The influence of seed rate and fertilizer type on growth of Tridax procumbens in subhumid Nigeria

Forage production of Tridax procumbens was examined from three seed rates (20, 40 and 60 kg/ha), four types of fertilizer [(unfertilized control, single superphosphate (SSP, 18 /P), NPK (20:10:10), and calcium ammonium nitrate (CAN, 25 /N)] and four harvest stages (6, 9, 12 and 15 weeks post sowing, WPS). Fertilizer rates used were 20 kg/ha P for (SSP) and 50 kg/ha N for each of NPK and CAN. Plant height (cm), density (plants/square meter) and spread (cm) were measured at 3, 6, 9, 12 and 15 WPS. Sampling for yield estimation in each plot was done at 6, 9, 12 and 15 WPS. Mean plant height with respect to seed rate, fertilizer type and growth stage significantly (P 0.05) varied from 18.5 to 23.5 cm, 12.1 to 22.5 cm and 8.6 to 18.2 cm respectively. Plant density increased significantly (P 0.05) with increase in seed rate from 46.0 plants/ square meter for seeds sown at a rate of 20 kg/ha to 64.0 plants/square meter for 60 kg/ha seed rate. Fertilizer type significantly favoured plant density, with NPK giving higher density than did SSP, CAN or the control. Plant spread was significantly (P 0.05) lowest 3 WPS, increased gradually with increase in the growth of T. procumbens until a maximum density (48 plants/square meter) was reached 12 WPS. Leaf and stem DM yields were significantly (P 0.05) affected by seed rates, types of fertilizer and harvest stages. Mean total (whole) plant DM yield increased with increase in seed rate with only seeds sown at 60 kg/ha recording more than 2000 kg DM/ha. Application of SSP, NPK and CAN gave more total DM yields than the unfertilized control plot respectively by about 69, 75 and 75 /. Total DM yield varied from 1024 kg DM/ha when T. procumbens was harvested at an earlier stage (6 WPS) to 2130 kg DM/ha at a later harvest (12 WPS). The main CP of leaf was significantly (P 0.05) affected by all the treatments imposed.