M. KARACHI and Z. MATATA

Tumbi Agricultural Research and Training Institute, Tabora, Tanzania

Abstract

Effect of age of cutting on the production and forage nutritive value of 9 Sesbania sesban and 5 S. macrantha accessions was evaluated over 4 growing seasons. The sesbanias were established annually and harvested at 4, 5, 6, 7 and 8 months of growth to estimate forage yield. Wood yield and plant mortality were estimated at the 8-month harvest. The forage yields varied from 0.1–3.8 t/ha with the highest recorded from the 4- and 5-month harvests. Plant maturity resulted in leaf fall but also an increase in the contribution of pods to total edible forage. Wood production varied from 1.4–6.4 t/ha. The local S. sesban accession T1 was best overall in biomass production. The lowest plant mortality rate (range 0–35%) was recorded for S. macrantha Accessions 017 and SR22 that maintained less than 10% death rate throughout. Major differences were also recorded in the concentrations of N (2.64–3.24%), P (0.18–0.27%), K (1.23–1.83%), Ca (0.71–1.54%) and Mg (0.20–0.33%) between the accessions. Age of cutting had no effects on P (0.20–0.24%), K (1.37–1.47%) and Ca (1.14–1.18%) levels but N (3.42–2.58%) concentration decreased and Mg (0.21–0.28%) concentration increased with forage maturity. It was concluded that moisture stress limited the potential of sesbania as a source of forage in the dry season and that plant mortality limited its use as a long-term source of fodder.