 33.1% participation and the first cut with the smallest share - 26.5 %.The second cut had the highest values of plant height 183 .Ocm, stem number perm2 128.0 and tillering coefficient 2.55. The most favorable ratio of yield structural elements stems: leaves: heads was recorded in the third cut. The percentage content of crude protein and calcium was the highest in the leaves, respectively from14.61 to 19.16%and from 0.507 to0.725%and that of crude fibre and phosphorus in the heads. The chemical composition of Sudan grass had the highest values in the first cut and these values progressively decreased in the second and third cuts.