Influence of cow manure and row spacing on growth, flowering and seed yield of Centro (Centrosema pubescens Benth.) on ferralitic soils of Benin (West Africa)

Centrosema pubescens (Benth) is identified as a tropical forage legume of considerable promise which can improve pasture in West Africa. A study on the influence of rates of cattle manure in combination with plant row spacing on the growth, phenology and seed yield of Centro (Centrosema pubescens) was conducted at the Teaching and Research Farm of the Faculty of Agronomy Science of University of Abomey-Calavi in South Benin. The site is located at latitude 6° 30’ N and longitude 2° 40’ E with elevation of 50 m above sea level. The area is characterized by ferralitic soils with low fertility, rainfall range of 1200 mm with relative humidity from 40 to 95 % and means annual temperature varying between 25 and 26 °C. Field experiments were conducted during 2014, 2015 and 2016 seasons. Five cattle manure rates (0, 4 tons, 8 tons, 12 tons and 16 tons/ha) and 40 kg P2O5/ha in combination with three plant spacings (40cm x 40cm, 80cm x 80cm, 120cm x 120cm) were evaluated in a 6×3 factorial laid out in Randomized Complete Block Design (RCBD). Each treatment was replicated 4 times. The growth and flowering characteristics measured in the field included number of branches 90 days after sowing, number of leaves 90 days after sowing, plant girth 90 days after sowing, flower initiation, date of first flower appearance, date of 50% flowering, pod ripping time and efficiency of flower for pod production. Seed components evaluated are pod length, pod wide, number of seed/pod, 100 seed-weight and seed weight/pod weight ratio. Seed yield were evaluated each year by harvesting pods from 4 randomly plants per plot. Pods were shelled and seed collected were weighed for seed yield calculation. Analysis of variance (ANOVA) was used to determine degree of variability at 5% probability level. Result obtained from data analysis showed that there was a significant influence of cropping season, row spacing, fertilizer and their three way interaction on seed production. Apart from the control treatment, seed yield was significantly higher in the second and third years (187.3 and 189.0 kg/ha, respectively) than the first (153.8 kg/ha). Influence of row spacing was observed on seed yield and plants established and 80 cm × 80 cm gave significantly more seed per ha (204.5 kg/ha) followed by 120 cm × 120 cm (179.0 kg/ha) and 40 cm × 40 cm (146.6 kg/ha). Seed yield was significantly increased due to application of cattle manure and application of 12 tons cattle manure yielded better than others. Neither row spacing nor fertilizer had significant effect on plant phenology. In contrast, efficiency of flower for seed production was influenced by fertilizer and cropping season. According to these results, it can be concluded that row spacing of 80 cm × 80 cm and 12 tons per ha cattle manure can be recommended to farmers for C. pubescens seed production in the region.