Effect Of Sowing Date, Phosphorus Level And Cutting Stage On Yield And Chemical Composition Of Centrosema Pubescens
The effect of four sowing dates (June 21, July 5, July 19 and August 2), three phosphorus levels (0, 30 and 60kgP2Os/ha and four stages of maturity (10, 12, 14 and 16 weeks post planting, WPP) on forage and seed production of centro were studied in two trials between 1991 rainy and 1992 dry seasons at Shika in the Northern Guinea Savanna Zone of Nigeria. In trial 1, the total dry matter (DM) yield declined between June 21 and August 2 from 2.3 to 1.2 TDM/ha, while for early and delayed cuts the range was 1.04 to 2.66 TDM/ha. Phosphorus application (0 to 60kgP2O5/ha) resulted in mean DM yields of 1.5 to 2.7 TDM/ha, respectively. Mean leaf content was highest(57%) for sowing between June 21 and July 5. Similarly, mean leaf content was respectively highest (63% and 55%) for cutting at 10WPP and the application of 60kgP2O5/ha. The N contents were best with July 5 sowing, when cut at 10 WPP at 60kgP2O5/ha. Sowing of Centro on August 2 resulted in the highest Ca content, while cutting 12 WPP resulted in the highest Ca content. Phosphorus content was not affected (P>0.05) by sowing date but was influenced by stage of growth and phosphorus application. The Ca: P ratio of the forage was affected by sowing date and cutting stage but was not influenced (P>0.05) by phosphorus application. The results indicate that for better yield the optimum stage of cutting would lie between the 14th and 16th week following planting. In trial 2, the variation in seeds per pod for plantings between June 21 to August 2 was from 16.5 to 14.5, while for unfertilized and fertilized plots seed number varied between 12.6 and 16.2/pod. The weight of 1000 seeds decreased with delayed planting. Phosphorus application improved seed weight. Seed yield was highest (lOOOkg/ha) for July 5 sowing with phosphorus application of 60kgP2Os/ha combination. The variation in mean seed yield for planting between June 21 and August 2 was 782.0 to 360.3 kg/ha. The application of 0 to 60kgP2O6/ha resulted in mean seed yields of 405.7 to 776.8kg/ha. The data suggest that early plantings (June 21st and July 5th) in combination with phosphorus fertilizer application (30 and 60kgP2O5/ha) will suffice for satisfactory heavier seeds and seed production per unit area.