Effects of different cutting stages on forage yield and chemical composition of sorghum (Sorghum bicolor L. Moench)

ABSTRACT EFFECTS OF DIFFERENT CUTTING STAGES ON FORAGE YIELD and CHEMICAL COMPOSITION OF SORGHUM (Sorghum bicolor L. Moench) Bilal AYDINO?LU Ph. D. in the Department of Field Crops Adviser: Prof. Dr. Sadık ÇAKMAKÇI July 2005, 123 pages This research was conducted in order to determine effects of different cutting stages on forage yield and chemical composition of sorghum (Sorghum bicolor L. Moench) at two location (at the experimental fields of Faculty of Agriculture, Akdeniz University-Campus and West Mediterranean Agricultural Research Institute-Aksu) for two years (2001-2002 sorghum growing seasons). The experiments were designed in a randomised complete block design with three replications. Sowings were carried out on 17 May for first year and on 22 May for second year at Campus location, and on 21 May for first year and on 1 1 June for 2002 at Aksu location. Plants were harvested at five different stages namely, panicle initiation, panicle emergence, milk, dough and full- maturity stage, respectively. Effects of different cutting times on plant height, forage yield, leaf, stem and panicle ratios, dry matter ratio, dry matter yield, crude protein ratio, crude protein yield, crude fibre, ether extracts, invert sugar, crude ash and certain mineral contents (P, K, Ca, Mg, Fe, Cu, Zn) were investigated. The collected data were evaluated by variance analysis and Duncan's multiple range tests. The research results showed that the highest plant height (222.1 cm) and the highest forage yield were obtained from dough stage (6988 kg/da), the highest dry matter ratio (32.31%) and yield (2210.0 kg/da) and crude protein yield (102.90 kg/da) were obtained from full-maturity stage. On the other hand, highest crude protein ratio was obtained from panicle initiation stage (8.32%). The highest invert sugar was obtained from milk stage (24.72%), also. The other traits investigated in this research were also affected significant statistically by cutting times. Consequently, dough stage was determined as a proper cutting time for sorghum in the terms of yield and quality in Antalya. KEYWORDS: Crude protein, dry matter, maturity stage, Mediterranean basin, minerals, Sorghum bicolor L. Moench COMITTEE: Prof. Dr. Sadık ÇAKMAKÇI (Adviser) Prof. Dr. Esvet AÇIKGÖZ Prof. Dr. Nihat ÖZEN Asst. Prof. Dr. Mehmet BİLGEN Asst. Prof. Dr. Mehmet KARACA ıı